XJ carbutator/air/fuel adj.

[dodjh]

What is the way to adjust your air mixture screws---I'm out
4 turns and need to fine tune the adjustment before doing sync.

dodjh

[Ken Talbot]

Tuning is a bit of an iterative process at the best of times. You may have to sync first, adjust the screws, then sync again, etc. Try starting at two turns out from lightly seated:

- warm up the engine and sync the carbs with a mercury tool or vacuum gauges
- adjust the idle down to approx 700 or 800 rpm
- adjust one pilot screw out slowly while listening very carefully to the engine sound and watching the tach needle
- listen for the engine speed to pick up a bit then fall off
- if it doesn't pick up, adjust the screw slowly in, again listening for any increase in idle speed
- when you her the increase, adjust past it a half turn or so, then come back to it again until you've got the sweet spot
- adjust the idle speed back down to your low starting point
- then work another screw, again looking for its sweet spot
- each time you get a screw adjusted, drop the idle back down
- once you've got all four screws set, resync the carbs
- take one more pass through the pilot screw adjustment for each carb, still working at 700 to 800 rpm
verify that the sync still looks good
- adjust the idle back to 1100 or so depending on your personal preference

BTW - this was lifted from a much earlier atricle I found using the search button at the top of the page. It really is quite amazing how many times most of the common topics have been discussed ever the years...
- go for a ride!

[dodjh]

XJ carburator/air/fuel adj.

Ken,

Thank you for the feed-back on this post---I will adjust them

like you said.

dodjh

[dodjh]

XJ carbs.

Ken,

I back off my idle screw all the way and its still idled up. There is no clearance between the screw and bar.

I have a tack with a pos. and neg. clamp---how would I hook that up? I thought there was a lead that goes to the coil
(on a car.)

I would set it (tach) on 4 cyclinder engine---right?

dodjh

[dodjh]

XJ carb

Ken,

I meant to say there IS clearance between the idle screw and tang it touches and the bike is idled up at least 1500 r.p.m.'s
I can push on the tang and it will drop the rpm's alittle but when I remove screwdriver the tang goes back up and the rpm's increase.

dodjh

[underdog57]

Is it Synced ??
Maybe an adjacent butterly valve holding the idle speed screw off the plate . Or throttle cable sticky ...

Bob

[Ken Talbot]

Is something hitting or blocking the head of the adjustment screw? You should be able to wind it down so it is well clear of the tab on the linkage. You may need to take the carbs completely off and disconect the throttle cable so you can check the operation of the main throttle linkage and the linkages between each pair of carbs.

I've never used a stand-alone tach - not sure how you would set one up. Is there a reason you can't use the one on the bike?

[dodjh]

XJ carb.

Ken,

The one on the bike is not registering--I have another set(speedometer and Tach.)

I cleaned the plugs with a spark plug cleaner (compressed air and fine sand.) It ran right off but after 5 to 8 minutues of running (trying do as you instructed in another reply,) it died.
I pulled #1 plug out and it was black from carbon build up.

I'm going to re-clean plugs and try again to sychronzice and set fuel/air mixture.

Thanks for your reply and thanks Bob for your,

dodjh

[cruiser]

Your post says XJ carb. Are you installing the YICS tool before adjusting?

[dodjh]

XJ carb

Yes I am installing the tool before sychronizing the carbs. Is that what you were refering to?

dodjh

[DiverRay]

If the plugs are black that quick, start you adjusting with the Float Level . You probably have one or more carbs set wrong, or a leaking "O" ring on the seat for the needle. Read your manual, and start at the beginning. You MUST adjust the floats, and THEN BENCH CHECK THE NEEDLES, before going on. I would also verify that the valve lash is within specs.

[dodjh]

XJ carb

Thanks Ray for your reply---I have another set (gone through also) and the floats were sticking obvious of fuel running out of them. I tapped on the bowls and they eventually stopped. This set hasn't done that so I thought the setting was right.

When trying to schyronzie, the idle will be at one rpm and before I can wrap up the process the idle will change and the bike is hard to recrank. I have to blow in fuel tank to get flow through my filters (one or both sides.)

I thought it was my throttle cable so I replaced it yesterday butstill having the effect as I had with old throttle cable.

dodjh