ET: Engine (Twin) Fuel and Carb Settings

Bill Thomas

Well Known and Active Forum User
VOC Member
Just a thought, We built an old Bike with standard Carb's a few years ago, And the Slides were very slack in the body, Gave us a bit of trouble at tickover, The air was going round the slide ??.
It was fine when riding, But at tickover kept going on to one cylinder.
 

Peter Holmes

Well Known and Active Forum User
VOC Member
Also when the slides are that slack you can normally hear them chattering back and forth, I think the bulk of the wear can be attributed to running without decent air filters, they may not enhance the look of the bike, but I would not run without them, think what it could do your bores.
 

Monkeypants

Well Known and Active Forum User
Non-VOC Member
Since it fouled a set of plugs running around the shop, I'm hesitant to richen the pilot settings, but I believe it ran a bit smoother with the air levers pulled on a small amount.

If this is an Amal setup and the air levers are just "pulled" a small amount, the chokes will be just lifted that amount from the full choke position. Pulled all the way back is choke off.
Pushed all the way forward is full choke. Pulled up just a little will still choke it some when riding.
Could it be that you are running with the chokes on and this is fouling the plugs?

Glen
 
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Bobv07662

Well Known and Active Forum User
VOC Member
No Glen, it fouled the plugs after a week of tinkering in the shop getting past, spigot air leaks, high float levels weak ATD springs and no road time to clear things out. Air levers fwd are on and down, levers back are off and up.
Thanks to the suggestion from Robert Watson, I applied non-hardening Permatex to the spigots and that has helped tremendously. The idle can now be lowered to a proper level, the pilot screws are much more responsive and the banging in the exhaust has been virtually eliminated.
Not claiming victory yet but I think I'm on the right path with all the help and suggestions I get from the VOC!
 

davidd

Well Known and Active Forum User
VOC Member
VP Fuels C9 is 94 octane and C10 is 100. Premium is somewhere around 92, but will usually work on a 10:1 piston with a Mk2 cam.

David
 

Bill Thomas

Well Known and Active Forum User
VOC Member
I am paying £1 .34p a litre, Instead of £1.06, Don't have a clue what it is, But can just hope,
The Bikes seem to run OK, They are 9 to 1s and Mk2 cams, Biggish carb's, Armours S/S straight though silencers.
 

Bobv07662

Well Known and Active Forum User
VOC Member
Was able to take the beast on it's first ride in New Jersey this AM...What a blast! Torque down low is very impressive, 3rd gear seems all you ever need.
Seriously, thanks to you all for all the help getting the bike sorted.
Now that I have a potato, potato, potato idle and no more vacuum leaks at the spigots a small issue has come up with the slide in the rear carb. Occasionally after using engine braking when coming to a stop it hangs up a tiny amount and the idle speed bumps up a bit. (100 rpm max bump) I can avoid the hanging up by coasting up to the stop or clicking the throttle closed a couple of times while slowing down. It appears the higher vacuum is pulling the slide a bit more than it is happy with. I can also tap the slide with my finger and it instantly returns to the correct lower idle speed.
Before I send for a pair of new carbs, has any one seen this before or know of any certain place to inspect the slide or carb body to look for the offending interference?
 

Comet Rider

Well Known and Active Forum User
VOC Member
Hi Bob,
Be careful if you do decide to go for new carbs.
I know Greg Brullis has commented on new bodies being out of round.
You can get new slides which may overcome you problems without having to change the carb completely

Best of luck
 
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