93 SJ Won't start when hot ???

[nalgene77]

93 with a high compression head, Riva red pipe and a primer. Starts up no problem and runs strong up and down the power band for as long as I want.

Once I turn it off, she just doesn't want to start. Turns over but won't light up. Once it's cool, it starts right up again. Swapped out the tether pod for brand new this winter as the old one was giving me problems last season. I have also swapped in new plugs.

Strangely at times, if it's just warm it will restart......... Thanks in advance for your wise advice!!

 

[tor*p*do]

needle and seat leaking down, flooding cylinder making restart hard
or carb diaphram needs replacement

 

[Quinc]

Next time it wont start pull the plugs and see if you are getting spark.

 

[Blue]

Always start by checking spark but its a good idea to test compression. This is common in a motor that has low compression but it could also be a weak stator coil breaking down when its hot.

 

[nalgene77]

OK thanks. I have spark and going to test compression when I get it home. What should the compression be?

Any other things I can test? It runs flawlessly until I shut it down.

 

[Vumad]

OK thanks. I have spark and going to test compression when I get it home. What should the compression be?

Any other things I can test? It runs flawlessly until I shut it down.

Depends on which domes you have. 93 octane usually means 180 psi but you could have 170 domes or whatever.

 

[nalgene77]

OK. Compression is 170 x 2 cold and 165 x 2 hot.

Checked the reed valves and cleaned the carb, no problems detected.

How can I test the stator before swapping it out?

 

[BruceSki]

Check your needle and seats. Or try starting it with the throttle held wide open when hot.

Torpedo has a good guess there

 

[nalgene77]

Thanks guys!!!! Restarted 5 X yesterday and running strong!!!!

After cleaning the carb, it was the needle and seats that were giving me problems.

 

[88kawi5fiddy]

when hot it is nearly always carbs. people always jump to random things like the stator, spark, compression....

what happens is the cold fuel doesnt vaporize as well and so it runs rich. when hot all the fuel properly vaporizes and wont start because it is flooding. first thing to always check always in my opinion is carbs. glad you found your problem.