I've got the hpd big bore race mod, that hasn't been running like it should, so I went to check the compression last night and I can only pull it through one compression cycle then I can't pull it enough to get a compression reading, I thought the gauge was bad so I checked it on my other sport and it works fine. I put the plug back in and tried to crank it, same thing, I didn't try to start it for fear of what might happen. I pulled the exhaust and intake to check for a fuel filled cylinder, no problems there, I also checked the squish band it's .060 so it's ok there, any ideas anyone? If there is no plug or compression tester in it, it cranks over just fine?[img]i/expressions/face-icon-small-confused.gif[/img]

 

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use the electric start. Or just start it and fine tune.

Pennyless has two Aaen 440 Polaris's, and they are very hard to pull through to get compression test.
They run 120lbs worn out and 175 to 200 fresh.

The biggest problem is air. take lid off air box box and run K&N filter, without filter skin.( or twin-air )
Jetting starts at 390 and up on 42 mm TRX carb.

Need good fuel, real good fuel, real 92 octane, or better!

The big bore kit are a pain in the butt to fine tune. So use a exhaust temp gage from Aaen or anyone, this will tell you jetting by tempeture. 1100 to 1250 max degrees at exhaust head before first turn.
This WOT temp.