I AM HAVING SOME PROBLEMS GETTING MY 4-WHEELER TO RUN RIGHT. I HAVE A 2001 AC 500 4X4 MANUAL.

WHEN I GIVE IT GAS, IT GOES, BUT THERE IS A SUBSTANCIAL LOSS OF POWER, AND THE 4-WHEELER KEEPS ACTING LIKE ITS WANTS TO DIE. I THOUGHT THAT MY CARB NEEDED CLEANING AND THE JETS MIGHT BE STOPPED UP, BUT I CLEANED THE CARB AND CHECKED THE JETS, AND THEY ARE BOTH FINE.

I THOUGHT THAT MAYBE IT WAS GETTING TO MUCH OR TO LESS AIR. I FOUND THAT THE HOSE FROM THE AIRBOX TO THE MOTOR WAS KINKED TWICE. I FIXED THAT, BUT IT CHANGED NOTHING. I ADJUSTED THE AIR/GAS MIXTURE WITH THE ADJUSTMENT SCREW ON THE BOTTOM OF THE CARB. IT CHANGED NOTHING.

COULD IT BE A LOSS OF COMPRESSION? COULD SOMETHING NOT BE TORQUED RIGHT. I JUST HAD THE TOP END REBUILT HERE RECENTLY.

I DON'T KNOW WHAT ELSE IT COULD BE. ANY SUGGESTIONS?

ANY HELP WOULD BE GREATLY APPRECIATED.

THANKS

DAVID

 

What about the valves being out of adjustment? This would cause a loss of compression and power, and make it hard to start. Might even cause it to run hotter than normal.

SJ

 

The guy who rebuilt my top end said that he had the valves adjusted and set them back to spec. I don't think that's the problem, but it's possible. Thanks for the input.

Come on guys. Keep the suggestions coming.

 

Once you start your bike and it runs for awhile, does the problem clear up after 15 min? If you have a winch and you use the winch at the same time as the gas, does it rev??

 

My other question would be to examine the plug color and double check the plug type?

Not sure of exact plug type off the top of my head...NGK ....?

Plug should be tan colored after engine is shut off at temp.
Plug color will tell you how or in wich direction to adjust the air/fuel mixture screw.

Might also check for an air intake leak around the carb boots. This can be done by spraying a little (I stress little) WD-40 around the rubber boots with the engine running. Look for a change in RPM's.

When I had the top-end of my 400 rebuilt I also had the cylinder, piston and rings replaced. So I had to break it back in like a new engine. Once my engine got broke in again the power returned and then my clutch started slipping. 10,000 miles will do that I guess.

SJ

 

No winch and no the problem doesn't clear up within 15 mins.

I just had a new piston, rings, gaskets, and a sleeved cylinder installed. There seems to be a small leak coming from the front of the head. My exhaust doesn't have a rubber seal where it bolts to the motor, but it didn't have one when I took it off. It has the correct spark plug in it, but I haven't checked to see what color it is now.

My starter clutch has gone out and the bike goes in the shop either later this week or next week to have that replaced. Oh and the bike has a new battery also.

Just today my start button stopped working. I bet that is just a bad connection in the switch or some corrosion. It has happened before and I already fixed it once (or thought that I had).

 

What about the fuel pump? Mine works off a vacuum that connects on the boot between carb & cly. or the vac. line could be cracked so the pump is still working, just not correctly.. Just 1 more thing to rule out.....

 

Also check your carb primer an make sure it not opening up that will cause the problem too.

 

Wanted to let you know I just rejetted my 07 650 h1. was gonna order jets online till I stopped by the Harley dealer, talked to the mech. that does rejetting on new Harleys after everyone changes pipes. A/C's & many Harleys use the same carbs.
Got my pilot and main jet for 4 dollars. Go figure...
By the way, made a very noticable difference. Runs much better..

 

My cat goes into the shop today to get the starter clutch assembly replaced. I will have them check the bike out and see if they know what the problem is. I will post an update when they tell me whats wrong. Thanks for all your suggestions, but I still haven't pin pointed the problem.