I purchased a 96 MXZ last year and have the problem of fouling the plug on the
PTO side. It randomly fouls out. Some times I only get to ride for an hour and some times a hole day. I do have a mechanical background and here is what I have tryied so far. New coil and wires, plugs are BR9's, carbs have been cleaned
out by me and then also a sled shop., have verified stock carb settings, exhaust
valves cleaned. no leaks in the vaccuum line to fuel pump or pump leaking fuel into case. compression is good and equal in both cylinders, carb boots look good, cable to oil injector adjusted correctly. Does anyone have any more ideas. I did replace the primer assembly as the last thing. Due to no snow I have not run the sled since then.
Thanks
Keith

Sounds like you've done a lot of work. Perhaps a change in the oil you are running might help. Just a thought.
Have you done a spark test with a large gap tester to verify both cylinders are equally strong?

Recheck your carb setting,needle on the pto might set too rich.........

double check spark plug gap at 18 thou,

try using br9eya's.

Thanks for your replies. I have switched oil to a synthetic oil and that did
not help. If my spark plug gap is to large wouldn't that effect both sides. I will
go through the carbs again the next time I get them out of storage.

Keith

main jets are staggered on those sleds. How is the float needle and seat?

I cleaned the carbs out once and things looked fine. I then took it to a local sled
mechanic for a second opinion and he said everything looked fine. I did question
having the needle and seats replaced and he thought they looked good. I am beginning to think that I should go ahead and replace them anyways. It was just that everything was starting to add up so I did not want to replace parts that were not bad. The needle and seats are of the viton tip type.
Thanks
Keith

i agree you might want to check the carbs i had a 95 mxz that would foul one plug out i had it looked at and it kept doing it so i took it to some one else and it ended up that the one float bowl was set to high

one thing you didnt mention is whether or not you did a good job of mechanicaly syncronizing your carbs (slides dead even with each other going up and down)also after that put a vacuum gauge on it and adjust your air screws.its quite possible they are out of sync with each other.

Thanks again for the help. I think that I did do a pretty good job of mechanically syncronizing the carbs. I use a drill bit to set them both to the same opening size. I do find it quite interesting that Mach925 had the exact same problem and that it took several people looking at the carbs to get them set right. I will also try and put a vacuum gauge on it. Going to find the problem one way or the other. 6-10 plugs a weekend is a pain in the you know what.

Thanks