Hey guys, I have a Mud Buddy 35 HD, I just put two new BPS heads and mikuni carb on it. Followed the directions to a T. my motor now will not idle, I have to pull on the throttle just to get it to run, I have tried tighting the throttle cable, with no luck. But the main problem is there is gas coming out of the Carb through the air intake everytime I pull on the throttle. Does anybody have any idea why this is happening, and what I can do to fix it?

Thanks,
Tanner Wildes

The accelerator pump "nozzle" or "jet" is facing the wrong way. It should be spraying into the carb when you give it throttle

yeah thats what I thought too, but it is facing into the carb, its like a cloud of gas coming out if it, not a stream of it.

Thanks,
Tanner

is it back firing through the carb? Need lil bit more details

Yes it is, the jet is shooting into the carb, not out. It's like a cloud of gas coming out. The engine only runs when I'm on the throttle, it won't run otherwise. And that is when the gas is coming out of the air intake.

Thanks,
Tanner

THe mist you see is the back firing through the carb while the accelerator pump is squirting at the same time making the mist, A carb will backfire under either a lean condition, or a malfunctioning accelerator pump. which to fix this you may need to make a little adjustment. If that don't fix it look for a vaccum leak. With new ported heads you created more air flow therefore you may need to increase fuel, air fuel mixture has got to be right

sounds maybe like its pulling air from somewhere other then the carb. except for when you are on the throttle and its pulling hard enough to pull the air and the fuel from the carb. got a good seal from carb to manifold?

The bolts that came with my intake adapter were about two threads too long and bottomed out just about the time the adapter got snug. After a few runs mine started acting up and wouldn't idle, turns the gasket between the adapter and the intake got sucked in. I went to Ace and got some bolts 3/16th shorter and a new gasket and good to go.

May not be the problem but worth checking... take the the gasket out and put the bolts back in to make sure they are seating enough.

I'm willing to bet you have an intake leak, leaning out the motor and causeing you back firing through the carb. Check and make sure all gaskets on itake said are tight and in good shape. You don't won't to run lean cause you'll end up burning up a piston.

To lean it'll back fire through the carb
To rich it'll back fire through exhaust

Same thing mine is doing going get a mikuni hopefully tgat will solve my problems

A flat cam will also cause a pop back thru the carb

I hope my aint flat i aint got an hour on my motor yet brand new cam at build

The motor would be making some noise if the cam was flat, you would have some other tattle tails also. More than likely your carb just needs some adjustment.

If you've read some of the other threads those heads have been known to have leaky vlaves, this would cause your motor not to idle correctly, rather an erratic idle or no idle at all.

did u replace the needle and seat that came with the kit. ? check for debris in the carb. also check to make sure ur pilot needle jets are not hanging up. make sure that your acc. pump linkage is fully relaxed at idle.then set ur acc pump. set ur idle mixture screw turned out two turns from seated position thats a good starting point. also check for a vacumn leak. u can use intake cleaner or propane to test for leaks. do a cylinder balance test. if u don't want to buy a tester. rig up a bushing to screw into head with a compression hose and air fitting. air up a cylinder using shop air and listen thru your intake and exhaust port for a leak. also can use soapy water to check for a gasket leak. around any mating surface as a head or intake gasket etc. every one puts out a questionable product from time to time but im heads are not as bad as some make them out to be. and yes a going flat cam will pop back thru the engine. disrupting the intake and exhaust cycles. and unlike u takem i have seen untrained techs setting valve lash on a going flat cam till they damn near run out of rocker arm adjustment. not knowing any better. with a popping sputtering gas spitting engine.

intake gasket

On the other hand just trying to help this fella out. Back on topic.

Thanks for all the help guys. I broke down and had to take it to the shop to fix it, I couldn't. Looks like I had the timing off, and the valves weren't seated properly. I really screwed up. Thanks for all the help though!

Tanner Wildes

well whats the verdict

dude i just got back to work, give me a break, i'll be here all weekend. lol