Author Topic: Can it be carb trouble or just bad carb settings?  (Read 4576 times)

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Offline TwoTired

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Re: Can it be carb trouble or just bad carb settings?
« Reply #25 on: March 02, 2013, 04:36:38 PM »
So can this point to something?

Possibly.  Have you check the point gap?
Lloyd... (SOHC4 #11 Original Mail List)
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Offline Jore

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Re: Can it be carb trouble or just bad carb settings?
« Reply #26 on: March 02, 2013, 05:56:30 PM »
I haven't, i'll get to that.

Can It be possible for one of the points to float under load or do something similar?
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Offline scottly

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Re: Can it be carb trouble or just bad carb settings?
« Reply #27 on: March 02, 2013, 07:00:51 PM »
Jore, PLEASE stop getting side-tracked by the ignition theories. A poor ignition WILL NOT CAUSE CARBON FOULING OF THE SPARK PLUGS! NO FIRE= NO SOOT.
Now you report that #2 carb is overflowing... Once again, you have a carburetor problem(s), not an ignition problem. (Not saying your ignition settings are correct, but that they can not cause your fouled plugs)
Don't fix it if it ain't broke!
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Offline wowbagger

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Re: Can it be carb trouble or just bad carb settings?
« Reply #28 on: March 02, 2013, 07:15:59 PM »
Being a noob and having just spent my morning setting the valve clearance and ignition timing, I can tell you that very little can be determined just by watching the points. Mine appeared to be functioning just fine, opening and closing in sequence, but the bike wouldn't run.

I dropped the $8 on a feeler gauge at Sears and measured them and found they were significantly off. I also found some of the valves were off as well. once set to the spec distance listed in the manual I was able to get the bike running and idling for the first time since I bought it in November.

That said, I agree with Scottly. Most of my efforts to date with the bike were getting the petcock and carbs to not leak, overflow, or stick open. Start with your carbs then to a full tuneup.

Offline Jore

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Re: Can it be carb trouble or just bad carb settings?
« Reply #29 on: March 03, 2013, 05:42:10 PM »
Thanks for the input, one question:

What parts from the carbs can I reuse? Locally I can get O-rings in every size, but the other thing are more complicated.
1975 CB400F owner
-Having a vintage motorcycle is like having a moody girlfriend.

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Offline TwoTired

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Re: Can it be carb trouble or just bad carb settings?
« Reply #30 on: March 03, 2013, 07:06:35 PM »
Unless corroded, mechanically damaged, or worn, all the metal parts are re-useable after cleaning.

Honda does sell a "kit" that includes all the gaskets need for a rebuild.
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline Jore

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Re: Can it be carb trouble or just bad carb settings?
« Reply #31 on: March 03, 2013, 07:42:10 PM »
Is there a parts number for the kit? I've looked around online and can only find full kits.
Like this one:

http://4into1.com/honda-cb400f-carburetor-repair-kit/

So in theory, could I just buy new o-rings?
1975 CB400F owner
-Having a vintage motorcycle is like having a moody girlfriend.

My 466 build: http://forums.sohc4.net/index.php/topic,146494.0.html

Offline TwoTired

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Re: Can it be carb trouble or just bad carb settings?
« Reply #32 on: March 03, 2013, 10:29:13 PM »
Honda Part number 16010-333-315  A Google search of the number came up with multiple hits.  Like this:

http://www.ebay.com/itm/Honda-CB350F-CB400F-Carburetor-Gasket-Set-16010-333-315-/380519833597

Cheers,
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline Jore

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Re: Can it be carb trouble or just bad carb settings?
« Reply #33 on: March 04, 2013, 09:18:58 AM »
Thanks TT, helpful as always.
1975 CB400F owner
-Having a vintage motorcycle is like having a moody girlfriend.

My 466 build: http://forums.sohc4.net/index.php/topic,146494.0.html

Offline Jore

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Re: Can it be carb trouble or just bad carb settings?
« Reply #34 on: March 10, 2013, 11:47:12 AM »
I've finally manned up and opened my carbs, I plan on tearing them down and then boiling them to get all the grime and gunk.
I'm using a manual by Tim Boughen as a guide.

This is how my bowls look:



They're cleanish I suppose, but I do have a hairline crack on one of the overflow tubes, and also the drainscrew on carb 1 got stuck, I've tried different drivers on it but I only managed to mangle the slot, so for now I'll just leave it there.

The other thing I noticed is my carbs don't have leaf springs, and now to the floats:



As you guys can see the floats on the outer carbs are way off, compared to the centre ones. But that's not the worse part, the posts on carb 4 look like this:


Basically a piece of wire and some epoxy. Number 1's also rough but not so much:



One of the posts is broken, but I'm guessing that can be fixed.

And finally on carb 4 I found this gem:




Now my questions are these:

What are the missing leaf springs for? Also around this forum I saw someone replace them by a coil spring, can I do that?

And what should I do with the damaged posts?
« Last Edit: March 10, 2013, 11:49:07 AM by Jore »
1975 CB400F owner
-Having a vintage motorcycle is like having a moody girlfriend.

My 466 build: http://forums.sohc4.net/index.php/topic,146494.0.html

Offline Deltarider

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Re: Can it be carb trouble or just bad carb settings?
« Reply #35 on: March 10, 2013, 12:09:37 PM »
Quote
What are the missing leaf springs for?

They hold the main jets in place.
Quote
Also around this forum I saw someone replace them by a coil spring, can I do that?
Yes, you could... if they're missing.
« Last Edit: March 10, 2013, 12:11:13 PM by Deltarider »
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Offline Jore

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Re: Can it be carb trouble or just bad carb settings?
« Reply #36 on: March 10, 2013, 04:43:54 PM »
I'm guessing then, that I will need to replace the leaf springs.

Is there a way to unjam things? the main jets won't even move
1975 CB400F owner
-Having a vintage motorcycle is like having a moody girlfriend.

My 466 build: http://forums.sohc4.net/index.php/topic,146494.0.html