Idea For simple diesel bike...

[IgorVigor]

I had a bit of a thought while fiddling with a 50cc scooter...

The drive system is a CVT gearbox which I have seen a lot of you use for diesel bikes...

So, if you took a working scooter (or one you know the CVT is in good health)

Fit the diesel engine in between your legs in a frame
Modify the scooter engine piece so you could run a chain and sprocket (or belt and pulleys) from the diesel to the crankshaft (or replace/modify the crank so its a straight shaft).

Would be a fairly easy and cheap method of a conversion.

Most 50cc scooters produce 3~6 hp and 125cc scooters produce between 8~14 hp depending on engine.

They all seem to use Kevlar drive belts now which are very strong yet small (less heat, same traction)

The one on the 50cc I was playing with had a V belt 3/4~1 inch wide and about 3/4 inch thick

I wouldn't recommend a large diesel, but a Yannmar (or clone of around 10hp should be fine)

And you could alter the acceleration/top speed by altering the sprockets and chain (belt and pulleys) from the diesel to the moped CVT.

Most 50cc scooters only rev to around 7000rpm so a 3600rpm diesel running a 2:1 drive the gearbox would equate to a similar speed

so the top speed would be around 40~50 mph depending on scooter, but it should get there quickly...

Just an idea I thought I would throw into the ideas pot

Any thoughts or questions?

[Sphere]

The petrol engines in scooters are really compact, even in 250/400cc models. Where would you leave the Yanmar/Hatz/Chinablock

[IgorVigor]

As I said, between your legs...

Even the smallest 50cc scooter has a good amount of leg room...fit the engine between your legs (and maybe a bit under the seat if wanted/required) and fit a pair of footpegs for your feet (if needed)

Jobs a good'un...

its only an idea...

Look around and you can get scooters for £100 running order...

Locally to me there is a Gilera DNA for £80, with spare engine.
Its a non runner because of an immobiliser or something...

Pics of a Gilera DNA if you dont know what they are:
http://www.maxmoto.co.uk/images/39%20Gi ... A%2050.jpg
http://www.tapetky.cz/wall/13611_1280x1024.jpg

Tempted to buy it because they do look quite nice

Believe it or not, they are still a 50cc scooter...it looks like a bike, but has a CVT gearbox...


EDIT:
the other thing is it would give a proven transmission though, so it might be a way of sourcing cheap CVT's for diesel bikes...
most scooters have a single sided swingarm, on which the wheel fits to a splined shaft, so you could mod the wheel shaft for a sprocket to fit, for a chain drive bike...

[Crazymanneil]

Hmm interesting idea. What rev range does the scooter have though? Might be tricky to get the cvt to engage properly with the limited rev range of the diesel but I guess that could be overcome by gearing before coupling to the cvt or modifying weights or whatever voodoo magic cvt works on...

N

[Sphere]

I see. Well I tried looking for dna 180 workshop manuals, since there is no point in trying to dieselize a moped in Holland. I could not locate anything useful except for easyparts. Well, I'm looking forward to see the details of this plan

[pietenpol2002]

Here's an example from Japan I posted some time ago. A rather crude arrangement and interestingly drives from the flywheel side, presumably for coupling to a jackshaft opposite the left mounted CVT. There is little narrative to accompany the photos other that to give it a positive report.

http://blogs.yahoo.co.jp/valkan243/17317150.html

[IgorVigor]

Hmm interesting idea. What rev range does the scooter have though? Might be tricky to get the cvt to engage properly with the limited rev range of the diesel but I guess that could be overcome by gearing before coupling to the cvt or modifying weights or whatever voodoo magic cvt works on...

N

As i said in an earlier post, basically run a 2:1~3:1 increase via a chain and sprocket...
The 50cc scooter I have in the shed revs to 7~7.5k rpm max

So accounting for a diesel that revs to 3600rpm and idles at say 750rpm.

a 2:1 (e.g. 36tooth sprocket on the engine, 18tooth on the jackshaft/crankshaft) would put the gearbox idling at 1500rpm and peak rpm of 7200rpm (ignoring any slight losses)
The scooter will do 45mph as standard so a similar speed should be ascertainable with the diesel engine...
If anyone is concerned about the bike trying to creep, I wouldn't worry...
The scooter doesn't try and move until 2.5~3k rpm, but that can be altered by changing the roller weights...
if you altered the weights so it would try and pull from 2000rpm, the diesel would basically have a usable rev range of 1000~3600rpm

The advantage is the extra torque you would have

if you used a 3:1 system, on the right scooter CVT, you could be up to 60~70mph...

Obviously, it would need to be tuned to your individual requirements...

