decreased acceleration CB750

BArTY

BArTY

Been Around the Block
after adjusting my valves (correctly) i noticed my bike to have a somewhat slower acceleration off the line and in low rpms. could this be a timing issue? the timing has been checked and is spot on, but im thinking i should try advancing it a bit. any other ideas? could this possibly be due to having a slightly rich mixture? as i said, i just noticed it after adjusting the valves. thanks
 
i may be running a little rich. i'm not sure how much to adjust the air screws to lean out a bit nor do i understand the process. do i need to adjust each airscrew on each carb and make sure i turn them all respectively? also how much should i turn each one and which way opens them up? am i on the right track with this assumption?
 
So the air screws on the sides of each carb do need to be equal. It's probably like 1 turn out +or- 1/8 of a turn. Turning the screws out makes it leaner and turning them in makes it richer.
Valves should be adjusted first in the tuneup process, with the engine cold. Then do the cam chain, the timing, and save the carbs for last.
I don't know the benchmark for the single idle screw adjustment, but it's probably in the manual. BTW, if you don't have one, download a factory shop manual for free on the SOHC4 forums.
The best way to tell if you're running rich is to read the plugs. I'm not especially good at that. What's your intake/exhaust setup? Are the carbs jetted to match it?
And it doesn't hurt to recheck your valve clearances after adjusting. It's taken me two or three tries to get them right. I mean it's a pretty tight tolerance, .002 and .003"!
 
If the only thing you changed was valve clearance and it now runs worse than previous, that's the problem.
They can't 'be right'
I don't know how many 'right' I've seen where they were either too tight, too loose or done on overlap.
If your having any trouble use go-no go (for intake, 0.0015 slides 'easy, 0.003 wont fit, ex, 0.002 slides, 0.004 won't go)
Make sure feeler is bent on the end to fit parallel to stem tip
 
Valves were done right, cam chain as well, timing was checked as is dead on. i am not running a stock setup. i have a modified exhaust and k&n air filters. The jets are also matched with this setup as done at a local shop. Like I said bike was running perfect after valves were done.

might also be a culprit now that i think of it. there was a small piece of silicone blocking the main jet in carb #1 that i removed and since has been running better. still decreased acceleration in low rpms and gear shifting. at least more so than before. i've had mechanics ride it and they tell me i'm crazy, but i know how it ran before and how its running now. something is just a bit off.

i'm thinking i either need to lean it out just a tad, or i need to advance the timing a hair. i havent messed with advancing timing before and i'm not sure how its done or what it does. i am currently running a dyna s ignition with 5ohm dyna coilsand new wires/NGK plugs.

thanks for all the replies and tips. you guys know your stuff!
 
Yeah man, I personally think cold weather affects a bit.
But others may think different.
 
It's not the weather... If the bike is warm a cool air charge is denser, and makes more power. And adjusting your air screw will do nothing for anything over idle. If your too rich you'll need to re-jet. I'm with PJ on this one. too tight or too lose. And I'm gonna vote for tight. It's the most common mistake when adjusting valves in my experience.
 
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