i have a partner 400 chainsaw which was is running badly, it was just about starting so i changed the plug, and it runs fine until you open to around full throttle and it bogs down as if something is stopping it going to full power iv'e been fiddling with mixture screws but to no avail any help would be much appreciated

steve, February 2008

Check for wasp nest blocking the exhaust.

Graeme, April 2010

Turn your high speed just screw OUT a half turn.

David, March 2008

"Adjusting and tuning a chainsaw carburetor"

http://chainsawr.com/?q=node/8

L. Chee, March 2008

Hi
It could be a couple of things 1st in the tank on the end of the fuel line is a filter this can block and can course fuel starvation second if the needles are set correctly the carburettor diaphragms could have gone hard and may need replacing as this governs the correct amount of fuel hope this is a help
Quince
www.swalelawnmowerandlandscapingservices.co.uk

quince, February 2008

Have u cleaned the air filter?

2 stroke, February 2008