Score:5, Offtopic

very interesting, unfortunately my english is very poor and i cannot write as well as i wish (only can read), but i like very much your idea. Regards from Europe (Spain), bye

Anonymous writes:

Eric,

Interested to see your posting on the Lohmann compression ignition moped engine.

There is a Dutch appropriate technology company, Practica Foundation, that is developing an 18cc microdiesel engine for pumping and generating applications in the developing countries.

http://practicafoundation.nl/technologies/microdiesel.html

Based on the Lohmann design it produces approximately 450 W (0.6hp) and runs on diesel and straight vegetable oil.

I agree that your idea for an open source "diesel engine" that runs on vegetable oil is a good one, and I would be keen to encourage further discussion.

I run an alternative technology group "Wastewatts" on yahoogroups and a friend of mine runs veg_oil_engines also on yahoogroups.

http://groups.yahoo.com/group/wastewatts/

http://groups.yahoo.com/group/Veg_Oil_Engines/

and perhaps you have seen this article about running a Lohmann moped

http://www.users.globalnet.co.uk/~pattle/nacc/arc0413.htm

It should be noted however that the microdiesel engine is only about 10% thermodynamically efficient (because of small size and two-stroke cycle), and more work is really necessary tomake it as good as larger diesel engines, to improve the specific fuel consumption - currently 300 to 400gr per hp/hr.


regards,


Ken Boak

London

Ken writes:


I love patent searches!!!

Here is the original patent for the Lohmann engine, filed in 1949 by Herman Teegen, complete with drawings

US Pat. No. 2583499

http://www.freepatentsonline.com/2583499.pdf


Enjoy,


Ken

James writes:

I agree and have been searching for a diesel moped or small motorcycle for some time to add to my set of diesel autos ( Vixen, IH Scout II, Mercedes 300D, Mercedes E320 D, and BMW 524TD). I did see a recent add fro a 50cc diesel scooter but when I called them it was GAS.

Ian writes:

I think it's only a matter of time before diesels become widely accepted in motorcycle applications. I suspect that an 18cc Lohmann diesel would be too feeble to propel any kind of vehicle. However, there are cheap Chinese diesels in the 5 - 6 HP range that would comfortably propel a light bike.

Angus writes:

I've come across this discussion googling to find a diesel motor scooter that I could run on biodiesel. I've come up with nothing.

Great project.

Ian, can you provide any more info to assist in locating supplier of these "cheap chinese diesels" that may be suitable for shoehorning onto a moped or bicycle.

I have found an enormous quantity of information on diesel motorbikes available - for example http://www.dieselbike.net/ Eric mentions the economy of diesel motorbikes in his original posting - has anyone searched for available smaller cc diesel motorbikes to see if a suitable motor is available as a starting point?

thanks,
Angus

Mike writes:

If somebody is looking for a small (50cc) engine why not look at engines installed in generators? I have a feeling that some may be diesels. So far nobody has found the answers to the diesel problems that they are heavier and more expensive than the equivalent gasoline engine. With such a small engine size it would be difficult to find a suitable injection unit which may be necessary for reliable running; witness the weird fuel mixtures needed to start a Lohmann.
We are now five years into a new century so I think we should be thinking of hydrogen power. An English company has made a really swish hydrogen motorbike. The Chinese have some really good electric bikes and scooters but as with everything electric they are hampered by short range. A small hydrogen powered generator running at constant speed to keep the battery charged would be an ideal answer to modern city travel.

peekay writes:

i would like to 'in'

great idea .. open source .. helps all

any progress on a modified lohmann design ?
with all the high tech materials now available
this could be a good design .. tiny, small,
pollution free (petrol emits too much CO, SO2,
NOx, PbO .. all of which cannot be seen but
destroy red blood cells)

the best parts i like are :

1. there is no pump, injector, nozzle, complication

2. the compression is variable


to all those who see this page .. just tell me another engine
which has these featurs together ! (maybe there will be some
which have either one or the other of these features)

..peekay

wtgee writes:

Hey all,

Just found this post while looking for information on converting my scooter to biodiesel. I am driving a TNG Milano 150CC and wouldn't be afraid to try something on my scooter but am pretty inexperienced. I am glad the post is new and it looks like interest in biodiesel is increasing.

Thanks for all the links and keep posting about the open-source idea. Is the idea that you will have instructions or examples on how to convert? What is the scope of the project?

Thanks,
wtgee

Anonymous writes:

Hi Eric:

Your idea off open source forum is a terrific one. In fact, I came across your blog when searching for a small diesel engine. I hope that this idea of small diesel - bio-diesel would be the natural extension - powered two wheelers take off. Thanks to all for great links. It was an interesting read. It appears that smaller engines are hard to find. I will let you all know if I find anything.

