4 STROKE When do you need CAM CHAIN??

[Dirtcrasher]

Well noone wanted to buy the 85 250SX motor for 300$ so I figured why the hell sell it?? I'll spend that much in gears and one way clutches alone if I ever need any parts and decided to keep it. I plan on building a motor for the 87 250SX with a cam and a high compression piston. But I wondered, does a perfectly good running engine that has always had oil changes need a cam chain and gears - or hell for that matter what about main bearings?? - Four strokes just don't seem to eat up lower ends very much but if I'm gonna do it I might as well do it well.

Will the chain have play in it like a bad drive chain?? Will the sprockets show rounding teeth?? The tensioner is self adjusting and not noisy so that doesn't indicate much for me.

Any ideas there four stroke builders???????

[thefox]

As long as the cam chain has been keeped ajusted the chain and gears don't wear that fast. I would just keep it ajusted and when it starts making noise and can't be ajusted anymore then it is time to replace it. I have bought 2 trikes with bad cam chains and they both were the type that looked like no maintinance was ever done to them. I have never replaced the lower end bearings though. I have thought about it wondering if it would make it easier to pull start since it seems that some bikes are easier to pull start then others.

-Andrew

[Tri-Z Pilot]

Yeah, check it like you do sprockets and chains, if they look like they are in good condition, just keep them.

[Dirtcrasher]

Thing is I have a 3rd junk motor in my cellar that had a nasty cam chain noise and it had an aftermarket chain in like advertised in Dennis Kirk but I can't feel any slop in it and I know it was the noise as all head components were tight and score free and the valves were adjuxted fine too - that chain was very noisy yet I couldn't feel or see the play?

The SX is self adjusting so you can't tighten it up - when it gets noisy and the adjuster is working fine thats when you junk the chain, sprockets and guides.