Chainsaw Repair

The Husqvarna 365 special and 372XP have air injection

The air injection on this Husqvarna can give confusing impressions?

To remove the air injection and the adjusting needle baffle and do nothing else - - the engine will run noticeably faster

But this faster running is because the engine is now running leaner. To re-adjust the needles to the same mixture ratio as before - there is little difference.

This difference in mixture level is caused by the ambient pressure level inside the air box and its effect on the metering valve diaphragm vent hole of the carburetor.