Delayed Throttle Response At Any Fuel Screw Setting.

[dadof2]

Might be best to do a basic carburation check first.

Check float level is correct and that air filter is clean and properly oiled.

As a guide:-

0 to 1/8 throttle mixture is controlled by air screw 5 mins running

1/8 to 1/4 throttle mixture controlled by slide cutaway 5 mins running

1/4 to 3/4 throttle mixture controled by needle / needle jet 2 mins running

3/4 to full throttle mixture controlled by main jet. 30 seconds running - assuming plug not too far off from 1/2 throttle run

You need to mark these throttle openings on your twist grip and ride with the throttle in the centre of each range for at least the running times above, with the engine fully warmed up. Use as high a hear as possible to keep the engine working steadily. You have to get the carburation correct at each stage before moving on.

At the end of each run do not move the throttle, pull the clutch in and press the kill switch at the same time.

Check your plug colour (centre electrode insulator) after each run. It should be pale chocholate brown, lighter means too weak, darker means too rich.

Edited July 9, 2013 by dadof2

[toman21]

The floats arms are a fraction above level which i believe is what there meant to be. The air filter is cleaned and oiled with foam filter oil after every ride. The spark plug always seemed to go black as if its too rich and that was with a 33/118 at 3 turns out?

That jetting is quite lean i thought as it made the bike make the characteristic lean bog sound. I read somewhere that if your piston rings are worn that can blacken the spark plug as it lets oil through????, is that true? I have changed the rings so ill see if it still goes black now. The crank seals have both been changed so there's no oil leaking in from there. Thanks for that guide ill give it a go!

[toman21]

With a 36 pilot and 118 main installed, at 3 turns out on the fuel screw it still bogged (only very little though)!!!!!! Turned it to 3.5 turns out and that sorted it. With the 118 that cope suggested it still revs fast and clean. 3.5 turns out seems a bit much for a 36??? I drove it around and the bike pulls more but still with a responsive throttle, seems fine to me now.

[dadof2]

Check the location of the fine wire clip that holds the float valve to the float arm. It needs to be in the fine groove that you can hardly see, not the deeper groove that only goes part way round the valve. If it is in the wrong groove it causes male part of valve to drag on female part causing erratic fuel level and the symptoms you describe. i think quite a number of carbs may have come with this fault being mis assembled when new.

cheers

[copemech]

With a 36 pilot and 118 main installed, at 3 turns out on the fuel screw it still bogged (only very little though)!!!!!! Turned it to 3.5 turns out and that sorted it. With the 118 that cope suggested it still revs fast and clean. 3.5 turns out seems a bit much for a 36??? I drove it around and the bike pulls more but still with a responsive throttle, seems fine to me now.

Well, that is good to hear then. The Dellorto is only SOO good, not fuel injection, you know. Might run it a bit lean for smoothness, as one seldom wicks them wide open like that for normal riding anyway, just find a happy spot. Open it a bit more in cool weather. I just works!