# Carbs



## browland (Apr 4, 2009)

Any carb experts left out here? I'm beating my head against the wall trying to fix one. I have worked on quite a few but this one is working me over pretty good. I have an all stock 750, ran like hell when I bought it, carbs had old fuel that set up in the bowls. Carbs are stock, no dynojet. But problem is I'm already sitting at 3 ,, .038 shims under each factory needle which has drastically improved overall running. I have ,cleaned the carbs 3 times, blown thru ea passage, slides free, without holes, carb boots replaced as they were cracked , exhaust leaks fixed, new fuel. Floats perfect in spec with manual. It cranks fine, idles great and is responsive as can be in the low rpm and idle to 1/4 throttle range. But from idle to wot it backfires thru exhaust . If I'm running down the road and ease into the throttle it's very slow to rev until i get up to the 3/4 to wot range. To me it still seems like I need to shim the needle more . But it seems like it is already to high. I haven't checked the tank for any issues, the tank vent I haven't yet checked. The vent lines on carbs are free and clear. Any insight from someone would be friggin awesome !!!im stumped . Thanks guys


----------



## DaveMK1 (Nov 8, 2009)

Water in the fuel maybe? 

Sent from my droid when I should be working. MIMB RULES!


----------



## J2! (May 8, 2010)

Do you have a wideband to check the af ? It does sound like you need one more shim under the needle.


----------



## dman66 (Feb 20, 2011)

I thought that backfiring out exhaust was from rich fuel condition ? If you got the stock needles,try putting them in with 1 #4 shimm under each. And usually when slow to rev up usually is too much fuel - on your bike sounds like it's in the needle range your rich. If you have dynojet stuff in the carbs the dynojet needles have adjustable washers..... Just thinking out loud here....I think you can go to 40 thou. on the shimms.Have you tried opening the gas cap just one turn out to see if tank vent is bad,have you tried your stock cdi without the Moose modual ?


----------



## browland (Apr 4, 2009)

dman66 said:


> I thought that backfiring out exhaust was from rich fuel condition ? If you got the stock needles,try putting them in with 1 #4 shimm under each. And usually when slow to rev up usually is too much fuel - on your bike sounds like it's in the needle range your rich. If you have dynojet stuff in the carbs the dynojet needles have adjustable washers..... Just thinking out loud here....I think you can go to 40 thou. on the shimms.Have you tried opening the gas cap just one turn out to see if tank vent is bad,have you tried your stock cdi without the Moose modual ?


this thing is bone stock, 1 shim under each needle is backfiring thru the carbs like crazy just trying to rev it up, 2 made it some what better, 3 made it driveable with out backfiring thru the carbs . Now its just thru the exhaust. Which sounds like a rich condition. Ihavent checked the fuel cap, ill try that tomm when I get home. It acts like its starving for fuel, until i go wot. Both sitting in neutral and driving down the road. I dont get it unless the pump is crap, then ill have to start all over again.


----------



## kevinryan7 (Jan 31, 2012)

I would drain the tank and start with fresh fuel. Even though you don't want to do it again, take the carb off, clean it, and return the mixture screws to factory settings with no shims. Are the plugs black and wreek of fuel? Even if they don't, go ahead and replace them. Pretty much, start from scratch with clean fuel and go from there. Return it all to stock settings, clean, replace plugs, and ad new good fuel like 90 octane or higher. Once that's done, fire it up and we can go from there. If you can, take video of how it responds once all this is done and we'll get it figured out. May be something as simple as going to bigger jets. I have an 05 650' snorkled, HMF exhaust, K&N filter and a Dynatek CDI and I run 142's and 145's.....instead of shimming the hell out of it and fully turning adjustment screws to get more fuel, maybe just go up a size in jets. Take some video with sound, post it and we'll go from there. Between everyone on here, we'll get it figured out brother.


----------



## dman66 (Feb 20, 2011)

Is it a stock vaccum pump - they're cheap new - or do you have the Mr. Gasket 42S electric fuel pump ? How about the cdi - maybe you're having issue with the Moose modual or combination of modual and the 6 deg.key ?


