Kawasaki Brute Force 200 same as Kymco MXU 270

[jpz]

Thanks guys. I picked up a new fuel filter today. Will try to install that in the next day or two. I did replace the plug, and have very similar results. Still wants to stall when revved. The plug looks lean as well, so I agree with all the above that I have a fuel deliver issue.

If the fuel filter doesn't fix the problem, I'll pull the carb back off and give it a more thorough cleaning.

I'll report back with my results. As I have said before, and I'll say it again, thanks all for the continued help. I'm hopeful to report a running quad one of these days!

[kp3004x4]

Good luck

 

[Mech]

Jpz..  All you need to do is pull the fuel pipe off the carb and check it flows plenty of fuel.. If it does, then you have a problem inside the carb.

[kp3004x4]

Yes sir mech is correct

[jpz]

21 hours ago, Mech said:

Jpz..  All you need to do is pull the fuel pipe off the carb and check it flows plenty of fuel.. If it does, then you have a problem inside the carb.

I agree, and that's what I initially did. However, due to this thing being such a bear to work on, I decided to run a straight fuel line to eliminate the fuel filter. It ran the same so my next task is to go through the carb as mentioned a few posts back.

[Mech]

A blocked float bowl breather can cause vacuum in the float bowl and then you get the same symptoms.

The first place to check, after you've checked the breathers, is the float needle. Some needle seats have a tiny filter above them, but they can just get blocked above the seat without a filter being there. Apart from a blockage the float might be set too high, or the needle might be sticking up. Some floats have a small spring that engages with the needle to make sure it comes down with the float.

You should check the diaphragm on the slide, and that the needle is secured and set to the right position.  You can do that before pulling the carb off.

[kp3004x4]

Yes,the needle can give you problems sometimes, make sure the settings are correct, to much or to little will give you flooding or starving systems.

[jpz]

Ok guys, found something that definitely needs replacing. The petcock is shot, I'm assuming the lovely ethanol gas we have is to blame.

I'm trying to avoid the dealer again, since the ignition unit took almost 2 months to come in.

Anyone have a resource for a rebuild kit, or a replacement fuel tap? It sure seems like Kymco parts are tough to locate.

 

See pic for as found condition of fuel tap

[kp3004x4]

If the pet cock is in that bad of shape ,then I would definitely check lines carburetor completely,most likely dirt and rust in tank. Will have to do a good cleaning on all.Most of the time you can clean till Christmas but if rust got in carb then you have to take off completely and let set in a carb cleaner of some kind. some times you just can't get the rust out deep in side of carb with the fine ports and all to make carb happy again,then will have to get another.this is the thing that makes you drink and you wife move in with mother. Hopefully it not as bad as it seems and you can get it running.and as mentioned in above text if you tried straight without filter then you will have trashy gunk in carb.

[Gwbarm]

Iv been getting my petcocks from amazon so far no problems, no leaks and works as they should.

[jpz]

4 hours ago, kp3004x4 said:

If the pet cock is in that bad of shape ,then I would definitely check lines carburetor completely,most likely dirt and rust in tank. Will have to do a good cleaning on all.Most of the time you can clean till Christmas but if rust got in carb then you have to take off completely and let set in a carb cleaner of some kind. some times you just can't get the rust out deep in side of carb with the fine ports and all to make carb happy again,then will have to get another.this is the thing that makes you drink and you wife move in with mother. Hopefully it not as bad as it seems and you can get it running.and as mentioned in above text if you tried straight without filter then you will have trashy gunk in carb.

The tank is actually plastic.

It may be hard to see in the pic, but that's not rust, it's the gasket that broke down. I'm assuming from the owner not treating the garbage ethanol gas in our area.

I did perform a thorough cleaning of the carb, and only decided to disassemble the petcock for S&G's before trying to run the engine after the carb cleaning. 

So now I'm at the point of needing to replace the petcock so I can get back to troubleshooting. 

