I've tried EVERYTHING. Yamaha G2 exhaust getting EXTREMELY hot.

[Boonamug]

I have a 1985 Yamaha G2 and the exhaust gets very hot, very fast. I have checked it with an infrared thermometer, and it gets about 700 degrees in like 3 minutes. The motor itself does not get that hot, just the exhaust. I have scoured the Internet for solutions and spent way too much time and money trying to solve this. It wasn't always this way.
-No, the air box doesn't leak. I've replaced the box, lid, and seal, all within the last 6 months.
-Yes, carburetor is authentic Mikuni. Cleaned multiple times.
-No, the "very fragile" plastic carb spacer is not cracked.
-Muffler is not plugged. Replaced it 9 months ago with a full Plowman's performance kit (Muffler and clutch)
-Brand new OEM CDI box.
-No, the motor cooling fins are not broken off or clogged.
-I've tried everything and could have payed for another one with the money I've spent trying to fix this.

It got so hot that the new muffler cracked just about an inch from where it bolts to the motor.

I can't give up on it now. Someone must have run into the same problem at some point.

Please help!

[Field6565]

Does Plowman offer any kind of carb upgrade or rejet with the free flowing muffler? I wonder if it's lean. Any problems prior to the new exhaust?

[CP241]

Originally Posted by Field6565

Does Plowman offer any kind of carb upgrade or rejet with the free flowing muffler? I wonder if it's lean. Any problems prior to the new exhaust?

Yes I believe he does.

I’d call him tomorrow. He’s be best equipped to answer I’d believe.

[Boonamug]

Yes, I received new jets with the plowman muffler. The new muffler was one of the attempts to solve the problem. Many people mentioned the "restrictive" or clogged original muffler as a potential cause.

[Boonamug]

No other suggestions?

[slonomo]

What did Don Plowman say? If you haven't called and talked to him, I would. He's a great guy and has "seen it all" with the Yamaha carts.

You mentioned the engine doesn't get hot...it should, it's an air cooled engine. Cylinder head temps should be in the 250 - 300 degree range.

Header pipe temps should be very very hot, not glowing red though. Although some small air cooled engines do have this issue if the engine is not moving and getting air flow through it.

When the temp is 700 degrees is that while driving or sitting still?

Is that temp on the header pipe that mounts to the engine?

Is this a G2 for sure? Is it 2 cycle or 4 cycle engine?

[griffo002]

One of then reasons a motor gets hot is if the timing is out...they don't need to be out by much to make them run hotter...Try retarding it a tad...not to much as it will kill your performance.

[CP241]

Originally Posted by griffo002

One of then reasons a motor gets hot is if the timing is out...they don't need to be out by much to make them run hotter...Try retarding it a tad...not to much as it will kill your performance.

Timing is electronic in the ignitor, and not adjustable on these.

[CP241]

Originally Posted by Boonamug

No other suggestions?

Yes

Call Don and ask him.

It sounds like you’ve spent a decent bit of money on his proprietary parts. Nobody knows his parts like he does. Anyone else here it would just be speculation

[Boonamug]

Yes, the cart is a 1988 Yamaha G2 type AB. With J38 4-stroke engine. I meant the engine doesn't get hotter than normal operating temp. About 300 degrees. The temperature of the muffler from where it bolts to the motor and beyond is where the extreme heat comes from. 700 degrees in 3 minutes of driving once around my block.
I have spoken with Don at Plowman's. He certainly is a wealth of knowledge. He is who I contacted after the "basics" didn't help. I then worked thru his list of potential causes and replaced numerous parts along the way. After all that, the muffler still got very hot and last week it actually caused it to crack.