Need Tri-z help

[1prl33]

My 85 tri-z has been in storage for 3 years. I got it out today, drained all gas, cleaned carb, fresh plug, she started right up! Then I remembered why i put it away. had top end done 3 yrs ago and when i ran it after it wouldnt idle rite. idle goes up and down on its own. AND there is a very peculiar knocking sound in the motor. The bike ran perfect before the rebuild. Anyone have any idea what could be going on with it? Any help would be appriciated. After 3 years on 4 wheels, I NEED a Z-fix. Thanx

[nachop]

I had the same issue on my 85 atc250r. It was a vacuum leak. It ended up being a leaking cylinder base gasket. In your case, I would use WD-40, or carb cleaner, and spray it anywhere air can get into the engine, intake, head gasket, cylinder gasket, etc. It might even be a seal.

[1prl33]

I fugured the idle problem was an air leak somwhere Havnt had time to check yet. I sent the cylinder to a reputable shop. It came back with a new piston. Im not sure what brand or if its forged. rod bearings were good, no play. It has made the knocking sound since then. Its actually worse when it gets warm. Like i said, that was three years ago. I dont remember all the details. Thought maybe I did something obviously wrong during assembly. Didnt want to take it apart if i didnt have to.

[nachop]

Three years is long time. Are you sure that the noise is new? Two stroke engines are pretty noisy. Now you did say you put in new top end. Did you verify that the clearance between the piston and head were good? If everything is within spec, I wouldn't worry about it. Good luck and post your results.