The International CBX Owners Association

Damn bob, cool your jets! It’s just somebody’s opinion same as yours, take it or leave it, no need to blow a gasket. Stick around everyone’s contributions are appreciated!

Even mine, most of the time! LOL

I took both Dave and Jeff's comments as meaning there comes a point of diminishing returns. Seeking perfection, while commendable, takes a lot more work for very little gain, when taken to that last bit. There has to be a reasonable point where you just say, "Good enough." That point is different for each individual.

My comment was solely about degreeing cams. I never advocated/nor would ignore any of the other things you mentioned. Custom degreeing of cams is in a whole other realm beyond insuring bearings are properly clearanced and piston/rings/bores are properly clearanced. After nearly 200 sets of carb rebuilds, I think I know a thing or two about perfection. Then there's the horrendous state of the rest of the bike, most of the time. A lot goes into making a bike safe and reliable to ride, it just does not include degreeing cams for 99 percent of owners. That's all I'm saying.

Dave

Ok after a hiatus I'm back on my project bike, was going to wait till I had her painted and more presentable to post a pic, but times are desperate, 79 Motor w/ VB64 carbs taken apart and clean thoroughly . So I found out I am not a tuner LOL. See pic below for exhaust I'm running. I feel like jetting is close, but need help to figure out which direction to go. I'm running #38 Slow speed and # 112's mains. I'm at Sea level. First few runs seemed to sound clean but last time out for a short run it sounded not as crisp maybe too fat then again what do I know first time on jetting. Maybe the 6 into 2 into 1 (Lazer) is the issue as far as tuning. I know Dave said Stock jets for for Stock intake and Paper filter, but could not get it to run good with stock jets, Tried 110's but seems better with the 112's. If it's sounds like it is fat would 110's and shim the needles be a answer?
If stock jetting is still recommended than I have a cleaning issue but I've blown cleaner through from the top down and from the bottom up all clear. About to go out and pull the carbs again.

Short Video below to hear. Thoughts ? Suggestions ?

https://youtu.be/Um40lhglRnI

I’m not a tuner either, but it sounds like it needs to clear its throat at lower RPM, then sounds pretty good up high. Have you synced these? I personally did not prefer the 38 slow jets. There’s no question it started easier with them and idled really well, but I felt like it was fat and didn’t pickup revs cleanly without a blip to clear its throat.

jt, have you pulled the plugs and looked at them yet ? I'll bet they're
very dark if not sooty black. Can you post a picture of them ?

Niles, No I have not sync them yet, I will do that once I get the carbs back on.

Bobcat, here's a couple of pics of the plugs from 4, 5 & 6 the others look the same cept # 2 was a whisper darker.
Thanks
JT

jt, what I see is uneven fuel delivery from low speed to midrange to main circuit.
If you are running 38 slow/pilot jets AND more than 2 turns out on the mix. screws
it is too rich at low speed (black rim of the plug) then it goes way lean in the mid
range, slide needle function (shiny porcelin) and, depending on the main jet either
continued lean or too rich. More in a few minutes...

...Restore the fuel/air delivery balance. What I would do is drill the 35
slow/pilot jets with a #79 drill bit making it a 36.75 (38s too rich). When
you go richer from 35 you go to a leaner mix. screw setting of 1 to1.5 turns
out (balance). Shim the needles .020"-.040" and go back to the stock 105
main jets. When you raise the needles, as the slide opens* it bleeds over to
the main circuit and richens high speed as well as the main. The main jet is
the last thing of all you need to change.

*transition from mid range to top end. It seems that your "breaking up" is
happening right where the slide opens.


Note; these settings are for sea level to around 2000ft elevation.
Above 2k ft would take leaner settings.

Note; If the needles had clip/groove, shimming the needles .020" = 1/2 clip position.

Reading back through this thread, most of what I said is repetitive.
Now that I've watched the video, looked at the plugs and considering the open (unsilenced)
ehx., I'll stick by what I said.

How many miles on this bike ? I know it's $ but put some fresh plugs in after changes. (D8EA).

Jeff, Dave : jets cooled, gaskets properly in tact.

Thanks Bob will give it a shot. Whats the best way to hold the plug screw that holds the needle in place. I've heard people used a drop of super glue and teflon tape any others tips?? I know need to slack the screw out a bit to allow the needle to move slightly.

JT

A drop of loctite. I've used the red , never had any trouble getting the plug loose.

If you must shim the needles, pocket the hold-down screw with a 1/4 inch drill. Much easier to service in the future.

Dave

daves79x wrote: ↑

Wed Aug 17, 2022 7:00 am

If you must shim the needles, pocket the hold-down screw with a 1/4 inch drill. Much easier to service in the future.

Dave

Pocket is not reversable and must be ,001" deeper than the shim thickness.

I know, I've done a bunch of them. Also have a bunch of spare hold-down screws.

Dave