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Author Topic: Fuel issue w/ 1 carb - maybe  (Read 976 times)

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Offline dq212

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Fuel issue w/ 1 carb - maybe
« on: July 06, 2011, 07:53:51 AM »
Hi,

I am working on my first Honda Four. It was a barn find, that I got off of eBay awhile back. I am very close to having it up and running nicely except I have run into something of a head-scratcher.

The problem is my number one pipe is not getting as hot as the other 3. This is causing some sluggishness coming off the line at red lights and the obvious lack of power. #'s 2,3,4 pipes are getting the typical discoloration and are super hot to the touch. I can at times grab #1 with my bare hand after idling for a few minutes.

The carbs are cleaned and re-assembled with new needles, jets, pilot screws, o-rings, and correct float heights.
There is spark. I get air pressure and some fuel smell out of the number one exhaust.
Timing is set, valves are set. Carbs are synced. I moved the plugs around to see if I had a bad plug.
The 2 ports on the petcock are running evenly. The 2, 3, and 4 spark plugs look good. #1 however is coming up fouled.
Sometimes it looks wet, other times just heavy carbon.

I'm not really excited about the prospect of pulling everything apart again without at least asking if someone might know what I could be looking for? Anything at all.

Thanks all.
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73 CB 500 , 88 NT650 HAWK, 75 XS650

Offline Duke McDukiedook

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Re: Fuel issue w/ 1 carb - maybe
« Reply #1 on: July 06, 2011, 07:56:46 AM »
Reclean with small wire in all orifices and compressed air. Reassemble.

Is everything stock on this bike?
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"Well, Mr. Carpetbagger. We got somethin' in this territory called the Missouri boat ride."   Josey Wales

"It's Baltimore, gentlemen. The gods will not save you." Ervin Burrell

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Offline WarwickE36

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Re: Fuel issue w/ 1 carb - maybe
« Reply #2 on: July 06, 2011, 08:17:37 AM »
make sure float height it correct, cyl 1 may be too high.  check for proper spark at 1 as well.
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" Why does anyone get offended by what someone does to their own bike? I dont get it. "

You made me think about it after I cheered knowing someone else would like to know what these control freaks are up to.
 Every time any owner strips whatever precious Honda part the horrified purists parts go up in value. That's not the part that bothers them.
 What bothers them is they sat up late at night, their breast full of wonder and estrogen, unable to sleep, dreaming about their lovely darling and all her glory... and next thing you know someone else doesn't share their emotional deluge and their reaction is they must spread their mind museum as far as they possibly can, taking over as much of the real world as possible.

Drink fast, drive slow, but ride it like you stole it

1974 Cb550 with style
2004 SV650s

Offline Duanob

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Re: Fuel issue w/ 1 carb - maybe
« Reply #3 on: July 06, 2011, 08:50:34 AM »
Quote from: Industrial-sized Dukiedook on July 06, 2011, 07:56:46 AM
Reclean with small wire in all orifices and compressed air. Reassemble.

Is everything stock on this bike?

Ditto I bet your slow jet is clogged.
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Offline Psychonaut

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Re: Fuel issue w/ 1 carb - maybe
« Reply #4 on: July 06, 2011, 09:00:46 AM »
Does it run ok at WOT at high revs? Is it bad just at low throttle input? Did you set the air screws?
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Offline dq212

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Re: Fuel issue w/ 1 carb - maybe
« Reply #5 on: July 06, 2011, 10:24:38 AM »
I'll get to checking the float heights again and blow out the slow jet with some compressed air next.
When I get going, it seems better, but there is a significant difference in the amount of carbon on the plugs.

Almost everything is stock except for the air filters.
I put some uni's on.  I re-jetted to 115 on the main jets and that's about it. It sounds sweet, I'm just hoping to get it sounding 25% sweeter. Air screws are a thing I've been playing with. I have them out to about 1 1/4 turns with this configuration.

Thanks for the different possibilites, seems like they are all things I can check in one session.

I'll let you all know how it goes.
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73 CB 500 , 88 NT650 HAWK, 75 XS650

Offline BeSeeingYou

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Re: Fuel issue w/ 1 carb - maybe
« Reply #6 on: July 06, 2011, 10:33:11 AM »
I don't think pipe discoloration is typical if you have the stock double wall headers.  Maybe running lean?  That's another issue but obviously the 1 is not firing or has a weak spark.  Replace your condensers and check the resistance of the plug caps.

