Hi, I have a question about a recent problem with my 1997 500 Xplorer. During the last time I was plowing snow (I have a Swisher 50" Plow), I could not get the motor to higher rpms. It would start missing, bogging down, and backfiring. I originally thought that it might be frozen water restricting the fuel flow. i left it in my neighbor's heated barn overnight- That wasn't it. Air filter looks good, Spark Plug Looks good. All Fluids are at recommended levels. It starts and runs fine until you try to run over 2500 rpms (I am estimating as there is not Tachometer). Anybody have any thoughts???

We have also checked the Spark Arrestor, that's fine. We replaced the Coil, that's not it. We adjusted the valves, we checked the timing, the checked the compression release, removed and cleaned the carburator. The motor Idles fine and runs fine up until around 2500 rpms (Again an estimate) and then it starts popping, coughing, spittting, and if you continue it will eventually cut out.

When we ran it with out the air box on, you could see gas blowing out the air intake of the carburator when you would try to rev it up.

Any ideas or comments would be appreciated!!!!

Thanks,

Mike

 

I don't expect this is your problem but it is too easy to not at least check. Make sure your throttle cable (ETC) is adjusted properly.

When you cleaned the carburetor did you actually remove/inspect the pilot and main jets to verify they were not clogged with debris.

Which coil did you replace? The high voltage? Trigger?

 

Thanks for the reply. My Neighbor (a Diesel Engine mechanic) did most of the work. I know he took the Carb all apart cleaned it and reassembled so I am assuming it is not clogged. He replaced the coil that is attached to the spark plug wire (Also replaced the spark plug wire). I wasn't aware that there is two coils. What and where is the other one? My Neighbor also opened the ETC box up on the handle bars and said everything looked fine. Where do you adjust it?

I am grasping for straws here, but is there a rev limiter or some RPM limiting safety cut off that I might have triggered?

Looking forward to an easy fix!!!!

Thanks,

Mike

 

If your neighbor really knows carburetors then he would probably unthread the pilot and main and visually inspect to make sure there was no debris in there. So, for the time being, I guess we can assume the carb is good. There is another coil (small one) that is behind the magneto cover. This one is called the 'pick up' coil. Its job is to sense the position of the flywheel (there is a little iron piece in the flywheel it senses) and send that info to the CDI (aka - black box or ignition module). The CDI then manipulates this signal and then sends it to the high voltage coil (the one you replaced).

When you take the ETC / throttle cover off there is a micro switch that can be seen. This not only needs to be completley clean but needs to be adjusted. If you have too much play in the throttle cable this switch could cause the problems you describe. So, make sure there is not much throttle free play. I believe there is an adjuster in the throttle cable just outside the throttle housing. Turn that to increase or decrease throttle cable play.

There is a rev limiter on your machine. Could that be causing the problem? I suppose it could be as a few other people have had rev limiter issues. There is a wire that can be cut to bi-pass the rev limiter so that would be a good test also. Unfortunately, I don't know which wire that is. You can either wait and see if someone else posts the answer here or start a new thread.

Confirm with your neighbor that the main and pilot jets have been inspected. Also ask your neighbor if the needle/seat were OK .. also ask about the float and it's height.


If none of the above are the problem, you might have an issue with the stator (the coil assembly under your flywheel)

 

Thanks, I will try adjusting the throttle first.

Prior to my neighbor throwing in the towel (I appreciate all the time he put in, he just got frustrated he couldn't figure it out) his last thought was the CDI box. The problem is a new one is $250.00 and you can't return it. The Coil was $140.00 and we can't return that either (Although my neighbor measured the resistance of the old one and it was way over spec. He measured the new one which is to spec, so I guess I needed it anyway).

Any thoughts as to whether or not it could be the CDI box?

Just a thought.

Thanks,

Mike

 

sounds like a needle and seat issue which is inside the carb. you should take the carb off yourself and go through it just to make sure. I had a Keinn carb once that had the needle and seat come apart due to the needle being a two piece which has a rubber tip as opposed to a one piece needle. I changed the needle and seat and it fixed my problem. they are under $10 so it's worth a shot.

 

It's possible that it could be the CDI and / or the stator. I would do all the free and cheap stuff first though. If, after you have exhausted everything else, nothing else works, then I might try a CDI. There are tests that can be done to validate a bad CDI or stator so I would still try those before you bought new ones. Keep in mind though, I have seen CDIs and stators both pass all the tests listed in the book but still be faulty.

 

Have you checked the buttons in the secondary clutch?If they brake it will cause symtoms like that too.

 

did you happen to check the exhaust lobe on cam when you adjusted valves?? was the exhaust valve way out of spec? you may have a worn cam lobe. it will cause the same thing you are talking about,especially since its blowing fuel back into filter box.

 

To Polaridoo, Ftwflh, Silverbuller2005, & Jeffro206,

I aprreciate all the help. First off, I adjusted the throttle cable (There was probably 1/4" of play) but it still has the problem.

With regard to the Secondary Clutch, the problem I have with the coughing, spitting, and stalling also occurs in Neutral, would the secondary clutch affect it in neutral as well?

With regard to the Exhaust Lobes on the valve cam, I am pretty sure my neighbor would have checked that out. Additionally, this problem happened all of the sudden. I plowed my driveway and it did fine, then I plowed my neighbors drive and it started doing it when I was almost finished with his. Would the exhaust lobes explain a problem that hgappened all of the sudden?

I do have another suspicion though. when I started it last night, it was very difficult to start (Barely turned over and battery is fine), and I noticed before that when I have tried to pull start it the darn thing nearly yanked me arm out of my socket (I'm 6'3"-300lbs). Is it possible that the decompression release is some how backwards? That would seem to explain the difficulty in turning over and spitting gas back through the carb. If so, how do I reverse it back?

With regard to the needle and seat, that was inspected and cleaned, looks good.

Again, thanks for your help and look forward to more info.

Mike