F1 lumpy low speed running.

[Skoti]

Sorry to keep posting as many questions, but this is the first F1 I've owned and I'm not sure what to expect of it.

At low speeds and around 2000rpm when riding through towns the motor feels lumpy, open the throttle a touch and it becomes smooth.

Is this normal   

 

[Bryanj]

No probably needs carb balance but do all the rest of the service items FIRST

[Skoti]

Hi,

Yes has had new plugs and points fitted.
 
Timing done with strobe light.
 
Carbs removed and cleaned out and balanced with mercury gauges.

Valve clearances and cam chain adjusted.

New after market air filter fitted.
 
Air screws adjusted to 1 3/4 turns out.
 
Idles at 1000rpm when hot.

Only on very light load and small throttle openings the motor is lumpy and erratic.

I notice that spark plugs No 1 and 3 are a little sooty compared to spark plugs No 2 and 4. Do you think I should turn the air screws out a bit more on carbs No 1 and 3 and see what happens? 

[Spitfire]

Mine is not impressed at slow running so I just go down a gear or two, works OK then.

Cheers

Den

[BigAl (Alan)]

I would go back to balancing the carbs again, well worth investing in a kit. I had similar problems with my CB750 but it did sort out the low rev lumpy/chain snatch problem

Good luck

Alan

[Skoti]

Fixed 

Decided to screw out No 1 and 3 air screw an extra 1/4 turn. Just been for a road test and it's nice and smooth now at low speed/revs.

Removed the plugs again and they are more or less all the same colour.

Amazed at how such a small adjustment can make such a big difference.

Summary:-
Carbs No 2 and 4 air screws are 1 3/4 turns out. Carbs No 1 and 3 air screws are 2 turns out.

I'm aware the normal setting is around 1 turn out but I fitted an aftermarket air filter and then read some where that they are more restrictive that the genuine Honda filter.