should these be strong enough

[minibikesrule]

yea it had a 21 speeds
and i dont have yahoo messanger sorry
my gear deduction should come tomorrow.
so with a gear ratios form 15:1 to 30:1 it should be better than a single gear

 

[mike75925]

ok are you going to use the gear stack as is. if so i would put the engine's chain to the inside, the other to the outside. by putting the drive chain to the inside both bearings will support/carry the shaft(longer bearing life). do you plan to use the deraillieur. if so, do you know how to rpm shift. give a lil gas and shut it down, should allow the on-the-go shifts as needed. my clutch bell was inside the reduction housing geared to the output shaft. sprocket was splined and c-clipped. i was to suggest welding your new engine sprocket to the old one, if it will. and make sure you center the smaller one.

 

[minibikesrule]

yea i was wandering about bearing life im gonna rebuild them tonight and make shure their packed with grease.
and im using the original deraillieur shifting shouldnt be too bad its just like riding down a hill at 70kmh and shifting and not doing it whilst accelerating.
i wish we had plentyfull second hand 4 strokes here in
new zealand the 2 stroke smokes and screams i had to put our mower muffler on it and its still disubingly loud.
ill post pics on a new thread when its finished.

 

[mike75925]

on the multispeed bicycles you have to have a lil acceleration to be able to change gears. if the motor sprocket is not moving the chains it will not change gears. try it you will see what i mean. stand next to the bike and try to change them, it jams. has to be rotating to switch.

 

[mike75925]

you can get smokeless 2 stroke oil.

 

[minibikesrule]

yea i get what you mean about shifting got to rev it so the sprockets work kinda like flywheels to keep it turning and shifting. some smokeless oil would proberly be better than the cheap stuff i have.
i rebuilt the bearings for the jackshaft there packed with grease andthey feel like real bearings now.

 

[mike75925]

cool.

 

[jr dragster T]

I've heard of smokeless oil. If the oil isnt burning in the combustion chamber what is it doing?

 

[minibikesrule]

good question i have no clue.
my old man had a cr480 which was ment to be 20:1 oil ratio but he got some expensive smokelss synthetic oil and then he was runing it 60:1 and that was about 12 years ago and it still runs today.

 

[minibikesrule]

wait dosent it smoke because some of the oil is burning?
so maybe the oil dosent burn as much as the other oil and is just spat out the exhaust?.
or maybe it burns but just way cleaner?

 

[porsche930dude]

Im usually the last one concerned about this but i highly recommend a chain guard on anything motorized using bicycle chain. I came awefull close to having a mangled face once.

 

[minibikesrule]

was that becase it broke and wraped around the sprocket and jammed the wheel

 

[mike75925]

i think the oil does burn cleaner, my ody calls for 20:1 but that is alot of oil, i have been running 32:1 with no problems and others run 50:1 no problems. the good thing about the smoke is you know there is oil in it.

 

[minibikesrule]

very true

 

[porsche930dude]

was that becase it broke and wraped around the sprocket and jammed the wheel

no it broke and wraped around and whipped while i was reving it bending over tuning the carb