Topic: At this point.........(MAGICAL ASS RAPE FAIRY STRIKES AGAIN)

[punch455]

I've had my carbs in and out of '78F literally 5 times in the last 2 weeks, and cylinders 3 and 4 still don't fire.  It's a little heartbreaking seeing guys out on their bikes now that the weather is getting a little warmer, and wondering WHAT THE H*LL is it gonna take to get out there with them... 
BTW, I just have to ask, what is a left handed cigarette? Do I wanna know?

[my78k]

one of those uhm....roll your own type of cigarettes.

Guys the biggest issue with the 77-78 carbs is by far the idle jets. make sure you pull them (are pressed in but with vise grips and care they do come out). Use compressed air and lots of carb soaking to get them clean. The guitar sting method works but I usually just use copper wire I have laying around. Also, make sure your accelerator pump is in good working order but do not put the diaphragm in carb cleaner! I realized that the diaphragm doesn't respond well to carb cleaner...actually it virtually melts it!!

Dennis

[Soos]

BTW, I just have to ask, what is a left handed cigarette? Do I wanna know?

If you don't already know.... you might not want one.
It's a hand rolled "cigarette" with the best stuff on earth god put on this earth IMO.

And it's not tobacco.




l8r


Oh and those '77/'78 cb750 carbs suffer a LOT of the problems that the cb650 '79/80 (non-CV) carbs suffer.
presses in slow jets, air cutoff diaphragms and accel pump...
A full quality re-build is costly on those.
Let alone all the extra passages needed to get clean.


IMO better to either search out a set of CV carbs that will work, or go with the earlier '69-76 cb750 carbs without the freikin' air cutoff diaphragms and the accel pumps...
Ok, the '69's would be almost as bad with the 4 individual carb cables....
but other than that, they are simple to rebuild, and cheaply found.
As well as plentiful kits out there for a re-build if needed.





l8r

[754]

I dont think carbs have to be cleaned that much, only once done right..

Let me guess, you figured you would be the lucky one that could clean it all out w/o pulling them jets .. well I bet them carbs showed you..!

Anyway, I never liked them  stock 750 carbs (any year)anyway.

[mlinder]

....Ok, the '69's would be almost as bad with the 4 individual carb cables....

Why does everyone say that...? They are easier to work on than any of the other carbs....

[Frankenkit]

you LIE, Mark, you LIE!


+1 on the stupid small idle jets.

[mlinder]

I swear, I'm not lying.

[Hush]

More to the point when working on these carbs........I lie I'm not swearing!

[mlinder]

If you had the K0 carbs, you wouldn't be swearing. They are easy :/

[cb750fbomb]

I'm not giving up. Screw that. I can't start something without finishing it. It's gonna run real good, get a paint job and I will be a good mechanic.

[mlinder]

I'm not giving up. Screw that. I can't start something without finishing it. It's gonna run real good, get a paint job and I will be a good mechanic.

There ya go. Go get 'em, tiger.

[Frankenkit]

You've gotta know, a couple times, the only thing keeping me from selling my bike was the fact I'd never get my money back.  That fact made me realize I would have to either give up and take a massive loss, or suck it up, open a can of whoopass and eventually have a good running bike. 

It's all good, just keep plugging at it.

[moham]

As a very wise technician once told me when I asked him what's wrong with a piece of broken equipment:

"Well Mo, it's either electrical or mechanical..."



There is a non-magickal solution to your problem.

[Head]

KO carbs are the easy ones to work on,I just pulled the slides and raised the jet needles one notch with out taking the carbs off.    Head

[mlinder]

KO carbs are the easy ones to work on,I just pulled the slides and raised the jet needles one notch with out taking the carbs off.    Head

thank you.

[Duke McDukiedook]

I hate it when the magical ass rape fairy visits me, it's never a pleasant visit; nothing at all to look forward to except an ass raping.

[PJ]

Best advice is pull them back off and don't plan on putting them back on in the same day. Pull all the jets and needles out and fill your float bowls with Simple Green and let them sit for 3hrs, pull each piece out one at a time and rinse and give it a blast with an air hose. Inspect... if you can't see light through it put it back in the Simple Green for another bath. Take the carb bodies and soak them as well but not for more than a 20-30 minutes. Simple Green is quite powerful for a cleaner and some have said it can damage soft metals if left on too long. I have used it several times without any ill effects. Take an air hose while the carbs are still wet and verify that if you blast a hole that a mist comes out somewhere proving that the passage is not blocked. Also check that the accelerator pump nozzle are also squirting a small jet on each carb, you can do this with water instead of gas but the bowls will have to be on and full of something for this test. 

