power jet issues

onebun · Post by **onebun** » Sat Nov 28, 2009 3:44 pm

ok guys pulled my airbox to get a better look at whats going on with my carb and found that when i pull the engine over the power jet is just dumping fuel in like crazy,i blew out my main jet circuit thinking it was plugged so the fuel was being pulled thru the power jet but no change. this does not happen on the other carb.any ideas whats going on?thanks john.

onebun · Post by **onebun** » Sat Nov 28, 2009 5:57 pm

don't know much about these power jet carbs and don't really understand how they work but i do know that they are vented and was wondering if that vent was plugged could it cause the power jet to pull more fuel into the carb? there is a visible stream going into the carb when i pull it over.thanks john

Post by **Vmax540** » Sat Nov 28, 2009 8:42 pm

John, What (if any) power/air jets are in the carbs ? The service manual shows the power jets should start adding fuel only from 1/2 throttle to full throttle.

Power Jet/ Power Air Jet L:135 R:130/ L:1.5 R:1.4

onebun · Post by **onebun** » Sat Nov 28, 2009 9:33 pm

hi chuck i stepped them up to 145)power jets) for both on the advice of the local yammie tech to ritchen it up for my aaen pipes as well as 370 mains.i 'm getting a lot of fuel out of the hole at the back of the carb on the left hand side,whice comes from the hose from the bottom of the carb,i have stock air jets.thanks john

sxr1000 · Post by **sxr1000** » Sat Nov 28, 2009 11:18 pm

The power jet carbs act just like a modern day dial a jet just not adjustable, and do not add fuel until WOT so it still points to to much fuel in the bowl.

opsled · Post by **opsled** » Sun Nov 29, 2009 9:32 am

sxr1000 wrote:The power jet carbs act just like a modern day dial a jet just not adjustable, and do not add fuel until WOT so it still points to to much fuel in the bowl.

Yes, To much fuel in the bowl. You have a needle/seat/float issue that is not maintaining the fuel level in that carb. When you pull over the engine the pump is adding more fuel and it is spilling out the P-jet. I would be willing to bet that if you had the slides up so you could see the main nozzle when you were pulling it over that fuel would be spilling there aswell.

Plugged vents would not cause this issue. If they were plugged air could not get in or out of the top side of the bowl causing a pressure buildup when the pump was trying to fill it and a vacume when the engine is trying to use it. That pressure/vacume would slow fuel from entering the carb and slow or stop it from leaving when the engine was running. In short you would have a "lack of fuel" problem.

If you notice the vent lines loop and cross over the top of the carbs on the intake side and back down ending below where the fuel level in the bowl should be. This is done so all the fuel in the bowls won't drain out the vents if the machine is on it's side or upside down (gas tank vents are done the same way and for the same reasons). Because these lines loop over the top they are higher than the main nozzle and the P-jet outlet so you will see overflow issues at the main nozzle and P-jet outlet (unless they are plugged) before you will see it from the vents.

The fuel level in the P-jet line should be the same as the bowl. If it is higher you have a fuel level control issue. It's that simple.

Good Luck,

Phil (opsled)

PS. If you ever change the lines on your P-jets make sure you get the CORRECT!! size (ID, OD) line as a replacment. Line that has to small of an ID can overfuel when running and line that is to large will underfuel or even render the P-jet inoperable.

onebun · Post by **onebun** » Sun Nov 29, 2009 10:44 am

great thanks guys!

onebun · Post by **onebun** » Sun Nov 29, 2009 5:02 pm

ok got at today did the blow test on the needle and seat it held,doubled checked the float heght it was ok,swap float bowl from the carb i know is working properly to the bad carb changed the fuel line from one outlet tp the other, still getting fuel tru the power jet,even bent the tang on the float to get to shut down sooner no change not sure what elese i can do i have a other carb comming

Bob Vehring · Post by **Bob Vehring** » Sun Nov 29, 2009 7:47 pm

When you did the blow test, was it light pressure. Remember the floats really don't push up with alot of force. I would guess that at the pressure the floats exert maybe the needle is not sealing. I would swap just the needle and seat from each carb and see if the problem goes with it.

onebun · Post by **onebun** » Sun Nov 29, 2009 8:10 pm

ya thats a good idea bob just to see if it jumps to that carb and then i know that needle and seat are bad.i started to blow soft and it shut off and i blew harder and it shut off there brand new i paid 126.09 $ gonna try that tommorrow aft.thanks john

onebun · Post by **onebun** » Mon Nov 30, 2009 8:11 pm

found that the vents for my float bowl were plugged together insted of off set so the air couldn't get out of the float bowl pressurizing it causing fuel to be forced out the power jet mind you haven't tried it yet but it makes sense to me and it was something wrong in the carb set up will try it tommorrow a.m. anybody have anythoughts on this? is my thinking on this correct? thanks john

Post by **tyler440** » Tue Dec 01, 2009 8:54 am

i would say your should be good to go now... if not your a heck of a lot closer... those vent thingys are kinda important

Post by **Vmax540** » Tue Dec 01, 2009 11:10 am

FYI.

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onebun · Post by **onebun** » Tue Dec 01, 2009 11:16 am

wow i got ripped!!!!!