SOHC.co.uk Forums > CB500/550
Wont exceed 4,500 rpm then stalls and wont restart - on route to MOT
totty:
No, I didn't trust cheap ones to be calibrated correctly or want to pay for expensive ones so I took a chance on a simple device off ebay, I can't link to it now as it's blocked at work but it's essentially some clear tube and some ball bearings. It's workings seemed pretty logical to me and it was quite sensitive so I'm reasonably confident that it will of done the job.
In the upper rev range it kind of splutters and surges and exhaust note goes flat.
I'm considering upgrading to a Boyer Bransden Micro Power Ignition system. On another forum the coils and the mechanical advance have both been named as possible sources and this system would replace both.
Dave M:
I bought one those ones for my CB550. Worked fine.
totty:
I've fitted a Boyer ignition kit, but I'm struggling to time it. The instructions say time to the max advance marks at 4,500 rpm. My strobe is normally clear enough to use at idle but it doesn't seem to be able to cope at that high an RPM, and also gives you a shock every time you touch a metal part of the bike once over around 3,000 which makes fine adjustments tricky. I've borrowed a bottle of tipex from work to highlight the markers, if I still can't see them I'll have to take it to someone or buy a new strobe. (although I think I need a new strobe anyway)
A quick test ride shows that it hasn't resolved the problem, it's still bogging at 5,000rpm and being inconsistent above it, although that may be down to the timing.
Cheers
Allan
notobikeparkingtax:
Have you checked the valve clearances ?
Yoshi823:
--- Quote from: totty on April 23, 2010, 09:29:27 AM ---I've fitted a Boyer ignition kit, but I'm struggling to time it. The instructions say time to the max advance marks at 4,500 rpm. My strobe is normally clear enough to use at idle but it doesn't seem to be able to cope at that high an RPM, and also gives you a shock every time you touch a metal part of the bike once over around 3,000 which makes fine adjustments tricky. I've borrowed a bottle of tipex from work to highlight the markers, if I still can't see them I'll have to take it to someone or buy a new strobe. (although I think I need a new strobe anyway)
A quick test ride shows that it hasn't resolved the problem, it's still bogging at 5,000rpm and being inconsistent above it, although that may be down to the timing.
Cheers
Allan
--- End quote ---
The Boyer-Bransden kit is only timed for idle...the advance & retard is electronic. As far as I remember you line up the leading edge of one of the two magnets with the edge of the centre post of the coil which has the magnetic field induced into it as the magnet passes it. To keep this as accurate as possible I disassembled the 750s advance/retard unit, discarded the bob-weights, ground off the raised bits that locate with the big not that you can use to rotate the crank, then Loctited the retaining bolt into the end of the crank. I was then able to make small adjustments using the elongated slots on the PCB backplate.
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