Regards,
simpleman

Plant Oils writes:

Open Source Diesel Moped? Good idea...

Come to think of it, why don't we have an open source biofuel movement? There are all sorts of feedstock being tried for biodiesel ( apart from the well-known soy & rapeseed & palm, we today have biodiesel from algae ( see http://www.oilgae.com ), biodiesel from castor oil ( see http://www.castoroil.in/uses/fuel/castor_oil_fuel.html ) etc...)...in terms of the biodiesel production process, there are still some obstacles to be overcome to make the biodiesel more economical and affordable...so my question is why not open source biofuels, or even better still, open source alternative energy, where the world's finest minds put their brains to work to figure out the best way to produce energy for the future??

I hope I am not building castles in the air...

PO @ Plant Oils Database - http://www.plantoils.in

GenWaylaid writes:

Aprilia spent a lot of time and effort developing a direct-injection two stroke motor they called the DiTech, and they sold them in scooters for a few years. If you wanted to build a more modern type of diesel moped engine I suspect this would be a good starting point. It was available mainly (perhaps only) in a 49cc displacement and it has a fuel injector much like today's common-rail diesels. Plus, two stroke gas engines tend to develop much higher compression than four strokes, so it would be closer to what is required for diesel.
To make the change to diesel you'd probably have to tweak the injection pressure, timing, and compression (via a modified cylinder head). It's still a lot less heavy-duty engineering than reconstructing an older engine design from plans. I'd suggest approaching a shop that restores old two stroke Vespas for help with the machining side of things. I know of one that has experimented with biodiesel in the past: http://www.ptownscooters.com/ (look under the "projects" link)

Anonymous writes:

As a youngster, some 35 years ago, I bought a tiny model airplane, 2 stroke, less than one cu.inch, started with a battery fed glow plug, run on alcohol/castor oil mix. Lotta smoke, though.

Then, there were tiny 2 stroke diesels, with a screw-on cylinder head, to vary the compression ratio.
They could be a starting point to experiment.

Anonymous writes:

In a "carbureted" diesel such as the Practica, compression ratio is adjusted to get proper ignition timing. This is the same way it's done in model aircraft diesels. Model diesels however use ether in the fuel to help with ignition and reduce the required compression ratio to allow light engines. I'm working on trying to get model engines to run without the ether, which is hard to get and fairly expensive.

Variable compression allows adjusting the engine to the fuel and load quite easily and cost effectively (compared to an injection system). It doesn't necessarily result in an efficient engine though. I believe that there are also issues with how fuel is actually burned due to the poor vaporization of diesel fuel.

I'll be watching here.

Greg

Anonymous writes:

Now I remember when I was selling some small hydraulic power packs (they could have been small gen-sets for the sake of this discussion) back in the early nineteen eighties, and they had choices of engines, including a couple of diesels. These were all small, one cylinder egines, and were all four stroke. The diesels we offered were an italian made Lombardini and a Robin-Subaru.
What I recall from demonstrating the power pack with a diesel engine, is that it was a lot of fun (to me anyway) to crank the engine while holding a valve open, which reduced cylinder compression to facilitate cranking and starting.

Now, let's take A LOOK AT two current, four stroke "small diesels" (and I think we have to go four stroke FOR BEST COMBUSTION/LOWEST EMISSIONS, HIGHEST POSSIBLE MILEAGE besides the high torque at low rpm WHEN IS REALLY NEEDED, SUCH AS UPHILL), and compare them to gas engines:



HATZ DIESEL 4.6 HP has a bore x stroke of 69 mm x 62 mm with a displacement of 14.15 Cu In., with a compression ratio of 20:1, a Max. Torque of 12.5 ft-lb @ 2300 rpm, dry weight: 62 lbs.

http://www.lombardinigroup.it/common/binary_reader.php?id_file=169&idtbl=2

LOMBARDINI DIESEL 6 HP has a bore and stroke of 82 mm x 66 mm with a displacement of 21 Cu In. with a compression ratio of 20.3:1, a max. torque of 9 ft-lb @ 2200 rpm, dry weight: 73 lbs.

http://www.northerntool.com/images/product/images/6059_lg.jpg

HONDA GAS ENINE MODEL GX-160, 5.5 HP has a bore and stroke of 68 mm x 45 mm. with a displacement of 9.9 Cu In., a compression ratio of 8.7:1, a Max. Torque of 7.9 ft.-lbs. at 2900 RPM, and a dry weight of 34 lbs.


http://www.robinamerica.com/engines/photos/large/EH025_lrg.jpg

SUBARU-ROBIN GAS ENGINE MODEL EHO25 Micro, 1.1 HP @ 7000 rpm has a bore and stroke of 34 mm x 27 mm, a displacement of 1.5 Cu In., a compression ratio of 8.7:1), a Max. Torque of 0.87 ft.-lbs. at 5000 RPM, and a dry weight of 6 lbs.


