Aaarrgghhh!! Damn Rattle.

[Yamaha Tri-Moto]

I know i've posted this before but maby ill have better luck this time. My tri-moto 175 2 stroker has an annoying rattle in the top end. I've redone the top end twice now and it still has it, everything was done correctly by a reputable shop. So what else could be causing this rattle. air leak? Fuel/air Mix? i feel like i have tried everything. any help would be great. Thanks.

[MTS]

Con rod Big end beaing coudld be toast, or did they just put new rings in? or did the bore it out put a piston in to?

[chris200x]

did they replace the timing chain? That usually makes that familiar rattling sound that you speak of.

[Yamaha Tri-Moto]

Everything new end bearing, new rings, new piston, bore job twice now. It has been done by 2 different shops and both times i get it back together it still rattles.

[thefox]

did they replace the timing chain? That usually makes that familiar rattling sound that you speak of.

2 strokes don't have timing chains.;)

[MTS]

did they replace the timing chain? That usually makes that familiar rattling sound that you speak of.
its a 2 stroke....:lol: :lol: :lol:

Are you POSITVIE its fro, your top end? and not a loose exaust or something?

[chris200x]

holey smokes! :eek: Maybe i should read the post more thouroghly. :rolleyes:

[Yamaha Tri-Moto]

it sounds like nuts and bolts rattling around when i slow down the idle the rattle also slows down.

[MTS]

it sounds like nuts and bolts rattling around when i slow down the idle the rattle also slows down.
It kinda sounds like it Could be from your Centrifical Clutch, worn out the shoes could be flopin around, i would pull the motor and the side case and thoughly inspect it, also i would check make sure there are not any loose bolts behind the pullstart cover rattling around in there.

[Yamaha Tri-Moto]

well when i put my ear beside the cylinder it actually huts my ear its so loud, so im pretty sure its coming from up there. Also the noise is heard most when at idle.

[holmstrom]

It kinda sounds like it Could be from your Centrifical Clutch, worn out the shoes could be flopin around, i would pull the motor and the side case and thoughly inspect it, also i would check make sure there are not any loose bolts behind the pullstart cover rattling around in there.
you dont need to pull the motor to take the side case off. Just the tire and the brakes. I guess if you used a short screw driver you wouldnt even need to do that. The pall spring on my pull start is gone and makes a pinging sound when it flops around, is that the sound you hear?

[Yamaha Tri-Moto]

Naw its more like nuts and bolts flying around in the cylinder. its loud. but when i slow the idle down the rattle slows down. Think it could be some kind of air leak?

[holmstrom]

its aloud ping. I dont ride that one, till i find a spring. Its that loud.

[Yamaha Tri-Moto]

ya i guess you might call it that lol. but still more like a rattle lol.

[holmstrom]

sounds like nuts rattling around in a can? I'd take your pullstart off and check to see if the spring is pulling the pall back in when youre not pulling on it. Mine just flops against the starter pulley and makes quite the noise.

[Yamaha Tri-Moto]

yes thats the sound

[holmstrom]

I'd take your pullstart off and check to see if the spring is pulling the pall back in when youre not pulling on it. Mine just flops against the starter pulley and makes quite the noise.

[Yamaha Tri-Moto]

I actually had the pull starter off already tonight becase the rope got stuck so I know everything in there is in proper working order, any other ideas, its been driving me insane for months lol. I wonder where Tim Sr. is, he seems to know alot about alot.

[Louis Mielke]

Was the lower rod bearings tight? I did the topend on a dirtbike once without really checking the lower end. Only 15 minutes of run time the thrust washers went out and ended up rattling in the lower crank case. Its amazing that they didn't cause a major lockup. I was so lucky. You sure your rod was good and tight? Alot of the 2 stroke tri-motos I've come across have had some sad looking cranks. no one ever bothers to do the lower end.

[Yamaha Tri-Moto]

That could be, how much play should that rod have??

[thefox]

I was talking to the mechanic at my local Yamaha shop and he said that with bad crank bearings you will hear a rattle noise that will get quieter when a load is put on it (like driving).

My YT125 has a little rattle to it also but I'm not going to worry about it, it's not too bad and it’s a beater not to mention it’s not really mine but my brothers:rolleyes: .

[Yamaha Tri-Moto]

Thanks man i think that put the problem to rest. I remember a year or so ago a mechanic told me that the bearings were going on it. How much if any would this reduce the amount of time my top end will last?

[RideRed250R]

could be the bottom end rod bearings just sounds like its up top