Power loss after running hard

[Tommy_J]

Hi. I hope someone can out help on a problem that has me baffled.

After accelerating hard through a couple of gears my 500af looses power. It feels pretty much exactly like fuel starvation but the flow rate appears to be ample. Its been triple checked.

Interestingly, the bike did this with a PJ carb and still does it with a dialed in PWK.

The head was just pulled to inspect for signs of detonation and everything was clean and healthy.

The motor has a 96 CR250 ignition which is assumed to be functioning as the bike starts first kick and runs great, accept for this weird behavior.

[seanmx57]

How are you setting your float height? Could it be low? How much compression does it have?

[Tommy_J]

The float was checked and appears to be in spec. I say appears because I'm not certain I was holding the carb at the proper angle, while facing north and pressing my tongue against the roof of my mouth. I really don't think its low on the PWK and it definitely wasn't on the PJ carb.

The compression is only 130. This was measured about 20 hours after a fresh piston and ring. I was surprised how low it was. Probably time for a nice round bore job for the next rebuild.

Could an expansion chamber leak cause symptoms of running lean?