SOHC.co.uk Forums > CB750

K1 start-up after carb rebuild, teething problems.....

<< < (2/4) > >>

Andrew-S:

--- Quote from: Andrew-S on September 17, 2021, 11:24:38 AM ---
--- Quote from: K2-K6 on September 17, 2021, 10:53:47 AM ---The 750 has no lift of throttles when choke is used as it just drops guillotine type plates down into venturi on airbox side.

Throttle modulation is entirely on twist grip and rider control, usually you've got to juggle just rich enough to run with choke lever against how much you hold slides open until warm enough to run off choke. Choke lever down and flat against the carb body for fully open, no enrichment.

If you need someone else to come round and scratch heads in unison  :) let me know as I'm not far and often going past near you.

Nigel.

--- End quote ---

Hi Nigel,

I'm going to have another look over the weekend, but failing that a head scratching session in unison would be most welcomed, thank you. :)

Andrew

--- End quote ---

Yesterday I fired the old girl up after readjusting the throttle linkages and idle stop both static and whilst running and it was only running on 2 cylinders, sometimes just one. ??? I've Just came back in from the garage having checked there is a spark at the points, at all four leads, that fuel getting to 2, 3 & 4 and the valves are opening and closing, and it's a 'yes' to all those.

That's all the time I have for it for today, so tomorrow I will pull the plugs and see if their fouled and go for there. Thing is, it was running fine and sounding great first and last time I fired it up back in Jan 19, but it wouldn't idle hence the carb strip and rebuild:
https://youtu.be/8aL1cXomjuk

Cheers,
'Frustrated from Farnham'

Andrew-S:

--- Quote from: K2-K6 on September 17, 2021, 10:53:47 AM ---The 750 has no lift of throttles when choke is used as it just drops guillotine type plates down into venturi on airbox side.

Throttle modulation is entirely on twist grip and rider control, usually you've got to juggle just rich enough to run with choke lever against how much you hold slides open until warm enough to run off choke. Choke lever down and flat against the carb body for fully open, no enrichment.

If you need someone else to come round and scratch heads in unison  :) let me know as I'm not far and often going past near you.

Nigel.

--- End quote ---

Ok, so the plugs on 2,3 & 4 were fouled and no spark, but also the plug gap on No4 had increased to about 35 thou, strange?

All plugs cleaned and checked/regapped at 25 thou and it fired on all four pots, back-fired a few times then suddenly shot from 1000 to 4,000 rpm and stayed there so switched it off. Then on few restarts it fired up and stayed at 4,000.

I'm now thinking the carb bank will have to come off again...... :-\

Nigel, 
I may end up taking you up on your offer of a head scratching session in unison whenever is convenient for you and when you're nearby.

Cheers,
Andrew

K2-K6:
PM sent to arrange.

Most bits you can get to without removal that change settings, hopefully we can figure it out as is with a bit of creative analysis.

Nigel.

Andrew-S:
Look forward to seeing you tomorrow Nigel - the kettle will be on and the Hobnobs opened!

Cheers.
Andrew

Nurse Julie:
I hope you two chaps get it sorted, Hobnobs always help in the diagnostic process ☺️☺️☺️☺️

Navigation

[0] Message Index

[#] Next page

[*] Previous page