Carb problems. your thoughts

timmyc

timmyc

New Member
I rebuilt the carbs on my 72 CB350 over the winter(a very long and cold one here in MI) and am just putting them back on. I thoroughly soaked them, replaced all the seals, adjusted the float level and reassemble them. I did not replace the primary and secondary jets (the ones supplied in the kits were incorrect #115, original is a #105). After adjusting the idle and mixture screws it runs pretty good from idle to about 5000 rpm. Above 5000 it sputters and will not go above 8000? The left side seams to be lean to ok(looking at the plugs) and the right looks a little rich? Any thoughts on what to look at next?
 
First and foremost... You didn't really clean them. To do so, you need to COMPLETELY disassemble the carbs. Remove all jets and clean all passages ways. Then, do it again. A sonic cleaner ($30 at Harbor Freight) goes a long way too.
 
I soked them, then cleaned them in a parts washer pumping solvent thru any passage that would take fluid, then put air thru the same way.
 
Sync your carbs. I find the jets in those rebuild kits to be total shit. I'd replace your new main jets with the original well cleaned ones or nos/ OEM replacements
 
Actually clean he jets?
Soaking to spraying junk on them doesn't count.

All of he aftermarket kits are crap in my opinion.
Poor quality.

Check the diaphragm for damage and insure it is working properly?

Do you even have a manual?
 
Soaking them in solvent also ruins the throttle shaft seals. They are felt and can be damaged with soaking. The proper way to soak them is to remove everything, as stated earlier, including the throttle shaft and seals.

Ultrasonic cleaning actually physically shakes loose dirt. Solvent will not remove a grain of sand stuck in a passageway. It will clean gas residue, but not non-petroleum based particles.
 
Ok, what I thought was a through cleaning may not be good enough. But the only reason I don't suspect dirt is I did not have this problem before I rebuilt them. The problems I had we're a leaky float bowl seal and I could not get the bike to idle correctly. Also I believe it was running rich, I could start the bike when it was cold without the choke. Thx!
 
Hey quick update... After reading my manual and further thinking... I found that the timing was way off and I that I have a failed head gasket... And WOW the carbs are just fine. THANKS so much for the knee JURK advise! Next I need help I will surely post it here!!!
 
timmyc said:
Hey quick update... After reading my manual and further thinking... I found that the timing was way off and I that I have a failed head gasket... And WOW the carbs are just fine. THANKS so much for the knee JURK advise! Next I need help I will surely post it here!!!
Click to expand...

I like this. Someone tells poster how to properly clean carbs because... carb problems! But they seem to be simply knee-jerk responses because: head gasket and timing! All you fucking knee-jerk carb people can go take a soak!
 
Hey Chicken, I missed the post where you tried to help the guy.




Sent from planet Earth using mysterious electronic devices and Tapatalk
 
Bikes don't get fixed on he interweb anyway.
They get fixed in the garage with tools.

Can only offer some advice on the limited info that gets posted online.

And has the OP changed the head gasket, done the timing right and put some miles on the bike?
 
mydlyfkryzis said:
Hey Chicken, I missed the post where you tried to help the guy.

Sent from planet Earth using mysterious electronic devices and Tapatalk
Click to expand...

Got to the game late, advice had already been offered, just trying to point out how lame it is to ask for specific help, receive it, and then be an ass to the people who wrote you with advice. And trying but apparently failing to be funny at the same time. I blame the beer.

*** I should add: completely conceivable that the OP doesn't know what knee-jerk means.
 
Chicken, my bad. Thought you were saying the advice was knee jerk. The wrong question is asked a lot.


Sent from planet Earth using mysterious electronic devices and Tapatalk
 
Many things don't translate well via web.
Sarcasm is one, engine running is another.

The web should not be a persons first "go to" when encountering a problem.
Manual or a person with experience should be.
It takes a long time to develop "an ear" for tuning an engine and you only learn that by doing, not reading.
 
surffly said:
Many things don't translate well via web.
Sarcasm is one, engine running is another.

The web should not be a persons first "go to" when encountering a problem.
Manual or a person with experience should be.
It takes a long time to develop "an ear" for tuning an engine and you only learn that by doing, not reading.
Click to expand...
You are correct frustration got the better of me. I have read my manual and the forums in an attempt to solve my problem. Many test rides and adjustments later i could not resolve the issue better but not right. So as a last resort I posted my problem here and received what I feel is the generic response to carburetor problems, dirt. So i began thinking what could be causing higher RPM problems. I reset the points and ran a compression test (90 psi on the left and only 50 psi on right not good). Taking a closer look I found oily residue on the right side just under the head. Frankly I am surprised it runs as well as it does. Now it's time to pull the engine and see what is going on valves, rings head gasket?? Thx!
 
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