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'03 Bayou 300 Running rich, choke, air/fuel screw question


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Just picked an '03 Bayou 300 2WD.  It runs ok, needs a little help though. Maybe someone can answer some questions for me.

1. The choke "off" position is the lever all the way right, correct?

2. The choke seems mechanically... funky. It has a little valve clamp around the rubber boot where it goes into the carb, seems kind of janky, I don't think there's typically a valve clamp on that part? The engine seems like its running really rich, smoking a bit, so I wonder if I can just completely remove the choke cable to see if that's part of the issue? But I don't fully understand the choke needle setup. Is "choked" when the needle is being pushed in, or pulled out? Like it I chopped the cable just outside the rubber boot by the carb, would I be permanently choking it or permanently unchoking it.

3. I've read that I can tweak the air/fuel screw and maybe fix the rich mix. Where is that even located, and if it's behind a cap that I have to drill out... where is that?

Thanks for any tips

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The choke position is as follows. When the choke is slid to the left when you sitting on the bike is ON slide it to the right and it’s OFF. I’ve attached a pic for you.  

The reason for your running rich maybe a stuck choke assembly so don’t be so quick to start adjusting the air fuel mixture screw just yet.  

I would take the choke assembly apart and check that the brass plunger is working correctly.  

If you need some direction on doing that we would be glad to help you along the way. 

Meantime here are the parts and what they look like for reference.  





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Thanks (as always) @Frank Angerano ! So the plunger is moving, I just wonder if it is not seating all the way and allowing extra fuel to sneak by.. the way the cable looks I feel like it could be twisted or messed up and not have enough play to allow the needle to "fall" all the way into the hole.

However my first fixes might be on the air side, I pulled out the air filter last night and found it was using a homemade PVC pipe filter "holder." The pipe used was much too long and extending all the way into the rubber manifold and hitting the other side, probably cutting off a significant % of the incoming air. So I'll try a new filter first and see if my mix gets a bit better before messing with the choke!

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OK, choke cable is on its way. And a new air filter.

In the meantime I have the air filter completely out of the air box and I'm still getting smoke, now I think the smoke is probably from burning oil. And there's some oil in exhaust, so I'm thinking this might be ... valves? Either adjustment, or replace the seals?

Guess I can start with an adjustment - it does sound a bit "clackity clack" ish so maybe that is a logical next step. 

What's the best oil for this situation - high mileage w/ smoking? I'm wondering what the last guy put in it, and if that could be part of the problem.


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Unfortunate the smoke would be from leaking valve seals or bad rings.  No oil is going too really help that.  

As far as the choke cable and assembly I think that will help out your running rich condition if that choke is not opening all the way.  

Valve seals are cheap enough but a pain in the as* to put In.  It’s ether pull the head or fill the head with compressed constant air and pull them out.  

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Will look at the valves tonight.. Interestingly I found this post https://www.kawasakimotorcycle.org/forum/showthread.php?p=2403491#post2403491

Which describes exactly two issues I'm having with my KLF300:

"How well/smooth should the centrifugal clutch work? This one will start to drag with a few revs then with a touch more will drag slightly more for a couple of seconds then jump to full engagment."

Yep, yep me too

"There is some smoke from the exhaust and quite a lot till its good and warm.. Some of which may still to burn off with a good ride as the exhaust looks black from rich running. "

Yep, also exact symptoms

"About valve seals and we have been told that it is quite common on these quads for the seals to harden and it may get better with good oil and some riding time."

Hmm, that would be nice


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On the centrifugal clutch, I just rebuilt a 220 that the centrifugal clutch was absolutely shot on.  It was worn to the point that there was no gap to spit the oil out.  So I took a cylinder grinding stone and ground out the ridges in the drum, finishing with emery cloth and buffed it smooth.  Then I cut grooves back in what little clutch material was left on the clutch itself.  Put it all back together, and it pulled like a champ.

Also, those Bayou/Lakota motors chatter even if the valves are spot on.  I don't know what it is clicking, but i've never heard one with some miles that doesn't chatter.

Love those motors though.  Typical older style, simple to work on, run forever.

