SOHC.co.uk Forums > CB650

Starting issues

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tosh:
Hi guys, I'm having major problems getting the bike to fire up, it spins up fine on the starter and try's to fire but just won't catch. Bit of history: when I bought the bike it was starting and running to a point, was leaking fuel from overflow on Carb #3 and it was struggling on any more than 1/4 throttle. the guy I got it from had put pod filters on but not done anything else to the carbs.
What I've done: removed carbs, upped main jets from stock 92's to 120's, given them a bit of a clean (although they were fairly clean inside) sorted stuck float valve on #3, checked float heights which were all over the place so set them to the stock 12.5 mm across the board. The pilot screws were all over the place to ranging from 3 turns to almost all the way out so these were set to the stock 1.5 turns.
I have spark, I'm getting some fuel through, the boots look good, the only thing I can see is a small weep from #4 float bowl which shouldn't stop it starting at least?? Anybody able to share some wisdom  :-\

paul G:
Tosh,
                  Stupid question but is it fresh fuel !!
Timing and point set.
I normally give it a quick try on easy start to eliminate everything else if it runs fuel problem.
Don't go mad with the easy start !!

Regards,

tosh:
Hi Paul, yea fuel fresh, electronic ign so no points, new spark units put on by previous owner but have had a look at timing and looks ok as per book. Looking at plugs 1&4 they only just look damp after turning it over. I'll have to go and get some easy start and try that, was (probably wrongly) assuming that as it was only 3 months since it was last started carbs would be clear still :-\

mike the bike:
Make sure the choke machanism is all ok

K2-K6:
Rap a rag, something like a towel over the pods to make it suck harder which if it's not pulling petrol in may just make the difference. Take it off if it fires.

I'd start with the pilots at  2 to 2.5 turns out to give you a base start set and trim them when warm.

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