97 sportsman 500 is sputtering after carb rebuild.
It idles great,rev it up in neutral and it sputters.
Go into gear and it sputters for a few feet or seconds or half way around the house... then it takes off and starts running ok. Let out of it while rolling and back into it and will sputter a little but will take off again.
Sometimes you can give it throttle and it will just sit there waiting, then will finally get going a little and then going better..

This was a basket case from previous owner.. and have been doing odds and ends on it getting it back to working correctly.

Background:
Prior to Carb rebuild.
I had a fresh plug in it. But was hunting at idle. Either it was too high or too slow and stall. and no hesitation or sputtering while riding.. it ran fine.
A little hard to start.

I did the carb rebuild and it still ran fine with no hesitation and at speed.. But would still hunt for idle..
I noticed the fuel pump leaking and not much fuel in the clear filter. so ordered a new one. figured it might be starving for fuel sometimes.
Replaced the fuel pump tonight along with adjusting the idle mixture screw back down to 1/4 turn..
It starts right up and idles great, no more hunting for idle.. Maybe idling a little on the high side.. but a constant.. no more really high or low idle cycles.

But now I have the sputtering issue.

I also replaced the stator, starter and fuel pump, lines and filter.

My shifter switch is not working, so it doesn't know if its in neutral or reverse, so the override shouldn't be the issue?
I also tried the override switch and it had no effect.

any ideas. I know I replaced alot.. but figure its still a carb issue.
would the idle mixture at 1/4 turn be the problem..
I tried the chock while idling.. and it idled faster, but didn't kill the machine.
didn't know it was suppose to until another thread I read.

I ran out of daylight.. so I'm just looking for best ideas to start out with tomorrow.

thanks.

 

Yes if you have the fuel mixture screw at 1/4 turn out,then that's too low. Should be around 2 turns out for starters. Plus air box and filter has to be on,air box lid must be tight. I guess you've pulled the black wire from the reverse over ride,if not pull it and see if it helps. One other thing is the cam problems on these models.Exhaust lobes are subject to wear. The lobe may be ok or may be partially ground down and this can cause problems. Even more so if really ground down. Then they would idle ok but pop back through the carb and no power at all. Here's an example. Bad Cam Pic - ATVConnection.com ATV Enthusiast Community

 

I had it about 1.5 to 2 turns out and then read somewhere that it should be 1/4 turn.
I'll adjust it back out.. hopefully that will cure it.
Funny how it would run good but idle like crap when turned out 2. with it that far out i couldn't find the correct idle screw adjustment. sometimes it would idle high so I would turn down idle screw.. then it would barely idle.. then I would bump it up barely and it would idle.. but hit the gas.. it would rev high and stay high.. bump it again and it might go back down or stay high for a while and then idle back down again..
Since the idle screw only opens the butterfly I thought the issue was too much fuel from the mixture screw.

maybe all of that issue was caused by a bad fuel line a bad pump.. low idle, just wasn't pumping fuel like it should.. run it around the house it would pump better due to higher rpm's..
guess I just gotta spend more time with it..
thanks

 

ok, I adjusted the idle mixture screw out to 2 turns. no help still runs the same.
idles fine. from a dead stop with any throttle position is will chug, spit and sputter. sometimes it just want even go. once I get it going.. then I can take it down the street and it will run ok.. but will never hit max rpm.
Even in neutral, with wot it will never hit max rpm.. most sputters and once in a while it might rev up to max..
I also tried removing the air box cover and did not help. runs the same with or without it.

I also have some blue smoke coming from an exhaust at the engine.. right there where it curves and has to springs. not all the time.. just after i run the rpm's up, let out of the throttle and back on it again.
I did put stabil and some seafoam in the fuel a few weeks ago. think this could be the issue? too much of that causing this?

any ideas.
gone to get some fresh gas and new plug. cheap stuff first.

 

Have you pulled the cam cover and looked at the cam? Eliminate it as a problem first. Look at the link I showed in the previous post. If the cam lobes are ok,valves are set at .006,then probably still carb related. Look over this pdf section from the manual on your BST34 carb and see if it helps on float settings and other adjustments.https://www.google.com/url?sa=t&rct=...U2gGlaHJWSIlbA Plus another area that can be causing problems is the belt and clutches. If belt is stretched/worn or the driven clutch ramp buttons ground down,this can affect speed and can actually act like a limiter. Just a process of eliminating one thing at a time.

 

I adjusted the valves when I first got the bike cause it was hard to start. I didn't notice any bad wear, but I wasn't looking for that specifically at that time.
guess I get to tear that back down.
I also replaced the buttons and belt during the rebuild.
This should be a fuel, cam or electrical issue. Since it happens in neutral just reving the bike.
The slow take offs should be due to the engine not reving enough to tighten the belt to get it to move..

 

Here is a video of the bike running.. also have a bad tick sound. Is that a bad cam or cam chain?
This is also at WOT.
I checked the float height using clear tube and it is at top of bowl like it should be.



http://vid954.photobucket.com/albums...psg60uf8io.mp4

 

Could be clutch making noise, or even a loose cam chain,plus couldn't see if air box was hooked up or not in the video. You can always pull the drive clutch off and eliminate it as a source of noise. Again look at the cam lobe and cam chain for slack if the clutch isn't causing the noise. Air leaks in the air box lids on this model or a cracked intake manifold can cause air leaks and cause the the limiting it's doing also. If you've pulled the limiter wire,no air leaks,cam lobe is not worn, an electrical break down can cause this limiting also. Use a timing light and see if the light is continuous when the engine is limiting or if the light flashes in unison with the miss. This is a quick way to tell if it's an electrical problem.

 

I might have found part of the issue.
I was out testing it and I got alot of smoke back through the carb. Then the engine stopped and the starter would just spin.
I pulled the cam cover and the chain was tight. I pulled the stator cover and the flywheel was loose.. I found that the shaft key was worn and broken in half
So the flywheel was free spinning and catching. I guess it might have been off enough to make it run poor and then sometimes ok?
Then when it broke all timing was off.

I'm gone shopping for a new key replacement.. Anything special about the key?
Guess I should have inspected it when I replaced the stator..

think this is the bad running issue?

thanks

 

5 mm woodruff key.Yes that can cause it to run crappy if the flywheel moved then the timing is off. look at the flywheel carefully to make sure the key slot isn't wallowed out.Put a tire iron or pry bar through the clutch into the floor board to lock the engine,torque the flywheel between 58-72 foot pounds.