A buddy of mine is buying a 2001 Raptor from a co-worker. It has a high compression piston, Pro-Circuit exhaust, and uni-filter. I assume it has a jet-kit but I do not know for sure.

Here is the problem. It currently has a hard stumble in the mid RPM range that clears out at high RPM. Makes it feel like it has one hell of a powerband. The owner says it has just developed this recently.

My first thoughts were that the jetting was out, especially the needle-jet. But the fact that the problem has only materialized lately doesn't quite jive. The bike has been in a pretty substantial wreck at one time (highly distressed plastic, dents in the lower A-arm, cracked grab-bar, replaced handlebars) and I am wondering if something that knocked loose during the crash could be causing the stumble.

Another thing I am wondering about. On the bottom of the water pump is a small hole that a small amount of coolent leaks out of. The hole does not appear to be threaded and does not look like a nipple for a breather hose that has broken off. Any thoughts?

If any one has any ideas I would appreciate the advice.

 

Has the bike been setting for any lenght of time????

 

Thought of that. Had my buddy change out the fuel with no effect. It could still be that there is some residue in the carbertors. The plan was to clean those out today but I wnated to know if there was something else I should also be looking for.

 

First; The small hole in the bottom of water pump is a BREATHER hole for the water pump shaft...When you get a WATER PUMP SEAL leak thats where you will notice it (from that hole)......

Second; Is this stumble you are describing happening while you are riding the quad??? OR while you are reving it up??? (listening to it run in a garage).....

 

Thanks for the note on the breather hole. I will let my buddy know that he needs to replace the seal.

As for the stumble, it happens when reving in neutral as well as when riding.

 

Check the float height adjustment that could be where your problem is.....if you don't know how to do this, Freez has a very descriptive post on "how to" do this adjustment on www . blue trax . com (take out the spaces)....good luck

 

Thanks for the help BigDaddy.

 

Disconnect the plug that is in your clutch perch, spray some wd40 around the little silver plunger thing, then push it in and out a few times to work the wd in. This happened to mine when it sat for a couple months over the winter, and it fixed the problem.

 

If the clutch perch switch (REV LIMITER) was stuck it would stumble right off the idle to WOT.....from Canucklehead describtion of this Craptors problem the rev limitor switch is not it......BUT if the quads been sitting for a while, a good SQUIRT of wd-40 in all the switches wouldn't hurt....