HI,
I have a 95 Trailboss 2x4. I will tell you what I've done to the engine, HOWEVER, the problem was there before I did anything.

I just put a Wiseco piston in, honed the jug myself.
White Spring on the clutch
Ported head-intake side matched to the intake boot. Exhaust side gasket matched to the Wiseco exhaust gasket. All the way into the cylinder, pretty extensive job.
Piped but the stock header/expansion chamber
Synthetic gear oil in the gearbox, not the Polaris stuff.
2 clips up from the bottom on the needle, and 2 turns out on the mixture screw.

Ok, I have broke the engine in. It runs good, actually really good. Not a Sportbike, but really good for what it was meant to be.
Anywhoo, It will Idle along great for as long as you wish. But, if you rev it in "N", as if you were showing off the pipe, it will high idle for a minute or two. Then will drop back down to the normal low idle. But, while it's ideling up, of course you can't put it in gear, so you have to wait until it will slow down.
The throttle cable was frayed a bit, I found that when I raised the needle. I cut of the frayed parts, but I'm wondering if the cable isn't binding and holding the slide up temporarily.
It almost acts like it's lean for a little bit after revving it. I'm not going full tilt Nascar rev, but enough to show off the pipe.

Any ideas?
Thanks,
Mike

 

if i had to guess, you have a air leak some where. maybe the carb boot, or the crank seal behind the clutch.

 

Crank seal common on these? I just did one on my KTM, I thought that was the only bastard machine I had. How does the clutch come off, do you need a puller? I 've had the long center bolt out, but seems like there's something else.
Thanks,
Mike

 

Hey, also,
Anyway I can hook up a tach to this beast? I am doing a few experimintal things and need a good rpm feed. Would of course prefer an inductive pickup off the plug wire, but any other easy ways for a tach?
Thanks,
mike

 

the screw on top of the carb for the slide could be backed out to far