Running to lean on one side

I recently had my bike tuned up after years of sitting. My mechanic told me both of my needles were in the lowest position in my original but rebuilt amals, and I may have to raise the needles if the bike should start to run too lean, but at the time the bike would idle and run fine.

Since then, one side has decided to run much too lean for a decent idle or performance, even after adjusting the fuel / air screw.

Knowing that my question is this, is it recommended to move one needle only, and not mess with the carb that seems to run perfect?

THANKS.

If it ran ok before, then it stands to reason that something must have changed in order for it to now be too weak.
My money would be on a blocked, or partially blocked pilot jet.
If that's the case, then raising the needle is not the answer, even if it does make the symptoms feel slightly better.
FE.

Fast Eddie said:

If it ran ok before, then it stands to reason that something must have changed in order for it to now be too weak.
My money would be on a blocked, or partially blocked pilot jet.
If that's the case, then raising the needle is not the answer, even if it does make the symptoms feel slightly better.
FE.

Click to expand...

I agree...time to clean the carbs. The change you are talking about should not be needed if it was running good before.

Fast Eddie said:

If it ran ok before, then it stands to reason that something must have changed in order for it to now be too weak.
My money would be on a blocked, or partially blocked pilot jet.
If that's the case, then raising the needle is not the answer, even if it does make the symptoms feel slightly better.
FE.

Click to expand...

+1 The clip position doesn't come into play until past 1/8 throttle, way past idle.

Yesssireee- bob Typical blocked pilot jet nonsense to deal with. Pull sick carb and clear pilot jet. :cry:

Changing the needle position affects the mixture at 3/4 throttle. If the motor coughs when riding the bike around a twisty road using various throttle openings, the needles are too low. Your idle problem is elsewhere and raising only one needle is not a good idea. Getting the mixture correct at 3/4 throttle is critical for decent performance, the rest is easy.

acotrel said:

Changing the needle position affects the mixture at 3/4 throttle. If the motor coughs when riding the bike around a twisty road using various throttle openings, the needles are too low. Your idle problem is elsewhere and raising only one needle is not a good idea. Getting the mixture correct at 3/4 throttle is critical for decent performance, the rest is easy.

Click to expand...

Not completely true. There is an effect from the needle position at 1/8th to 1/4 throttle. Not at idle. So if poor idle and adjustment does not effect it, the pilot jet is likely dirty.

thanks guys, so 2 weeks when I rode around, it was pulling hard but when letting off, it would really pop and that cylander wouldn't idle smoothly, came back and the plug was white thus indicating too lean, or so I thought. I adjusted the fuel /air screw and it seemed to run better, didn't check too much after that.


Now, it still pulls fine but at idle, end of muffler is barely hot and you can hear that every stroke isn't firing, when compared to the other cylinder.

Knowing that, is it still likely the idle jet?

I should also say that the float sticks on this carb if I don't pay attention. When I turn on the fuel, this carb can puke out gas if I don't pay attention. Does this matter or just a separate condition. ?

Too clean the pilot jet, do I have to pull the carb? or can I unscrew it from below by just dropping the bowl?

So get to work. Pull the carb. Jeez. Use a shortened allen key for this. It's really awkward. Carb cleaner, fine banjo or guitar wire poking and twisting. Lots of threads on this ,it's real obvious to us,always drain gas before long term storage ,short term ie: winter use a little gas stabilizer and run it through. Have fun, workbench and don't overtighten anything. :|