97 XP compression???

[pags1220]

Hey guys. I picked up a 97 XP about a week ago. When I tested the compression everything was pretty good. They po stated the motor was rebuilt recently. I'm guessing just the top end as you can see the new gaskets and what not. On a crappy harbor freight tester it was reading 110 psi. Being they read low I'm guessing its about 135psi. I took the carbs off for a rebuild. And decided while they were off to spin it again. (Probably not a good idea) now the first cylinder closest to the stator is reading 30 psi? Is this normal if the carbs are off?

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[Coastiejoe]

Hey guys. I picked up a 97 XP about a week ago. When I tested the compression everything was pretty good. They po stated the motor was rebuilt recently. I'm guessing just the top end as you can see the new gaskets and what not. On a crappy harbor freight tester it was reading 110 psi. Being they read low I'm guessing its about 135psi. I took the carbs off for a rebuild. And decided while they were off to spin it again. (Probably not a good idea) now the first cylinder closest to the stator is reading 30 psi? Is this normal if the carbs are off?

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If only the carbs are off, then something is wrong...
You could remove the intake and the exhaust and it should not in theory affect compression.

 

[AdamXP800]

Yea, something is definitely not right here. What is the pto cylinder reading?

 

[pags1220]

110psi in PTO cylinder. With a cheapo gauge. It was reading even right before I pulled the carbs. I think the cheap gauges read about 20 psi lower. Is it worth it to purchase a top end kit already bored? For the 300 I wouldn't mind having a reliable ski. Plus I could do the work myself

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[AdamXP800]

If it comes to that, I'd just go ahead and do a full rebuild or buy a reman engine with a warranty honestly

 

[pags1220]

Trying to stay away from doing a full rebuild. I'm going to reassemble everything today and check it again. If worst comes to worst I'll pull the head and expect. I just don't want to end up doing that and everything ends up looking good. Po also stated it only has about a hour on the rebuild. Maybe the rings haven't set ?

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[brianmcb]

I would doubt its a fresh rebuild if it's only showing 130psi on a good quality gauge. Fresh 787 should puff up to 150ish. My 96 gtx shows 138psi on the original engine with 110hra


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[pags1220]

Wellpppp. Assembles the fuel system all so nice and clean and neat. And whata ya know. Looks like I'm taring Down this top end this weekend. Hopefully its just a mistake the po made and I won't have to order too many parts. I also heard that if you bore the cylinder too much over you have to do some rave valve mod?? Is this true or is it more simple then I think it is??

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[AdamXP800]

I hope you didn't pay a running ski price always always test ride. But atleast you'll have a project to work on.[emoji570]

 

[pags1220]

1050 on the trailer.

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[AdamXP800]

Ouchhhhhhh

 

[pags1220]

At that time it had even compression. I guess the spx for 200 on a trailer was a better steal lol

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[Coastiejoe]

I would get an accurate gauge. The compression number is very important to know when you are chasing an issue.

Even at 130 you are on the low end..

 

[pags1220]

There is def no compression in the stator side cylinder. If you place your finger over the plug hole you can feel it is very weak. I'm going to tare In to it this weekend. Maybe its a bad o ring or gasket. I'll post up some pics after I pull the top end for your guys opinions. And I'll also be buying a better gauge this weekend too. Thanks again for all the info guys. Always a great help

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