SUBARU-ROBIN GAS ENGINE MODEL EHO35 Micro, 1.6 HP @ 7000 rpm has a bore and stroke of 39 mm x 28 mm, a displacement of 2 Cu In., a compression ratio of 8.6:1, a Max. Torque of 1.30 ft.-lbs. at 5500 RPM, and a dry weight of 8 lbs.

http://www.honda-engines.com/modelslarge/GX25.jpg

HONDA GAS ENGINE MODEL GX-25, 1.1 HP has a bore and stroke of 35 mm x 26 mm. with a displacement of 1.5 Cu In., a compression ratio of (8.7:1), a Max. Torque of 0.8 ft.-lbs. at 5000 RPM, and a dry weight of 6 lbs.


http://www.honda-engines.com/modelslarge/GX35.jpg

HONDA GAS ENGINE MODEL GX-35, 1.6 HP has a bore and stroke of 39 mm x 30 mm. with a displacement of 2.2 Cu In., a compression ratio of (8.6:1), a Max. Torque of 1.37 ft.-lbs. at 5000 RPM, and a dry weight of 7.3 lbs.

To get an idea of current retail prices for some of these engines, go to: (no commercial endorsements implied)

Diesels : http://www.northerntool.com/webapp/wcs/stores/servlet/CatDsp?storeId=6970&N=76+85&Ne=2
Gas : http://www.northerntool.com/webapp/wcs/stores/servlet/CatDsp?storeId=6970&N=76+2000008&Ne=2000002

Comments:

- As can be seen above, micro four strokes gas engines, perfectly suited for motorizing bikes are already available, and these units are the ones already reporting mileages in excess of 70 mpg (30 kpl)

- Based on the engine data provided above, I estimate that a scaled down version of any of the currently available smallest four stroke diesel engines, could result in a four stroke micro diesel, under 3 Cu. In. (50 cc), complete with injection pump, pressurized oil lub, OHC, low noise level, dry weight under 10-12 lbs, meeting EU, CARB regulations with a retail price under $500 (further reduced with volume sales), and yielding upwards of 200 mpg (85 kpl). Such four stroke micro diesels engine(s) are well within the current production capabilities of any of the factories above.

- As to the potential market, it could be huge. I can see the millions of peasants and lowly paid city dwellers around the world with mild to temperate weather, who make minimum wage and who must commute long distances by human pedaling bykes or worst, in public buses, with fares eating deeply into their meager salaries and taking a lot of commuting time. For these people, a very high mpg, high torque at low rpm (less wear, safer speeds) micro diesel, purchaseable thru low interest micro-credits, could make a huge difference in quality of life (more time for family or own micro businesses (micro-taxis, small cargo deliveries, etc), with increased safety (flywheel solid state generator for lights/radio). I for one, would just enjoy puttering along on leasurely drives at 200-300 mpg- And then there is the possibility of using bio-diesels. Oh boy. Just love the thought of it.

Anonymous writes:

(Hopefully) corrected/completed version of previous post:

Now I remember when I was selling some small hydraulic power packs (they could have been

small gen-sets for the sake of this discussion) back in the early nineteen eighties, and they had

choices of engines, including a couple of diesels. These were all small, one cylinder egines, and

were all four stroke. The diesels we offered were an italian made Lombardini and a

Robin-Subaru.

What I recall from demonstrating the power pack with a diesel engine, is that it was a lot of fun

(to me anyway) to crank the engine while holding a valve open, which reduced cylinder

compression to facilitate cranking and starting.

Now, let's take A LOOK AT some current, four stroke "small diesels" (and I think we have to go

four stroke FOR BEST COMBUSTION/LOWEST EMISSIONS, HIGHEST POSSIBLE MILEAGE besides

the high torque at low rpm WHEN IS REALLY NEEDED, SUCH AS UPHILL), and compare them to

gas engines:

http://www.northerntool.com/images/product/images/6041_lg.jpg

HATZ DIESEL 4.6 HP has a bore x stroke of 69 mm x 62 mm with a displacement of 14.15 Cu

In., with a compression ratio of 20:1, a Max. Torque of 12.5 ft-lb @ 2300 rpm, dry weight: 62

lbs.

http://www.northerntool.com/images/product/images/60548_lg.jpg

Subaru Robin Diesel Model DY23 has 4.8 HP @ 3600 rpm, Max Torque of 7.7 ft-lbs, a

