I own a 2007 Kawasaki Brute Force 650. After the first 3 months of owning this unit it became very hard to start and would not maintain idle. It will crank and crank, & crank, then backfire through exhaust and carb before finally starting. The only way to keep the unit from dying after startup was to manually turn the idle up about 3 turns. After the engine warmed you would have no engine braking, and very high idle, you would again have to adjust the idle, down this time. Once it warmed up it ran great and restarted fine.

I took into two dealers 5 seperate times to correct this problem. The first three trips did no good what so ever. The fourth trip they finally corrected the problem, only to have it last for 2 months. They claimed they adjusted the valves, reset idle stop on choke plates, and synchronized the carbs. Now 2 months later I have the same problem. It does not seem to be a cold weather problem since it has occured off and on since July.

Kawasaki intially admitted to me (while unit was under warranty) this was a known problem with this engine and to have dealers contact them when I took it in, as they had a remedy for it. As stated before the first three times they (dealers) could not fix it. Now that the unit is 2 months out of warranty Kawasaki is claiming that I did not properly maintain the unit (simply a bunch of BS) and not willing to work with me. I am amazed at how well documented this problem was under the warranty period, only to have them argue with me and blow me off now.

If anyone has seen this problem and has a remedy I would appreciate any help. Since Kawasaki is no longer willing to accept responsiblitly for this problem I am sure it is going to cost me a small forturne to correct a problem that should of been corrected under warranty.

FYI[img]i/expressions/face-icon-small-disgusted.gif[/img]
This unit has also been in two other times (while under warranty) to have the valve cover gaskets redone because they leaked oil.

 

I have a new 2007 BF 650I, sure hope this doesn't happen. it is a little hard to start but it does idle. thanks for the heads up.

 

Usually the dealer cant fix it, because it would require the jetting , be made richer, and the emissions would be higher, and by law, they cant do, or suggest that. They have to follow the kawasaki recomendations, they cant just go on their own.
Either the pilot jets need to be bigger, or it might just need the mixture screw richened. The idle circuit is too lean (backfire and popping thru the carb are both symptoms of lean).
Do you try to use only pure gasoline? If you use ethenol blended gas, try a full tank of pure gas (no alcohol), and see if it improves. If it doesnt, then the jetting needs to be corrected. Just remember, the dealership cant and wont do it for you. Either you find someone who can, or you need to do it yourself, and its not that big of a deal.

 

jhb,
"After the first 3 months of owning this unit it became very hard to start... "
So, quad started fine during the first 3 mo? If so, this is not a factory carb setting issue. Something else has changed during usage. However this still could be carb issue like poor quality fuel prematurely gumming up or some tiny debris "partially" clogging up the pilot circuit of your carb.

"very hard to start and would not maintain idle..."
This is a very typical symptom of partial clogging of the pilot circuit and/or tight valves.

"They (dealer) claimed they adjusted the valves, reset idle stop on choke plates..."
Ask this dealer to show you where the choke plates are on your BF650 carb. There ain't any. You got hosed.

"The fourth trip they finally corrected the problem, only to have it last for 2 months..."
Valves would tighten up after about 50~100 engine hrs on BF. Do you use that much in 2 months?

Do following:
1). Check/replace plugs.
2). Check compression
3). Check choke system. Actually it is a fuel enrichening system, there is no actual "choking" on the BF's twin carb system and choke is a mis-leading terminology on BF. It is a small plunger (there is one for each carb) that opens and closes to provide extra fuel when you push the choke lever. Check to see if the plunger compelety opens when you push the choke lever all the way. And check to make sure the plunger moves freely - no sticking.
4). Fuel gumming up is my bet. Get a $3 Techron fuel system cleaner (8 oz bottle) from WalMart and ride full one tank. This is a lot easier to clean gummed up carb than disassemblying the twin carb system. If this solves your problem, add fuel stabilizer into your gas tank next time when you are not riding the quad.

