400 f2 carbs

[cliff7]

My bike starts first time and seems to perform cleanly through the revs. It idles fine at 1200rpm and will idle slower although a touch lumpy. However the idle mixture screws do not seem to make a lot of difference when adjusted. Is this normal? The carbs were professionally rebuilt last year.

[K2-K6]

Where do you have the screws set now?

And how far do you move them? Going down below 1/2 (not to set them but to judge if there's any change) and up to near 3 turns out should at least let you hear a response from each cylinder if adjusted while running.

Doesn't sound too bad though from your description of how it runs at idle.

[cliff7]

Thanks for response. I have screws set about 2 turns out and even when screwed right in (gently) the bike still idles. Does a plug check on idle help as previously I have only done this on more open throttle settings? Maybe a colourtune!

[K2-K6]

Slightly odd signals it's giving you.

Are you confident there's not an air leak?  Spray something like WD40 around carb to head rubbers while running to see if you get a change in speed. Also can the tickover idle speed master control be turned down enough so that it stalls at idle?

[cliff7]

Thanks. I'll try that and yes, it will stall when main idle screw is set low. Rubbers are a bit hard but no problem fitting carbs. Also trying to work out how to upload a video so maybe someone can help me identify a mechanical noise (clutch?) on idle.

[philward]

I don't think you can upload a video Cliff, I have a youtube account (easy to open) - post the video on youtube, then cut and paste the youtube link (of your uploaded youtube video) to your forum post - hope that makes sense

[cliff7]

Right, I'm not very computer savvy but know a man who is. He's out on his FJ1200 at mo but will ask him when he's back. Thanks.