Displacement of 14 Cu In (230 cc), Max 4.8 HP @ 3600 RPM, Max Torque ftlbs/RPM 7.7

ft-lbs @ 2200 rpm, Bore and Stroke 70mm x 60 mm, Compression Ratio 21:1, Dry Wt of 63.9

lbs.

http://www.lombardinigroup.it/common/binary_reader.php?id_file=169&idtbl=2

LOMBARDINI DIESEL 6 HP has a bore and stroke of 82 mm x 66 mm with a displacement of 21

Cu In. with a compression ratio of 20.3:1, a max. torque of 9 ft-lb @ 2200 rpm, dry weight: 73

lbs.

http://www.honda-engines.com/modelslarge/GX160.jpg

HONDA GAS ENINE MODEL GX-160, 5.5 HP has a bore and stroke of 68 mm x 45 mm. with a

displacement of 9.9 Cu In., a compression ratio of 8.7:1, a Max. Torque of 7.9 ft.-lbs. at 2900

RPM, and a dry weight of 34 lbs.


http://www.robinamerica.com/engines/photos/large/EH025_lrg.jpg

SUBARU-ROBIN MICRO GAS ENGINE, MODEL EHO25 , 1.1 HP @ 7000 rpm has a bore and stroke

of 34 mm x 27 mm, a displacement of 1.5 Cu In., a compression ratio of 8.7:1, a Max. Torque of

0.87 ft-lbs at 5000 RPM, and a dry weight of 6 lbs.

http://www.robinamerica.com/engines/photos/large/EH035_lrg.jpg

SUBARU-ROBIN GAS ENGINE MODEL EHO35 Micro, 1.6 HP @ 7000 rpm has a bore and stroke

of 39 mm x 28 mm, a displacement of 2 Cu In., a compression ratio of 8.6:1, a Max. Torque of

1.30 ft.-lbs. at 5500 RPM, and a dry weight of 8 lbs.

http://www.honda-engines.com/modelslarge/GX25.jpg

HONDA GAS ENGINE MODEL GX-25, 1.1 HP has a bore and stroke of 35 mm x 26 mm. with a

displacement of 1.5 Cu In., a compression ratio of (8.7:1), a Max. Torque of 0.8 ft.-lbs. at 5000

RPM, and a dry weight of 6 lbs.


http://www.honda-engines.com/modelslarge/GX35.jpg

HONDA GAS ENGINE MODEL GX-35, 1.6 HP has a bore and stroke of 39 mm x 30 mm. with a

displacement of 2.2 Cu In., a compression ratio of (8.6:1), a Max. Torque of 1.37 ft.-lbs. at 5000

RPM, and a dry weight of 7.3 lbs.

To get an idea of current retail prices for some of these engines, go to: (no commercial

endorsements implied)

Diesels :

http://www.northerntool.com/webapp/wcs/stores/servlet/CatDsp?storeId=6970&N=76+8

5&Ne=2
Gas :

http://www.northerntool.com/webapp/wcs/stores/servlet/CatDsp?storeId=6970&N=76+2

000008&Ne=2000002

Comments:

- As can be seen above, micro four strokes gas engines, perfectly suited for motorizing bikes

are already available, and these units are the ones already reporting mileages in excess of 70

mpg (30 kpl)

- Based on the engine data provided above, I estimate that a scaled down version of any of the

currently available smallest four stroke diesel engines, could result in a four stroke micro

diesel, under 3 Cu. In. (50 cc), complete with injection pump, pressurized oil lub, OHC, low

noise level, dry weight under 10-12 lbs, meeting EU, CARB regulations with a retail price under

$500 (further reduced with volume sales), and yielding upwards of 200 mpg (85 kpl). Such

four stroke micro diesels engine(s) are well within the current production capabilities of any

of the factories above.

- As to the potential market, it could be huge. I can see the millions of peasants and lowly paid

city dwellers around the world with mild to temperate weather, who make minimum wage and

who must commute long distances by human pedaling bykes or worst, ridin crowded public

buses, with fares eating deeply into their already meager salaries and taking a lot of commuting

time. For these people, a very high mpg, high torque at low rpm (less wear, safer speeds)

micro diesel, purchaseable thru low interest micro-credits could make a huge difference in

their quality of life (more time for family or for own micro businesses (micro-taxis, small

cargo deliveries, etc), with increased safety (flywheel solid state generator for lights/radio).

To the former, add the (presumably) not negligable numbers of diesel lovers, meddle class

workers pressed by ever increasing oil prices, ecologists/sustainable energy supporters, etc.

I for one, would just love to put-put along on leasurely drives at 200-300-400 mpg. And then

there is the possibility of using bio-diesels. Oh boy. Just love the thought of it.

