Hello, I have an A65 Lightning - it was running ok last year but now I have a problem. The carbs are very new (Amal with standard jets) and the bike starts quite easily and ticks over at c1000rpm for maybe 20-30 seconds are so but then dies. As soon as I open the throttle it also dies! I wonder if it is some sort of fuel starvation and have checked the filters but am at a bit of a loss so any advice would be gratefully received, cheers,
Stuart.
The first question to ask if whether it has fresh fuel or is it a year old?
Although it sounds like fuel starvation, if your Lightning is the same as mine, the fuel supply is separate to each carb and, if one side develops a problem, I would have thought it would continue running roughly on one cylinder? However, if the tank breather via the little hole in the petrol filler cap is blocked, this may give you fuel starvation on both sides. Easily checked by loosening the filler cap to make sure air can get in. Otherwise, the problem could be electrical.
If a single carb, main jet blocked?
thanks for your replies gents. Fuel is new and I'm probably not reaching the main jet as I'm not even on half throttle. After some patience I did manage a brief run but it wasn't running well and having checked the plugs it looks to be running weak so I'm going to raise the needles (it is twin carbs) tomorrow and see what that does.
Hi Stuart,
Any progress?
If the bike had been running OK then the needle position is unlikely to be causing the problem. The problem with the cutting out after a few seconds or on opening he throttle suggests the pilot jet is partially blocked. There have been a few post about this recently and it seems to stem from the modern ethanol fuel being left in carbs for long periods. Even putting fresh fuel in may not remove any blockage. As a minimum I would suggest some carb cleaner squirted through the pilot air hole in the front of the carb. and also through the pilot air screw hole after removing the screw.
If that does not work then a deeper clean may be needed.
Dave.
With a twin carb Lightening, it is unlikely the problem is due to just one of the carbs - as said, if this was the case, the other cylinder would continue to try to run, whereas, this problem appears to be affecting both sides in the same way?
I assume the carbs are ' very new' but presumably were the ones fitted a year ago when the bike ran properly. If so, it's unlikely there is a problem with its jetting. However, if the carbs have more recently been replaced, I would definitely go to the AMAL web site and check the jetting they recommend and also what is listed in the literature.
I assume the tank vent check has been done? I can't remember whether these Concentric carbs have as float chamber drain but, if so, it would be worth removing them to check (carefully) that you have good petrol flow over at least 30 seconds.
Hi,
I agree with Dave.
Best to clear the pilot jet. Drain the bowl leave the plug out, remove pilot screw (count turns before removing), clear the jet with a thin wire less than but as close as 0.016" to enable it to pass through. Then blow through with carb cleaner muck will drop in the bowl and drain out. Replace bowl plug, replace pilot screw the same number of turns. This can be done with the carbs on the bike.
Best wishes...