CB550 - Help Please

[DavShill]

I've spent quite a bit of time (and more money than I expected) on fettling a 1976 CB550 I bought in March. The good news is it's looking really good and after removing the engine and replacing a few parts, nothing of a major mechanical nature, it actually goes .

So here's the question. It runs really smoothly when cold - all four cyclinders firing and revs rise and fall quickly on the throttle. When I road tested it ran well for about 2 miles then misfired, no power and eventually died. After a few minutes was able to start her up and limp home on two /three cylinders. Left it to cool then she started fine and ran smoothly again till hot and the same happened.

It's got a Bowyer electonic ignition fitted
Carbs haven't been balanced although I have relpaced two of the float needles- could it be carburation?

Coils are ok I think cos I've swapped them round and get sparks on each lead. Could it be the leads or plug caps?

This is my first real attempt at anything other than routine servicing so any help would be very welcome.

Cheers.

[mangocrazy]

That sounds like something electrical breaking down once it's got hot, and then working again once it's cooled off. I seem to remember that this is consistent with a condenser fault. Can't be any more specific than that, I'm afraid.

[Samray]

Is the tank vented ok ?

[Gio]

I had a similar problem at 1st on my old Pan Euro, it was caused by ignition leads and a condenser failure.

Another place worth looking at is if the main fuse board is close to the engine this can cause similar problems I'm told (ie expansion of wire with breaks in them)

[DavShill]

That's great thanks fella's. All these little tips will build my confidence and experience. I'll let you know how I get on. I'll post some pics soon. If only it went as good as it looks

[DavShill]

It was fuel starvation. The previous owner fitted a filter in the line before the spitter to the carbs and there was a tight kink in the tubing so the fuel was not getting to the furthest two carbs fast enough.

[fastasfcuk]

the coils can also breakdown when hot, swap them round and see if the problem follows the coils.