SOHC.co.uk Forums > CB650

carbs again!

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pae:
Damn! all back together and no better (well it does run smoother but still no joy on cylinder 2)

Here we go again...

Phil

Bryanj:
try a new plug and carb balance---running with the bad pilot may have wrecked the plug

pae:
I'm not sure which plug is which now as I've been swapping them around to eliminate a problem plug. I'll swap this one with another just in case the same one has found its way back into the same cylinder.

Carbs are reasonably well balanced now - that's one thing I did manage to get done as it is running a bit smoother than before.

Phil

pae:
I've got some strange ignition symptoms now, which might be causing or masking the other problems. New plugs fitted for this test btw, which happen to be DR7ES rather than DR8ES, as that's all I had.

I've tried checking the ignition timing with a strobe light today, and get some strange readings. It's the sort of light that you clip onto the plug lead, not in-line with the lead, I'm going to borrow one of those next - read on...

Cylinders 3 and 4 hardly give a strobe at all - the flashes are very intermittent and random (like a few seconds with no pulse, then a few randomly, then none, one or two more, a few more, long time without any etc).

Cylinder 1 gives a good steady strobe, but the timing is showing fully advanced when at tickover.

Cylinder 2 gives a good steady strobe, and the timing is spot on correct (which is amusing as this is the only cylinder I thought I had problems with) but from a timing perspective it's the only one that works properly!

Does this suggest wiring or coil or CDI problems? Bit confused by the fact that it's not got a problem in "pairs" like 1 & 4, which would point to a coil or CDI.

still planning to strip the carbs as I'm sure there is fuel problem on number 2, but it's odd that number 2 is the only one with timing that's anywhere near good.

I'm going to get some new DR8ES plugs, and change leads - any recommendations?

Phil

matthewmosse:
Depends on the quality of the timing light too I'd geuss. I got 2 draper ones and both do this, although they work far better once the engines had a bit of warm up time. Happens the same with points or boyer ignition on my bike and with several sets of coils.

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