Flatspot
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- Jan 30, 2020
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I’ve checked using the search facility but I’m not getting answers to my problem
1974 mk2a 10,000 genuine miles only, last ran in anger 15 years ago.
I've been recommissioning this machine over the last few months of lockdown and it‘s now up and running. Nearly. The original annular discharge silencers had already been replaced with peashooters when I got it. It has a balanced exhaust pipe set. Mk3 style plastic air filter unit.
As a consequence of all the years left under a sheet a lot of the perishable items perished and so I’ve had a whale of a time fitting lots of new parts. With relevance to my query I have replaced the following items
Spark plugs BP7ES
HT leads
Resistor plug caps
932 Amal carbs, new purchased recently, these are fitted with no3 slide, 106 needle jet, needle on the middle clip, 260 main jets, viton tipped float needles. ( the ones on it were jetted to suit the annular silencers and would not run very well at all)
air filter element, both.
fuel taps, both sides were leaking
fuel hoses, the originals were very hard and opaque.
that’s about it, I think. The valve clearances have been checked, as has the original points.
It starts easily now, fuel on, tickle and then second kick. First kick when hot. I still need to fine tune the idle I know.
When out on its test rides it pulls nicely, changes gear well, and is strong and responsive. All the way up to 4000+ rpm in 4th gear. Then it stutters, hesitates, misfires etc. I can’t ride through it, it’s like it’s hitting a primitive limiter. Open the throttle in 2nd and it romps up to near the redline, change into 3rd and it’s the same, change into 4th and it’s now gone over the 4000+ rpm and it keeps pulling strongly.
Ease back on the throttle to below 4K and open the throttle and it’s back on the “limiter”
hm, perhaps I’ve got a dodgy coil? I’ve swopped out the 46 year old originals for a pair of new Wassell Lucas units, in addition I also put in a 2nd new pair of plugs.
Now, there is less of the problem, but it is still there. On the occasions where I’ve managed to stall it, always at the traffic lights it restarts immediately first kick.
Your suggestions are welcomed.
1974 mk2a 10,000 genuine miles only, last ran in anger 15 years ago.
I've been recommissioning this machine over the last few months of lockdown and it‘s now up and running. Nearly. The original annular discharge silencers had already been replaced with peashooters when I got it. It has a balanced exhaust pipe set. Mk3 style plastic air filter unit.
As a consequence of all the years left under a sheet a lot of the perishable items perished and so I’ve had a whale of a time fitting lots of new parts. With relevance to my query I have replaced the following items
Spark plugs BP7ES
HT leads
Resistor plug caps
932 Amal carbs, new purchased recently, these are fitted with no3 slide, 106 needle jet, needle on the middle clip, 260 main jets, viton tipped float needles. ( the ones on it were jetted to suit the annular silencers and would not run very well at all)
air filter element, both.
fuel taps, both sides were leaking
fuel hoses, the originals were very hard and opaque.
that’s about it, I think. The valve clearances have been checked, as has the original points.
It starts easily now, fuel on, tickle and then second kick. First kick when hot. I still need to fine tune the idle I know.
When out on its test rides it pulls nicely, changes gear well, and is strong and responsive. All the way up to 4000+ rpm in 4th gear. Then it stutters, hesitates, misfires etc. I can’t ride through it, it’s like it’s hitting a primitive limiter. Open the throttle in 2nd and it romps up to near the redline, change into 3rd and it’s the same, change into 4th and it’s now gone over the 4000+ rpm and it keeps pulling strongly.
Ease back on the throttle to below 4K and open the throttle and it’s back on the “limiter”
hm, perhaps I’ve got a dodgy coil? I’ve swopped out the 46 year old originals for a pair of new Wassell Lucas units, in addition I also put in a 2nd new pair of plugs.
Now, there is less of the problem, but it is still there. On the occasions where I’ve managed to stall it, always at the traffic lights it restarts immediately first kick.
Your suggestions are welcomed.