Thanks Roy for answering all the questions. Ill be stopping at the local motorcycle dealership tomorrow to get a 140 jet. I was wondering how that primer pump separated from the bowl and glad to hear it will come right off. The coldest I normally ride is 25F (Ill let you do the C conversion). This will be my project for the weekend and will let you know how things work out.

Thanks again,

PS: What type plug do you run with your set-up?

 

Roys/Minehunter:

Just got back from riding the Cat 500 the first time with the new 140 jet. I ran it about 1 mile and then did the plug check (did it twice). The new plug (CR7E) was white instead of brown and/or brown/black as I had hoped for and backfired when I came to a sudden stop and turned it off. Do I need to ride it longer to check the plug condition? I was riding at around 8,000 ft. and the temperature was about 25F. Does these symptoms indicate a lean condition? What do you think is the problem as the only difference I can see is that I use a K/N filter.

Any suggestions or ideas?

Cat3608
2001 500 Manual

 

Backfiring can be a couple of things. The jetting is too lean, or it could be caused by an exhaust leak. Since you haven't touched the exhaust, you're probably running too lean. I would go up a size or two and try it again.

Mark

 

Hi there CAT you did the jetting job,no big deal is it.I will tell you that a white plug is to lean,,,dont drive until you get a larger main,,.Your engine will run way to hot and you may burn the rings,,,,,as for your back-firing,you may want to make sure that the engine is up to temp first and then do the test again.If it still pops then adjust your pilot jet.You will see it on the bottom of the carb I think..It is recessed in the carb and is spring loaded.You should try 1/2 turn in ,,clockwise,,, this may help.You will just have to go in and out on the pilot till you get it right with your new jet.I think the stock setting is 2 3/4 turns(not sure)I made a scratch on the carb with a nail to keep the stock setting in sight if I put it to far out of wack.Good luck on the pilot,,the tricky stuff starts now.
Dont forget to get a larger main,,,I run a 142 main with no problems.

 

Cat i did not tell you that i am at sea level and still stock filter ,so you may need to really keep a eye on the new jet ,,higher elevation will lean out a engine on its own anyway.You may not get to go any smaller at all.

 

Hi Roys:

Nice to hear from you! Well I stopped yesterday and bought a 142 to try it out this weekend. What does the pilot jet control in the carb? I thought at higher elevations you experience a rich condition versus a lean condition. Isnt this why you drop your jet size to compensate for the decrease in air (maybe Im just confused)? Would using a K/N filter flow more air so you wouldnt have to drop as many jet sizes than with the more restrictive stock filter? Ill let you know how it works out.

Thanks for the help!