550 xp troubles

[Samcronkite]

I have a 2 year old 550xp that has about 10 tanks of gas through it. I believe the decomp. Valve stuck open and burnt the piston. I replaced the piston and ring, cylinder was fine. Now the saw starts and idles but won’t rev up, it bogs and smokes like it is getting to much gas.
It has been to a dealer, they tested it, put on a new carb. Still didn’t work, got husky to warranty it and put on another carb, still same problem. So I have the saw back still not running right.

Any ideas as to what would cause this problem?
Thanks.

 

[Andyshine77]

I have a 2 year old 550xp that has about 10 tanks of gas through it. I believe the decomp. Valve stuck open and burnt the piston. I replaced the piston and ring, cylinder was fine. Now the saw starts and idles but won’t rev up, it bogs and smokes like it is getting to much gas.
It has been to a dealer, they tested it, put on a new carb. Still didn’t work, got husky to warranty it and put on another carb, still same problem. So I have the saw back still not running right.

Any ideas as to what would cause this problem?
Thanks.

Are you sure the cylinder was fine? Has the saw been vacuum/pressure tested? The older 550's had some QC issues with some of the transfer seals and a few other bits.

Check the muffler spark arrestor to make sure it's cleean, that can be real easy to overlook.

Make sure the dealer programs the carb to match the coil before it's installed. I've heard dealers were just installing AT carbs without programming the AT system on the carb first. These carvs are blank from the factory and will not function properly without the proper firmware.

After all that is looked at the ignition coil would be the next thing to check.

 

[Samcronkite]

Thanks for the reply.
What on the saw how should it be vacuum/pressure tested?
Is there anyway to test the ignition coil? Or is it a replace and see.

 

[Andyshine77]

Your dealer should have the proper equipment to vac test the saw. You have to block off the intake and exhaust ports, than put a vac and presser pump with a gauge on the saw. Anytime a saw burns up like this a vac pressure test must be performed. Not sure is these AT coil can be tested for proper function or not, check the other things I mentioned first an go from there.