Anonymous writes:

Ooops! Got it almost right, but for the link to the price of diesel engines:

http://www.northerntool.com/webapp/wcs/stores/servlet/category_6970_76+85

Anonymous writes:

Hey fellows, let's not forget the rotary engine:

http://www.keveney.com/Wankel.html

http://en.wikipedia.org/wiki/Wankel_engine

and let's refresh our basic knowledge:

http://www.keveney.com/Engines.html

Anonymous writes:

My dear bhtoefr:

I didn't mean a rotary engine moped. Just for info and comparison purposes and also it help understand the right balance weight/power/torque/mpg/price/desired road speed/etc.

Long post, four places above this, contains the info that leads me to conclusion a mini/micro(under 50 cc/3 cu in), four stroke diesel, OHC, direct injection pump, pressured lub, EU/CARB compliant,
power around one hp, beatiful torque, even at idle, in excess of 1.3 ft-lb, retail under $500, mpg 200+,300+,400*, is well within currently available technology/manufacturing capacity.

Go micri diesel moped/bike kits!!

P.S. Ohio's mopeds'speed limit just right. We want everybody to enjoy their rides and arrive safely at their destinations, not end up like windshield swatted insects

Anonymous writes:

Now, to see an actual modern german diesel motorcycle:


http://www.motorbiker.org/blogs.nsf/dx/06232006102016MWEBSQ.htm

just for info.

Grant Connor writes:

The Diesel cycle is more efficient thermally than the Otto cycle (gas engine). A Rankin cycle engine (turbine) is better yet. The cost is in the manufacturing of blades. For diesel engines issues are cold start and power to weight ratio. Small generator diesel engines are sold by major companies such as Cummins, Perkins, and Isuzu. Royal Enfield is producing a diesel motorcycle engine and Kawasaki has thoughts of going public with their miltary motorcycle.
The question of how much power is needed for a moped is influenced by the aerodynamics of the machine as well as the weight. See craigvetter.com for a streamlined body for a scooter. A good fairing design for a mountain bike would allow 20 - 30 mph cruising on the level WITHOUT an engine. A nose cone 22" in diameter at the handle bars and 44" long can be clamped to the head tube. A similar sized cylinder tapered to a fin is mounted to a seat post rack. With wind resistance cut, power needed for 20 mph is under 200 watts. A small 0.6 hp engine for starting from a stop sign or climbing hills might be sufficient. In NY state any motorised vehicle must be registered and pass inspection. This includes lights and turn signals.
I would expect a small generator type engine with electric motor and ultracapacitors as structural members. A target would be at least 500 mpg at 50 mph for a single rider. Compare this to the 2 passenger Aptera trike claiming 330 mpg highway. My 1.8 L 5-spd Ford Escort gets 35 mpg highway or 175 passenger mpg seating five people. Climate, terrain, fuel availablity, and technical support will shape solutions to transport needs. I am adding this site to my favorites. Keep looking and thinking about the future. grantconnor@yahoo.com

Rob writes:

I run mopeds, my 2 cycle Yamaha from the early eighties with my 150 lb body gets an honest 110 to 120 mpgs depending on how fast I push it. I goes an easy 35 to 40 mph. The thing that seems to make a difference is the two speed tranny. My other Yamaha and my Honda with single speed trannies don't go as fast, ride as well or get as good mileage. It's hard to beat a small two cycle for simplicity and power. With oil injection I don't get billows of smoke. My Solex which really doesn't get the claimed mileage does smoke some but any two cycle running synthetic at 100 to 1 ratio runs pretty clean. I'd like to put the small Honda or Subbie on a bike and see how the miles stack up. I like diesels and found this place looking for a small diesel engine for an old generator that I want to use with my alternate energy system.

The best to me is still electric. I love it but we have the wrong idea about their function.

Nice chat.
Rob

Rob writes:

One more thing. I called Audi about getting the 1.2 turbo here in the states, the one that gets 90 mpgs and they said it isn't going to happen.

I guess I'll have to make my own. How about a small Yanmar in an old Toyota body that shuts off at lights?

rizzdizzl writes:

this appears to be a modern reincarnation of the lohman. However the engine
is mounted on the wheel rather than the frame


http://www.engadget.com/2006/05/10/the-wheel-turns-your-bike-into-a-moped/

Anonymous writes:

I want to hear more about the Metro with a diesel engine. Who, where, how can I get blueprints? Paul

Anonymous writes:

Hello, I just stumbled upon this thread. I was the proud owner of a lohmann powered early 1950s roadster type bicycle in 1980. The little motor started easily and was well constructed. The controls were unusual in that it required two twist grips. One controlled the compression ratio and the other the throttle. I had hoped to use this machine as serious transportation, but while the motor propelled me along fine on level ground, I nnede to assist it on uphill grades. I found that the extra weight and friction of this unit was not worth the boost it provided. I continued to ues a human powered bicycle for daily transportation instead. I left this bicycle stored in a friends barn and took my conventional bike on a year long extended trip. While I was travelling, the barn burned down and the lohmann was destroyed. I salvaged the burned carcass but many light ally parts were melted. I like the idea of an open soure disel moped project!

