i have a 98 polaris 400 sport with a K&N air filter. before any mods everything ran fine and dandy. would pop up from a stop to a wheelie. ect. i added a hotseat pipe and clutch kit and also a 250 main jet. the carb needle is set in the middle. the low end is very LOW and has trouble getting up and going for around the first 1sec to 1 1/2 seconds. also it does it more after ive been riding for a while and the bike gets hotter it kind of boggs down and then it kicks in and goes. mid and highs are very fast but its just the low end. i called Hotseat and they said they have had trouble with the pipe/clutch mod and recommended i lower my pilot jet from stock(35) to 25 or 22.5
everyone else said they usually go higher on the pilot after that kind of mod but who knows.. i sure am confused.
anyhow, i tried the 25 pilot jet and left everything else the same and it seemed to have helped but after about 1 1/2 hour of riding the low end starting bogging from a dead stop again.
i noticed today while cleaning it that the air filter was very dirty and as i slapped it around it would drop a lot of dust. i cleaned and recharged it but have not tried it again. might a dirty air filter cause that?
any help would be great. ive spent around $400 at dealers trying to fix this problem as well as their labor for the mod.

i also bought the oil pump block and was told by Hotseat to use 40:1 mixture and am using Polaris Premium oil(the gold oil jug)
thanks for any help
victor

 

After cleaning the filter try it again .

Hotseat pipes are adjustable . Add as many spacers as you have in the pipe kit . This will make the bottom end better .

Let us know if this helps . There are a few other things that could remedy the problem , lets start here .

Be careful with the lean PILOTjet .(EDITED TYPO BY RICK) On a long cruise with low throttle openings you may melt a piston .

 

The 250 mainjet is probably correct for a pipe like you have . I was refering to the pilot size and what its affect may be on long cruises atlow throttle openings . (I corrected that post I was thinking pilot , and typed main )

The airbox mod works fine , but really , we need to get things sorted out before you add more parts .

Clean the filter, and try a test ride .

 

thanks for replying. i forgot to mention that i did add the 2 spacers that were sent with the pipe.
what do you mean to be careful with the lean main jets? is running a 250 too lean?
when you say," a long cruise with low throttle openings you may melt a piston" are you referring to having too small a pilot jet?
victor

 

i noticed that in RCR's site you have a mod air box and was wondering if it would make a difference in my bike and also if it would worsenn my problem with my air filter getting clogged. i ride in dusty type trails and am usualll trailing others and so am always in dust clouds. thaks again rick
victor

 

A dirty air filter will definately make your quad bog. My Xplorer did this last summer. By the way, are you sure about the 40:1 ratio on Polaris Synthetic Gold oil? I am running that pre-mix too but at 32:1... just curious?

 

If it is not the air filter try moving your needle clip up and go to a local cycle shop and get a washer that will give you a half position(1/16 I think is the size). This should solve your problem. However do plug reads to be sure. I had the same problem with my sc400.

 

I've alwaysrun 40:1 pre-mix. You can run anything you are brave enough to run. I use 40 because it's easy with 1 pint to 5 gal.

 

I emailed Polaris Industries some time ago asking what they recommended for pre-mix when the injector was removed. The said 40:1.

 

I aggree with Bubba . I have had to do that before too .This could very well solve it if a clean filter doesn't .