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Running rich?

Posted: Mon Jan 18, 2016 12:15 pm
by cross
My bike seem to have very rich smelling exhaust, especially when i start it cold and let it idle few minutes. Few guys that i ride with also told me that riding behind me my bike smells very rich.
Everything is stock, jets, paper filter, spark plugs look grayish white which i think means lean. Bike starts easily when cold as long as fuel bowls are full.
I do not have high idle when choke is applied as i adjusted the choke idle level fork on the carb wrong. Bike runs fine, no issues what so ever other than that rich exhaust smell.
Originally when i cleaned carbs i had fuel mixture screws out at 1 1/4 but when i did a valve adjustment i opened them to 2 turns out and i did not have that rich smell.
Another thing that i noticed is that after a ride break, i need to twist a throttle few times for bike to start when before with 1 1/4 turn out, bike would start with just a push of a button. Second thing is that before that change, bike could of gone a full week before i needed to blow into the vacuum line to fill the fuel bowls, now only few days.
I'm do for a valve adjustment and i'm planning on doing that beginning of next month and i could pull the carbs out again at the same time and check on things only not sure what exactly.

Re: Running rich?

Posted: Mon Jan 18, 2016 5:31 pm
by daves79x
What kind of mileage are you getting? That's the best gauge of carb richness. Many CBXs I've had/ridden, especially late models due to the negative air behind the fairing, have had that 'rich' smell, but were just fine carb and mileage-wise. Anyway, without a heavy throttle hand, you should be getting at least mid-30s, over 40 at steady cruising speed. Also, CBXs in good tune should show almost white plugs.


Dave

Re: Running rich?

Posted: Mon Jan 18, 2016 5:53 pm
by cross
I was getting well over 30 with mixture screws 1 1/4 turns out, after that i adjusted them to 2 or perhaps 2 1/2, it's a lot less.
I'll be doing a bunch of work next month on it and I'll re check carbs again.
Is it possible that there is some fuel seeping into the crank case and making it smell extra rich?

Re: Running rich?

Posted: Thu Mar 02, 2017 3:28 pm
by Irishman1
It's so nice that so many members respond and are quick to help on the is forum isn't it?. Hmmm

Re: Running rich?

Posted: Thu Mar 02, 2017 6:50 pm
by daves79x
Most people actually think so, sorry you don't.

Dave

Re: Running rich?

Posted: Thu Mar 02, 2017 8:14 pm
by cross
Irishman1 wrote:It's so nice that so many members respond and are quick to help on the is forum isn't it?. Hmmm
Actually people on this forum are amazing. The knowledge and willing to help is unmatched on any other forum

Re: Running rich?

Posted: Sat Apr 08, 2017 10:27 am
by mlynch001
Sasha,

One thing that I noticed that you said was that you "Blow" into the vacuum line to fill the float bowls. That is a vacuum operated valve, so you would actually pull a vacuum on the line, not blow into it. This may simply be semantics, but the valve could have a perforated diaphragm, which would allow fuel to be drawn into that one cylinder and make it very rich. This would be obvious, since you would have on cylinder of six that had a black or sooty plug. You have checked the air cut diaphragm for condition? I have an 82 and it has a slight rich smell, this is common to bikes of the era. (I worked for HONDA from 1983 to 2003) Dave is correct, the mileage and spark plug condition are your best indicators of "rich" or "lean". My bike gets fuel mileage in the mid 40's consistently and sometimes smells "Rich". Not at all suggesting that you don't have an issue, just giving a few observations based on my experience. Best of luck to you.

Re: Running rich?

Posted: Sun Apr 09, 2017 8:17 am
by Rick Pope
There's an unused nipple on the vacuum diaphragm, opposite the vacuum side, to which you can attach a length of hose and blow, overriding the spring.

Re: Running rich?

Posted: Sun Apr 09, 2017 8:28 am
by daves79x
That unused nipple is actually the 'vent' for the vacuum side, so yes just blow and hold on that line to override the vacuum and fill the bowls.

Dave

Re: Running rich?

Posted: Sun Apr 09, 2017 10:20 am
by EMS
Originally, the "unused nipple" has a tube connected to it, that routes down to below the bike together with the carb vent tubes. If you look for an "unused nipple" you may not find it.

Re: Running rich?

Posted: Sun Apr 09, 2017 4:51 pm
by cross
Yes, I have small vacuum hose routed behind left cover and always blow into it and watch the flow in the fuel filter.
Once it stops flowing I start the bike. This is after it sits for a while