Plugging compression relief ports

[bajardine]

My brother in law just bought an '03 Vertical Edge 800 with a set of twin SLP pipes on it. The previous owner rode it at a lower elevation so now we need to get it set up for 7-9,000 ft. I was looking at SLP's instructions for the twin pipes and they say that all their setup information was based on the compression relief ports to the cylinders being plugged. In fact they say:

"SLPhighly recommends plugging compression relief ports in cylinders. Testing has shown a horsepower increase of 1.5 to 2 and an engine speed increase of 150 to 200 RPM."


How does one go about plugging the compression ports? I'm not familiar with them since I ride a different make snowmobile. We could always pull off the cylinders and send them to SLP but that seems like a PITA, especially if we could do it ourselves.

 

[bajardine]

Anybody know what I'm talking about?

 

[Goinboardin]

Yes. I recently rebuilt an 04 800, and also saw that on SLP's tuning setup. I found that the older cylinders, from 2002 (casting number 3021202), did not have that decompression hole so I ran those instead.

As far as plugging the existing holes in a cast number 3021339 cylinder, I'm pretty sure SLP welds them, which probably needs to be followed by renic'ing ($$). I've heard of guys using JB Weld, the hole does have coolant flow nearby so it may not get terribly hot... not really sure what to think of that though.

I never ran the sled before I built the motor, so I can't say if it was "worth" it to go without decomp holes.

 

[turbolover]

plugging the Decomp holes

They dont weld em the thread the hole and screw in a plug.
No renicing involved.

Had em do mine but they are a half hour from my house.