Now you can reassemble and install the carbs.

Please don't think your done yet... Things such as valve adjustment, timing, point gap, GET NEW SPARK PLUG CAPS, and especially the BATTERY, etc, will all have an effect on how well your bike runs. These things need to be checked and corrected one at a time. If you try to cheat and just let something go well... "you know who" shows up and it gets ugly again

NOW you can Sync the carbs and hopefully all is well. If you are having problems with a rough idle or a dead miss at idle, pull one plug wire at a time (a nice set of plug wire pliers are not mandatory but it does kinda hurt)and find the one that doesn't make it run even worse and you can narrow your search down to one cylinder, then it's either gas or spark that is failing.

[gerhed]

I REALLY wish I would have never bought this motorcycle 

I screwed around with my carbs for 10 years.
Went nuts.
Was mean to loved ones.
-- finally went with Cycle-X.
I am now a much more complacent person.

[fuzzybutt]

Phil, does the tank not set like it's supposed to with those cyclex carbs?

[gerhed]

Phil, does the tank not set like it's supposed to with those cyclex carbs?

Fuz,

The tank is off a CB360 and no it doesn't sit all the way down
on the frame due to the need to clear the throttle cables that
come out of the mikunis.-so I've got it jacked up a bit in the back.

Phil

[Frankenkit]

The magical assrape fairy stretches my o-ring.

[OldSchool_IsCool]

The magical assrape fairy stretches my o-ring.

and is making my #1 & #3 drain valves (or overflow tubes) drip and is keeping #1 and #2 pipes from getting hot following a top end rebuild.  I hope it isn't also keeping oil from flowing to my cam bearings!  Maybe its just first-time rebuilder jitters.  Prolly just the oil I put into the plug holes to keep the cylinder walls moist.  --sigh--

[cb750fbomb]

I think the carbs on the 1st gen 750's are complete pieces of junk.  I too have wasted far too much time trying to clean/tune/balance them.  They are 40 year old technology that really wasn't that great when they first came out, IMO.  Add to that 30 years of grime and wear and its amazing they work at all.  Really, I feel your pain.


Dump them.  I use a bank of CV carbs of a 1985 CB650SC now.  They are amazing compared to the stockers.  No dripping floats, easy to balance, easy to adjust.  I know some guys here love to old school carbs, but I have never looked back since abandoning them.

What would I need to do to get a set of those carbs set up for my bike besides change jet sizes and what jets would I got to?

[mlinder]

I think the carbs on the 1st gen 750's are complete pieces of junk.  I too have wasted far too much time trying to clean/tune/balance them.  They are 40 year old technology that really wasn't that great when they first came out, IMO.  Add to that 30 years of grime and wear and its amazing they work at all.  Really, I feel your pain.


Dump them.  I use a bank of CV carbs of a 1985 CB650SC now.  They are amazing compared to the stockers.  No dripping floats, easy to balance, easy to adjust.  I know some guys here love to old school carbs, but I have never looked back since abandoning them.

What would I need to do to get a set of those carbs set up for my bike besides change jet sizes and what jets would I got to?

I think you're crazy (ton cafebob).
The 1st gen carbs are the easiest to tune, jet, or otherwise work on, of all of them. They also work wonderfully.
I would change them, however, for whatever they were using on the late 70's kawis, were it an easy swap.

[cb750fbomb]

I think you're crazy (ton cafebob).
The 1st gen carbs are the easiest to tune, jet, or otherwise work on, of all of them. They also work wonderfully.
I would change them, however, for whatever they were using on the late 70's kawis, were it an easy swap.
[/quote]

That's the catch. An easy swap. I would happily change carbs that were easier to adjust, rebuild or whatever IF it were an easy swap. But I don't know enough about all this to have any idea what would be an easy swap. Jetting could be figured out, but would the carb manifold boots on the engine side fit, what about throttle cable requirements, choke cable requirements..............