Bayou 300 carb problems

[workhorse]

I think I fixed the darn thing. For the fifth time I disassembled the carb and again found nothing apparent so I soaked it in white vinegar for three days. Ended up with a bunch of small brass particles and a tiny, tiny spider. Blew it out with air, reassembled it and it works great, for now.

Hi.

The same problem occurs on the bayou 220. I've had mine for 20 years, and one of the main problems is the mikuni vm24ss carburetor.

While the 24ss is a simple carburetor it also has a major fuel quality & contaminant problem.

I've cleaned and flushed the entire fuel system and all it takes is a tiny bit of rust or old gas to block the carb.

There is such a tiny confined space between the float tank and the main jet needle that just about anything can block the fuel from exiting the carb into the motor.

I did the same as you and it does indeed work. Methyl Hydrate also works on shelack build up, and of course the air compressor.

I found that the flaw was the bottom float chamber gasket. Once it becomes thin (compressed) over time .

I changed the gasket and it worked. I then put the old
gasket back on and put the new one over it to see if that improved the spacing and it did an excellent job. Even with the second gasket the floats did not need re-adjusting.

Lastly i added a generic in-line fuel filter between the tank valve and the carb fuel hose.

I hopes this helps.

[pdefina]

I have a 2005 bayou 250 with vm24ss carb. It finally got it where it runs good, unless you hold the throttle down too long, then it bogs as if it runs out of gas. It's fine with shorter stabs at the throttle and feels fast and runs well, but if you hold it down it bogs.

I have adjust the floats until I'm blue in the face, figuring the bowl is not filling fast enough. Can't get it right. I have clean the fuel line, tank, pep **** etc... Gas flows very well out of the fuel line. The plug is dry, it's not running rich at all.

Any ideas? Also, can I replace it with a generic vm24 carb? The intake side is a little smaller, 28mm vs 35mm, will that matter a lot? Thanks

[pdefina]

What I meant is, it boggs after it accelerates for a second. It feels great when you punch the throttle, then after a second or two it boggs. like the bowl is empty. Then it starts right up and runs great again, until I hold the throttle down too long...

[workhorse]

What I meant is, it boggs after it accelerates for a second. It feels great when you punch the throttle, then after a second or two it boggs. like the bowl is empty. Then it starts right up and runs great again, until I hold the throttle down too long...

Hi. I just about forgot about this thread.

The VM24ss carb is a touchy thing. I am aware of your exact problem mentioned above. You don't really need to adjust the floats all the much. You do need a new float needle with the rubber like cap on the end, although my rubber tip has long since disintegrated and it still works . At the bottom of the main jet (brass fittings) is a hexagon head brass nut like fitting. You need to remove the main jet (unscrew) and then unscrew the hex head like brass nut at the bottom of the main jet you just unscrewed. Check the rubber o-rings at the same time.

Now look carefully at the hex head fitting and the brass main jet . Each has a set of tiny side holes near the threads , and are almost invisible to the naked eye when dirty. You need a small/tiny pin like the ones for holding the hem of a piece of clothing for sewing. You need to pass the pin in and out of those holes several times each at the same times and blowing air into the fittings to clear and debris the cleaning does. Use some rubbing alcohol on the pin to finish off any stuck on residue.

The Bottom hex head side hole is a little larger but gunk gets into the tapered lip of the side hole and will block the main jet if you don't properly clean it all the way through and around.

I have an eraser like tool called a rust eraser that looks like a rectangular pencil eraser. It's rubber mixed with brass dust, and is a great 5$ tool for removing to gunk on brass.

Sandflex Rust Eraser Fine

Lastly the front adjustment screw on the carb which is on the outside of the carb pointing downward on the side facing the engine. If your float needle is old then you need to tighten the adjustment screw to tight then unscrew it 3 whole (360 degrees) turns. Then you have a 1/2 turn to play with either to 2 & 1/2 turns or 3 & 1/2 turns.

2 & 1/2 turns is the factory setting but after a year or so the carb adjustment should be set to 3 complete turns.

The VM24ss is a lower two stage fuel vapourizing type . Unlike a Honda carb the vm24ss has it's smaller misting holes at the bottom. There are some advantages to this but they do end up clogged very easily. Hence the need for one or two inline fuel filters.

[pdefina]

Thank you so much for the reply. I will look at this again when i get home, but i have cleaned those holes very well, and even had a kawi dealer put the carb in their Ultrasonic cleaner. The holes in the main jet looked perfectly clear and I checked them all 62 times that I removed the carb to adjust the float I will play with the fuel air mixture screw again and check the o rings.

What makes me think the bowl is running out of gas is that, shorter stabs at the throttle are flawless. For instance, in first gear i can nail the throttle and win out first gear and it feels perfect and never dies or boggs. But if I wind out first and shift into second and keep the throttle nailed, then it boggs and dies, like the bowl ran out of gas??? Then it starts and runs perfect...

[pdefina]

One other thing, what do you think of me buying a generic vm24 mikuni carb for $70.00? Will it work? Thanks again!

[workhorse]

I don't recall seeing a generic vm24ss remember it's an SS model they are quite unique. I have tried the ultrasonic cleaner as you did and i still had to manually clean the jet holes myself.

You should also check your engine to carb manifolds both the metal and rubber connection seals that hold the carb to the motor. On kawasaki these have to be very very tightly connected with no air gaps. That too could cause your problems on higher gears.

