Honda-SOHC

SOHC.co.uk Forums => CB750 => Topic started by: dieffe on March 30, 2015, 09:39:59 PM

Title: 750 K1 carb trouble
Post by: dieffe on March 30, 2015, 09:39:59 PM
Me again.
I have a bit of a problem with fuel coming out of one (or more) of the carb overflow pipes when the pipe is leant onto it's side-stand. It doesn't happen on the main stand so I assume there is an issue with too much fuel in the float bowls. Assuming it's the float heights, can I check the float heights with the carbs still on the bike or do I have to remove them?
If it's not the float heights, then any ideas what else. I have renewed the fuel tap rubbers as they were perished so now that is fine.

Cheers. (again)  :)
Title: Re: 750 K1 carb trouble
Post by: Lobo on March 31, 2015, 02:21:45 AM
Hi Dieffe,

Unsure of whether you've just rebuilt these carbs - ie all new & fresh. If so, they just might need settling in.. on both my 400/750 there were initial overflows, but after a light tap with a screwdriver head & a couple of outings all 8 carbs quickly settled down.

As an aside, (& for different reasons - ie modern fuel) I turn off the fuel a mile from home & run the carbs dry if putting the bike away for a while.

Don't rush in if ya don't have to!
Simon
Title: Re: 750 K1 carb trouble
Post by: mick on March 31, 2015, 07:50:06 AM
you will have to take the carbs off to set the float heights properly  ;) cheers Mick.
Title: Re: 750 K1 carb trouble
Post by: UK Pete on March 31, 2015, 08:28:51 AM
I have had similar problems in the past with other bikes, i have taken the carbs apart and the float height was good, it turned out to be the float valve  letting by a small amount of petrol only seeping slightly but enough to overfill the bowl
pete
Title: Re: 750 K1 carb trouble
Post by: dieffe on March 31, 2015, 05:10:53 PM
Well I popped the carbs off today as I am annoyed that I neglected to check the float heights before fitting them in the first place. Don't ask me why, just impatience I guess. No. 1 was way too high but the other three seemed pretty close, so I am glad I did it now. I don't know if it's my imagination but as well as not yet leaking it does seem to start easier and tick over better.
I have set the air screws at 1ΒΌ turns out, should I try setting them with it running or leave what seems like well alone?

Thanks all for the advice on the carbs, I am glad I checked them now.  :)
Title: Re: 750 K1 carb trouble
Post by: dieffe on April 01, 2015, 11:24:07 PM
The carbs are still oozing petrol out, this time it appears to be from between the bowl and the body. I have ordered some new bowl gaskets, my logic being that they may well be 44 years old and therefore somewhat past it.
We will soon see. if they still leak I will bin 'em and put some flatslides on.


Just kidding.  :D
Title: Re: 750 K1 carb trouble
Post by: dieffe on April 07, 2015, 09:55:08 PM
I'm sure I read somewhere that the bowls can still leak even with new seals fitted. Is it worth coating the seals with something like ThreeBond (which is the only sealant I have) or the like?
Title: Re: 750 K1 carb trouble
Post by: dieffe on April 10, 2015, 04:57:06 PM
Just whizzed the carbs off again and fitted the new bowl seals and stuck a bit of petrol resistant sealant on for good measure. Just ran the bike up and so far no leaks.  :)
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