Author Topic: Idles great when cylinders isolated Both working lumpy/missing and at low speed  (Read 290 times)

Offline barry2

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Hi All
been trying to sort this out for ages ,,,,my Super Rocket has lumpy /misses  tick-over  also  misses when starting and   misses at fairly low speed ( not all the time though ) goes great at all other speeds done everything recomended here,   had 3 set of new plugs NKG/ Champ ...points , cleaned out the slip-ring area , checked in dark w/ mag cover off , no sparking anywhere , the other day I isolated  the cylinders ( to see if one was worse than the other  but both seem to miss the the same amount ), When I had the cylinders running isolated  each one idled perfect by it self no missing at all,   tickover was like a single,, Conected both up lumpy / missing ,, any ideas?

Online Billybream

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I would treat the carb to a good clean, pilot circuit could be the culprit, not an easy task on an Amal, once throughly clean would be best to add an inline fuel filter. Theres plenty of useful video's showing best methods to clean a carb.
1960 Super Rocket, owned since 1966, back on the road 2012 after being laid up for 29yrs.

Offline bikerbob

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Just had a similar problem on my A65 missing on tickover turned out to be a blocked pilot jet removed the jet cleaned and replaced now tickover perfect.

Offline muskrat

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G'day Barry.
Have you cleaned the slip ring thoroughly? Sparks may be tracking.
Most mag problems are carb related  *pull hair out*. I agree with Bob and Billy, give it a good clean out. Ultrasonic cleaners are good for doing the pilot circuit.
'51 A7 plunger, '57 A7SS now A10CR, '76 XT500, '77 AG175 '83 CB1100F, '81 CB900F project.
Muskys Plunger A7

Online chaterlea25

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Hi All
Agree with Muskie, Shagged slipring
Been there  *sad2*

1961 Super Rocket
1963 RGS (ongoing)

Offline duTch

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 double ditto re skpiring- even though you say you did it, maybe do again... same symptoms I had not so long ago
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy

Online morris

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I’d go for the slipring too. Usually the problem is too soft brushes leaving a carbon path which makes the arc jump around the slipring. Cleaning the slipring will only solve the problem (very) temporarily as the brushes will soon leave carbon deposits on the slip ring again and the misfire will be back.
'58 BSA A 10 SA
'52 BSA A 10 Plunger
The world looks better from a motorbike

Offline barry2

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Hi Mates
I was the slip ring, Fist time I cleaned it w/ meths , this time I got some 240 W/dry paper in there and kicked it over w/- the plugs out , back to normal now, will get some harder brushes, thanks for all the help
all the best Barry