97 xp backfiring issue found problem

[Hurban96xp]

Well i finially got feed up with working on my 97 xp. The motor would bearly start and backfire and bogg down and cut off. Tonight i just took the motor out and on the back side of the motor, there was oil everywhere. I just painted the motor when i put it in and it didnt run but maybe 2 or 3 mins. I grabed a flash light and looked close while i turned the motor over and i feel air coming out of the cylinder base gasket. I pulled the head then the cylinders off and sure enough the pto side gasket was all there but missing about 3 inches of it and the mag side was missing 4 inches, the missing gasket was no where to be found. How could this have happened. I did buy this motor used off ebay and it did look like the head bolts have been taken off before. i wonder if the guy pulled it apart and just slaped it back together not knowing that he riped the gasket and it wasnt there anymore?
Im glad i found the problem but mad that i got screwed on ebay. the guy said it ran fine. What should i do just slap new gaskets in? or do a rebuild. the motor had good compresion.
thanks guys

[mikey20]

Re: 97 xp backfiring issue found problem

backfiring can cause a base gasket to blow out ,it can also damage your rotory valve ,after you repair the base gasket assuming there is no damage from the three inch air leak you will want to double check your timing on the rotory valve,inspect for damage and excessive clearance as well.

[David3aces]

Re: 97 xp backfiring issue found problem

Pistons look good?

[Hurban96xp]

Re: 97 xp backfiring issue found problem

Yeah pistons look good. The motor didnt really backfire, it was popn not loud just runing really rough and bearly would run. YOu couldnt even give it gas and it would cut off. When i could get it started it would just pop back through the carbs and cut off. Sorry for saying backfiring but there was no real loud hard backfiring just running really rough. The motor did this from day one when i put it in, it never ran. i looked in the ski and everywhere and could not find the gasket. i got a digital camera if anyone wants to see pics. thanks

[Bill O'Neal2]

Re: 97 xp backfiring issue found problem

Actually, the gasket gets sucked into the motor and eaten up and spit out the exhaust pipe.

Your backfiring was caused by the missing base gasket material. They backfire when they suck air and go dead nuts lean like that.

If your pistons look fine and clyinders look fine, just buy a new base gasket and put it back together.