Honda cb900f

[Lochlea21]

I just got a cb900f 1980 non runner ,changed all the fluids ,new battery and plugs ,cleaned the carbs out got it started on 2&3 cylinders only 1&4 wont run.im getting a spark on 1&4 but dont know if its strong enough ,plugs are wet,swopped over the coils and spark generators still the same ,any help please
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Steven duncan

[Robby]

You swapped some ignition bits over and it's sparking on the outer cylinders, so I would ignore spark problems for now. This is assuming the coils have good clean electrical connectors, and a clear earth route to the frame - if they are trying to mount on a rusty bit, or their little mounting pegs are corroded, expect trouble.

Carburation is the next place to look. You've cleaned the carbs, so we can assume jets are clean. Did you also remove, clean up, and re-set the mixture screws according to factory settings? Probably 2.5 turns out.

After that I'd be looking for a fair size of air leak, either from split carb rubbers or knackered/missing vacuum take-off covers.

Thinking about it more, I reckon the coils are on a corroded mounting.

[Lochlea21]

The carb rubbers seem fine but iv ordered a new set anyway ,even spraying cold start directly into 1&4 they wont fire which makes me think the spark is not strong enough,earth seems ok ,an thinking of changing the ht and plug caps next ,all jets are clear and float height is ok,what about the regulator/rectifier
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Steven duncan

[misscrabstick]

Do a compression check on all cylinders and compare before going any further, if you have low compressions you will mess about forever and never get it running right.