Bogging off idle, running out of fuel....

[vdubn]

So, here is how it all started. We bought this bike with FMF Fatty's, and with stock pilots, 280 mains, and not sure if the needles were stock or aftermarket. Bike started and ran ok, but fluttered badly on the bottom end. You really had to throttle into it and slip the clutch to get going, once going, it was fine. So, I looked at the reeds thinking that there may be a problem there. The reeds were aftermarket, not sure what manufacturer, but I noticed that they weren't setting on the reed cage, they appeared to be open at all times, so I swapped a used stock set of them over to the bike.

 

At the same time, the pipes were getting stripped, so I took my Toomeys and carbs that were jetted for the toomeys, and swapped them as well so I could go riding. So, in the end, my pipes and stock reeds, and carbs were all put onto my sons bike, and it ran excellent.

 

Last week his pipes came back from stripping, so I put his pipes and carbs back on, this time I went up to 300 mains, 27.5 pilots, and kept my stock reeds in there (thinking that since the bike has K&N's without airbox, it could use the extra fuel).

 

So, I didn't fire it up before we went riding (first mistake), I figured it would run fine. We get to the dunes and fire it up, it runs fine, until you put it in gear and it dies. After working on it for 3 hours, cleaning the carbs, checking carb syncronization, verifying the slides are in the correct carb, checking float level, checking that the jets are in correctly, etc., I find NOTHING WRONG!

 

So, when it starts, it will run perfectly when the choke is on, and for about 30 seconds after the choke is off, then it starts to stumble if you give it any gas. I see plenty of smoke, so it isn't running lean, and the plugs are wet, but it is definately running out of fuel. I checked the flow from the tank, it is perfect.

 

Once it starts to stumble, if I pull the choke out, instantly the rpms come up, and it runs ok for another 30 seconds or so.

 

I checked to see if my stock reeds had any issues, and they look totally fine. I resealed the intakes just to make sure there were no vacuum leaks, and it runs the same afterward.

 

Sorry this is so long, but I have gone through every option I know. The next thing I am going to try is switching my carbs back onto his bike, its the only thing I can think of that would have any effect. TORS is totally gone, no parking brake, no TORS module, nothing.

 

Have any of you just had a carb act up like this?

 

Any help is greatly appreciated!

 

Dean

[JKJK]

I would check the float hights.It sounds like your confident it's a fuel starvation prop.The choke tube feeds of the bottom of the bowl so it allways has fuel.If the floats were set to high,their will not be enough fuel available to create a smooth transition+it will act like your describing.

[vdubn]

They measured right at the 20-21mm mark

[JKJK]

I would try bending the tabs slightly on the floats,to allow more fuel in the bowls.Even if they are within spec.

[mud91]

If you plugs are wet, how is it running out of fuel? Maybe is not firing correctly, did you check your electrical. I know u can check your stator and coil with a meter but you cdi I don't think u can check that unless your have a friends to swap out with.

[vdubn]

I spoke to a shop close by, and they mentioned that it sounds like an issue where the pilot jet circuit is probably plugged. Out at the dunes I couldn't blow anything out, so I'll pull them all apart tonight, blow the carbs out completely and see if that is the problem.

[reded]

Raise the needles all the way up, clip on bottom position. mine did the exact same thing when i bought it. I don't know how the guy even rode it like that, wouldn't pull at all. After raising needles it ran like a champ!