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2005 RM125 ~ Rattle

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Good day ladies and gents, i have a 2005 RM 125 pretty much fully modded except being bored out. FMF Gold series head pipe, FMF Shorty Tailpipe, Vforce 3 Reed Kit, Excel Rims, Pro Taper bars, Racing Clutch, ASV Snap off Levers, After market tripple clamp, risers, plastics and graphics and a few other things here and there. When the bike runs i can hear a slight rattle coming from the engine.. now i know two strokes arent the quietest thing in the world but i do believe this is a new sound. I do need to re-piston and ring the bike FOR SURE... its probably been 60-100 hours since doing so... but the sound seems like its coming more so from the bottom end. So the questions is: Can a simple need of a new piston and ring cause the rattle? Or am i looking at a bottom end issue? Is there anyting specific i need to look for to try to source the sound (certian types of markings on the piston, play in the rod... etc..)? Also, since this bike has yet to be bored, when getting the piston and rings hould i go ahead and bore it over? or keep standard size? Any help is appreciated, thank you guys!! (p.s. this is my first post, im new to this... ill try to get some pics of the bike up soon if it will help... just let me know) Merry Xmas and godbless! BRAPP!!

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sounds like you have pistion slap. when you tear the bike down take the new ring and put it in the cylinder, there should be a certin amount of gap. if its off then you need a new cylinder.

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60-100 hours on a 125 piston must be some kind of record. Pull the top end off and check for play in the rod and main bearings too (basically there shouldn't be any vertical movement in either).

Note, these cyclinders are not normally rebored- they have a thin plated coating which sometimes can wear through & that coating then has to be replated - but maybe you just need a new piston kit and gaskets etc (personally I think genuine Suzuki ones are best), you won't know until you strip it.

Post some pics up when you dismantle it if you need a 2nd opinion about anything.

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my 1999 rm 125 made the same noise that your describing it started to make the noise when the top end started to go when i was raceing my friend in a rain storm up and down a field (over revved just a bit lol)

once you hone the cylinder and put in a new piston and rings (i would go with wiseco) it should stop and bring your compression back up and bring the bike back to life

also check your compression if you can mine was at 40 psi at about 20-25 hours

and clean your power valves with some sand paper to get the carbon build up off so they don't stick

most seal kit come with a power valve seal kit any ways

long story short my bikes at 140 psi + compression now

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Thank you all so much...this is Christmas weekend so I may not be able to get to it til Sunday or Tuesday. When I get it apart I'll post some pictures. Will the top end kit come with the gasket for the powervalve? Our do I even need to worry about replacing it? Thank you!

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yeah, just be prepared to have to split the bottom end or take it to a shop and have the bottom end rebuilt. If it has that many hours on the piston I can't imagine how many hours it has on the bottom end :bonk:

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