I broke open the old fuel filter, and shockingly it was clean with no debris. So I'm hopeful the carb will be OK once I can get a new petcock installed.

Stopped at the dealership today, and unfortunately it is on B/O with no return date.

I found a few "universal" ones on Amazon. I may need to go that route if I can't source an OEM one or a rebuild kit. The dealership said they haven't sold rebuild kits in years, people just replace them. 

[kp3004x4]

Ok understood,no rust is good 👍 but also some times that corn whiskey gas does gum up like that,like a gel ,if it is in carb could have a major issue ,cleaner should get it going. I have installed aftermarket motorcycle petcock on quads. Works fine and fairly cheap,good luck🤞

[jpz]

I had to order the petcock online, found a resource with the help of local dealer. Unfortunately the local dealer couldn't even get it, as it is on B/O from Kawasaki. Just hoping the place I ordered from is correct when they say "4 in stock" and I get 1 of them. Haha.

Carb has gone through a very meticulous cleaning just before deciding to disassemble the petcock. I never tried starting it or introducing fuel since the cleaning.

Keeping my finger crossed this finally helps but I won't know for a week or so. My son plays travel baseball and we are leaving the state for a week long tournament on Friday. 

I'll update this post once we return and I can get back to working on the ATV.

[Mech]

Good work on the family activity..  Nice to see.

[kp3004x4]

Yes need more family,less phones.  Good luck on bike.

[jpz]

Hey guys. Back on the saddle. Minor progress, but still not running correctly.

Had carb soaking for a few days to hopefully clean everything. 

Replaced petcock, drained and added a few gallons of fresh fuel.

Quad started immediately, and idled great. Now it will Rev a bit higher, and smoother than before but still not to full Throttle.

I'm torn on taking the carb back apart and trying to find something I may have missed.

Alternatively I have been reading about "limp mode". Before I dig too far into the carb again are you guys familiar with these bikes having a limp mode? I would have assumed that was specific to FI models, but some facebook pages are telling me it is on carburetor models as well.

Any thoughts on the mentioned limp mode before I dig back into the carb?

[Mech]

I've only heard of limp mode in EFI.. 

It will need a computer of some sort to have a limp mode.. 

[Mech]

From 1/4 up the fuel is being metered by the slide needle, which is easily accessed, So I'd take the top off and raise the needle a notch as my  first step.

[jpz]

2 hours ago, Mech said:

I've only heard of limp mode in EFI.. 

It will need a computer of some sort to have a limp mode.. 

That's what I figured as well. Never heard of limp mode on a carbureted model.

[jpz]

Hey guys. Back on this project.

Bike still runs lean. See pic of spark plug. 

I have tried shimming up the needle, with no luck. still runs lean and is very slow almost impossible to accelerate. 

I did find something today that is bothering me. In the pic of the underside of the carb, the red arrow points to the bottom of the port that the starter jet threads into. When I spray solvent in the treaded area where the jet would be, the solvent comes out the small hole marked by red arrow. 

This doesn't seem right to me. I feel like this hole should be plugged?

Thoughts on both pics?

[Mech]

No that doesn't seem right at all for there to be a hole by that arrow. That should stop fuel being lifter through the idle jet.,,  Except.. you say it idles fine !! Does it respond to adjusting the idle mixture ?

Does it have a diaphragm on the side of the carb ?

That plug is lean alright, but not too lean for a modern machine.

If it idles then it won't have an air/vacuum leak. If lifting the slide needle made no difference then it's either a blockage of the fuel, or too much air getting into the mixture.

Have you checked the air metering jets at the air-box side of the carb are there ? And have you followed the drillings making sure the big one is going to the main jet ? And have you had that brass tube the main jet screws into out ? And at the top of that brass tube, does it poke out into the venturi ? Some have a separate short tube on top of that tube and if that was missing the main wouldn't discharge right.

And.. have you ever had this bike running right, or did you get it not going ?  Do you know it's history ?

