84' Cr250 problems

[MWC]

Ok, I have a friend who has a 84 cr250. He has not ridden it in a few years because he says that after he bored the jug and installed a new piston it lost all power at the bottom end. Not the normal shitty 2-stroke bottom end but worse. He says that he has to rev it up very high and then let the cluch out slowly to get it going. Once it is up to speed it runs completely normal. He has tried every jetting option and even had the bottom end gone through to find the problem, but to no avail, can anyone tell me what they think might be the problem? I may buy this bike, but he does not want to sell it to me in this condition.So I am interested in getting an answer to this problem. thanks for any help.

[88lt250racer]

Has he checked the compression?

[MWC]

I am not sure I will ask him

[MWC]

he says the compression was good

[ONLY2STROKES]

my 84 cr80 has the ATAC powervalve system (automatic amplification chamber) i think thats what its called...but it ran the same way when the cams for the power valve were worn.it was not opening and closing correctly.im not sure if the 250's have the same setup,but i'd check into that too.

[88lt250racer]

Close ATAC= automatic torque amplification chamber and yes the 84 250 had it as well.

[88lt250racer]

your close, ATAC= Automatic Torque Amplification Chamber and yes the 84 250 had it.

sorry for the double post I didnt think the first one went through

[ONLY2STROKES]

ahh...hahaha...yeah i forgot the T=torque...but that might be the problem though..

[Kane]

Had a similar problem on my 81 CR125. No ATAC. Tried absolutely everything to cure the problem. Finally got an aftermarket pipe and it made the world of difference. Never did figure why the original pipe was causing the problem. Likely not your problem though. I agree, I'd look into the ATAC. You might look into the timing being off as well.

[Meh]

Originally Posted by Kane

Had a similar problem on my 81 CR125. No ATAC. Tried absolutely everything to cure the problem. Finally got an aftermarket pipe and it made the world of difference. Never did figure why the original pipe was causing the problem. Likely not your problem though. I agree, I'd look into the ATAC. You might look into the timing being off as well.

I had that, only i had a Big Freakin Hole in the pipe, right off the flange....rusted n blew it out...Cracks also give you Hell...i would look at the pipe real close...