Carb question ?

[pearljam724]

Being the center cylinder has a different jet size. Are there any other components in the middle cylinder carb that is different from the right and left ? Are pilot jets all the same? How about clip height on jet needle? All same height?

[Old School]

Both of my 750's are jetted the same on all three.

[pearljam724]

Both of my 750's are jetted the same on all three.

Thank you. You're referring to the main jets? I assume you have the same main jet size in the middle carb that are suppose to be on the two outside carbs. Did that improve lean or hanging throttle conditions that may have been present before you added the large main in the middle? You know concerning the bulletin about the over sized air jet in the intake bell mouth. Or did you change all of those too?

[Old School]

My jetting (mains needles idle) are the same across all the carbs. The main jet should not have much effect if any on the throttles "hanging" or slow to return to idle. Most of the time this is caused by the idle being lean (air leak, idle jets plugged or restricted, even the carbs not in sync good). Because of an inbalance, the idle adjustment screw ends up set too high and the engine won't idle down correctly. The "jets" in the air filter area or bell mouth are "air bleeds" for the idle and main circuits. If they become plugged or restricted, they will cause the engine to run rich. They should always be checked, as a plugged one can have you running all around try to tune the other jets.

[tz375]

On early 750s I think that the needle jets are different as well.

On 550s I have no idea. What do the parts list or spec bulletin say?

[pearljam724]

On early 750s I think that the needle jets are different as well.

On 550s I have no idea. What do the parts list or spec bulletin say?

Sorry, I'm referring to 750's. Different middle main jet, that only pertains to the air cooled bikes? 550's, etc ?

[pearljam724]

My jetting (mains needles idle) are the same across all the carbs. The main jet should not have much effect if any on the throttles "hanging" or slow to return to idle. Most of the time this is caused by the idle being lean (air leak, idle jets plugged or restricted, even the carbs not in sync good). Because of an inbalance, the idle adjustment screw ends up set too high and the engine won't idle down correctly. The "jets" in the air filter area or bell mouth are "air bleeds" for the idle and main circuits. If they become plugged or restricted, they will cause the engine to run rich. They should always be checked, as a plugged one can have you running all around try to tune the other jets.

I think you misunderstood the question.

[bill in okc]

When my 550 was stock, as I remember, everything was the same except for the middle main jet size - The choke circuit is also only on the left and middle carbs.

[tz375]

According to the parts lists and the carb manual, 74 on used a smaller main jet in the center pot and that was the only difference I remember. The other jets were the same in all the 74/5/6 carbs I have rebuilt.

J & K use small mains in the center pot and IIRC they also had 1 step smaller needle jet.

[pearljam724]

According to the parts lists and the carb manual, 74 on used a smaller main jet in the center pot and that was the only difference I remember. The other jets were the same in all the 74/5/6 carbs I have rebuilt.

J & K use small mains in the center pot and IIRC they also had 1 step smaller needle jet.

Much appreciated. So, the needle jet was smaller 74-76 on the stock needle too?

[Old School]

Sorry, I guess I am crossed up as to your question. The first post sounded straight forward, and then in your second post it sounded to me like you were trying to solve an issue with the throttle hanging.

At any rate, maybe my explaination will help someone out there with the throttle hanging. Lol

[tz375]

Not exactly . 74-77 with BS490 CV carbs all used a Z-0 needle jet in all three spots.

The J&K that had a P3 in the center and P-4 in the outer cylinders IIRC

Check the parts lists and Carb manual to be sure