what is the stock cylinder pressure for an 88 zilla? i amn looking at another one that makes 120 lbs with the throttle wide open and the engine warm. is this a decent measurement or is it going to need a rebuild?

 

That sounds a little on the low end. Blaster is 125 and I thought that was low, the 250 Qracer stock is around 155-160.

 

The stock Quadzilla only has 120-125 psi. You can't compare readings from different makes and models. The LT250 has 175 psi after a fresh rebuild and the 250R Honda has 145 psi. A larger piston cannot tolerate as high of a C.R. and still run on pump gas. Detonation will result since the flame front has to travel so much farther than in a 250cc machine. I have a 59cc dome in my head and only have around 135 psi. However, both my engine builder and CT Racing recommend race gas for this set-up. I know Duncan Racing even recommends race gas for a stock 500 due to its problems with detonation.

 

okay, so the engine is probablly in good shape. I knw there are other variables, but it runs great, idles fine, dosent miss a beat from no throttle to steady WOT, clutch dosent seem to slip and all the gears are there and shift fine. Is thre anything else to llok for in a motor to see if it is good or not?
The bike im looking at is an 88 zilla (I plan on building twins over the winter) in fair shape. tires are junk, fenders are junk, but all suspension joints are good, no oil leaks from shocks, steerning stem is straight, rear bearings are good, axle seems straight, brakes work well, but every bit of paint on the thing is junk.
Do you guys think it is worht $2600?

 

If the owner will let you do it you should remove the flyweel cover and check for play in the main bearings. If the flywheel moves up and down at all, you will at least need new bearings and, at most, bearings with new case inserts.

 

to check crank play, i can remove the flywheel cover on the left side, and he might let me, but is there anyway to check crank play on the right side?
do i check play simply by moving the flywheel, or trying to move it up and down? and if I feel anyhting it needs work, or is there a way to meausre play?
thanks.

 

You have to hold the flywheel real firm so that you can be sure where any movement comes from. You should not feel any movement when pulling straight up and pushing straight down. If either bearing is bad (left or right) you will feel it at the flywheel.

 

if he rode it and there no vibrations i doubt theres crankplay?

 

I've replaced my bearings twice and had the cases inserts installed. They never got so bad that I noticed more than normal vibration. An air leak will usually develop if the bearings are bad long enough for an engine vibration (if you wait that long to change out the mains, you have most likely done some damage to the top-end). Based on the good running condition of the described LT, it probably doesn't have an air leak but could still have weakening bearings.

 

my 86 lt250 has a some vibration when im just about toped out in 5th gear is this normal? [img]i/expressions/face-icon-small-confused.gif[/img]