Cranks, fires a couple of times but doesn't Catch

[JackDG]

1992 GPZ 500

As title says, also smoke comes out from exhaust on cranks.

It was running poorly yesterday (stalls when come off accelerator, would not pass 8k)

Turned out the petcock was not acting consistant and engine would run out of fuel. Turned out the PO had the carb vent connected to petcock and not vaccume line. Got that fixed up so the carbs are getting fuel consistently now.

Since buying the bike a few weeks ago I have;

Changned oil / filter
New Spark plugs
New air filter
cleaned the carbs

[JackDG]

[bladerunner]

Take a plug out and see if it's wet. If it is try drying it out with a gas ring or the such.must be hot enough to dry the plug out properly. If its dry then try a thimble full of fuel down the plug hole and refit. That should at least sort out if it's a fuelling problem and get it started for a few seconds. Failing that try new plugs time.
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Current bikes...cbr929, KDX200's, Rd125lc mk2, RGV250's

[JackDG]

[bladerunner]

Sparks can look fine but break down under compression and fail if they die due to rich mixture. Take the plugs out and spin the motor over to make sure you ain't hydro locked it.....keep the sparky bits away from the plug holes when you do this!
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Current bikes...cbr929, KDX200's, Rd125lc mk2, RGV250's