Kawasaki Brute Forum banner
1 - 20 of 51 Posts

·
Registered
Joined
·
52 Posts
Discussion Starter · #1 ·
Just bought it.its a 06 brute 750 with 840 big bore kit. The carbs were sucking up alot of oil and was clogging them so it wouldnt run. I removed the air box and lines and just blew air in the carbs.got it running but was sputtering bad and wouldnt hit high rpm. Put my hand over the intake with carbs off and intakes and valves were dry so im assuming oil was getting sucked up from the air box. Anyway i took the carbs apart and cleaned them. The pilots are 42 and front main is 170 and rear is 175. Those jets seem right for a 840 kit and fmf pipe at about 0ft?
Im installing a catch can for the crankcase vent.
The adjusting screws were 2 turns out and from what i can see the slide and needle is stock
 

·
Super Moderator
Joined
·
14,011 Posts
Well..if oil is getting to the carbs it can only be coming from the crank case vent going to the airbox from the crank case. That oil can only be going through the intake trach and mixing with the air/fuel charge before entering the cylinder. OK...let's back up a bit. That oil coming through the vent tube can only do that if..-there is excessive blow by, the engine is at an extreme angle..more then 48 degrees, is being held at near its maximum RPM of about 7750 for sustained periods or the air filter is very blocked-up. If course it could also be overfilled with oil as well. Anyway you should pull the vent line from the box and run it until it gets warm and see how much flow it has. There should not be much if the rings are sealing well. Do know that these BBK kits with 11:1 and higher pistons are known to over-pressure the rings and cause a lot of leakage. So..for now a catch can will help with that.
In any case the air box lid must be on and sealed tor the CV-K carbs to work correctly and as for the jets...sounds close and a bit over..especially the pilot being #42. I would have thought #40 would be plenty. You can come down one or two sizes with the mains and see if it gets too lean and if so go back up a bit.
 

·
Registered
Joined
·
52 Posts
Discussion Starter · #4 ·
Ok. I have the crankcase vent to a catch can and so far just light oil residue in there, nothing to amount to anything. I pulled the plugs today and they were black. I took the 3 washers off each the needles i put on thinking it was needed so it wouldnt run lean..sputtering at low speeds is almost gone. Gonna test the plugs after awhile riding and if there still black im going to back down 5 on each main till its good then fine tune from there.
 

·
Registered
Joined
·
52 Posts
Discussion Starter · #5 ·
If i go down to 40 pilots(42 were put in from po) how would i know if it works better? I read about the different circuits and what they control but with the pilots it started fine and seemed to run good above 1/4 throttle
 

·
Registered
Joined
·
52 Posts
Discussion Starter · #7 ·
Ok i messed with the air screws, at 1 1/4 turns out and the low speed miss is gone. Seems my mid range has suffered alittle. Could that be due to removing the shims i had on the needles? Theres no dead spots just doesnt seem to pull as good at mid range and now my off idle throttle pulls are great and i think the low end is spot on. Just dont know if i should try shimming the needles. Tops out about 68mph with the small 24" tires on it.
 

·
Super Moderator
Joined
·
14,011 Posts
Ok i messed with the air screws, at 1 1/4 turns out and the low speed miss is gone. Seems my mid range has suffered alittle. Could that be due to removing the shims i had on the needles? Theres no dead spots just doesnt seem to pull as good at mid range and now my off idle throttle pulls are great and i think the low end is spot on. Just dont know if i should try shimming the needles. Tops out about 68mph with the small 24" tires on it.
24" tires? who would put such a size on a Brute? 25s were stock. The fact that you went below 2 turns out says the idle circuit is getting too much fuel. It should be between 2.25 and 2.75 turns out from closed. That will however have an effect on the intermediate/main overlap point as it will lean it so that fact that you felt it means yes, you need to put the shims back in on the needles but NOT more then .040. That will allow the mains to start a bit sooner and progress faster, stopping that lean point. For now go back up to 1.5 - 1.75 on the A/Fs with the shims.. but strongly consider the #40 pilots in the future. Also check your float levels per the manual with the tubes...very important they be right on.
 

·
Registered
Joined
·
52 Posts
Discussion Starter · #9 ·
I bought the wheeler the way it is. On honda stocks.not running...
Idle circuit being to rich would be the pilot to big? On the needles there is a flat plastic washer on both, is that stock or did someone maybe put them on there? I looked online but didnt see any washers at all on the parts diagrams.
 

·
Registered
Joined
·
52 Posts
Discussion Starter · #10 ·
Also im going thru gas like crazy.. Bet i dont have more then 30 miles and my gauge is already flashing. Im only driving it around my property and a few times up the rd to check top end. When i filled it i kept top in it off shaking it to get all the air out of the tank..
 

·
Super Moderator
Joined
·
14,011 Posts
Also im going thru gas like crazy.. Bet i dont have more then 30 miles and my gauge is already flashing. Im only driving it around my property and a few times up the rd to check top end. When i filled it i kept top in it off shaking it to get all the air out of the tank..
Well..probably needs some better tuning and jetting but Brutes aren't known for fuel economy. Those 05s-07s stock only got at best between 9 and 13mpg. Add a BBK and cams and that down to..like 5-6...or less. Pretty useless for trail riding. OK for drag racing where you aren't too far from fuel I guess.
 