Also check you main jet (throttle) needle spring to see if it's loose, you may need to stretch it a little to get some more resistance. If the throttle needle is loose inside the jet it could be bouncing around and cutting your fuel supply.

I have adapted a carb for a 250cc honda atv to a bayou before but it's a pain to run the cables but if you have the time.

[pdefina]

Yeah, there is no generic vm24ss. There's just the vm24. The vm24 has just a local choke, which should be fine (I can reach down for the choke). The only thing that bothers me is the vm24 is 28mm at the intake and the vm24ss is 35mm at the intake. I may lose some power but, if i could the thing to run decent for $70.00 I'd be happy...

Will look at everything you have posted though. I'm almost ready to spend the $310.00 for a new vm24ss. I so wish I could find a carb expert who I could pay $100.00 to fix this thing. But I took it to my local dealer. $105.00 later, I was readjusting everything they messed up When I get through with this stupid carb, I will be the local expert lolol...

[workhorse]

I would not recommend such radical changed in intake size. The suction/compression stroke will probably cause a vapor lock with a smaller carburetor. This is why i adapted a honda carb instead with dual air/fuel mix adjustments on a clients bayou.

To be honest it's not worth paying for a new vm24ss . Even if mine has 20,000+ miles on it , the moding of a honda carb is a much better choice from my experience.

[pdefina]

I tried adjusting the Air/fuel screw un the carb with no results. I removed the needle jet again, took it apart, and it's clean as a whistle. The atv runs good enough to use, but holding throttle down still causes it to bogg. At 2.5 turns it would not run, It ran at 3 turns and I ended up with it at 3.25 turns. Sometimes it winds out with bogging much, other times it boggs almost right away when holding the throttle down. Gas never leaks out of the overflow so the needle is seating properly.

I give up Which Honda carb should i look for as a replacement? I'll search the thread for it, I know someone listed the model number somewhere.

Thanks for you help. I now know a ton about carbs, but still can't fix this one...

[Firemans house]

on the kiehin carb i have i cant find nothing on it it is a cvk v659 hq5 any help with the fuel line routes would be helpfull it has to ports and one overflow at bottom i guess one is for fuel from tank and one is a vac. but which is which any help please

[marineswarm]

My 1993 KLF300 2x4 Bayou Ran fine when i bought it, Not wont run with out choke, Which tells me that its getting too much air. After removing the many times cleaning and rebuilding still runs like crap. So I Blocked off some of the intake, on filter side. After tinkering with how much to block off, Runs like a brand new old one. I read all this and i dont know if i want to go down the route of the carburetor on ebay. Maybe When i am bored some time and have some extra money. I adjusted the fuel air thing all the way in and slowly back out. till pretty much all the way out. and still didnt run right. Not a clue.....why not, so this was my quike fix,

It back fired through the carb a lot and the back end of the carb was always wet with fuel. Whats that mean? any one know?

[bluebayou]

Newbie question about cleaning. I've got it all taken apart. You guys were talking about soaking the carb in white distilled vinegar or other carb cleaner. The manual says to use a mild cleaning solution then clean in hot soapy water and rinse in cold water. The ports for the carb vent and fuel line are plastic and the manual doesn't describe pulling these out. I don't know if I'll break these if I try to force them out. They are attached firmly? Are you guys just pulling these out with pliers or do you clean the main body of the carb without soaking it? Please advise. The only things I would be soaking then are the pilot air screw, starter jet, needle jet, air bleed pipe, needle valve and main jet? I noticed a little gunk on the air bleed pipe but don't know if that was causing the carb to remain stuck open?

[RCW]

I am not a proponent of using vinegar or lemon juice to clean these carburetors. If you look at the parts diagrams these carburetors do not have replaceable float valve seats, so any acid can damage the machined valve seat in the carburetor housing and ruin it.

My suggestion is to purchase a non-foaming carburetor cleaner from Honda or Kawasaki, Honda makes the carburetor, and use only that to clean the carburetor.

As for the plastic connectors, do not screw with them. They are a press fit and after they are installed they are not intended to be removed.

I am not clear on what was stuck open, but if it was the main air valve you will need to refer to the parts diagrams and determine the problem. Sometimes that problem is as simple as someone flipping the carburetor upside down with fuel still in the bowl and ruining the 100+ dollar diaphragm. Other times it may be a gum build up in the venturi that is sticking the throttle valve, or it may be some linkage component missing or broken.

[bluebayou]

Ok, thanks. I just explained to the mechanic that worked at the dealership about the gas continuing to come out of the overflow after turning the machine off and he said it meant the float was stuck open. He mentioned about bending the tang but I didn't know what he was talking about.

Now that I've got this thing apart, I noticed that the bottom or the end of the shaft of the part labeled the Vacuum piston isn't smooth. It almost looks like it was melting, is that possible? I'd post a picture of what it looks like but not sure how to do that.

[stephen141]

I am new to this site.
I have a 86 bayou 2x4 300
I just installed a brand new carb that is good for 86 up to 2005 the bike starts perfect but seems to lose power when going up hills. The pieces I have changed to get it running are a new carb,volt regulator,new battery,new plug. I would like to know if its the air mix not adjusted or something else,also how many turns for the air screw.

[stephen141]

I am new to this site.
I have a 86 bayou 2x4 300
I just installed a brand new carb that is good for 86 up to 2005 the bike starts perfect but seems to lose power when going up hills. The pieces I have changed to get it running are a new carb,volt regulator,new battery,new plug. I would like to know if its the air mix not adjusted or something else,also how many turns for the air screw.