70cc 2-stroke auto clucth electric/pull start

flat battery syndrome. damn! forgot to get a decent battery to replace the chinese muck!
So if the dodgy chinese electric start can be fixed, and the engine can pedal/bump start anyway, then the (stop, get off your bike and) pull start is fat that can be trimmed! Yay. So now what is the width, and do you need to have wonky crank arms or can it have betterer ones? o_O
And what is the angle of frame V, anyone? o_O
 
Yay. So now what is the width, and do you need to have wonky crank arms or can it have betterer ones? o_O

Looks pretty fat to me lol. I've got a set of those bent pedal arms and they are ok but way to dam short. It feels like your peddling a dang kids bike with those things on. If I could get someone to make bent peddle arms with 170mm length I would be so happy! I have a pull start on my 66cc and love it but the downfall is the stubby bent crankset required to clear the pull start housing.
 
I have just been cuting old bike ones and weld it on the out side not the pretty thing but works good don't need a 3 pice crank because I don't have a 3 pice the bits in the kit where useless and by the looks my feet would hit this is on a 4 stroke
 

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I'd have thought a SBP four stroke crankset and the wide bb they supply ought to do it..?


The problem with those is they throw your peddle drive side chain line off pretty bad, at least on a single speed bike. A single speed bike with a bottom bracket in a 68mm wide bottom bracket housing should be between 103-107mm so your chain line isn't wayward. They will still function even with the chain at an angle but in my opinion, it's not ideal at all. If they had a spindle that you could mount a chainring as close to the bottom bracket housing as required and then mount just your pedal arms on the ends of the spindle it would be better I think. But all would be solved if someone produced a crankset with angled arms that were a more comfortable peddling length. I haven't measured the length of the pedal arms on the stubbers but I bet it's around 150mm.

I have just been cuting old bike ones and weld it on the out side not the pretty thing but works good don't need a 3 pice crank because I don't have a 3 pice the bits in the kit where useless and by the looks my feet would hit this is on a 4 stroke

If I had the Tools and the ability to make one, I would definitely try! That doesn't look to bad though man.
 
I found a mig welder for $200 gas or gas Lees is my best friend for workers on their bikes metal super glue so easy to use
 
Ah I see now the cranks are the same normal shape and a few lengths and they do the bb with a 206mm keyway axle, a "chainring adapter" and various spiders to mount standard bicycle chainrings onto. Having the cranks straight is right though. If the chainring can be mounted in the right place using the adapter and spider then it should work with direct drive and single speed afaics.

Anyway I think perhaps the engine mount V angle is too far off for mountain bikes and will only suit road cruisers like the one KC has built. Perhaps I will stick to dreaming of doing something with the 12v output... a hybrid high power ice with legal electric wheelchair! :eek::D
 
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So if the dodgy chinese electric start can be fixed, and the engine can pedal/bump start anyway, then the (stop, get off your bike and) pull start is fat that can be trimmed! Yay. So now what is the width, and do you need to have wonky crank arms or can it have betterer ones? o_O
And what is the angle of frame V, anyone? o_O
centi clutch...no bump starts.


you could swap the BB to take splined cranks, and then its easy to chop up some steel cranks(im thinking some of those freestyle BMX ones with the split clamp type ends) and re-weld at angles/lengthen etc... gotta get the pedal axle dead square cus boy, that having any wonkiness is darn obvious...and annoying.

sounds easier than using long BB axles and then spacing the chainring to suit... been there, hated that...

170-180 are really nice lengths, much over 175 does start making cornering while pedaling a tad dicey though..
 
centi clutch...no bump starts.


you could swap the BB to take splined cranks, and then its easy to chop up some steel cranks(im thinking some of those freestyle BMX ones with the split clamp type ends) and re-weld at angles/lengthen etc... gotta get the pedal axle dead square cus boy, that having any wonkiness is darn obvious...and annoying.

sounds easier than using long BB axles and then spacing the chainring to suit... been there, hated that...

170-180 are really nice lengths, much over 175 does start making cornering while pedaling a tad dicey though..

Okay no pedal start (disappointing) so the electric just needs to be 100% reliable.

I think bent / angled arms just put too much stress on the clamp (or whatever interface is used) for the kind of mountain bike use those 5 horses are begging for.
I had some steel pinch bolt cranks, they creaked a lot so I got Primos (alu), lol.

Buying a welder, learning to weld.. To me it seems easier to buy plug n play bits and really try to avoid any fabrication.

Mmhm, 170/175s are fine, I had some 180mm Profiles.. No need but they were nice for gate starts. :) (off topic!)

I still can't believe the V angle they have given it! I tried to measure it off my screen but I'm on a phone so it does weird stuff when I touch it. :rolleyes:
 
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