Anonymous writes:

Sorry for the typos on the previous post.

Anonymous writes:

I just got back from China where electric mopeds sell for US $ 200.

How about a microdiesel hybrid moped, fitting a microdiesel engine and sterter/generator instead of more batteries?

12V 24Ah battery weighs 19lbs. Challenge would be to get the engine and genset into a similar space and weight. Not impossible.

Imagine going to the store and filling your moped tank up with a couple of pints of pure vegetable oil for 100 mile range.


Best wishes for 2007.


Ken

London

Anonymous writes:

Eric & List

Looking at the cross section drawing of the Practica engine, about half the weight and half the components are used solely in the 2 stage reduction gearbox.



With the micro-diesel hybrid generator application - all this weight and complexity could be thrown away reducing the engine to around 12 or 15 lbs weight.

The starter generator could be based on a modified dc permanent magnet motor weighing around 5 lbs. So for about 20 lbs you have a complete hybrid powerpack that runs on cooking oil.

When you don't need it for recharging the moped, it could be used for powering house lights, or computer or any other application requiring small amounts of dc power.


Ken

Anonymous writes:

See www.ecorider.us for info on a 230cc Hatz diesel two wheel ATV built in Scotland and sold through dealers in US.

Grant Connor writes:

See www.ecorider.us for info on a 230cc Hatz diesel two wheel ATV built in Scotland and sold through dealers in US.

Anonymous writes:

To complement info on chinese mopeds selling for $200 in China, the chinese made Moskito 2 cycle 35cc gas engine kit mount inside frame of byke, right above pedals, retails in Chile, southamerica for less than US$300 and a lot of bykers who use their bycicles daily to go to work are snapping them up as I can see it with its 170mpg.

For the life of me, I don't see any reason why a microdiesel of similar displacement yielding 300+mpg, could not be mass made for a cost only 30% higher than its gas brother, to account for extra beef to take higher compression and injection system.

Now, one thing that seems to have been neglected all along this discussion is the beautiful ability of diesels to deliver high torque at low revs, which is what we need for low wear. See, after all we are talking of a very light vehicle that doesn't need to break any speed limits, just get you to your destination safely and economically.

Anonymous writes:

To partially answer a question posed by a fellow blogger up above, I exhibit what appears to be a reputable chinese small diesel engine manufacturer (there are many at:
http://www.alibaba.com/productsearch/diesel_engine.html

example.

www.kipor.com

their site from China is slow to open, therefore one can try one european distributor site which shows the smallest diesel made by Kipor, which retails at my neighborhood diesel engine dealer for some US$530, but remember we are talking about a 4 stroke , 192 cc engine, while we only need a 50 or less cc.
So with mass production I can venture to guess a retail price around US$200, which with mileage in excess of 200 mpg would be very appealing to many around the world.

Anonymous writes:

I need to correct my immediate preior post.

As I checked up and down several hardware stores in town, I found chinese made diesel and gas engines all over the place, with my prior quoted price for a Kipor diesel, one cyl, 4-stroke, 211 cc, down to USS$370.

Hey, fellows, I don´t see why Kipor could not scale down this engine to 50cc or less and sell it by the millions to up and coming bikers round the world, eager to improve their lot.

Carl Sweden writes:

I have been owner of two German maid Lohman 18 ccm diesel moped engines.
This was in the 60th
Wonderfull little things, I miss them.
Regards
Carl.

Anonymous writes:

for Larger Two-Stroke Streetbikes?
By Yossef Schvetz, Contributing Writer

I was sure that all I had to do on my trip to Rome was enjoy the great Italian food supplied by Piaggio and sample their new 4 stroke 125cc Vespa ET4 model. But as I arrived at the press conference it turned out that a few 50cc versions of the new model awaited us too. "Must be Piaggio's regular 50cc two stroke engine in there..." I mumbled to myself while chewing fresh Italian prosciuto ham from the buffet. How wrong I was as that little tiddler turned out to be the real ace up Piaggio's sleeve. With all due respect to the Vespa's 50th birthday and the important new ET4 125cc model, the understated 50cc ET2 is the one that really deserved the spotlight.

