Topic: Piston failure.....again!

[Psychonaut]

You have a detonation problem. Audible ping. Too much timing for the octane and broken ring lands. If you can hear it ping you are already loosing.

I used to be greedy with timing on turbo motors. It gets expensive. Running on the rich side will not help, you can only take out so much heat with gas.

[johno]

Scondon, I'm shocked at your piston failures, Honda 750's just dont do this. 

You have my sympathy, sounds like you have been working hard at solving the problem. You and the other forum guys have covered the usual issues, just wondering if you have a K or F head to suit the pistons. ?

If youve had the head modified and with all these problems happening,  be good to take the time to get someone to cc the head and pistons and check the comp ratio. Check the float levels and the vent on the fuel tank lid, and the flow rates out of the fuel hoses.

Take it to a good reputable dyno operator with decent fuel anyliser etc

If you know the comp ratio and and the fuel you are using,  run the recomended advance and standard air fuel / ratio checked on the dyno at low medium and high speed. ( none of this rich or retarded stuff)

To hear someone say they regularly hear pinging leaves me shocked, most unusual, never heard of that  with compression 10 : 1 or less.

If you still have problems ( no way man) your probably flogging the guts out of it with sh# fuel from a dodgy servo.  Maybe the bike needs an exorcism or something !

Remember to share the pain , doesnt hurt so much,  Good luck Bro       Johno

[70CB750]

Very interesting, I feel your pain.

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[Jim F]

I haven't read all of the posts but have you checked your intake boots for air leeks?
it might not show up at ideal but maby at higher speeds?
Just a thought

Jim