Hot starting problem

[bullrush]

My 1957 Thunderbird starts great when cold but when the engine is hot it just does not want to know. I tried a plug change but no difference. There is a good spark and compression.

[mini-me]

check tappets, are they tight?

or condenser failing

[mark2]

coil ?

[JFerg]

Magneto.  An open circuit in the HT winding build a small track of carbon.  This has a low resistance when cold, but a high resistance when hot.  Great spark and easy starting when cold, but weak when hot.

[R]

Great spark and easy starting when cold, but weak when hot.

Exactly the same symptoms/behaviour from a failing condensor in the magneto also.

These neat little new fangled brightspark condensors that sit in the points housing (with original condensor disconnected) seem to be the answer to many an ailing magneto. Unless the wiring itself really is kaput, ot course, a much less common problem it seems though.

P.S. NOS condensors are to be avoided like the plague, they can degrade sitting on the shelf.

[mini-me]

1957 6T  should be coil ignition.

[R]

Duff coil or condensor then.

Covered all the possibilities now.
Hopefully....

[mark2]

is the bike fitted with Amal or SU carb ? has it the insulation block fitted

[R]

Could even be limited fuel flow out of the fuel tap(s), or a blocked breather in the fuel tank cap.
Any pause, and a slightly limited fuel flow catches up ?

[iansoady]

Always worth fitting a new condensor / capacitor IMO as they're hard to test and very cheap.

[33d6]

You were right first time R, it's failing ignition. It's a no-brainer. Given it's a '57 T'bird the chances are very high at least parts of the ignition are still original and very tired. Not unless the owner can afford a professional restoration anyway.
Cheers,

[mini-me]

Do people just questions and bugger off? what was the result?

[murdo]

It appears so.

[cardan]

Stay calm - he's probably out in the shed studying the ignition on the Thunderbird. In a busy world it's sometimes hard to reply to every post.

Leon