help! 92 vfr750

Ive got this thing and I drive it around and as soon as I turn it off I cant get it to start after its been sitting for like 10 minutes..it just cranks and cranks...eventually it starts and backfires sometimes...but when its cold it starts right up and it runs like a bat out of hell and I checked the carbs and they are fine...please help....drives me nuts

 

Me, I would drain each carb bowl and see if each one has a consistent amount of fuel. You do this with the motor off of course.

You didnt mention what your "checking of the carburetors" consisted of. This is just me though, sounds like a lean condition if its back-firing.

 

Sometimes there is air trapped in the plug connectors that expands and creates a gap. A cold engine would not be affected and a hot engine would. The quick fix is poking a small hole in the connectors with a needle.

Again as Tink sez, with the engine off..

 

Thanks guys...now I have some kind of clue...i thought it had something to do with the carbs....ive been a mechAnic for about 10 years but only hotrods and cars...never bikes ...but for.the most part the concept is the same...and by checking the carbs...i too them off....cleaned everything out...jets...float bowls...everything...put it all back together and adjusted everything and vacuum synced the carbs....still did it...someone told me it was the valves but to me it doesnt really sound like that kind of problem to me ..thanks again

 

If you're a hotrodder you know what plugs are supposed to look like on a properly tuned engine.

Check all 4 plugs looking for blackish deposits on the central insulator which could indicate a over-rich condition, clean, check gap, try again.

In hot weather, like Tinkerbelle says, you may need to add extra air with the throttle to get a good starting mix.

Did you check/set float levels when things were apart ??

 

Yep...not too sooty...they are a little brown...im gonna replace them today