well I thought I had finally got to the bottom of my rough running/idling issues. Someone in one of the replies said that it sounded like it was running rich. The other night I went back to basics, set the volume control screws (fuel) on the main throttle to 2 1/2 to 3 turns. Did a bit of experimenting and realised that with the idle mixture screw fully closed, it was still running (I presume on the main mixture), so I turn down the mixture screws on each carb and the engine stalls. I then screwed open a touch the idle screw, starts her up and she ran on idle. Went for a run, she ran really well, no hesitation and after a couple more tweeks with the idle she was ticking over without stalling. The bus now has the acceleration back that she used to have. The issue now is she wont run from cold on the chokes, I assume either the fast idle isn't working or does this rely on fuel through the main jets to run, answers greatly appreciated.
One thing at a time. At idle, when it's warmed up (off choke) if you remove the short 1/2" pipe from the left hand air filter arm, can you hear a loud sucking noise? If not, it's idling on the idle jets alone and not the idle circuit. This will be because the throttle stops are wound in too far - they should be just touching.
Hi Zed, Loud sucking noise was present ( I had opened up the mixture screws on each carb a further quarter of a turn prior to that!). Does that make sense ??
That's a good start. You realise there's screws on the top of the LH carb for the idle mix and speed? If you unplug the furthest away cut off solenoid the revs should drop by about 1/2. With that unplugged, you can then set the mixture screws you've been adjusting. When you have them right, plug back in, blip the throttle (because it likes it) and then set the mix and speed on the idle circuit. When all that's done, hopefully it'll start and run on choke.
Thanks again Zed, yes I have been fiddling with the screws on the top of the LH carb, will have another fiddle later, too dark and wet now and away at the weekend so will have a look again on Sunday, sounds like I am not far off then! With the RH solenoid disconnected, what am I trying to do with the mixture screws? Just get it running smoothly? They are a bit of a mystery these carbs, suppose like everything, once you have done it its easy the next time... then perhaps the ratwell article may mean something to me (on the setting up of carbs)... Thanks Again
Follow the instructions on; http://itinerant-air-cooled.com/viewtopic.php?t=7767 Follow these to the letter, and in the correct order and they'll tune up fine. Good luck!
LH- furthest away from you - it's the idle circuit cut-off solenoid. Yes turn in until it falters, then out unitl it runs best, then back in 1/4 turn. Then do the other carb, then connect the wire back on, adjust the speed if needed and do the idle mix. The itinerant Link above is spot on of course - set aside some time to do it properly once and for all.