[IgorVigor]

Here's an example from Japan I posted some time ago. A rather crude arrangement and interestingly drives from the flywheel side, presumably for coupling to a jackshaft opposite the left mounted CVT. There is little narrative to accompany the photos other that to give it a positive report.

http://blogs.yahoo.co.jp/valkan243/17317150.html

Thats basically what I thought of doing...

personally if I had built that bike I would have used a clockwise rotation engine and retained the pull start/crank starter instead.....

But oh well, I'm sure he/she had their reasons...

[Blunt Eversmoke]

Thump! ya'll.

My interest in diesel biking has, sadly, always been passive due to severe financial restrictions until recently; not surprising, thus, that I came to the same idea of a Cheap (with a capital C) scooter conversion.
To this date, I have:

Used Hatz E 673 LHK, requiring some sort of overhaul (LOTS of white smoke)

Rolling chassis four-stroke chinese 50, OK engine, dead electrics

one spare engine/CVT/suspension unit (further: engine block), complete with alternator


Now to scheme out what I want to do:

I have to keep the whole engine block, for a variety of reasons. Apart from the most prominent (CVT, suspension), there is the possibility to supercharge the diesel engine free of charge, converting the petrol 50 to compressor duties.

Questions:
How well can I expect such an arrangement to perform? Can I utilize some sort of automatic valves or is it better to use the standard cylinder head/camshaft affair, with some modifications?

Have a nice day!

[DieselFly]

If you plan on using a 50cc volume cylinder to fill a 280cc cylinder you will get negative boost. Even if you spin it 2 times faster it won't provide any boost. Nice thought but buy the time you factor in friction and pumping loses you would have to spin you 50cc at a RPM that would make one want a cement wall between you and it. But it never hurts to think and imagine

Sean

[alexanderfoti]

Im hoping to use a 500cc supercharger on my 407cc Single cylinder to get it up to around 14 hp ish.

[Blunt Eversmoke]

If you plan on using a 50cc volume cylinder to fill a 280cc cylinder you will get negative boost. Even if you spin it 2 times faster it won't provide any boost. Nice thought but buy the time you factor in friction and pumping loses you would have to spin you 50cc at a RPM that would make one want a cement wall between you and it. But it never hurts to think and imagine

Sean

I am out for quite modest boost since I dunno how much the old Hatz can handle; that and the fact that I need to run the 50 at 3-4 times the speed of the Hatz to make the scooter scoot as it did before while not overrevving the diesel (and having an 80 cc cylinder somewhere in the shed if I fail with the 50) has me repeating the question: Do I have any chance?

[XLerate]

Have a friend here, once known as 'Roger Ramjet' who had his AA Top Fuel dragster supercharger explode in his face on a 1/4 mile run. Pictures are on the net.

Engine was turning high 9,000's & huffer was over-driven around 2:1. Again, he was running nitro-methane fuel. He survived & is okay but was badly scarred for life & getting doused in nitro didn't help, neither did the fire. Over-driven superchargers are real nasty critters, especially made from something never designed to rev that high: BE CAREFUL BOYS!

On original topic if you could use this thing a lot, even on an estate or whatever, it might be worth the bother to dry sump an engine. I consider this for other diesel builds as you can then lay any engine in any position you want!

It isn't rocket science so most any of us here could figure it out and do the conversion. Don't think it would be expensive at all, unless I'm overlooking something. Also a dry sumped laid down engine is going to have a much lower center of gravity for some serious handling improvements in the twisties....

[DieselFly]

No it won't work you will not be able to move enough air. Don't forget it costs hp to turn a supercharger so even if you get some modest boost it will be consumed running the workings and pumping losses

[pietenpol2002]

I'm with DieselFly on this one. Do the research, then do the math. Supercharging is possible, but not by the means you propose. And losses are a significant consideration. As an example, the race prepared Rolls Royce Merlin powered Mustangs at Reno have a supercharger that CONSUMES 1200 hp. It first has to pay for it's own losses (1200 hp) before it begins to contribute anything to the race. Of course, on a bit grander scale than with our little rattlers.

The opposed piston DKW is an example of what you're proposing. However, compare the displacement of the combustion chamber to the pressure chamber in the links below. Wild guess, but the pressure chamber could well be twice the displacement of the combined combustion chamber.

http://picasaweb.google.com/massive146/ ... 9815986994
http://picasaweb.google.com/massive146/ ... 3434886482

Having said all that, please don't give up on the idea of supercharging. I'd love to see what you could do with it.

[DieselFly]

between 66-75% of the power that a jet engines turbine produces is used to turn the compressor section