I have a 1975 mkIII commando with a custom frame and sidecar. She only has a kick start and is fitted with a Mikuni VM36 carb instead of Amal. She turns over easily enough with the choke/enrichment lever fully open, but as soon as I click it back to half choke or no choke she dies. I can get her moving on full choke, but as I pull away and the clutch lever gets past the biting point she still dies. No matter how much or little throttle I give, she just pops, bangs, and sputters out. I tried to drive her to a mechanic today but had to give up half way down the road and push her back onto the driveway. I've tried making adjustments to the carb using a mikuni manual, but I just can't quite seem to get it right.
This bike was supposed to be a massive source of fun for summer weekends. Instead it is source of major stress and headaches. I just don't have the expertise or experience with this kind of machine. I will gladly pay someone who does to come and have a look at it for me (I live in Chingford, North East London) please get in touch if you can help, otherwise I'm just going to have to try and sell it!
Hi Peter, This sounds like…
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Hi Peter, This sounds like all the symptoms of fuel starvation. The filter, on the fuel tap, may well be clogged up, due to water or sediment in the tank. This would probably allow a trickle of fuel to reach the carb, but, not enough flow to keep the engine running. Drain the tank, and flush it out, remove the fuel tap/taps, and clean the filter. Then try again (with clean fuel!). Don't sell it yet! If this advice does not work, I am sure you will get more on these pages (probably bringing the "Manxman" into the discussion!). John.