On a side note l would like to see a picture of your XS650. :)
« Last Edit: July 06, 2011, 10:34:43 AM by srust58 »
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Offline dq212

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Re: Fuel issue w/ 1 carb - maybe
« Reply #7 on: July 11, 2011, 10:54:27 AM »
Ok.

so I haven't checked the condensers yet, but I did disassemble the carb 1 again and very meticulously blew out everything with compressed air and carb cleaner and more air paying special attention to the slow jet.

So far, so good. I reset the points and re-adjusted the ignition timing. Started it up and got some good heat on that pipe. Finally getting hot air out of the pipe.
The discoloration could have been from running it too lean for so long in my diagnostic process and developed into something of a red herring.

I will definitely check the condensers, although they are new, but could be faulty, and I will check the resistance on plug, but I did swap that one out recently. None of this could hurt.

But thanks again for all the helpful responses. Always good to have some sense or what one could be looking for.

I guess it's just time to ride now and see how it goes.
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73 CB 500 , 88 NT650 HAWK, 75 XS650

Offline dq212

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Re: Fuel issue w/ 1 carb - maybe
« Reply #8 on: July 21, 2011, 07:10:47 AM »
Ok.

Things are looking good, but

Now I'm getting some quick backfiring at 1/2 throttle and up.

Not entirely sure where to start.
I was going to make sure that the exhaust gaskets are tight and sealed. Obviously that should happen anyway.

I was also wondering if I should lean or richen the needle by adjusting the slot position?

As always, thanks in advance for any suggestions.

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73 CB 500 , 88 NT650 HAWK, 75 XS650

Offline Duke McDukiedook

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Re: Fuel issue w/ 1 carb - maybe
« Reply #9 on: July 21, 2011, 01:18:02 PM »
Probably still too lean if it is backfiring at 1/2 up.
Did you perform a full tune-up on this bike?

Is the tank clean- meaning no rust at all?

Is that Hawk fun to ride?
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"Well, Mr. Carpetbagger. We got somethin' in this territory called the Missouri boat ride."   Josey Wales

"It's Baltimore, gentlemen. The gods will not save you." Ervin Burrell

CB750 K3 crat | (2) 1986 VFR750F

Offline dq212

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Re: Fuel issue w/ 1 carb - maybe
« Reply #10 on: July 22, 2011, 10:48:22 AM »
The Hawk is a great ride. I've actually taken it cross country and back. Really a special machine.

Anyway, yes the CB has been fully tuned, but I'm struggling a little with pilot air screws and the needle jet position. My next play is to drop the needle down to slightly richen the mixture and get back to square one with the pilot air screws.

I'll be doing this tomorrow. If anyone out there thinks this the wrong move, I'd love to hear from you.

Thanks all.
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73 CB 500 , 88 NT650 HAWK, 75 XS650

Offline WarwickE36

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Re: Fuel issue w/ 1 carb - maybe
« Reply #11 on: July 22, 2011, 10:57:16 AM »
Definitely dont lower the needle to richen the mixture...lower the clip i.e. raise the needle...I figure thats what you meant but just in case
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" Why does anyone get offended by what someone does to their own bike? I dont get it. "

You made me think about it after I cheered knowing someone else would like to know what these control freaks are up to.
 Every time any owner strips whatever precious Honda part the horrified purists parts go up in value. That's not the part that bothers them.
 What bothers them is they sat up late at night, their breast full of wonder and estrogen, unable to sleep, dreaming about their lovely darling and all her glory... and next thing you know someone else doesn't share their emotional deluge and their reaction is they must spread their mind museum as far as they possibly can, taking over as much of the real world as possible.

Drink fast, drive slow, but ride it like you stole it

1974 Cb550 with style
2004 SV650s

Offline dq212

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Re: Fuel issue w/ 1 carb - maybe
« Reply #12 on: July 29, 2011, 06:36:42 AM »
yup, that's what I meant.

Basically took the carbs all the way apart...again.

It works great. Very responsive. Way better than what I was willing to accept without know it's potential.

Thanks.
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73 CB 500 , 88 NT650 HAWK, 75 XS650
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