----------



## kevinryan7 (Jan 31, 2012)

My bad, I was looking at the info you had listed in your signature.....oops. Thats why i mentioned my settings with my mods. Either way, stock bike should run fine at stock settings.....thats what it was meant to do (i know it doesnt always go that way though) Return it all to stock settings and we'll go from there. stock settings shouldn't be far from where it has to be with a bone stock bike. Maybe a few things got out of whack when you were adjusting everything trying to get it figured out. I've had to start from the beginning many times and slowly work it to perfect tuning, and it generally works pretty well


----------



## kevinryan7 (Jan 31, 2012)

dman, I think you're doing the same thing I did. I think he's referring to a different bike than the one in his signature........if so, oops x2 :34:


----------



## browland (Apr 4, 2009)

kevinryan7 said:


> My bad, I was looking at the info you had listed in your signature.....oops. Thats why i mentioned my settings with my mods. Either way, stock bike should run fine at stock settings.....thats what it was meant to do (i know it doesnt always go that way though) Return it all to stock settings and we'll go from there. stock settings shouldn't be far from where it has to be with a bone stock bike. Maybe a few things got out of whack when you were adjusting everything trying to get it figured out. I've had to start from the beginning many times and slowly work it to perfect tuning, and it generally works pretty well





kevinryan7 said:


> dman, I think you're doing the same thing I did. I think he's referring to a different bike than the one in his signature........if so, oops x2 :34:


sorry guys, I did buy another one for my kid, not the one in my signature. I went thru the stock settings this morning. Started back at ground zero lol. New fuel, 93. took the carbs off, cleaned again , blew thru all passages, checked floats,reassembled and its no good as factory. then went thru the shimming process. it does have the factory fuel pump, and new plugs, they arent fuel fouled either, they are really clean, white actually, like its lean. I cant see the carbs really being the culpruit anymore. I think it has to be on fuel delivery. i swapped the cdi from my other brute, nothing changed.


----------



## browland (Apr 4, 2009)

almost ready to torch it, i wish i had of not bought it now, but i figured with low hours and miles it would only need some cleaning up and carbs cleaned from sitting. live and learn i guess


----------



## DaveMK1 (Nov 8, 2009)

Pull the fuel tap on the tank. There is a small plastic fuel screen on it and make sure it isnt clogged up. Ethanol is a biatch on these bikes especially of it sits with out treatment. Bad thing is if it is the filter you need to buy a new fuel tap, cant just get the filter


----------



## kevinryan7 (Jan 31, 2012)

Are the bowls filling up like its getting a lot of a fuel but only burning so much of it? Or is it not getting enough fuel until you make these crazy adjustments?


----------



## kevinryan7 (Jan 31, 2012)

Worst comes to worst, I have one for sale your son would love to romp around on :chewbacca: Never hurts to try right?


----------



## browland (Apr 4, 2009)

DaveMK1 said:


> Pull the fuel tap on the tank. There is a small plastic fuel screen on it and make sure it isnt clogged up. Ethanol is a biatch on these bikes especially of it sits with out treatment. Bad thing is if it is the filter you need to buy a new fuel tap, cant just get the filter


fuel tap? Is that the on off valve i have read about?


----------



## kevinryan7 (Jan 31, 2012)

Sorry, dancing Chewy always cheers me up when I'm pissed......thought he might help the situation. And I can assure you that the 05 needs no carb work....runs like a friggin champ!


----------



## browland (Apr 4, 2009)

kevinryan7 said:


> Are the bowls filling up like its getting a lot of a fuel but only burning so much of it? Or is it not getting enough fuel until you make these crazy adjustments?





kevinryan7 said:


> Worst comes to worst, I have one for sale your son would love to romp around on :chewbacca: Never hurts to try right?


its not getting enough fuel, which is why i have shimmed the crap out of the needles. its fine and revs clean sitting there, until i go from idle to wot, then it pops out of the exhaust. yeah i wish i had found a better wheeler 4 weeks ago lol


----------



## browland (Apr 4, 2009)

kevinryan7 said:


> Sorry, dancing Chewy always cheers me up when I'm pissed......thought he might help the situation. And I can assure you that the 05 needs no carb work....runs like a friggin champ!


haha Its cool, i just want to figure out what im not catching. My other brute has had similar issues but with knowing which area of the carb to adjust it was simple, this one is just a pita


----------



## Saintsation (Mar 2, 2011)

hey man i had the same issue with mine tryed everything put a new stock exaust on a little better but still backfiring. so i said the heck with it and baught an after market exaust (super pro dual muzzy) made a world of a difference. i first stared with a jet kit to get it rich well that worked but it was too rich so put the aftermarket exaust on fixed my problem runs great now. i went through every possibility let the carbs sit in carb cleaner twice 24 hours each time even ordered one new slide and some o rings and some other little stuff but changing the exaust made a world of a difference


----------



## dirtydog (Nov 11, 2009)

Did u pull the chokes? Didnt see anything on that. And still didnt hear anything on af screws. Did u adjust them? Sounds to me like a pilot issue. They control up to a quarter throttle.