Simply put, the 50cc ET2 has the most sophisticated two-stroke engine ever mass-produced. Period. This little wonder is already able to pass the stringent European emission regulations coming in the year 2000 without a catalytic converter! GM, Ford, Toyota, Subaru and many others have been spending mega-bucks trying to develop clean two-stroke engines for their cars while Honda has been persuing the same goal through the development of their experimental (and expensive) EXP-2. However, the EXP-2's technologically advanced engine and all of the auto engines are yet to reach production. It is an impressive coup indeed for a small factory like Piaggio to produce a clean two-stroke ahead of all others.

So why are all the factories interested in two-strokes? Loads of power, light weight, few moving parts and low bulk. But stand behind any idling old RD Yamaha and the two stroke engine's pitfalls become clear (or rather obscured in the smoke...) Massive amounts of pollution mean a death sentence for two-strokes in many countries. If it only could be made to burn cleaner we would have a powerful, light and inexpensive power unit.

The main reason for the pollution created by a normal two-stroke engine is the "short circuiting" that occurs during the transfer process. Fuel-air mixture sucked into the combustion chamber rushes out the transfer ports and helps to drive the previous cycle's burnt gases from the cylinder. Although most of the fresh mixture remains inside, a small percentage sneaks out to the atmosphere through the wide-open exhaust port. Without any physical barrier between the fresh mixture and burnt gases this is unavoidable. That small percentage of unburned fuel multiplied by thousands of RPM gives the EPA and other green operations fits. It also hurts the engine's already poor mileage.

Circumventing this problem is deceptively simple: Use clean air during the transfer and clearing of the cylinder and wait until all ports close to inject the fuel into the remaining air. Big two-stroke diesel engines have been achieving remarkable efficiency doing just that since World War II. No fresh mixture can escape and by the time the exhaust port opens the burning process will be over like in any good four-stroke mill. Most "new" two-stroke experimental engines use this approach.

However, this is easier said than done. What works for a 70" stroke marine diesel two-stroke turning at a lazy 100 RPM doesn't necessarily apply to a 50cc piston buzzing at 10,000 RPM. Injection time is the limiting factor: A four stroke electronic fuel injector has more than 180 degrees of crankshaft rotation to spray the fuel into the turbulent air stream flowing through the intake manifold. A fuel injected two-stroke injector has about one third of the time available to deliver its load to a rather stationary mass of air. These problems have drawn engine developers away from the direct-injection idea to the stratified-charge concept. By pre-mixing the fuel needed with a small amount of air and spraying that rich mixture into the cylinder the time problem can be solved. However, this requires a separate system supplying pressurized air. Fuel will already be broken up into droplets by the time it's being sprayed and the rich mixture jet can be aimed at the spark plug, ensuring reliable ignition. The resulting flame front can then easily burn areas of leaner mixture.

Engines using an electronic injection-stratified charge system are available, but at a price. It's a complexity and cost toll that makes the whole equation of emissions and performance-per-dollar dubious. The cost of computer controlled injectors and sensors might be acceptable in high-end products like the new Bimota 500 DueV, but this is hardly the answer for the hordes of cheap, small two-strokes now polluting the streets of the globe.

Enter Piaggio's greatest stroke of genius since introducing the Vespa. The engine's bottom end is a regular clean burning two-stroke that pumps in clean air that will be transferred to the cylinder through the ports. Incoming air is throttled by one of the bores in a special double barreled carburetor. This half of the carb doesn't have any fuel jets, it only flows clean air. The real action happens in the cylinder head where a tiny crankshaft drives a small piston. This piston, of about 0.8" diameter, acts as a pump sucking an extremely rich gas-air mixture through the other half of the double barrel carburetor. On its downward stroke it compresses the rich mixture to about 70 PSI at which time the rising pressure raises a spring loaded poppet valve off its seat and the charge is squirted into the cylinder. There it is aimed at the spark plug area and ignited. The combustion pressure immediately shuts the spring-loaded poppet valve and from then on its just a "regular" stratified-charge ignition process with the flame front igniting those lean mixture areas in the cylinder.

A tiny 0.9" stroke crankshaft is driven at engine speed by a toothed belt drive. Total displacement is about 6cc and in order to meter fuel exactly the bore at the "mixture side" of the carb is a miniscule 4mm. (In my model airplane days I would have given an arm and a leg for a 4mm carb for my 0.049 cu.in Cox engine.) The pumping piston has to be timed to work with the cylinder, though the exact moment for injection is controlled by the poppet valve's spring preload. The simple beauty of the beast is hard to miss. Perhaps the most important aspect of the Piaggio engine is that it achieves what others have been trying to accomplish with complicated electronic wizardry through relatively simple and cheap mechanics.

