My son's '97 LT80 piston decided to seize during a ride. Cooling the engine barley got us back to camp.

Disassembled the top end and noted deep scoring of the piston and some aluminum deposits on the cylinder. The piston is stock and more than likely has never been replaced before, we bought the quad used.

I ordered a Wiseco .040 over to cover any cylinder scoring. After installing the new piston, rings, wrist-pin and bearing, with a bored and honed cyclinder, I decided to not trust the auto-oiler. My belief was that it may have been the cause of the failure.

Then I emptied the gas tank and filled it with a 32:1 mix of new gas and Maxim oil. Plugged the auto-oiler tube and its carb inlet tube.

The quad ran great for about 10 minutes. It started to make a knocking sound and I immediately shut it down. It would not turn over until the engine cooled for a short bit.

I noticed that the quad did not smoke as much as it did before the first failure and was using the auto-oiler.

I then removed the auto-oiler and noted that the drive mechanism would not turn when the engine ran. The auto-oiler pump spinndle does spin freely. Right now I am in the process of removing the trans cover to inspect why the auto-oiler drive it not working. This still does not explain why my pre-mix fuel did not smoke and possibly damage my new piston and cylinder. I would rather not depend on the auto-oiler, but instead mix my own. Do I need to richen the ratio? Change jetting?
Any other suggestions. Looks like I will be pulling the top-end again for inspection, hope theres no damage.

Thanks,

John

 

When you go pre-mix you need to remove the pump drive off the end of the crankshaft (lil black plastic piece).
w/no oil in it, the pump will freeze up like anything w/o lube.
Jetting is fine.

Frikken Weisco piston....they need a careful break-in. Dam things swell more than my belly on a good nights drunk. [img]i/expressions/face-icon-small-happy.gif[/img]
When you remove the head and find there is scratches,etc. just sand the bageezus out of the piston in the area and lightly sand the cylinder at the area effected also.
I usually go thru the sanding part 2 times before they will run, but then they are trouble free for a while. [img]i/expressions/face-icon-small-smile.gif[/img]
If worried, get a zuki piston (1.0 over). They are trouble free.
FYI: weiscos only when the bore goes to 1.5 and bigger.