2009 Ski Doo 800R - Base Gasket - Need your help guys - UGH!

[BriPar]

Hey Ski Doo'ers, need a hand here.

Rebuilding the top end on my 2009 800R and I am in my garage, stuck on this problem!
Blew the base gasket after an overheat, so I am replacing the pistons, rings, gaskets, etc....

Here is the problem:
Looking at the gasket kit, there are two, a thick and a thinner base gasket.

Of course, I don't have the old one to compare and searches on-line have not been helpful.

Need your help here.

Many thanks in advance.

 

[jimfsr]

You have to assemble the whole thing w/o a base gasket. Use a piece of soft core solder and lay it on top of the piston through the plug hole, rotate the shaft through a couple of revolutions and see how thick the solder is. This is called checking the squish. (the space available above the piston) The solder will only flatten out at the edge of the piston. Measure this thickness and check with the dealer for that specific model for the proper squish measurement. Measure the gasket thickness and subtract that from the squish measurement to determine which gasket to use. Or, just put in the thickest gasket and don't worry about it. The motor may not be at the best possible configuration for performance, but you won't have any high compression issues(detonation) Honestly, seat of the pants, you wouldn't notice the differance anyway. Using the thinnest gasket may result in a high compression situation, which would require high octane fuel and possibly cause detonation under load.

Jim

 

[BriPar]

Jim - So many thanks for the detailed instructions and after all the work I have done to get the motor out, etc., this is certainly an important process to ensure the rebuild is completed properly.

Two questions and I should be all set here:

Is soft core solder something available at any parts store (Napa, etc.)?
When doing the squish, you mentioned that the base gasket should not be installed, but how about the head gasket?

Thanks again,
Brian

 

[snowbuff]

Base gaskets for doo's have up to six, paper punch type holes in them. How ever many holes are punched, determines the thickness of them. Jim is correct on one way to do this, but you should be able to contact a dealer to find out which one (how many holes) to use. If you do it Jim's way, you would need to have the head gaskets installed to get the correct squish reading.

 

[ezra]

check over at http://www.dootalk.com/ some one over there would know.
back in the day on zrt we would use a thick base then shave the head to change port timing was very efective on the cat trippel

 

[mjkaliszak]

Above true... I think they are recommending the 8 hole gasket for those motors. You can call MCB or Big John @ sledhead racing in Minnesota. I'm not exactly sure but I just put a 8 hole in my 800 P tek, I believe the 800R is a monoblock and that will determine which gasket to use. Either 6 or 8 , I think the AM shops are recommending 8 due to the fuel we r buying it is of inconsistant quality.

MJK

 

[jimfsr]

Jim - So many thanks for the detailed instructions and after all the work I have done to get the motor out, etc., this is certainly an important process to ensure the rebuild is completed properly.

Two questions and I should be all set here:

Is soft core solder something available at any parts store (Napa, etc.)?
When doing the squish, you mentioned that the base gasket should not be installed, but how about the head gasket?

Thanks again,
Brian

In the case of the ski doo motor, the head uses o-rings, which do not add any thickness to the squish measurement as it is metal to metal. If there were a head gasket than yes it would have to be there. Solder-anything that would be used for pipe sweating/plumbing work is fine.
Again, this procedure is for max performance, use the thickest one for safety if you cannot measure it accurately.

 

[dab102999]

Second what jim said..u aint gunna notice the different gasket on the fun meter and the time u will spend tryin to figure out which one to use will be waisted riding time...unless u r lake racin and tryin to get every 1/10 of a second u can...

 

[sledheadjoe]

If you have gone with an aftermarket gasket rather than OEM Doo, each hole on a Doo gasket represents 0.1mm. So measure the two gaskets you have with a caliper and use the one closest to 0.8mm thick and you'll be fine.

Above true... I think they are recommending the 8 hole gasket for those motors. You can call MCB or Big John @ sledhead racing in Minnesota. I'm not exactly sure but I just put a 8 hole in my 800 P tek, I believe the 800R is a monoblock and that will determine which gasket to use. Either 6 or 8 , I think the AM shops are recommending 8 due to the fuel we r buying it is of inconsistant quality.

MJK