2008 Brute Force 650 Carb Questions - Kawasaki ATV Forum
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post #1 of 16 Old 04-21-2017, 08:33 AM Thread Starter
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2008 Brute Force 650 Carb Questions

Newbie here... I recently purchased a used 2008 Brute Force 650 (KVF650E) which had been setting for at least a few months and, as expected, the gas went bad and plugged the carbs. The bike has about 300 miles on it. After some initial work (see below) I now have it starting easily and it accelerates well, but the engine won't idle -- it dies without the choke being partially open or with some help from the throttle. The A/F screw seems to have no effect (regardless of where I put it) and the idle adjustment hand screw is all the way in. The diaphragms appear to move smoothly under throttle. I can adjust the throttle cable to prevent the engine from dying, but it's idling way too high at that point.
So far I've:

1)Installed a carb rebuild jet with all new jets, a/f screw (gasket included), gaskets, diaphragm air jets. Main jets are sized at 142 and at 40 for the pilot for both carbs.
2)Cleaned the card multiple times.
3)Drained and refilled the tank with "real" gas.
4)Disassembled the carbs and soaked the bodies in cleaner
5)Checked/adjusted the valves
6)Installed new foam air filter/ (Kawasaki brand.)
7)Replaced the fuel filter -- which I'm now wondering if it's restricting field at low RPMs?
8)Inspected the boots at the top and bottom of the carbs and don't see any signs of cracks.
9)Replaced one diaphragm -- due to me damaging it


I think I still have a carb issue somewhere on the idle circuit, but I'm not finding it. With the carb disassembled, I can blow air through the pilot jet and have air coming from all sides. Ditto for both parts of the main jet. I can blow air through the A/F screw area and feel air on the other side for the carb body, choke uptake (correct name? -- round brass tube in the float bowl). Also, I can blow air from the side port (the small round covered area). The two short, small brass openings at the top allow air to pass downward. I've used a bread-twist wire to open most of these areas. I've sprayed carb cleaner all around the carb manifolds and haven't found any leaks.

I can tell that the previous owner had someone work on it because the main jet was missing from the rear carb, and the main jet for the front carb was setting in the bottom of the bowl -- in short, I'm not sure what all may need to be reviewed.

Questions:
1) Someone has installed a fuel filter, which I replaced. It's one of those fine screen units. Do these typically present any fuel flow restriction?
2) I noticed that the pilot jet is shorter than the main jet, so is it possible that the float level would be set incorrectly where the main is getting fuel but not the pilot?
3) Any there any other air ways I can check for blockage?

What should I look at next?

Thanks for any help!
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post #2 of 16 Old 04-21-2017, 08:38 AM
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Still dirty.
Air blowing through means that air can blow through. Not fuel, and the right amount of fuel. The holes in the emulsion tubes are still plugged, and the idle circuit as well.
Take the carbs to a shop that rebuilds carbs and have them cleaned in an ultrasonic cleaner.

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post #3 of 16 Old 04-21-2017, 09:00 AM Thread Starter
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I can blow carb cleaner through the same areas I've blown air. For example, I can blow cleaner through the body openings under the jet screws.

Is the float height a possibility? I'm not sure if the previous owner jacked with it, so I didn't want to start changing the float height unless the different height of the two jets could make the lack of idling possible. Also, I've not found any source for checking the float height yet on this model.
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post #4 of 16 Old 04-21-2017, 02:30 PM
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Carbs are still dirty.
Ultrasonic clean them.
The fuel filter is not a concern.
The float levels should be at least checked, and you can find that info in the service manual, which you can download a free service manual pdf on the internet. The floats set too high would be overflowing gas from the carbs - set to low - no power in mid and WOT.

