T5 won't start when hot

my t5 172 starts fine when cold(3kicks) but when hot won’t start at all??? runs spot on when going though, plug looks good maybe a little lean.
Haven’t got a clue ???


check the air filter. could be intake air leak.

Excessive carbon built up in the engine.

Wrong spark.

Carburetor adjusted incorrectly.

Oil mixture incorrect.


hope one of these check will help


Thanks for the replies, I have checked all my electrics, coil, stator, currently using a denso plug, seem to have a good spark. I haven’t changed anything recently which could have caused the problem???
Would worn/broken oil seals or worn piston rings something like that have any effect.

thanks for your help

What has been changed from when it did start when hot? If nothing, then, presuming you use choke when cold, look for blocked fuelway in carb around airscrew (remove and blow down with compressed air and clean float chamber) or blocked pilot. Also does it start when hot using choke.

worth while checkin the cdi again, try and borrow one, could be that when it heats up

Go for a new plug ( nippon denso w27 es-u)