bayou 220 atv problems

[country_boy]

Im now thinking the problem its the CDI box, I rebuilt the carburetor, replaced the ig. coil and plug. It idled great for 5 min. then the exhaust started to pop for a while and then died. I pulled the plug and its carbon fouled. I put a new plug and now it will only idle for seconds every time I hit the starter. When its on choke it idles longer at a higher rpm then dies.So that tells me its either a spark issue or its still too rich. Am I correct or wrong?

 

[San Antone RR]

Does it start after all cools down and do the same thing?

 

[country_boy]

Yes. for some seconds. with new plug

 

[robin303]

Did you play with the jets on the carb.

 

[country_boy]

Running stock new jets, very basic carburetor rebuilt by a professional. Valves are set correctly, getting great compression. Its doing the same problem it did when I first got it. Idles great for a while, exhaust pops, then plug fouls, then dead. I think a new cdi wont hurt, plus if its solves the problem great, if not keep on the check off list.

 

[San Antone RR]

Have a CDI you can swap from a working unit? Not cheap and if it isn't your issue, you can't return it.

 

[TexMex247]

The best way to check for spark is with an in-line flasher, or to completely remove the plug and hold it(w/wire attached) against the cylinder head. You can see it spark pretty easily or at least get shocked trying. Also be sure and check that the ground wire from the battery(green or black (-) wire) is firmly attached to the frame,motor and/or chassis. A loose ground will keep your coil from firing as well. From the high idle problem, I would guess that you have a vacuum leak at the manifold which you can find using carb cleaner(spraying on the body of the carb while running) with the air cleaner attached. Good luck with it, one of these days I'll try to help you out in person w/ this thing and your dodge truck.

 

[country_boy]

The best way to check for spark is with an in-line flasher, or to completely remove the plug and hold it(w/wire attached) against the cylinder head. You can see it spark pretty easily or at least get shocked trying. Also be sure and check that the ground wire from the battery(green or black (-) wire) is firmly attached to the frame,motor and/or chassis. A loose ground will keep your coil from firing as well. From the high idle problem, I would guess that you have a vacuum leak at the manifold which you can find using carb cleaner(spraying on the body of the carb while running) with the air cleaner attached. Good luck with it, one of these days I'll try to help you out in person w/ this thing and your dodge truck.

The manifold meaning the intake manifold from carb to engine? I replaced the air boot to carb.

 

[TexMex247]

Yes, the manifold attaches the carb to the cylinder head. You want to leave the airboot on so the carb cleaner doesn't just go right into the carb. The idea is that the carb cleaner will suck into the leaky area and make the idle speed change from the excess fuel entering the motor. Some 4 wheelers may have the carb bolted right to the head but the concept is the same. There is some kind of O-ring or gasket between the carb and head that could be leaking. A CDI unit is usually an all or none type of component, no spark or hot spark, rarely just weak. Also, if you can, I would consider disconnecting the kill switch if you can isolate just the kill wire. A bad switch can interupt spark to the motor as well. If I remember right, it is a multi-function switch that may need to be plugged in to run though. Lastly, how high is the compression, using a guage, it should achieve at least 100psi of pressure while cranking for at least 4 or 5 seconds. Using your finger is not the best way to check. On a single cylinder motor, compression is what creates engine vacuum that actually draws air through the carb where it is mixed with gasoline before it enters the engine. As a 4 cycle motor, you always have to remember, suck, squeeze, bang, blow. Those are the four cycles of that engine. suck = vaccum, squeeze= compressing the fuel rich air,bang=combustion, blow= exhaust flow. A low compression engine typically will only idle with the choke on because it needs to be "force fed" fuel to run. Try some of this stuff out and post an update when you can - Texmex

 

[country_boy]

Well I checked some things. The intake is fine, orings are still good. Theres a back fire through the carb that Im noticing with the air filter off ever so often. Which doesnt make since when I did the valves following the book. I set the cam where the indent mark it and the crankshaft lined up where the t is stamped on the wheel.

 

[country_boy]

It is running lean, Im thinking the fuel bowls need adjustment. What ruler/tool do I use to measure the height? The manual says -5 mm to +1.5 mm

 

[dobarker]

You may also check the needle, i recently rebuilt a mule's twin carbs due to what sounds like the same problem, what I found was that whoever "rebuilt" the carb before me had somehow managed to get the needle held in upside down on one of the two.
It sounds like you're on the right track, get the adjustment set right and blast out the needle valve with carb cleaner after checking to be sure it's set right and not corroded itself.

 

[TexMex247]

When I adjust valves on smaller engines, I prefer to align them to "base circle" on the camshaft. That is basically the area that sits completely opposite of the lobe. That is the area where the largest gap will be present between the valve and rocker arm. Timing marks are ok to use but I personally prefer to go base circle and then adjust lash. If you think you have a lean condition, I suggest using a propane torch and feeding the gas into your airbox while the engine is running(torch not lit of course). If you hear an audible change in idle quality, you're probably headed in the right direction. I like to use a "dry" fuel source to help diagnose those problems on a smaller engine, it can be a very useful diagnostic tool because it relies solely on engine vacuum and disregards any problems within the carb. Good luck with it - Texmex

 

[rayetter]

One thing I have seen often is the where the throttle cable goes into the carburetor, unscrew that and pull out the plunger to see if it is installed correctly. I have a honda 3 wheeler that did that when i first got it, i found that the plunger was in the wrong way and the adjustment screw was keeping it open, resulting in high idle and fouling of the plug. And one other thing, the needle should have a circlip on top in a groove, there should be a few different grooves and if it is on the wrong one, it wont run properly. Hope this helps, good luck.