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Fuel flowing out of left carb (carb kits)

Fuel System: Gas (Petrol) tanks, Carburators
Hahnda
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Joined: Wed Nov 02, 2005 2:36 pm
Location: Cameron, WI

Post by Hahnda » Wed Sep 20, 2017 12:43 pm

The kits I sell have JIS threads on the jets.
There are some kits out there that are incorrect though.

I can also swap out the bowl gaskets for the round corner style if needed.

cadman
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Joined: Sat Dec 08, 2012 5:12 pm
Location: Georgetown, TX

Carbs

Post by cadman » Sun Nov 12, 2017 4:47 pm

Several problems I have had with carbs both Dream and older 4 cylinder models.

1. The tang on the float where the needle touches it gets a small "divet" in it. If the float drops low enough the needle will catch in the divet and either not push the needle up or push it crooked. Sometimes you can sand that area smooth.

2. If the gas in the float bowl drops low enough the float drops too low and wedges against the needle and won't go up. I have solved this by soldering a small copper tab on the float hinge to restrict its downward movement. Very common problem on early 4 cylinder bike even with new floats and needles.

3. Poor mating of needle and seat. Just a very small mismatch can cause a slow leak. I have a simple tool that attaches to a drill so I can use rubbing compound to either spin the needle or the seat to "lap" them together for a better seal.

4. New rubber hose will shed very fine rubber particles which will wedge between the needle and seat causing a slow leak. I use alcohol and compressed air to clean fuel line before installing.

Billiam
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Joined: Tue Sep 06, 2016 2:48 am
Location: Berkshire UK

Post by Billiam » Sun Nov 12, 2017 6:47 pm

It happens on occasion, on other bikes as well as the 305. Just try turning the fuel off, rev her up a few times. When it stops turn the fuel back on and away. The vibration from the motor seems to settle the needle valve on its seat.
Happened a few times on my completeley refurbed carbs. AOK now.

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G-Man
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Location: Derby, UK
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Post by G-Man » Mon Nov 13, 2017 1:17 pm

4into1 also have the round bowl gaskets.

G

3030vision wrote:
cknight wrote:Agree with Stan on the needles and seats, but if you HAVE to get rebuilding kits, I've had very good results with the ones from scramblercycle.com. Regards, Chase
I haven't given up on cleaning the carbs further, but I was looking at the kits on scramblercyle.com and I noticed a few things that their kit might not make work for me:

- It doesn't appear that they provide gaskets for the round-style carbs
- It doesn't sound like they provide early JIS thread pitch main jets

4into1 claims that their kits are they only ones on the market that have the early JIS thread pitch jets:

http://4into1.com/carburetor-rebuild-co ... uper-hawk/

Have folks had decent luck with those?
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160
'66 Matchless 350 '67 CL77
'67 S90 '77 CB400F

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