Need help with pistons
- Thread starter Jakem1
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- 1996 seadoo xp
Are you boring for the first size over? If you are 82.14 mm pistons
Yes but I can’t find the right size pistons.
Would these be the right ones? One is 82 mm and the other 82.5 mmm
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The 82.5 will work, it’s the second size over, but you will have to have the guillotines on the rave valves trimmed back With these. Buy your pistons first and then take the pistons to your machine shop before they bore out the cylinders. I seen 1st over (.25mm) pistons for sale at Partzilla.
WSM - 010-818-04K - Piston Kit (786cc), 0.25mm Oversize to 82.25mm Bore for sale online | eBay
Here is a set for .25mm over
Here is a set for .25mm over
Thank you for the info. I’m new to the whole rebuild aspect and the terms, would boreing out the cylinders be something I could do?
Also just to throw out there i orders pistons that were 1MM over and they were to big.
You presently have the original cylinder bore, it’s never been bored out, it’s an 82 mm bore which is why your pistons have the markings 81.89. Cylinder to piston clearance is approximately 0.10mm. ( check your manual though) 81.89 + 0.10 = 81.99mm, basically 82mm. You can make the cylinders larger by boring them. The first time you have them bored it would be .25mm larger then .50mm .75mm and last one is 1.0mm which is the largest you can go. That’s what you have, I wouldn’t use them because if anything ever happens to the engine you wouldn’t be able to bore them again. You can’t bore the cylinders yourself, you will have to find a machine shop in your area to do this for you. Make sure they chamfer the ports on the cylinder, take your new pistons to them along with the clearance specs.
Ok thank you, that makes a whole lot more sense.
Thank you. If I didint get my cylinders bored, what size pistons would I need?
If I didint get my cylinders bored, what size pistons would I need? Would it be the same size?
It would be the same as you have 82mm
I have 81.89 tho
If you buy pistons for a standard 82mm bore they will be 81.89
Spider4real
Active Member
Wait. Why are you rebuilding the top end? I assume because you are lacking proper compression. If you put new pistons in the same size back in with new rings you will have accomplished nothing. It might work for a short time but you will be right back where you started in no time. Spend the money and do it right. Get the cylinders bored and buy proper pistons to match. Otherwise you are just wasting money.
Agree with spider
Unless you mix your cylinder bores and they are within spec
Mic not mix
So do you suggest having then bore .25mm - 1mm?
my pistons are 81.89. Cylinder to piston clearance is approximately 0.10mm 81.89 + 0.10 = 81.99mm, basically 82mm. Now my cylinders measure up to about 3inch 1/8 and the pistons that I ordered measure up to about 3inch 1/4.
I’m just trying to understand how much needs to be bore.
If you don’t have any damage that would require boring more than .25mm over then yes that’s what I would have done. Buy the pistons first, take them to the machine shop
With you along with the spec sheet showing the piston to cylinder wall clearance and they will
Know how much to take off. Don’t forget to remind them to chamfer the ports
With you along with the spec sheet showing the piston to cylinder wall clearance and they will
Know how much to take off. Don’t forget to remind them to chamfer the ports
I really want to get them bored but it’s a little on the expensive side.
I know it’s not a good option but should I get the same exact size pistons and replace them or a different size?
Spider4real
Active Member
You cannot use a different size without boring the cylinder. These things are made to very tight tolerances.
I personally took my cylinders to the machine shop first and let them know all the current size pistons I could get and they told me what size I needed to buy based on how much material they had to remove to make the cylinders round again. I went from standard to 0.25 over.
I personally took my cylinders to the machine shop first and let them know all the current size pistons I could get and they told me what size I needed to buy based on how much material they had to remove to make the cylinders round again. I went from standard to 0.25 over.