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@MarkinAR this is valuable info!! Thank you! Googled and found this really good write up of a mod for the centrifugal clutch https://nicholasfluhart.com/2015/01/08/project-bayou-300-4x4-clutch-repair/

I will give it a shot and see if it fixes my low-rpm clutch slipping issue.

I adjusted the valves last night but had to run to work before I even got a chance to fire it up, so not sure what the results were yet... The intake seemed a bit loose and the exhaust seemed a bit tight...

 I also found once it was on the nice level garage floor that it was overfilled with oil. 

We'll see where things stand after all these little tune ups, I suspect I will end up finding a mechanic to do the valve seals when all is said and done.

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Yep I used feelers, intake I set at .15 and exhaust at .20 ... I did not check compression before, that was dumb, I should have. And I haven't checked it after but I have an old compression gauge somewhere which I will dig up and have a look. 

Also, Attached is a pic of the exhaust valve cover - can't tell where that somewhat fresh oil is originating from, but it seems to me to be originating from the bolt that goes in where the decompression lever is. The valve cover itself was on really good and seemed sealed up so I don't think it was coming from there. 



IMG_2235 copy.jpg

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What I’ve always done on the valve caps is add a drop of high heat silicone right over the rubber gasket on the cap before i put it  back to be safe weather it needs it or not.  

Second is loosen and back the two bolts next to the de comp lever out about a quarter inch which is just enough to add a drop of the same silicone on both sides of the washer and send it back in.

That should fix up the problem.   The small tube of the silicone has that tapered clear nozzle on the top. I cut just enough off to have a small worm like flow. Most importantly is spray a bit of carb cleaner to get any grease/oil off of all areas.  

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Fired it up after work and it seems slightly happier and quieter than before the valve adjustment. It's still smoking but not *quite* as bad as before. Smoke is during uphill acceleration, or parked in neutral at high revs. (Does this mean rings more than valve seals?) And I will take your advice and seal up those bolts & covers.

Waiting on a new oil filter before I drain it again and check out the clutch and try this whole honing / grooves trick.

By the way, what do you recommend oil-wise for this situation.. a well worn engine, and slippy clutch. I live in an area where it rarely drops below 40° and will probably always be riding on warm days, I'm thinking 20w50 mineral to seal things up a bit and give the clutch the friction it needs.

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I would think more so the valve seals but it’s hard to tell. Valve seals can be replaced without pulling the head off. The piston is brought all the way up and there is a part that screws into the spark plug hole that connects to an air source.  That keeps constant air pressure on the valves so you can take the springs off and change the seals.   The air pressure keeps the valves up.  So maybe you should look into this. At the very least pull the valve cover off and turn the air on you will clearly hear some air coming from the seals and you can even spray windex on the valve seals and see bubbles.  

Or you just tear the bike apart and do seals and a piston for about $150 bucks in parts and be done with it.  

Either way start with a compression test just to see where you are at.  

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The real trick when  using  air pressure to  hold the valve closed is to get the motor  on  exact  top dead center on compression. If it  is the slightest  degree off TDC the  air will  push the  piston  back to the  bottom  of the  stroke , either  back  or forward depending on  which way  it was off TDC.

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Adding some Dremel grooves in the very very worn out centrifugal clutch worked wonders, it pulls much sooner & stronger now. 

I changed the oil for some Shell Rotella 15w40 diesel oil and that also seems to have helped the wet clutch and helped the smoking at low revs. I still get smoke at high revs but since I'm just putting around on it, I think I'm going to leave it alone for a bit and just enjoy this quad that I got for a few hundred bucks. No sense in rebuilding it given the type of use it is going to get. I'm not confident in my ability to replace the rings or valve seals myself, maybe in a few months I'll take it to a shop.

The one thing I will probably still need to do is get some tires. Factory it's supposed to have 22x9x10 on the front, but 22x8x10 seems more readily available online. I can safely go down an inch in width I assume? Rims are 6" wide. 

On the back it's supposed to have 24x11x10s, but I thought if I went down to 22x11x10s I would gain a little low end torque, is my thinking here correct or am I being a dummy. 

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