Just reassembled the bike after installing stage 7 needles, 150 mikuni main jets, and replacing two coast enricher diaphragms there were completely deteriorated. I've got all the carbs sync'ed, and it runs great everywhere except for a hesitation when coming off idle from a stoplight, and a hesitation when blipping the throttle to downshift. When playing with the fuel mixture screw, I noticed that the right rear carb did not have any effect on idle regardless of where the screw was set. With the other ones, I noticed at least some change in idle when the screw was seated all the way. So I'm concluding that the right rear (#4?) is not working at idle? While the carbs were out, I checked the dry float levels, and pulled the jet block and checked everything. Where should I begin to try to troubleshoot this?
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davesax36
Well-Known Member
Was there junk in your carbs when you took them apart? Did you also replace your fuel filter and or check the blak plastic section of your fuel pump for rust or other crap? Any of these things could be allowing tiny particles into your carbs which will plug pilot jets almost instantly. There's a how-to on fuel pump disassembly. Also search on here for "carb bible". Welcome to the board.
Also, I don't know how well that combination of needles and jets works relative to whatever exhaust you have.
Also, I don't know how well that combination of needles and jets works relative to whatever exhaust you have.
What are your needles set to? Did you clean the three bypass holes below the throttle late? I get those with a strand of electrical wire. I would also drain that float bowl to see if anything comes out and if so do a wet level check.
Draining the carbs into a white cup and checking each will tell a lot.
Black particles are what you are looking for, especially if you're running
Ethanol Fuel. Definitely sounds like #4 has troubles.
What Pipes are you running with 150 jets?????
Black particles are what you are looking for, especially if you're running
Ethanol Fuel. Definitely sounds like #4 has troubles.
What Pipes are you running with 150 jets?????
sdt354
Well-Known Member
Start with a good carb sync, then adjust the A/F screws.
The right rear carb is #3, here's the set up.
^
front
#2 #4
#1 #3
rear
Just curious....during sync, when you blipped the throttle, did #3 & #4 rods drop down before #1 & #2, or did all four drop at about the same time?
^
front
#2 #4
#1 #3
rear
Just curious....during sync, when you blipped the throttle, did #3 & #4 rods drop down before #1 & #2, or did all four drop at about the same time?
davesax36
Well-Known Member
Specific questions like this are why we all come here for help instead of going to the dealer or a mom and pop shop.
Sent from my Galaxy Nexus using Tapatalk
Damn right !!!
Can you clarify which bypass holes? I'll drain #3 today (Thanks for correcting my Danny), and see how it looks.
4 > 1 Kerker/Supertrapp.
Can't recall. I'll hook up the sync tool again and find out. What the significance of that though?
Agreed. People with the same bike are much more helpful in troubleshooting than general mechanics.
There are 3 bypass holes and are in a triangular formation and are covered by throttle butterflies at idle. When throttle is applied, holes are uncovered thus providing supplemental pilot mixture.
tugla
Well-Known Member
also is the cable slack set in your throttle
Had some time today to toy with the bike. I raised the idle screw a bit so it's idling around 1500 RPM, and the bike seems to run more or less normal now, although I'm assuming it's because the idle circuits aren't being used with the idle screw so high? I also did the "shotgun" method in hopes I could avoid pulling the carbs apart again.
I rode it around briefly (10 miles or so), carb 1 started leaking fuel out of the vent tube on top, which I read means the float wasn't draining properly? It had stopped by the time I got home. I drained the carb and didn't see any particulates or signs of debris in the fuel.
Also, the exhaust for the problem cylinder, #3, was running significantly cooler than the others (~50-60 C vs 150 C). I thought it was my IR thermometer at first, so I sprayed some water on the pipe right where it connects to the head, and sure enough it didn't evaporate instantly like the other 3 cylinders. So I'm thinking it's either very rich or not firing? Oddly enough, the bike seems to run very well. Should have some time tomorrow to recheck wet float levels and check for spark. Don't think spark is an issue though because I did coil on plug swap recently and I swapped the coils around today and nothing changed.
I rode it around briefly (10 miles or so), carb 1 started leaking fuel out of the vent tube on top, which I read means the float wasn't draining properly? It had stopped by the time I got home. I drained the carb and didn't see any particulates or signs of debris in the fuel.
Also, the exhaust for the problem cylinder, #3, was running significantly cooler than the others (~50-60 C vs 150 C). I thought it was my IR thermometer at first, so I sprayed some water on the pipe right where it connects to the head, and sure enough it didn't evaporate instantly like the other 3 cylinders. So I'm thinking it's either very rich or not firing? Oddly enough, the bike seems to run very well. Should have some time tomorrow to recheck wet float levels and check for spark. Don't think spark is an issue though because I did coil on plug swap recently and I swapped the coils around today and nothing changed.
