At what point do I rebuild my top end
- Thread starter gusthebus
- Start date
You are past due for pistons and rings
You should find a different compression tester, maybe the one your using is inaccurate, at the compression you mentioned it should be hard to start when in the water
What should I get, will I have to get machine work or are there any drop in pistons ? No scoring, bore is fine
Myself, I chose cast pistons over forged on the 2 snowmobile top ends I have done. The bores that I did were nicasil plated and well within specs to just drop in new pistons and rings. I believe the seadoo engines have cast iron sleeves which can be bored and honed. I would mic the bore to see if it is still with in spec, take 6 measurements and check for out of round bores as well as piston to cylinder wall clearance. If your within spec which I doubt you are you could hone the cylinder and put in new stock size pistons and rings. If out of spec, buy 1 size over pistons and take them to machine shop to have cylinder bored and honed to match cylinder. I’ve never had to have a cylinder bored but when I do I’m going to take the specs to them. make sure to ask if they are going to add a chamfer to the ports.
Get a different tester, you can borrow one form O'Riley and AutoZone.
You have to have the cylinders measured for wear.
99.9% of the time with low compression you need to have the cylinders bored from a shop that know what they are doing and oversized pistons installed. Just throwing in new standard size pistons almost never works and you will just be doing it again.
You have to have the cylinders measured for wear.
99.9% of the time with low compression you need to have the cylinders bored from a shop that know what they are doing and oversized pistons installed. Just throwing in new standard size pistons almost never works and you will just be doing it again.
If you want to do the measuring yourself to check the bores before taking to a shop you will need a dial bore gauge and a caliper. I bought the Fowler dial note gauge and Mitutoyo caliper, just make sure you get the right caliper as they come in 1 inch increments. If you have the tools you may want to just double check the clearance between piston and cylinder wall before installing. Also get some feeler gauges for measuring your ring end gap, very important. To bad BRP didn’t use nicasil on these Seadoo’s it would have made the top end rebuilds so much simpler. 2 of the snowmobiled I did had 24,000 km and barely any wear at all. Tough stuff.
Not really, Yamaha tired that and it became a throw away cylinder. These watercraft don't just wear out the cylinders with mileage like other vehicles, they damage them so boring an iron cylinder is the way to go.
Yes, very expensive to have them replated if required, as long as you get to them before rings or piston skirts break and score them they wear forever. Or at least the ski Doo ones.
That is the problem on the watercraft, not sure what it is but they keep running on one cylinder until the bad cylinder is properly trashed.
