Hi Guys

I'm in need of some advice in order to get my quad running in a reliable manner.
I bought the unit about a year ago, and I did not come across this problem until warm summer days came along.

Here is what happens.

The quad starts perfectly, in any type of weather, I can hop on and ride away on full throttle with full power. If I keep riding, keeping the speed up, I can go on until the tank runs dry, however, if I slow down after the engine warms up, in a minute or two of just idling the quad will start miss firing. Since it starts miss firing, riding it becomes harder and much jerkier, and eventually the engine will stall, and will not restart properly until it cools down. With much effort and a lot of full throttle I can get it going, but it's not plesant at all, and I can't imagine it being good on the engine either.

I have performed many different tests to try and track down the problem. I know the carb is fine since as long as there is a spark it will fire. I bought a spark tester, which showed that the spark does go missing when it warms up, but I have not been able to figure out where the spark goes.

I went through the entire wire harness, diconnected any aux devices, checked all connections with a multimeter, replaced the ignition coil, spark plug, and wire. I tested the CDI unit as outline in my Clymer manual and it seems fine as well.

I pulled the spark plug out and held it to the engine as I tried the starter, and I get a spark, but it's very very faint at times, or just does not appear at all.

The last item on the list is the magneto/stator. My neighbour suggested getting it rewound to see if the pickup coil for the ignition signal is the problem. (I might confuse terms here, since I have not opened this thing up just yet)

I have a theory that when the engine warms up, something expands just enough to cause the already faint spark to vanish, but I am looking for other suggestions as well.

It's my understanding that replacing the magneto/stator is no walk in the park, but I've done much more complicated jobs before. I was wondering if anyone perhaps remembers what is involved in the procedure, and what parts and seals are a good idea to replace at the same time.

I know the crankcase cover has to come off, which involves a seal for it, but what else?

I want to order the parts, and get this job done so I can enjoy my quad for once.

Thank you in advance

xp190

 

Replace the stator, I had the same thing on a 300 king quad,remove recoil housing and left engine cover , you will need a flywheel puller and be careful when pulling engine cover as tranny gears like to follow, you can use sylicone to reseal case if you dont get a new gasket

 

xp190 i know this maybe a dumb question to ask , but have you tried a new sparplug ?

And the gap setting i have had some honda's that wouldn't run on the factory spec on the plug gap , and my brother had a Kawasaki KLF 300 Bayou 2x4 that wouldn't run on the factory spec either , i had to gap them at .030" for them to start and run right ; i'm not saying that kerbirds is wrong about the stator just saying try the easy and cheapest thing's first !.....

 

Williebee no such thing as a dumb question, but yeah, I tried a few spark plugs with no luck, honestly the last remaining part of the entire ignition system that I did not test/replace is the stator, so I'm ordering a new one to have this machine running properly [img]i/expressions/face-icon-small-smile.gif[/img]

 

Hi Again Guys, I'm still in need of some help with this machine.

I relplaced the stator, not a cheap part, and not an easy job, but I wanted to reseal the engine at the same time, so I pulled the engine out of the frame and took care of everything in one shot. I just got back from a weekend at the cottage where I took the machine for a test run after all the work... It still does the exact same thing. It will start perfectly, it will run like a champ for the first 15-20 minutes at any speed any conditions, then as soon as I slow down, which is what leads me to believe this is a heat related issue, it will start missing. If I keep the speed up, and the airflow through the engine, it will go on forever, but if I stop and let the warmed up engine idle for a few moments, right away it will start missing, and if I leave it, it will get worse and worse until it dies within seconds from the moment I stopped.

I replaced the stator, the ignition coil, tried various spark plugs, check the ignition computer, and did anythign else I could think of but this thing refuses to run when warmed up.

One thing came to mind after this dissapointment, and this is not an area I'm a pro in. The Clymer manual calls for a hotter spark plug depending on the conditions you use the machine in. Now from the top of my head I can't tell what I have in there now, but lets say it's what the manual states to use which is probably what I did. How do I find a hotter plug for it? what impact can a hotter plug have on my engine? Are there risks involved with this?

Any input will be appreciated.

TIA

xp190

 

I would consider yanking the carb and going through it. It sounds like it might be running rich. Does it start without the choke? Does it seem to run much better during the colder part of the day? And I would also re-think the ignition system (CDI or coils)--although it test fine, it might be an intermittent issue that doesn't show up during testing. Try swapping with a known good part.

 

HI Erwin, I cleaned the carb, although I have not tampered with the mixture yet, I'm not sure how to yet, I'll look into it. It won't start without the choke on a cold engine and it runs rather poorly with the choke on once it starts warming up. All ignition components were replaced along with the stator and pick up coil with known good parts since after everything was replaced, it still showed the same symptoms.

I have a theory that it's the spark plug that fails due to overheating, maybe it's just the wrong plug for the engine and weather conditions, I'm going to try a colder plug and see if that makes any difference at all.

Other then that, I'm still in the dark with this issue and it's killing me, never came across a stumper like this before.

xp

 

Hmm... I really doubt that a plug a range or two off, in the absence of extreme weather conditions, could affect your quad to that extent. I guess the best clue you have is the weakening or disappearing spark. There has to be a short somewhere, a wire touching hot metal, something is being overlooked...

 

I'll be working on it over the weekend, I'll let you guys know what I found, if anything.

 

Well, another weekend went by and I still could not figure out the problem. I did a compression test on a warm engine, right after it stalled, and it showed 115 PSI, service limit is 114, and it should be betweetn 180-200, so it's rather low, but none the less everyone assures me it should still run.
Since I got fed up, I took the quad to a dealer, told them the problem, and asked them to look into it. That was saturday, I got a call today, Monday, and was told that it's ready to be picked up. For some reason I don't think the problem has been fixed, but I will find out soon enough.
Further more, I tried a colder spark plug, it made no difference, I pulled it out hot and it was white as paper, serious sign of overheating, so even if the dealer fixed something, riding on an overheating engine is not going to get me far and will cost more money in the long run to repair.

I got a few private messages with regards to this problem, I'd ask that everyone post here so we can all share the knowledge and ideas. Someone out there must have a clue as to what's going on. Air cooled engines have been around for a century now and I find it hard to believe that no one knows anything about them, or how to troubleshoot them.

xp