[jpz]

I'm thinking the same thing as you, that opening would restrict fuel from entering the idling circuit. It will idle all day if I just let it idle, so I'm assuming it gets enough gas for idle. Once you start to increase the RPM, if you go quickly it cuts out, if you go slowly it will steadily raise RPM. It sputters, and hesitates and at times seems like it will die but will eventually get to higher RPM, I don't think it has gotten to full RPM yet.

I have not adjusted the idle mixture much. It has a security screw and I don't have the right screwdriver for it. I ordered a set off Amazon, and to my frustration they don't work. If I'm careful, I can adjust the screw with a set of slim needle nose pliers. What I did was verify the factory setting of 1.5 open from close.

Shimming up the needle made a minimal improvement. When I first got it to run, any increase in throttle would cause it to stall. Now, I can slowly increase throttle and get the bike up to about 20mph.

I'm not familiar with the side diaphragm you mentioned. I am fairly certain this does not have a side diaphragm. I'm not at home at the moment, but I can post additional pics at a later point if needed.

I will double check the air metering jets next to make sure the big one goes to the main jet. I have removed the main jet brass tube (emulsion tube I think it's also called?), and the additional piece that actually protrudes into the carb body and cleaned them both, and carefully installed the small piece correctly.

When the bike was first given to me, it was not running. Would not start. The history told to me by the owner who is not mechanically inclined is:

The electric start stopped working, so we used the pull start, it became harder and harder to start using the pull start to the point that it no longer started, at that point we left it in the garage. It sat in his garage for a good 6-8 months before it was given to me. He did not stabilize the fuel, ever. I don't believe he was even familiar with Stabil. A new battery fixed the electric start "problem"

I think the history, or lack thereof is what is hurting me the most.

I'm torn, because it clearly runs lean but I can not find a vacuum leak, or a  fuel clog anywhere. I was debating on installing a jet kit but the bike is stock so there shouldn't be a need for one. 

I'm getting to the point of thinking about replacing the carb. Our area uses Ethanol gas, the bike is 3 years old, and has never been stored correctly. I'm wondering if damage was done to the carb that would require replacement?

I think I got all your questions answered. Thanks for your help, and I'm curious of your thoughts for me to move forward.

Definitely getting to the end of my rope, but I really don't want to give up. I've put in so much time, and want to see this thing run again.

[Mech]

Not knowing what might have been done is a bit of a bother.

First up, have you checked the ignition timing is right ? And is the plug the right heat range ? And, have you checked the exhaust isn't partially blocked, and that there is plenty of fuel getting in past the float needle. Using the drain screw is the simple way to check there is plenty of fuel getting into the carb fast enough. Blocked exhausts manifest at higher revs. If you can attach a vacuum gauge and rev it up the vacuum will fade away if the exhaust is blocked.

Then the way forwards is some very careful test riding trying things to ascertain where/confirming the problem is in the carb.

So... the idle screw, can you just use a small file or saw to modify a screwdriver ? It's important the idle mixture is set right, and at a minimum throttle setting. There are two idle discharge holes into the venturi and it's important that at idle it's only discharging from the one near the engine, and drawing air in through the second one near the airbox, then as the throttle opens slightly the second hole starts to deliver fuel as well giving a richer mixture to accelerate. That won't be your trouble though if it gets up past about 1/4 throttle before faltering.

Then there's another enrichening system for accelerating from about 1/4 to 3/4, that being the drilling the emulsifying tube fits into, and the tiny holes in the side of the tube. At low throttle settings that drilling fills up through the main jet and the fuel goes up over the tiny holes, and then as the slide needle starts to use fuel it draws fuel in through the tiny holes as well as through the main jet, until the fuel level in the drilling lowers and then the emmulsion tube lets air in through the tiny holes making it slightly leaner. Initially though as you open the throttle the raised fuel level works as an acceleration enrichener. Once you are on the upper range of the needle, and  the main jet, the fuel is being mixed with the air from the tiny holes. If those tiny holes are too big, then it starts out sucking too much fuel, then goes much too lean, or, if  the float level is so low that they never get covered with fuel, then it runs severely lean as soon as the slide needle comes into play.

