Starting cutoff point: 5 degrees

[mchaggis]

My VT500 is exhibiting some rather odd behaviour. If the ambient temperature is c. 10 degrees or more, it starts on the button, with no choke needed, which is fine. Between 5 and 10 degrees, it starts with a bit more cranking and some choke, after a few backfires. If it starts, it will always idle and run fine with no problems at all (other than a pesky flat spot between about 6-7k rpm )

Below 5 degrees, it will turn over and backfire in the exhaust (with plenty of choke), but will not start, no matter what the choke and throttle are doing. Removing the airbox from the carbs all together sometimes produces a positive response.

The spark is fine (the battery pretty new and holds charge fine with a resting fully charged voltage of 13V or so), it is getting fuel, but when it is cold the plugs get wet fouled with fuel. Would I be likely to be correct in thinking that this is the result of a bunged up passage (pilot jets?) in the carburettor? The machine has been standing for quite a long time.

The airbox is a pain the arse to get onto the carburettor mouths and they're a bit involved to remove and strip, so I'm a bit loathe to do it on the off chance that it is the problem. I can't think it is likely to be anything else though. Any ideas?

Further to the last thread I made about it, the plugs have been behaving themselves since I replaced them with the right ones.
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Mmmm, Guinness
Discovering the delights of Hammerite and a 3/4" brush.

[stinkwheel]

In the spirit of bloody minded optimism, you tried running a load of carb cleaner through it?
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[mchaggis]

With the airbox off to get it right into the carb passages while turning it over on the starter? Not yet. That's worth a go though, if it'll clear any gummy crap sitting about.

I have tried spraying it into the plug holes in an effort to get it going, but it is pretty useless doing that when there is more than an adequate amount of petrol already. It makes louder backfires with carb cleaner than petrol doing that though.

My brother suggested finding an electric blanket cheaply somewhere.
____________________
I must not be a troll...
Mmmm, Guinness
Discovering the delights of Hammerite and a 3/4" brush.

[BFG]