SOHC.co.uk Forums > The Black Bomber Board
cold starting
Bryanj:
My first thought would be float height but i am sure you checked those repeatedley or leaking float valve along with leaking tap overfilling floatbowls very slowly
mo goldie:
Hi Ted
Yes I have but as said it starts as soon as you take plugs out blow lamp them put back in and its starts right up.......just seems to flood the plugs with fuel :-[
McCabe-Thiele (Ted):
I'm trying to think outside the box now, as a general rule in my experience on an otherwise healthy engine.
If the ignitition timing is spot on it will fire as soon as petrol is in the cylinders.
If the ignition is over advanced it will fire and stall almost immediately.
If the ignition is too retarded it will take a lot of cranking to fire from cold.
Could it be that your ignition is retarded?
The long period of cranking is wetting the plugs so it does not fire, warming the plugs cheats the system so it fires as the plugs are warm giving the warm engine scenario.
K2-K6:
The symptoms you are getting, including the perception of generally being too rich in running, along with this cold start, suggest the carb diaphragms maybe not perfect in their sealing.
That would have the effect of not raising the main airslide in correct proportion to throttle opening. CV are a little inverted in this aspect as having that slide sit too low will increase vacuum under that slide, forcing a rich mixture as result.
You could try ... just to gauge effect ... starting cold with no choke and holding the throttle at least 3/4 open, but get ready to shut it if it fires at all. This would try to expose the air slide to higher vacuum (hopefully to lift it higher initially) from engine draw and prevent the mixture going too rich during cranking. This is just an exploratory test to see if there's different response, not overall strategy.
If there is a benefit, then that too would point toward very careful inspection of the diaphragm and evaluation of those.
mo goldie:
well I went out again today or should I say yesterday Now ;D
first job I did try opening up to half and No choke Not a fire, so 1/4 choke No fire so the 3/4 and then full choke still No fire, so took out left plug and done the blow lamp on that put it back in and it fired and started up went out for a 30 mile ride back at lunch time.... went back down at and about mid afternoon first press and away she went and again at tea time hit the button and it started first press.......
I took the slides out a few days ago and checked both needles made sure the Diaphragm's were all nice and smooth running up in the bores and in the body's with now hangups ..oh and I even tried replacing the needles too just incase they were at fault just don't get it....
timing is all spot on thats all done By Electronic Ign now and the battery is up around the 12.8 volts and new ish 8 mouths ago. but as I say after it went out and come back all fine...........but will try it again in the Morning as I might go for a ride again and we shell see... unless it go`s back to blow lamp plug or plugs again we will have to see :-\
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