Has any one here experienced a no power / surging effect from low throttle to mid throttle?

The quad runs great from mid throttle up to full throttle.

I checked the plugs (2) they are O.K., and put fresh gas in with Lucas injector cleaner and the problem still persists.

I did notice the exhaust leaking at the donut at the "Y" pipe at the manifold which would probably cause the occaisional backfiring when I let off the throttle but what's causing the hesitation/missing/surging/low power effect at low to mid throttle?

Thanks in advance for your response!

 

The exaust donut leaking may cause it, is the throttle cable adjusted correctly, should be 1/8 inch slack on the thumb control.The pilot jet may need cleaned in the carb, will it Idle? Take some carb cleaner and spray the intake boot from the motor to the carb, if engine smooths out the boot is cracked, I've replaced several of these.

 

I checked the throttle cable for the clearance and it seemed to be within spec. I'll have to purchase some carb cleaner tomorrow and spray the intake boot as you indicated. The engine does idle although it could be smoother in my opinion. When I nail the throttle, there is absolutely no hesitation either. It takes off like a rocket. Thats what baffles me.

This intake boot you speak of, a common thing to go bad?

Can it be replaced without pulling the gas tank off?

Thanks Kerrbirds!

 

Yes very common, you can replace it by removing air box, then the carb from boot , may have to cut the zip ties to get enough slack in the throttle and choke cables, remove gas line from carb , take carb back in air box location then get a 1/2 socket and fairly long extention,reach in from air box area, remove 2 bolts that hold boot on, new boot ie 55-60 bucks, seen several on the older machines go bad.

 

I ran to the store after work today and purchased some carb cleaner.

All confident and thinking this has got to be the problem, I went straight to the quad with the cleaner. I started the machine up and let it idle a bit and started spraying here, there and any place I could where the boot meets the manifold and where the boot met the carb. I'm sorry to report that there apparently isn't a crack in the boot because the engine idled normally without a hiccup.

(That was a good test to conduct. I remember doing that on a carburated vehicle years ago looking for a vacuum leak...thanks Kerbbirds. )

So, passing this test, what should I look for now?
I welcome any ideas.

 

Have you done the recall on the vent line from the motor to the airbox? Mine ran bad because the little filter freezes in the winter then cracks and sucks air where its not supposed to, ther is a recall on them they replace it with just a line and no filter, might be it. If thats not it, take the bowl off the carb and remove the jets and clean all potrs and holes good with carb cleaner, maybe pilot jet has saomething in it.

 

OK, I'll do some fact finding on that line.
Thanks for your advice and experience!

 

I just had the exact same problem with my 2002 sportsman 700...I took it to the dealer, they replaced the needle and seat in the carb...but it still did it, so they adjusted the float and it has been running great ever since. Most likely it is running lean for some reason, this is the most likely reason with this particular quad.