·
Registered
Joined
·
52 Posts
Discussion Starter · #12 ·
Im gonna get 40 pilots and a few different sets of jets. All you can smell is gas when its idling..
I dont trail ride much. Just gonna use it for yard work. I just got a good deal on it so i took it.
When you have just a big bore kit does the carb require rejetting from stock. I know a pipe and or aftermarket air filter will require rejetting.
 

·
Super Moderator
Joined
·
14,011 Posts
Im gonna get 40 pilots and a few different sets of jets. All you can smell is gas when its idling..
I dont trail ride much. Just gonna use it for yard work. I just got a good deal on it so i took it.
When you have just a big bore kit does the carb require rejetting from stock. I know a pipe and or aftermarket air filter will require rejetting.
Oh yeah. And the BBK will require an aftermarket complete exhaust but..JMO, I think if those are Keihin jets..he went way to far. As I recall.. they came stock with 152/158. I would have thought only a 3-size up from there at sea level would be close. Oh and if is smells very rich at or near idle, might also want to check the choke plungers and their cables. It is common for then to not seal or the cables to bet twisted or rusted so they won't close. If one or both is not sealed, it will pull raw fuel from the bowl all the time and be very rich. Just something to check.

This is the Kiehin Jet chart:

 

·
Registered
Joined
·
52 Posts
Discussion Starter · #14 ·
So a 160 and 165 be a good start? And it has a full hmf performance brushed exhaust. Choke plungers are seated properly. I made sure of that when i had the carbs off and cleaned them(choke lever is broke so its not hooked up there)
 

·
Super Moderator
Joined
·
14,011 Posts
So a 160 and 165 be a good start? And it has a full hmf performance brushed exhaust. Choke plungers are seated properly. I made sure of that when i had the carbs off and cleaned them(choke lever is broke so its not hooked up there)
If the air box is intact and the lid has a good seal...and it doesn't have snorkels...if it were mine..I would start there. Just know it may not be right yet...this is a hit & miss type of thing. Remember the mains..or these main jets only effect fuel supply from about 1/8th throttle up. If it's rich below that...it's the pilot and the A/F setting...or high float levels..or choke plungers. The shims on the needles...consider those as doing 1/2-size on jets as well as enriching the charge at overlap.

One other thing to consider is the HMF full system. Need to check with HMF as they might want you to run the same size jets front and back. Kawasaki does them different because of heat..the rear being a little richer makes it run a little cooler, but the flow of the aftermarket pipe may cause a problem. If they say with your system to run the same, then start with the 165s for both. You may still need to go up or down one from there...and I would start with no shims on the needles and add them when I get close but just under what it needs. This is going to take patience...and time. But should be worth it in the end.
 

·
Registered
Joined
·
52 Posts
Discussion Starter · #16 ·
Hmf recommends 155 front and 165 rear. My air box is sealed good and no snorkel. Only seems rich at idle and up to id say 1/4 throttle.im gonna drop my main sizes to 160 and 165 and check the fuel levels. Whats the specs on fuel levels. I didnt pay no attention when i was cleaning the carbs but i just assumed they were not adjustable
 

·
Super Moderator
Joined
·
14,011 Posts
Hmf recommends 155 front and 165 rear. My air box is sealed good and no snorkel. Only seems rich at idle and up to id say 1/4 throttle.im gonna drop my main sizes to 160 and 165 and check the fuel levels. Whats the specs on fuel levels. I didnt pay no attention when i was cleaning the carbs but i just assumed they were not adjustable
It's all here in the service manual. Link good for 48 hours so download it soon.

 

·
Registered
Joined
·
52 Posts
Discussion Starter · #18 ·
Thanks. I needed that
Im looking at main jets and pilot jets. The stock part numbers come up as kawasaki parts. What types of Keihin jets are the same? I see alot that match the shape of the ones i have and just curious if they are the same and will work. Like are ebay keihin replica jets the same as original keihin jets? Wheres the best place to get them if ebay isnt good
 

·
Super Moderator
Joined
·
14,011 Posts
I got all my Keihin parts from PJ Motorsports. Here's a link:
Go to the Keihin Jet section, there are two that list: "Kawasaki ATV, Street and Offroad models with CVK, ATV’s with CVKR-D (V-Twin ATV) ". One is brass the other is Nickle plated..choose yours. Below that are needle shims and pilot jets. As I recall you need the N424-22 in the #40 x2...:)
 

·
Registered
Joined
·
52 Posts
Discussion Starter · #20 ·
When i had my 400ex and had it bored to a 416 with k&n filter and exhaust, when i jetted that i did it by reading the plug. I warmed the motor up then took it down a long rd and got up to 6th gear then held it wide open for a few seconds then immediately shut it off then checked the plug and i kept messing with the jets till i got the tip of the plug to a light toastish color.
Is there a method like that on the brute to do?

I know i need to get my idle so it isnt rich then go from there but all i need to do there is change the pilots to 40 then adjust the air screws right?

And how do i know if i got the main jets right and shims right on the needles?

And whats the difference in needles on the front and rear carb. I just noticed the numbers are different on the online diagram. Is one better then the other?
 
1 - 20 of 51 Posts
Top