Overheating Tri-moto 125?

[400ccHomemade]

I have a Yamaha 125 Tri-Moto. It runs awesome for about 15 minutes, then it runs bad, then terrible, then it barely runs at all. I really get the feeling that it is getting hot. Why would it get hot though? There's no radiator, no fan, its just free air. Maybe it's too lean? What else could cause this? It's really a shame, it runs great for 15 minutes or so.

[yamahaman89]

it could be when trailprotrailpro automatic clutch get warm it slips really bad

[rustbucket]

ty new rings mine used to do the same deal run good then fade a little then die rings cured it

[kando]

It's probably getting hot as there is no hone pattern left in cylinder walls. Oil has no place to sit on wall, thus no lube lots of heat. I'd say rustbucket is right on the money. Top end worn out , give her some attention.

[400ccHomemade]

Thanks for the ideas. I'm pretty sure it's not a clutch thing, because it dogs, not slips. The rings/hone thought sounds about right to me. Where would I go about getting parts for this old beast?

[edog]

Conntact the yamaha dealer they might have parts.Check ebay as well.

[kando]

I would do a compression test first just to make sure. We are not experts just helpful advice, as for the overhaul get everything measured to see if rebore is needed for new piston/rings or just a hone job and rings. Usually it is worn enough to go with boreing it out. As for parts go to Yamaha or aftermarket I think denniskirk has piston and rings.

[rustbucket]

Yamaha still makes the piston rings they are $10 apeice, they also have the reeds too but they are of a slightly different design, they now have two petals, wiesco makes pistons too

[400ccHomemade]

How many rings does it have? My Ski-Doo only has one ring per piston. I didn't think of the reeds, tey are probably shot too. *sigh*

[kando]

I take you didn't have time to tear it apart yet, ther is only two rings in there.

[400ccHomemade]

Nope, didn't tear it apart yet. Probably won't for awhile. I have a bunch of "toys" so I can only spend money on 1 or 2 at a time. I need a few parts for this first.

[400ccHomemade]

What other things will I need? Like gaskets and things I mean.

[kando]

2 rings, intake, exhaust, head, and base gasket. If your just doing a hone job and slapping rings in it.

[400ccHomemade]

Well, not to sound like I'm cheaping out, but, I could just leave the intake on couldn't I? I mean, slide out the carb, and leave the rest? I see no reason why I couldn't, except maybe room getting the jug off.

[rustbucket]

If your not going to replace the reeds yes, but it seems to me that there wasn't a gasket on mine I want to say it had rubber on it, the exhaust you could make from some gasket paper, i never had one on my 125.