2001 CR125 engine noise question

[500 dirtrider]

I know, I know, the CR125 is known for the "death rattle" but I don't think that this is what I have. I just installed a ProX piston, new ring, and new wrist pin bearing, ect. The rod was tight with no slop, I mic'ed everything and the tollerances were more than good. The old piston had no signs of the death rattle by showing the tell tale marks on the top edge. I really don't know if I have a problem, but here is the deal. I have a '90 CR500 and just sold a '92 KX125. Neither of these had this sound but it may just be me. This bike has a FMF Fatty pipe and it is newer than all of the others. I can best describe it as it just sounds different than I'm used to and the sound is not at idle but a constant thing. The "death rattle" is supposably a rattle at idle that goes away, this sound is all of the time. The motor sounds sweet and it just may be a tinny sound because of the Fatty, I just don't know. You "experts" with a mix of the old and the new bikes tell me, is it my immagination or does this '01 CR125 sound different than I'm used to.

 

[marcusgunby]

Could it be the alu frame-that makes the engine sound worse.

 

[JANDERSON]

I wood/moto ride and the difference between a spark arrestor and stock silencer changes the whole sound on this beast. If it's running good I wouldn't woory too much. By the way how does your bike respond from the bottom? Does it tend to bog unless you really use the clutch alot? I'm assuming you have left the carb jetting stock. I've played around with mine but have never really found anything that works too well. But back to the noise, the pipes do make a difference.

 

[500 dirtrider]

So far it seems to run well, the throttle response is crisp and it sounds pretty good. I'll have a better idea after Sunday when my son takes it out to break it in. I just rebuilt it and the pipe just came back. My initial observations were during the first start up, it hasn't been in the woods yet. I took it down the street once but being used to a CR500, I'm not a good judge of 125s. The jets are stock and I haven't played with it. The low speed jet was so clogged up when I tore it down, I really didn't have a good feel for the jetting.

 

[marcusgunby]

On my 01 i went to a 40 pilot jet to help the throttle responce.

 

[1989kx250]

same

i have a 1989 kx 250 with brand new crank and piston, bored 65 over and seems like i have the same problem ringing hollow sound as you, please send me an email at lucasschmiesing at yahoo if you find anything else out about it.

 

[usgpru27]

Does the sound lesson when it is hot and the piston expands? My 01 does make some rattle when cold through the rev range and gets better when hot..