Yamaha Phazer Low Comp. Pistons or Head Spacers - Snowmobile Forum: Your #1 Snowmobile Forum

ktmrider37 · 06-23-2009, 08:25 PM

I am looking to drop the compression on my '07 phazer 500 by means of either low compression pistons or a head spacer.

Does anybody know of anyone who makes either?

Thanks

**RJ Gleason** · 06-23-2009, 09:12 PM

ktmrider37 · 06-23-2009, 09:22 PM

i'm part of the clean snowmobile challenge team at northern illinois university. part of the competition requires the use of ethanol based fuel, we are running a turbo as well. we had some issues with over heating and feel that reducing the compression would give us better engine life as well as dependability while running around 12lbs of boost.

**smallengineguy** · 06-24-2009, 07:27 AM

Good idea. Any boosted motor needs low compression. Have you considered making a spacer block or stacking the gaskets?

ktmrider37 · 06-24-2009, 10:22 AM

I've have considered stacking up 2 gaskets. it has the multilayer steel style gasket. We had a little mishap up at competition last march with a quick disconnect coolant line coming clicked. Engine got extremely hot, we thought we tossed the motor, but we pulled apart the head and found the piston and valves all checked out, but there was a nice gouge sp? out of the head and block.

There was a machinist on hand and he milled the head and we sanded the block down. we think we lost somewhere between 9-15 thousands already so stacking gaskets may only get us back to stock compression.

Making a spacer is what is looking to be our only option. We can't find anyone who makes low compression, so we may be making our own head spacer.

Have you made one before?

**RJ Gleason** · 06-24-2009, 12:05 PM

Either use a spacer of have the heads milled for more clearance.

SkiDoo86 · 06-24-2009, 12:33 PM

Cheapest way and a good way would be to design up a head spacer in AutoCad or Mastercam, and have a waterjet cut it out. Not to mention probably be the quickest. And You could have multiple ones made. Milling the head is also an option like Rj said, but is more time consuming. And will be a little more expensive.

**smallengineguy** · 06-25-2009, 07:20 AM

Go on eBay and find an original cylinder for it, so it's not milled to begin with. Then double the gaskets.