5-7HEAVEN
Well-Known Member
each to their own... they just look really rough left in the case. neat auto chain oiler if you can keep it... fuelling can be a bit nasty, unless you use a seperate tank.
sprockets... #25 chain is pretty common, and certain scooters use flats on the shaft. pretty easy to file a flat on the crankshaft. the finer the chain, the easier it is to get large reductions in a small space. and they run quieter.
you retain stock air filter, but need to change throttle mechanism. ditto on choke, possibly. the stock exhaust will do if you like snorting twostroke residues... otherwise, tuck it away somewhere neat with an extansion. if it comes out too close to your back, you get a dirty big stain on every shirt you wear. the exhaust clings to your back like its slipstreaming well, it is, really... so get the outlet low to the ground as possible or youll stink.
and lastly... the handles isolated from case.... forget it. just mount up off the bar bolts. if they can hold a bar still, hopefully theyll keep the engine still...
back on previous post...when i said 100:1 ratio...thats from engine to CRANKS. as mentioned, the bikes gears then gear UP.
so, in granny gear, youll have 1:1 on the pedals to rear wheel. or 100:1 for the engine, give or take a few decimal places given sprockets available etc.
in high gear, if you have a 55 chainring and an 11 rear... or 1:5... your engine will have 20:1 by the time it reaches the rear wheel.
even 20:1 as a final ratio is pretty low geared.
meaning 50:1 would be more than adequate. 50:1 and you could tow a bus...
10:1 and if the engine will wind out enough...hope you have brakes!
15:1-18:1 is a nice "fixed gear" ratio, the HT can get away with 12:1 if you dont mind pedalling hills a lot...
my only gripes here...
chainsaws output on the right hand side.
9t chainring to a 34 rear sprocket may be good reduction for the ENGINE, but when it dies and you have to pedal home... youll be spinning those pedals and not going anywhere. think MTB in super extra low 89 degree gradient climbing granny gear...
and that is how fast theyll be spinning when youre riding under power....
work on the idea that you do not, ever, want to pedal more than 90rpm. unless you like knee surgery.
its either a lot of reduction before the cranks, or seperate to the cranks altogether, ie, the other side...
USE STANDARD GEARS IF GOING WITH BIKE CHAIN. DO NOT USE THAT SHIMANO...BIOPACE? STUFF!
If I'm understanding correctly, 100:1 without engine built-in gear reduction would be impossible with one jackshaft.
That'd be like a 10t engine sprocket and a 1000t (one thousand teeth!) chainring. The sprocket would be taller than the bicycle.
With conventional 10t/25t jackshaft combination, you'd need 5 jackshafts to get 97:1 gearing. 2.5 x 2.5 x 2.5 x 2.5 x 2.5 =97.66:1
You'd need four jackshafts like that to get 39:1, which is lower than necessary. A 32.72:1 gear ratio at the chainring is a great combination, before it reaches the 8-speed cassette.
That 9t/34t was suggested if the OP removed the pedals as he had mentioned.
If the engine has reduction gears, then much higher gear ratios can be used in the calculations.
If the engine has 5:1 reduction gearing, then a single jackshaft of 11t at the engine and 72t at the chainring gets you 32.73:1.
I use standard Shimano or KTM 8-speed bicycle chain from 24t chainring to the cassette. It works well and reasonably priced.
I'm beginning to realize why there aren't many 2-stroke engines running thru chain drive.
If pedalling I'd suggest 24t at the chainring. That's what I have, and pedalling is easy going.
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