I just recently bought a 1986 250r in great shape. The owner said that the motor was on its first over bore with about 80 hours on it maybe. I decided to do a compression check on it but kinda messed up and now I am at school and the quad is an hour away tell me what u think though. What i did was hook up the tester in the plug hole and kicked away while cold? I didnt start the motor at all the whole day and i didnt hold the throttle wide open though. I got 152psi max with a closed throttle. What do you all think about the condition of my rings/cylinder? thanks

 

ttt

 

Many variables in question... First of all, to be somewhat accurate, you should hold the throttle wide open.
Typically you'll get a lower reading if you don't.

152 isn't bad... not nearly as high as I run, but mines not stock either... depends on whats been done to your bike... if it's a stocker, that's decent, modified, it's pretty weak.

My $.02

 

As mentioned, hold the throttle wide open when kicking it over.
You should have at least 170 lbs of compression. If less than that, its probably time for a rebuild. If its got 80 hours on it, its probably close to being due.

Crank it over with the throttle open, and see what you get.

 

152 is pretty low, try it with the throttle wide open and kick it 3-4 good full strokes. I am in the process of rebuilding my 86 right now. The cylinder was only on its first overbore but had gotten so egg shaped the engine could be started by hand. Check your piston, most 85-86's I have seen apart had a crack on the intake side of the piston, including mine. I am shooting for 190-200 lbs. of compression to run well with my porting.