Help a newbie! (chain keeps throwing itself)

[tasrob020]

Hey all,

i just bought a 90cc pit bike for like 150 bucks, its got a bald back tyre and the chain keeps coming off or breaking.. i just put a new link on it today and i had it fairly loose, maybe 2-3cm loose.. and i set off for a ride, the chain came off three times and the 3rd time it broke the link.... im pretty sure it broke after it came off.. also the rear sproket bolt holes on the hub, 3 out of 4 are broken sorta, i just tried to fix it with washers, it all sits flush and is on nice and tight.. how much for a new back rim, sprocket and tyre? and chain? (the chain i have now is 420 pitch unless i got the wrong chain or something, its sits nicely on the sprocket)

and how loose is the front sprocket supossed to be? it doesnt come off, it just wobbles a bit, is that normal?

any ideas how to identify my bike? i'll post up pics later, its got like a chassis code on the rear swingarm...

also one of the exhaust studs is snapped of in the bore.. anyone know if the make a small enough easy-out or will i have to drill it out and use a heli-coil?



cheers for any and all help,
rob


edit: also can i put a chain tensioner on this thing? the chain gets looser as the swing arm goes up and down... and its missing the muffler too, i have to WALK it to the bush

and i was gonna shave the head down a bit, i can cc the head and measure the bore and stroke myself, but what compression ratio would you guys consider using on a dodgey 90cc (87cc i think) crappy chinese motor?? i heard most of em are 8.8:1.. would they suffer a terrible explosive death if i tried to run 10:1? (i filled up with optimax today.. don't know how full it was but it only cost me $2... lady at the servo looked at me a bit funny though. lol

 

[Dreadful]

Hey mate welcome to the fun times that is pit bike maintenance.

Firstly don't trust the marks on the swingarm ... line the wheel up by eye ... no **** alot of marks on chinese swingers don't line up ....this could be a reason for throwin chains ....as for tensioners ???? should have some so yeah they SHOULD be there .

Should find a small enough easy out ...or drill em .

100 bucks or so should get ya a backwheel ... not sure about muffler.

 

[Dreadful]

Oh yeah a new 140 lifan motor is only about 300 bucks

 

[tasrob020]

yea, i redid the back wheel before i went for a ride, and there is no chain tensioner (the roller kind not the adjustable nut kind) on this thing, i saw one on ebay, just wondering if i could simply bolt it on, i can obviously drill a new hole for it

that was actually gonna be my next question.. im in tas so where would be my best bet to find a cheap 140?? i guess that means im gonna need a clutch lever?? also ive senn hydraulic brake kits on ebay, are these universal? will they bolt on to any 12 inch rims?

i saw a set of complete wheels/tyres for 220, but they were 10/12, i dont know what i got now, but wouldnt i be better with 12/12??

also how often should i change my oil? after every ride or every 4 hours? or something like that? it wouldnt surprise me if this thing never had the oil changed in its life..

also the rear mudguard thing is snapped off... how universal are they??


cheers,
rob

 

[Dreadful]

yea, i redid the back wheel before i went for a ride, and there is no chain tensioner (the roller kind not the adjustable nut kind) on this thing, i saw one on ebay, just wondering if i could simply bolt it on, i can obviously drill a new hole for it

that was actually gonna be my next question.. im in tas so where would be my best bet to find a cheap 140?? i guess that means im gonna need a clutch lever?? also ive senn hydraulic brake kits on ebay, are these universal? will they bolt on to any 12 inch rims?

i saw a set of complete wheels/tyres for 220, but they were 10/12, i dont know what i got now, but wouldnt i be better with 12/12??

also how often should i change my oil? after every ride or every 4 hours? or something like that? it wouldnt surprise me if this thing never had the oil changed in its life..

also the rear mudguard thing is snapped off... how universal are they??


cheers,
rob

Yeah bolt it on

Have a look at the sites sponsors ...someone will have a motor but best to suss what the bike is first when ya can post a pic ...If it's an orion it can be done but it's a bit of a hassle

Brake kit pretty universal I THINK .

10 inch back and 12 front is a popular choice .

About that

A couple of mudguard designs but pretty universal

 

[tasrob020]

just trying to post up a pic...

 

[Dreadful]

don't bother with that one mate just ride it till it dies

 

[tasrob020]

whats so bad about it? it goes preety hard, i can still put a lifan motor in it cant i?

is the chassis itself that bad??

 

[SnItChY]

dready is right just keep her going as cheap as possible and then burn it

be cheaper to get a whole new bike and start from there

 

[tasrob020]

fair enough... i'd never be able to afford a decent bike... can i get just like a good frame from somewhere cheap and go from there? it'd be easier for me to make it piece by piece and i could build it the way i want it...

any ideas?

cheers,
rob