Newly acquired machine,fairly new concentric 930 carbs. fitted. Engine starts initially but won't idle. Carbs. removed and cleaned/checked. Slides synchronised, pilot jets 1 1/2turns out. Tappets reset. Fuel flowing into float bowls OK. New spark plugs fitted. Any ideas please.
Hi,
Have you got chokes fitted? If so close them to richen the mixture and let it warm up a bit.
Dave.
Dave, using a bit of choke to start, then holding throttle at 2000-2500 rpm to warm up, but engine stalls if shut off throttle.
Hi,
Try a bit more choke and let it warm up a bit more. When the engine gets a bit lumpy open the chokes fully.
See how that goes.
Dave.
Dave, have just read a post regarding brass/viton tipped needle jets/float height etc. Symptoms are similar so Will check that out and maybe contact Amal if no joy. Thanks for the input.
It might be worth searching the internet for "Bushmans Carb Tuning Secrets".
This will show you the idle passages, which may be blocked? After blowing out, I spray WD40 into them so I can see they are actually clear.
I did the WD40 thing ,Steve. All passages clear.
Good man. You say screws 1 1/2 turns out. This is only a starting point. They should be quite sensitive to turning. Set each one to highest tickover speed and then reduce throttle screws as required. Apologies if you already know this, but I obviously don't know how much experience you have.
It's well worth checking the float heights. Bushman tells you how.
Assuming the slide is not worn, spray oil onto the flanges and spray grease onto the inlet valves, to check for air leaks.
If you are able to get it to tick over, place a hand behind each exhaust to be sure they're even.
Does your carb have removable pilot jets?
Carbs removed again, float height checked ok. Run engine until hot and fine tune pilot jets. Idle is better but blipping the throttle does not give clean pick up. Runs better over 3500-4000 rpm indicating the problem remains with pilot mixture. Removed plugs, left one wet but has good blue spark. Swapped plugs but left side not running as hot as right side. Tried R (Resistor)plugs as Boyer electronic ignition fitted but still the same.
sounds like a black and decker job on the pilot jets.
Hi,
Do you have air filters fitted? The standard jetting is for when filters fitted. The slide cutaway is specified for filters.
I think this is right, removing the filter allows more air in so the slide cutaway is now too big and the mixture is now weak. This will affect pick up from tick over.
Dave.
Dave, understand what you're saying, but doesn't explain why left pot running "cooler than the right" Also, if carburation was way out with the filters removed, both cylinders would be affected. Looks like i might have to get the carbs ultrasonically cleaned even though they are fairly new.
Thanks for all your input.
ps Does anyone know if better to use R plugs with electronic ignition. i've put NGK BR8ES plugs in. Any advance on that...