Vintage and Classic Hondas

carb issues?

_‹ Previous Topic Next Topic _›

Classic

List

Threaded

6 messages Options

longshanks

carb issues?

So I'm not sure whether my bike is running rich/lean or neither. The main issues are hesitation, stumbling, and missing at any rpms below 3.5k. Also, if I do a quick snap of the throttle while riding the bike, it stumbles hard and then takes off. I recently took the baffle off the muffler thinking it would lean out the bike by providing more flow. By doing this it got rid of the problems at low rpm but the mid range and top end were really lacking power, especially the top end. It just felt dead. However, it wouldn't bog if I did a quick snap of the throttle. I should mention that the carbs have been synced and are jetted with 120 mains and have pod filters. The exhaust is a 4-1(MAC maybe?) with a Vance&Hines muffler. Timing has been done, points set, valves adjusted, and the compression is 120 across all cylinders.

TOOLS1

Re: carb issues?

Administrator

What year, and model is your bike? It sounds like a rich hesitation.
TOOLS

Life is not about the number of breaths, you take, but the moments that take your breath away.
I don't have an anger problem. I have an idiot problem. Hank Hill
Never confuse education for intelligence.
Happiness is a belt fed weapon.
I just can't imagine what could go wrong.
No fire? No explosions? So whats the point of your story?
Those who are too smart to engage in politics are punished by being governed by those who are dumber. ~Plato
It couldn't be done, but the darn fool didn't know it, and did it anyway.
We all got problems. Ksharp
I like vintage bikes because they take me away from the clutter of technology that I work with everyday and back to a simpler time of mechanical elegance and simplicity.. "ninadm"
Darkwing Duck: The worst part of public transportation is the Public.
"That is awesome shit there" Re-Run
"Fear nothing, attack everything" Eric Berry
" Oh, you read that on the internet? Clearly it IS a massive problem. Of course it CAN’t be normal operation."

1976 CB 750-A X 2
1977 CB 750-A X 4
1977 CB 750-K
1976 CB 750 F
1981 CB 750
1966 Kawasaki SG 250
1981 KZ 750 LTD
1973 CB 350
1979 CM 185 Twinstar
1982 Honda XL 80
South of Eden (Kansas City MO)

longshanks

Re: carb issues?

1976 CB750 K6. I would like to have the baffle off if I can.(Love the sound) But if I did I think I would have to richen up the main jets because it felt so flat. Maybe my problem is the pilot jets are too rich causing hesitation on the lower end? It seems so because when I open the exhaust up like I said it would be effectively "leaning" out the bike, right?

I should also mention that when I stop at lights I can smell fuel. I also pulled the headers off yesterday and I could definitely smell fuel off the pipes.

TOOLS1

Re: carb issues?

Administrator

It sounds like you are on the right track. Have you done ant plug chops? What are your needles set at?
TOOLS

longshanks

Re: carb issues?

No plug chops yet.(recommend a spark plug socket for quick removal?) The number 1 cylinder is running rich after looking at the plugs but the rest look halfway decent. Although I still suspect that overall its running rich. Can one cylinder running rich cause these problems even if the rest are running ok? I also haven't checked out the needle positions yet and I suspect that no. 1 is off or I'm at least hoping since that'd be a easy fix.

Also, for plug chops do I need to run it in top gear on WOT? or can I use 3rd or 4th gear? I live in Los Angeles so its hard to find a good stretch of road! ;)

Re: carb issues?

Hmmm...

Having the same issues on the same carb. I have checked the jetting, it's stock. The only other things I can think of are...

1.) the air passage to the air bleed is blocked.
(To get that cylinder close to running right, I am having to turn out the air bleed screw til I'm worried it will fall out from vibration.)

2.) the needle in that carb is raised compared to the other carbs. The PO did so many screwball things it would not surprise me at all.