Tapping/Rattle Rm125 2001

[Bishbash25]

Hello all i have recently purchased a 2001 rm 125 very cheap as it had a non starting problem.

what i found problem wise was piston had worn well not to sure what had happened but ring was stuck in where piston worn away and burr on top of piston.

Looking at cylinder bore was ok so don't know what caused it? but could only replace a piston that was taken out of bike few months ago along with ring (looked fine)

Fitted piston and started the bike fired first kick but there is a sort of rattle tapping noise thought at first was stone in exhaust but checked.

Also i did not take exhaust port apart and check could that be a problem? or could small end bearing on conrod causing rattle or is there a major fault i am missing.

Am i right if piston was wrong bike would of told me by now and stopped working?

Need help or advice from anyone would be grateful.

Bishbash25

 

[Chili]

Am i right if piston was wrong bike would of told me by now and stopped working?

Not necessarily it may rattle around in the bore until it shatters apart.

 

[Bishbash25]

What can cause to rattle around in bore ? seemed snug fit also no score marks visual or felt from wear from old piston problem.

could bearing on piston rod be the problem. (Best not fire up anymore)

Bishbash :(

 

[Bishbash25]

Anymore suggestions to the rattle/tapping noise sorry to be a pain just seeing if there was more options to why its like it.

bishbash :bang:

 

[Chili]

Best bet is to pull it apart and check your clearances, as well as the rod for any crank play. If the previous piston had been stuck I'd be likely to check to make sure the cylinder hasn't worn out of shape slightly.

 

[Bishbash25]

The old piston wasn't stuck it was the ring scraped into ring gap as if something had scrapped past where the exhaust port is, but looking at the cylinder bore it looked fine no scrapes or scratches so something telling me it scraped past something around the exhaust port.

Bishbash25

 

[_JOE_]

Pull it down and measure everything. Excessive clearance somewhere is the most likely culprit.

 

[FNG]

but could only replace a piston that was taken out of bike few months ago along with ring (looked fine)


I am assuming you put a used piston-ring in? A piston with 20 or 30 hours on it can "look" fine but be junk.

If so, then take it apart and have the bore measured, then buy the new appropriate piston-ring aling with a small end bearing and associated gaskets. Take apart and clean the power valve, then put it back together and ride it.

 

[kawraper]

Is it a very loud rattle. Theses 2 smokes tend to have a rattly sound to em. I thought there was something wrong with my bike. I checked compression and it was fine. It ran like a raped ape. So I just rode it. Then I noticed my buddy who just did a topend on his 07 only had about 2hrs on it was making the same noise. Its been a few months and niether bike has blown up. I dunno if its the reeds or the powervalve or what but if I heard that noise coming from a car engine Id be worried.

I guess the point is, is the noise a very pronounced banging or is it just a little rattly sounding?