An added bonus of the Piaggio engine is that the lean overall mixtures possible with the stratified charge leave big amounts of oxygen in the exhaust gases. This oxygen can be used later in a catalytic converter to burn hydrocarbons and to further clean the exhaust. I would also offer Piaggio the idea of counter-rotating the overhead crankshaft in the opposite direction, thus getting a balancer shaft in the bargain. Are we entering the era of OHC two-stroke engines, meaning OverHead CrankShaft? Or is it rather OHP2 standing for OverHead Pumping Piston? Remember you saw it here first!

The claimed performance of the ET2 on the spec sheet wasn't too promising (more on that later), but I just had to take a spin on the bike that holds what might be one of the most important engines of the 21st century. The ET2 is basically an ET4 model with a smaller engine and therefore handles as well as its bigger brother. Weight is ten pounds less than the larger bike but still twenty pounds more than most of its competition at 230 pounds. Performance is also hampered by required horsepower limits. The maximum output is not claimed and top speed is noted as : "by law code". In Italy, 50cc scooters are aimed at 14 year-olds who ride helmetless, so the laws are rather restrictive.

After riding the torquey and responsive 125cc ET4 the ET2 felt entirely gutless. But in my experience with Italian 50cc scooters outputs grow a healthy 6-7 bhp when the things are de-restricted for export markets. A proper test ride will have to wait till spring 1997 when the ET2's worldwide marketing begins. But just to make sure that it wasn't your standard issue two-stroke I put the ET2 on its centerstand and revved the guts out of it. Nothing, absolutely nothing came out from that exhaust pipe. Try that on any other two-stroke engine and you will appreciate the achievement. So its hats off to Piaggio, and I believe that some engineers in Detroit and Japan will have to take off their hats as well.

Specifications:

Model: Vespa ET2
Type: Single-cylinder, air-cooled two-stroke
Bore and stroke: 40mm by 39.3mm
Displacement: 49.3cc
Compression Ratio: 11:1
Carburetor: Weber/Dell-Orto/Mikuni Two-Phase
Transmission: Automatic Centrifugal
Body: Load-bearing, pressed sheet metal
Suspension: Hydraulic Single Shock(front and rear)
Front Brake: Single 200mm Disk
Rear Brake: 110mm Drum
Seat Height: 805mm
Fuel Capacity: 9 liters
Weight (wet): 92kg

Anonymous writes:

Continued from previous post:

.......therefore, boys and girls, according to at least the following article:

http://www.motorcycle.com/mo/mcvespa/et2.html

the "intrinsically" polluting nature of the 2-stroke engine is not so, and indeed a clean burning such engine was introduced to market a "long" (as far as these things go) time ago by italian scooter maker Piaggio, in their Model Vespa ET2.
According to the report in question, "to make sure that it wasn't your standard issue two-stroke I put the ET2 on its centerstand and revved the guts out of it. Nothing, absolutely nothing came out from that exhaust pipe. Try that on any other two-stroke engine and you will appreciate the achievement"

I wonder what did happen to this "clean" burning 2-stroke engine in the ensuing years? Was it taken up by other/all 2-stroke engine manufacturers, as it should? or did it not live up to its promise, and if so why? or was it simply ignored by some unknown reason?

I realize this "appears" off our own interest on a micro (less than 50cc) diesel for mopeds/bycicles, however, I can see how the same concept applied to the 2-stroke gasser could be somehow applied to make a "simpler, cheaper" (no injection equipment, like the Practica) 2-stroke diesel, cleaner burning yet than its gas cousin and rendering our much coveted and desired 300-400+ mpg motorized bike.

Anonymous writes:

following up on a previous post, several places above, I keep finding the chinese made Kipor, 5 hp, 4-stroke, diesel, cheaper and cheaper. This time at US$280, down from US$370 on my last quote. And remember, this is retail price for a full featured, standard diesel engine, injection pump and all and 200 cc or thereabouts.

Anonymous writes:

here here

Adam writes:

I am researching building a biodiesel motor scooter and have really enjoyed reading these posts - thanks everyone. When looking on the dieselbikes.com site I was turned on to the small diesel engine designed by Indian man Mansukhbhai Sanchaniya - about 3.5 HP and ideal for small motorcraft. I found an informative posting here:

http://www.nif.org.in/innovation/tid/130?from=35 (scroll down to about the third innovation on the page)

However, I found nowhere any info on how to actually buy one or find one in the states. It seems like it could be great for our project. Anyone heard of this or know where to buy one?

Adam

Mark writes:

Hi !
Great thread so far.
Did any of you know about the Royal Enfield Diesel-converted Motorcycles ?
There used to be (and probably still are) quite a few of them running around India.
For the older Enfield bikes, here's the detailed diesel conversion showcase which boasts a 400cc air-cooled,direct-injection, single piston diesel engine:
http://www.altmann.haan.de/riding_on_salad_oil/
how about slimming down this 400cc design to a 50cc power plant ?