 

Ok yes I probably do ride it that much. For the two months it ran good I apparently put 40 hours on it. That seems a little premature to me for a valve adjustment, but I am not a professinal mechanic. How do I check to see if the plungers are working? I can tell you that once engine starts on choke it runs ok for about 10-15 seconds, then you have to pull choke off because engine starts to sputter. This leads me to believe that the choke is operating properly, but again I am not a mechanic, and maybe the plungers are sticking. I have put new plugs in it, does not seem to help. Had a hell of a time starting it this weekend, spent 45minutes the night before the ride to load on trailer, and 1 hour the day of the ride trying to start. Changed the plugs out two times trying to get it to start. Both times the plugs came out damp with gas on them. I run 87 octane fuel in the BF that you would buy for a car, and do not put anything else in it.

Thanks for your suggestions hopefully I can pin it down

 

The choke (I hate to use this term - fuel enrichening) plunger is located on the left side of the carb at the ends (one for each carb) as you are sitting on the quad. Just follow the choke cable toward the carbs. The single cable will split into two, one for each carb. Remove a small screw for a cap that holds the plunger which is a small piston shape (cylindrical) meta, maybe 1/4" dia, made of brass that is spring loaded in the aluminum bore of the carb. To check the proper operation of the choke plunger, with the cap open, push the choke lever all the way open position - does the plunger open all the way in the bore? Then, push the choke lever all the way to close position - does the punger close all the way in the bore?
Your problem sounds so much like clogged carb but how can it clog up if you put 45 hrs in two months? By the way the hour reading on your meter is not accurate - always more than actual because that's key on time not running time. Mix carb cleaner fluid in your fuel tank and see what happens - that's easy and cheap.
I don't want to underestimate you but just to make sure... you are not opening the throttle (like giving gas) when you start the engine with the choke on, are you? You shouldn't be.

 

Yes,
That is the only way I can get it to start. I always try to start it choke off first, then go to choke on, and then push the throttle if need be. Here lately the only way I can get it to start is to open the choke, and mash throttle. I spent 1 hour trying to start this damn thing Sunday. We drained the ATV Battery, and another, changed plugs twice, (each time the plugs were damp with fuel) and then resorted to jump starting it from another ATV. We finally got it going, but it did take 1 hour, it was very cold out about 28-30 degrees. Once it started and got warmed up it ran really well all day, and always restarted fine. Once I trailered it home, (about a 30 minute drive) I could not get it to start, gave up and pushed it in the garage.

 

I also start mine with the choke on and give it some throttle. I then turn the choke off and continue to give it gas so it dosen't die. I still give it gas untill it holds it's idle on it's own. then it runs fine all day.

 

If your choke system is operating correctly and your carb is in a good health, when starting cold, opening throttle is not necessary. Actually, it would make the starting harder/longer (but eventually starts).
Here is how it should work:
When Cold:
Full choke, throttle closed, start engine. Slowly reduce the choke until it reaches normal idle rpm or just little higher, put in gear and start driving. Then completely turn off choke while moving. Even in average 20 deg weather here, I start my engine and get going in less than 5 seconds with this method.
When Hot/Warm:
Fully closed choke, slightly open throttle or as blipping, start the engine and drive.

 

<div class="FTQUOTE"><begin quote>Originally posted by: jhb211221

Yes,

That is the only way I can get it to start. I always try to start it choke off first, then go to choke on, and then push the throttle if need be. Here lately the only way I can get it to start is to open the choke, and mash throttle. I spent 1 hour trying to start this damn thing Sunday. We drained the ATV Battery, and another, changed plugs twice, (each time the plugs were damp with fuel) and then resorted to jump starting it from another ATV. We finally got it going, but it did take 1 hour, it was very cold out about 28-30 degrees. Once it started and got warmed up it ran really well all day, and always restarted fine. Once I trailered it home, (about a 30 minute drive) I could not get it to start, gave up and pushed it in the garage.</end quote></div>

What you are describing is very normal on BF's!
They start great withouth the "choke" when it is hot outside, but when it is open all the way it will only run 10-15 second and will begin to "choke". You can get a feel of it and readjust the choke lever to be barely "on" and it should idle until warm up with no problems. It you can't "get a feel" of it, simply give it a little throttle for 30 sec. or so, and it should idle fine. You will have to let it worm up or it will run bad. I guess that is corrected on the 08 BF's with fuel indjection.