95 XP800 - won't rev up and little power

[Jimnut]

I recently purchased a 95 XP800 for a price I couldn't pass up. I have had it on the water a few times now trying to troubleshoot why the motor feels as if it has no power at all. Some of the things I have done so far are:

Replaced grey fuel lines
Cleaned carbs and internal filters (everything looked very nice inside)
Cleaned rave valves
replaced wear ring

It behaves pretty good. Will idle just fine but terrible throttle response and it never really feels like it opens up and revs like it should. ( I have a 95 SPX with the 657x engine and it is easily twice as fast and exciting to drive). 3/4 - full throttle is required just to get on plane at any decent pace. Again my 650 SPX will walk all over this thing.

Tonight I removed the water box and then took apart the water regulator and the rubber diaphram was in really bad shape and wasn't sealed at all which effectively rendered it useless. Also noticed that the box had a lot of water in it (few inches deep when you looked down the exit port. I've read up on how the box needs to clear itself out to reach max RPM's and obviously that isn't helping the situation but It doesn't seem like that would cause all of my issue.

I have also done a compression check and the readings are 150 (mag) and 155 (pto). The motor was rebuilt 4 years ago.

Sorry for the long post but I am running out of ideas on what is holding back the RPM's and the power I know this machine is capable of. Any suggestions on what I should check out next?


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[Dr Honda]

An 800XP should be a little rocket.

Since you have good compression... and you don't have the normal "Fuel" issues... Id say you need to check the rotary valve clearance, and timing. Also... you will want to check the ignition timing.

 

[brock1]

just have to ask what did you pay for it . thats what i want to sell my 95 xp with the 720 to get ...they are supposed to be a blast to ride

 

[Jimnut]

An 800XP should be a little rocket.

Since you have good compression... and you don't have the normal "Fuel" issues... Id say you need to check the rotary valve clearance, and timing. Also... you will want to check the ignition timing.

I just looked through the shop manual on the procedures you mentioned and everything looks pretty straight forward. One thing I did notice is that if the ignition timing is indeed off the only way to change it is with an MPEM programmer which means I would need to take it to the dealer.

Also I cannot find a manual for a 95 xp800, only for the 96's. Also none of the 95 manuals have anything the references the xp800, they only talk about the 720's. One of the things that worry me is that I have read the timing is different on the 95 800's.

Do you know of a good place to get the timing degree wheel? I already have a dial indicator that I can use for TDC.

Thank you for the help!


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[Jimnut]

just have to ask what did you pay for it . thats what i want to sell my 95 xp with the 720 to get ...they are supposed to be a blast to ride

Paid $1000 for it. Hull is in great shape and came with a very nice single place Shoreland'r trailer. Once I figure out what is holding the ski back it will be a VERY nice ski.




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[Jimnut]

Well after doing some more research today I was told to check the rectifier by testing the voltage on the battery with the ski off and then running and it appears that the rectifier is bad. I was using an older analog meter so it was hard to tell but there doesn't appear to be any increase in voltage with the ski running. I am going to test this with a better meter tomorrow. Hopefully this fixes it as I am heading up north tomorrow for the rest of the week and I would really like to spend most of the time on the XP rather than the SPX!

 

[Dr Honda]

The quick test is to unplug the rectifier from the system. If it runs... then that's the prob.

Yes... the 95 800 was not a common ski. And... I think it was an update to the manual. As far as I know... they were the same engine... as far as timing. But, they did have a different pitch on the gear for the counter balance, and the threads on the PTO. (so the PTO, crank, and balance can't be swapped into a new engine)

 

[Jimnut]

Well I swapped rectifiers with a known good one from another ski and while the ski ran better ( is now just as fast as my 650 SPX instead of twice as slow haha! ) I think most of that was due to me fixing the water regulator on top of the waterbox. I did notice though when I had the carbs apart someone had put 147.5's in the mains instead of the factory 145's. I don't recall what the pilots were. I plan on rebuilding the carbs in the coming week or so to eliminate that from the list of possibilities. If that doesn't solve it I will be checking rotary valve clearance and timing along with the ignition timing.