SOHC.co.uk Forums > CB350/400

Carb settings cb400f with 4-2 exhaust

<< < (3/4) > >>

Erwin83:

--- Quote from: Tomb on November 23, 2016, 03:47:16 PM ---I usually treat the o-ring getting fuel on it making it swell as a sign that the fuel level is too high, As the fuel level should be lower than the bowl mating face, in an ideal world we shouldn't need an o-ring. For this reason I rarely replace the 0-ring.

--- End quote ---

Yeah, the float bowl drain is clearly higher then the O-ring's position, so it's clear the fuel level was too high.
I hope this is solved by putting the float's at 23 mm now.

Let's see. I hope I don't get home finding my garage smelling like fuel later-on...

Erwin83:
Continuing on this topic.

So, by now i've:
- set valve clearance
- changed points and set the point gap
- synchronised the carb
- tried several air mix screw settings from 1,5 - 2,5

Situation is:
Bike runs really well.
- good cold start
- good cold idle
- good through the revs

Once hot, everything is still Ok, apart from idle.

Plugs seem to read rich (carbon black, dry deposit)

I'm thinking float level, perhaps go from current 23 to 25 mm (lower the fuel level in the bowl)

Please comment and share wisdom  ;D

Brian G:
I do remember reading that float needle valves in some of the aftermarket carb kits have a slightly different overall height than the originals. That would certainly affect float level. For that reason, I used the original needle valves - which had next to no wear - with my new carb kits.

Regards,

Erwin83:

--- Quote from: Brian G on May 08, 2017, 11:07:08 PM ---I do remember reading that float needle valves in some of the aftermarket carb kits have a slightly different overall height than the originals. That would certainly affect float level. For that reason, I used the original needle valves - which had next to no wear - with my new carb kits.

Regards,

--- End quote ---

That is very useful information.

I tested something:
I closed the fuel tap and let the bike run (hot), hence slowly lowering the fuel level in the bowls.
It actually seemed to idle better after a short while.

So i think it's worthwile to try and set the carbs slightly different.
Let's see what happens.

andut:
Hi Erwin,

Just seen this post and your resurrection of another, older post on the same topic.

I think your 'fuel off' test is probably an indication of a rich at idle condition and you may want to consider going down a size on idle jets (likely to give you a bigger tuning change than can be achieved by the idle air bleed circuit) if your float height adjustment does not provide a permanent fix.

I also had similar O ring growth with the Keyster kits and changed them for viton seals from ebay (seller gerben1956) that are much more durable.

Andy

Navigation

[0] Message Index

[#] Next page

[*] Previous page