05 Brute 750i Stock engine/ Muzzy Pro exhaust,Dynatec cdi,Vision Bruiser 14" wheels, 26" Bear Claw HTR Tires,3" intake snorkle - restricted,2" CVT snorkles,10" electric fan with custom mount,Mr Gasket Fuel Pump ,rejetted at #40 pilots,2 3/4 out on A/F screws,stock needles shimmed .030",# 158/# 158 main Jets
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post #5 of 16 Old 04-21-2017, 06:43 PM Thread Starter
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Thanks for the support. I'll make another attempt at cleaning and find the specs on the float height.
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post #6 of 16 Old 04-22-2017, 05:14 AM
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I dont use the tube method to set the float height - I invert the carb until i see the float stop, then adjust.
Here is a good vid example , but not a Brute carb -

05 Brute 750i Stock engine/ Muzzy Pro exhaust,Dynatec cdi,Vision Bruiser 14" wheels, 26" Bear Claw HTR Tires,3" intake snorkle - restricted,2" CVT snorkles,10" electric fan with custom mount,Mr Gasket Fuel Pump ,rejetted at #40 pilots,2 3/4 out on A/F screws,stock needles shimmed .030",# 158/# 158 main Jets

Last edited by dman66; 04-22-2017 at 05:19 AM.
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post #7 of 16 Old 04-22-2017, 08:14 AM
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Idling with the choke on tells you it's a dirty carb.

2002 698 Prairie
VFJ 11.5:1 coated pistons
FST Stage II Cams
Fundy Performance Porting, 1mm milled off heads
Kibblewhite valves
Crossover intakes
Modded airbox
Full Muzzy
Custom machined stock weights
VFJ Springs
DynaTek CDI
Other weird stuff

2011 Stratos 186XT Bass Boat
Mercury Optimax 115hp
Minn Kota 70lb 24v trolling motor
Lowrance HDS 10 Electronics
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post #8 of 16 Old 04-23-2017, 04:20 AM
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he said he replaced the jets, there isnt anything on this carb that needs anything else seems like more of a setting issue or not back together right. would get a hold of a manual and make sure they are right and stock jet settings, the diaphrams and springs in particular are easy to mess up, you cat go by what they were when you got it they have been messed with. also alot of people have issues with non oem jets and parts, if you got aftermarket stuff that could be your problem. its always best to just clean the jets, poke them out, spray, and blow them once you can see they are clear put them back in

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post #9 of 16 Old 04-24-2017, 06:27 AM Thread Starter
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Progress update: I made another attempt at cleaning and focused mainly on the tiny holes in the venturi located right below the butterfly. When I block both the pilot jet opening (with jet removed) and the choke enricher hole (in the venturi) and spay carb cleaner in the a/f adjuster screw, fluid does spray out these tiny holes. I don't know if these holes were open before -- they are so small I've had a hard time getting anything in them to help clear any blockage that might be present. Also, fluid flows between the pilot jet and a/f adjuster screw hole when I spray in the pilot jet hole. So I have at least some degree of opening between the pilot jet and a/f screw, and the a/f screen and venturi openings.

But while reassembling I decided to blow some air into the pilot jet hole with the a/f screw set the usual 2.5 turns out, and the a/f screen wouldn't let any air to pass to until I had the screw somewhere close to 4 turns out -- which sounds unusual based on what I've read in other posts here on the forum. I went ahead and mounted the carbs just to see if I'd experience any change in performance and it's still the same. Next I'll take them back to the bench and compare the new a/f screw from the kit with the one I originally removed. At this point I'm thinking either the new a/f screw, spring or rubber o-ring is bad or there is issue around the a/f screw opening. What I can see looks clean for the a/f screw opening.
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post #10 of 16 Old 04-24-2017, 03:37 PM
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thats not right shouldnt be four before anything happens, after you figure that out, the 2.5 is a get it running setting. then you warm it up and adjust the screws for max rpm at idle then cut it off and even them out

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2006 660 Rhino 27 mega mayhems

2003 650 Prairie mud lites(sold)
2008 700r Raptor se (sold)
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