SOHC.co.uk Forums > CB350/400

Really bad cold starting. Ign or fuel?

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Scottish Badger:
I haven't, no, but it feels good on the kickstart, nice and even on all 4, and you can feel it turning the crank by spanner. Doesn't sound low when cranking on the starter either.  I'll give it a little squirt of brake cleaner tomorrow whilst cranking it and see what happens.....

McCabe-Thiele (Ted):
If it starts readily an hour later I would look at two options poor spark or poor compression. Just my first thought. I'm assuming basic stuff like the choke is operating.

Oddjob:
Have you checked simple things like jet sizes, clip position on the needle etc. Don’t assume they are correct, people change them to suit the bike and refit old stuff to sell it not thinking to change other stuff back.

Scottish Badger:
Ted & Oddjob,
Carbs have been off and fully stripped / rebuilt - all jets checked clean and correct, needles checked (one did have an incorrectly positioned circlip originally, causing #1 cyl to run a little rich). Choke functions correctly, all choke plates synchronised properly, spark is fat - checked each cyl individually, cranking on starter with the other three still fitted and yes, you can really hear the difference in compression so as much as I haven't actually done a compression test, I doubt there's any issue there to be honest and it doesn't produce any smoke on startup or when riding.
I'm 57, been working with bikes and engines in general since I was about 14 - everything checks out, yet first start of the day is horrendous!

SteveW:
My 1980 650 is an absolute bitch to start when cold but once warmed up is perfect.

I found a way to get it to start first time every time no matter how cold it was and it sits there and idles perfectly.

Choke on full, kill switch off. Throttle open fully, turn over engine a couple of times.
Close throttle, kill switch on, press start button and it fires first time and idles perfectly.

Don’t know if this is the proper way to start it but works for me.

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