99 XC500 backfirs and not power part II.

[hattrk4me]

Here's an update to my problem.

Ive rechecked my compression at 135 psi each cylinder, cylinder heads look fine. I replaced the plugs the thing runs great for 15 mins then it starts coughing and losses power, and again the plugs are fouled.

The carbs have been cleaned 3 times in the last 2 weeks, Ive drained the tank and found about a table spoon of water. Is this turning into an ignition problem?

thanks in advance

[Surface Tension]

Did you notice if you were blowing black smoke when it was running good?

What did you use to clean the pilot and main jets with? Being brass its not to hard to ever size them.

Is there any obstructions in your air box or muffler like a mouse nest?

Did you remove the plugs and turn the engine over to see if the engine is loaded up with gas?

Are the plugs wet or are they sooty.

Is it coughing or is the backfire raw gas being ignited in the muffler?

Yes a coil can work fine then turn weak as it warms up. I would have a fresh set of plugs to throw in as soon as the symptoms return. If its bucks and farts right away you could have a coil on its way out. I would then take the coil in and have it tested.

[Gus]

similar symptoms were happening to my brother in law's artic cat last year. Had the carbs worked on, the coil's tested and swaped, checked compression and then.. we ended up taking apart the fuel pump and a diafram was bad on the pump. $15 rebuild kit and it ran great. No more flooding out, fouling plugs, dumping raw gas out the exhaust, or backfiring.

[lawdog]

I'm thinking this sounds like a gas/air thing too rather than ignition... I'd check too to make sure you have the carbs back together right and that the needles are set right and the same on each carb. Sounds to me like something is loading up and flooding out those plugs in a big hurry.

[hattrk4me]

Carbs are re-assembled correctly.

One plug seems to be the fouling plug, its wet after idle, after a short run its dry and fouled.

The smoke I get is a very strong exhaust that burns my eyes. smells thick with fuel.

[lots of luck]

Problem is in the make, should have bought a Cat!!

Just kidding, this is Jason R.,worked with you here in E.P.

How's it goin bud? Shoot me an email sometime.

jroberts(at)htpo(dot)com

[Macgyver55]

Since it runs ok for a while then goes bad, it seems that it would be more likely electrical. Heat can cause a stator or coil to act up.

Another thing to check (more of a long shot)on the fuel side would be the float.

A cold engine requires more fuel to run right. After warming they require less fuel to run good. (possibly explaining the short period of running ok)It's not so common but it could be a bad float if its the fiber style. It will sink and act like it is flooding even if it is adjusted correctly. I've seen them go bad from sitting in bad gas. Otherwise if it is a plastic style check it close for cracks.

Let us know what you find.........

[hattrk4me]

Jason,

sent ya an email. Good to hear from ya again. is only been about 3+yrs

[hattrk4me]

panfish,

I know for a fact there is little play in the cables now. I'll check them tonight.

thanks.

[panfishhunter]

One thing to check, because i have seen this before on a polaris. the choke cables maybe adjusted too tight, thus causing an overload of gas in the engine when at an idle or slow speeds, causing the fouling of the plugs. there should be a 1/16 or 1/8 inch of slop in the cable next to the carborator when the choke is off, if not then they are adjusted too tight causing it to dump fuel in the engine all the time.. just one more thing to check..

[hattrk4me]

Well, I checked the choke cable, loosend it up and still no change. Is there a way to test the coil with out trying a new one? I'd rather not spend the $100+ to find out its OK.

[gjk1970]

Most dealers should be able to bench test your coils for you. Also with the way it is sounding s=did you pull the plugs down under the exhaust ports. Should be 10 milimeter heads on them pull them and see how much fuel you may have loaded up in the engine. Let it drain out and see if this helps. Just got done working on a Polaris that was a headache for me and pulled those plugs and she started right up and purred away. Not like a Cat Like a Polaris should...lol But otherwise it seems that other posters are guiding you in the right direction. As a coil starts getting hot it tends to start acting up. Good luck and hope you can get it fixed and ridable while we have the snow to ride on..

[Knotwood]

Try using a timing light to see if the spark flashes are steady at all RPM's. Any blips or sudden drops indicate something: too rich of a condition to fire plugs, stator, wiring, switches, losses to ground or break of ground in circuit, not necessarily the coil. Sounds to me more like a float is either sticking, level too high, or inlet needle is letting gas thru, try a static test when the carbs are off, fill up the bowls by using a fuel source connected to the carb inlet spigot, try moderately jiggling the carb around, see if any weeping gets into the throat. Can you switch carbs, does the same cylinder act up?

[hattrk4me]

I’ve got a friend of mine with an 2000 XC 500, used the same coil/CDI. I’m going switch it out with his and see what happens.

[lots of luck]

Strocum,

My first sled I had was a 1994 550 Pantera EFI and I had a situation somewhat similar. But, being a rookie and not knowing much I didn't know something was wrong. My symptoms were cold hand and thumb warmers and dim lights, well I had nothing to compare against. Well while riding it hard one time, I gave it a good jolt and all off a sudden my lights were bright and the warmers got hot. Then it all went back to what it had been minutes before. I went through that entire sled and cleaned every connection, which didn't resolve anything. The other symptom was after riding it really hard and then shutting it down for the night, you had to put new plugs in the next day for it to run properly. I guess due to improper amount of spark, causing the plugs to foul.

Well I think my problem was a stator, but I never messed with it, it was sold before the start of the next season.

Sounds like you either getting (1)too much fuel or you're (2)not burning out what you have or (3) have an obstruction in your air box, not getting enough air.

Fill us in on your saga. We might all learn something.

[sledhead]

Ok sounds like you went through the carbs right and everthing is dandy there. I would venture to say the this is an ignition problem, could be the ignition coil, or it could be the stator. At this point i don't know. What you need to do it take a multimeter and get the spec for the igntion test the igntion coil and record what you get test the stator and record you findings. Then run the sled until it acts up. retest the ignition coil and stator and compare to the spec. If one or the other is way out of wack theres your problem. Its could also be as simple as a throttle switch, kill switch or ignition switch.

[hattrk4me]

Tested the CDI its OK, electrical is OK. Now I back into the carbs.

[sledhead]

In one of your previous posts you said your buddie had the same machine, did you swap out just the cdi and the coil? or did you pull the flywheel and change stators to? I would still say it's not the carbs. Try unplugging the single black wire from the cdi box. That is the curcuit cutoff for the ignition switch and kill switch, see if it runs good. you willl have to reconnect it to shut is off as this wire bypassed those two swtiches.

[hattrk4me]

Well, I'm giving up. I hauled it to the dealer and I'll pay the High $ to get it fixed, what ever it may be. Thanks to all the posted.