Those two acceleration systems interact with the idle and main fuel and air jets to ensure the mixture is right at steady throttle settings, but richer when we are accelerating.

When we are test riding, it's good practice to take note of not only how much throttle causes the problem, but also how long it takes between opening the throttle and the problem to manifest. How it reacts if we ease the throttle off very slightly is a bit of an indicator of what's happening too. If for instance the fuel flow into the carb is restricted, then we can open the throttle and it will run ok(all else being right), till the fuel level drops, and that can take from a few seconds to ten seconds or more depending on the amount of restriction, whereas if it's the emulsion drilling being full of crud and so not holding the right amount of fuel, or, the emulsion tube having being changed with one the wrong diameter(which effects the amount of fuel being held in the drilling), then the problem manifests almost instantly.

Perhaps too much information, or more than you really wanted, haha, but you sound pretty onto it and so hopefully that will help you pin-point what's going wrong.. 

And yeah, if it idles then it won't be a vacuum leak, they manifest bad at idle but have almost no effect at throttle.

As far as the ethanol idea goes.. it looks too clean and nice to have been eaten up by that... Not that I'm too familiar with the problem because over here we only put ethanol fuel in things made for it..  which means modern cars and not bikes. 

[Mech]

So..  I was trying to find a manual for the 270 because I only have a manual for the 250/300, but I found this picture of the inside of the carb and it looks like that hole by the red arrow is normal on these things.. Weird but true.

I also found a reference to some "pair solenoid", which it turns out the 250/300 have, and yours might too. It's not an electrical solenoid but a vacuum operated solenoid, and if it had a diaphragm with a hole in it , it could let too much air in..

MXU300.pdf

[jpz]

I will look into all that you mentioned. Thanks for taking the time to type it all up. 

You know, it's really funny that you mentioned the "pair solenoid". In my most recent troubleshooting, I was looking for any type of vacuum leak that could be causing the lean run condition and I found the that pair solenoid (so the 270 does have it). I was a little thrown off by it, and assumed it to be something emission related and decided to leave it alone. I will also go back, and take a much more detailed look at it, and see if in fact it is defective.

The kids return to school next week, so we have some back to school shopping to complete this weekend, so it could be a few days before I report back.

Also, really weird that the hole in the carburetor under the starter jet is normal. I thought for sure this hole would be a problem. I spend a few hours looking through the internet trying to find any pictures/videos similar to the one you posted. All I found was images from the opposite side. Glad you solved that mystery as well.

Thanks again!

[Mech]

No trouble..  Hope all the explanations made sense. It does to me.. But it's language I'm used to, and I wrote it.. Haha. Ask away if there's anything confusing.

That "pair valve"(air valve I think), won't operate at idle or it would bugger up the vacuum. It uses vacuum, probably from a port somewhere that only gets vacuum when the throttle is open, so under the slide probably, to open.

 

[jpz]

Well I finally have some good news to report.

The bike is running great! 

After going through all we previously discussed, and not finding anything wrong, I decided to plug the pair valve.

The bike immediately ran better, full throttle with no problem. Runs great up to 20mph, which is the Kymco limiter in the CVT. 

After months and months of fighting this, to say I was excited would be an understatement!

I have to assume the pair valve is defective, and was letting unmetered air into the engine.

Now I need to work on removing that limiter in the CVT.

Thanks Mech and all that contributed to this battle. I really appreciate the help!

[Mech]

Oh good news. We need some wins !

 

[jpz]

And the final report on this project. The governor has been removed, and the quad is a beast. Runs up to about 37mph now.

What a project this became. Glad it is finally over. 

Once again, thanks to all that helped me along the way. It is much appreciated!

[Gwbarm]

Glad you got it going, you have worked hard on it.