95 XP question

[diamond_paul]

New to the site, first post. Lots of great info on this site.

I ended up getting this ski for $150.00 with a trailer so I could not really say no.


The motor runs fine at idle so I did some inspecting and I have 135psi in the front cylinder and 0psi in the rear cylinder. One would assume it needs new rings, but wanted to be sure that was the problem before I tore into it. I am pretty sure that the carbs are due for a rebuild also.

Edit: Forgot to mention its a rotax 717 engine.

 

[JPX]

Low or no compression most likely means rings. Plan for top end rebuild.

Doing carbs is a good idea while everything is torn down.

 

[diamond_paul]

Thanks.

Thats kinda what I figured. I will get a cold beer and start tearing her down tonight.

I have found out that no mechanic around her wants to touch it. They just want to sell me a new engine for $2000.00.

 

[diamond_paul]

Got the head and cylinders off tonight. There is a hole in the rear piston and the cylinder is trashed. Needless to say I need new cylinder heads and the rest of the top end. FUN FUN FUN!!!


I will have the parts in a few weeks I hope.

 

[derek]

ebay. cyls are cheap for 650's. make sure you get the RIGHT cyl. there are 2 650's the standard and the 650X. (it is also possible you have one of the first 720 skis.) the part number on the rear of the cyl ends in 380 for 650 and 382 for 650X. you probably need a head too.

 

[diamond_paul]

The motor is the 717/720. My machine shop says they can resleeve it if need be, so I am going to let them try that first.

The head is pretty much junk. I found one for $40.00 so I am good on that. I am used to working on Chevy V-8's, so when I had the whole top end off in 35 minutes I was suprised to say the least....lol Piece of cake!

I am pretty sure the wear ring is bad also, but looking at the shop manual it looks like a royal pain so I might wait a week or two before I get started on that.

 

[JPX]

If you've worked on car engines, it is a crack up to see a 2-stroke in pieces for the first time......unbelievable simple in comparison. Glad that you found a definitive problem so you can definitively fix it!

I understand that if you put it off after the engine is back together that you want to ride some more this season. But for the wear ring, you should just do it while everything is in pieces.

The reason why is that once your engine is running, you are going to be irritated about the power output with a jet pump that is not working its best. This assumes that the wear ring is indeed worn out - check clearance just to see where you stand.

Sounds like you can be running in less than $500 for this boat! At a $150 purchase price and some repair parts, you got a SMOKING deal!

 

[diamond_paul]

Yea its gotten worse.......

I need a new block also. I found a crack on the top of the block where the rear piston smacked it. My machine shop says they can fix it, but I dont know how. I found one at a junkyard for $50.00. That means a full rebuild for me..........Good thing I got alot of beer and like wrench turning.

I took the drive system off and the wear ring looks pretty good actually. I might go ahead and replace the impeller with a aftermarket since I already have it apart.

All and all it looks like $600 will fix her and get her running, so at $750.00 its still a deal. I dont plan on riding it this year so I am waiting to do the wear ring and stuff til later. Too many projects at one time confuses me....lol

 

[derek]

keep an eye out over the winter. these engines get real cheap on ebay. don't resleeve-too expensive. buy standard bore jugs used and rebore them for 30-40 bucks a hole. or else, bring ski to jersey and i will match the buck fifty you paid for it. heck-i tried!