Well, my stupid quad is overheating. I just got the engine rebuilt and rode it about 2 hrs with out a problem and then I opened it up in 5th gear probably 7/8s of full throttle for like 2 min, and it overheated and has been doing so ever since. When it idles, its fine, but as u get riding, it boils the coolant. Im pretty sure its circulating because the radiator is getting warm, but it just over heats. Its very lameo! someone help me, I cant ride for more than 15 min..

-nick

 

let's see
what's the overbore on the pistons? Supposedly banshees start to overheat at .080 over but mine doesn't. Also check your radiator pump. It might be shot. maybe a clogged hose somewhere too.

 

Are you positive that you did not swap the upper and lower hoses on the radiator? it's hard to do because they are molded ....but possible none the less.

Are you still running the stock plastic impellor?
Did you rejet with the new pistons? maybe you are lean?

just some ideas.

 

I think Sayit_fmf hit the nail on the head right there..... Have you check any of your jetting since you got the overbore? Checked your plug? Sounds like you could've had a lean condition, and now it has advanced.... I'd check your jetting. Maybe time to pull apart the top end again and see if you stuck a ring, or have a blown head gasket, etc.

 

If the jetting is off that bad, you're eating through a piston. It wouldn't bubble the coolant first, it would erode the piston. If you're bubbling coolant, you may have a head gasket leak which is causing cylinder pressure to enter your cooling system through the water jackets. I would suspect this first since you just had it rebuilt and the head was off. I've seen it many times on LC two strokes. Drain the coolant, pull the head, and check the gasket and head area for evidence of leaking compression past the head gasket. Also check the head for flatness now that it's been heated up a few times.

 

In the short term the symptoms would show as an overheating bike.. The pistons can take a good amount of abuse/heat before they start to "eat through" as you put it.
I have rebuilt a good number of banshees...rarely do I see a piston with a hole in it. When you do...it is usually water related..or a seriously bad jetting job.