----------



## kevinryan7 (Jan 31, 2012)

So is it doing it in neutral at wot? Or when it is in drive at wot? About what percentage throttle does it start to make the pops? Doesn't need to be exact, just a rough estimate.....if its only doing it at a certain load percentage and up it will help narrow down the issue.

If its good from starting, idling and about 50-60% throttle, but bogs and backfires over that, then I would think your pilots are fine. It's after that point when the mains kick in and if that's where your issues lies then I would start there. If the mains are completely clean (and I'm sure they are because you've cleaned it a million times) maybe try going up a size?

The problem is its feeling like its starved for fuel right?....with needles shimmed like 3ft up, lol, and mixtures screws all the way.....maybe trying out larger jets would help? Worth a shot and they are fairly cheap. I have some extras in the garage that I can mail to you, no cost at all. Worst comes to worst, you have a set of larger jets if you decide to do exhaust and all that fun stuff.


----------



## kevinryan7 (Jan 31, 2012)

Plus I have the stock ones off mine I can send so if you want to try drilling a set up a tiny bit at a time you don't have to worry about screwing up your original ones.


----------



## kevinryan7 (Jan 31, 2012)

And don't beat yourself up over buying this thing.....hindsight is always 20/20 and we've all done it before. We'll get this things up and running in no time and all will be right with the Force again......at least dancing Chewy thinks so :chewbacca: !!!! YEAH!!! Sorry, had to put in that little pun......Star Wars.....the Force......Kawasaki Brute Force.......bazinga!!!


----------



## browland (Apr 4, 2009)

dirtydog said:


> Did u pull the chokes? Didnt see anything on that. And still didnt hear anything on af screws. Did u adjust them? Sounds to me like a pilot issue. They control up to a quarter throttle.


Yes choke pluggers are new as well. A/f screws have been set, however the rear doesn't have any effect ,close it completely and no change


----------



## browland (Apr 4, 2009)

kevinryan7 said:


> So is it doing it in neutral at wot? Or when it is in drive at wot? About what percentage throttle does it start to make the pops? Doesn't need to be exact, just a rough estimate.....if its only doing it at a certain load percentage and up it will help narrow down the issue.
> 
> If its good from starting, idling and about 50-60% throttle, but bogs and backfires over that, then I would think your pilots are fine. It's after that point when the mains kick in and if that's where your issues lies then I would start there. If the mains are completely clean (and I'm sure they are because you've cleaned it a million times) maybe try going up a size?
> 
> The problem is its feeling like its starved for fuel right?....with needles shimmed like 3ft up, lol, and mixtures screws all the way.....maybe trying out larger jets would help? Worth a shot and they are fairly cheap. I have some extras in the garage that I can mail to you, no cost at all. Worst comes to worst, you have a set of larger jets if you decide to do exhaust and all that fun stuff.


It starts and idles great, revs good too. Until you go from idle to wot then it pops thru exhaust , it's messin up from 1/4 to 3/4 . I have a ton of jets . And thanks for the offer. So I come home this morning to mess with it.crank it right up , then I take the fuel cap off and it's total **** all over again. Rich as can be , so that being said I'm guessing it's the vent or the supply stopped up. I put the cap back on but it didn't cleaR up after a few minutes of running. At least I think I'm narrowing it down to the tank side , so I can start all over again after that's resolved. Effin pos lol


----------



## DaveMK1 (Nov 8, 2009)

Your fuel tap is on top of the tank behind the fuel pump. It has a slotted valve on it that says prime/fuel (or on. Can't remember now). I would pull that out and check the condition of the filter
then go from there. 

The right way to start the carbd bikes after the bowls have been completely drained is to shift the tap to prime, crank it until it fires than shift it back to on
Sent from my droid when I should be working. MIMB RULES!


----------

