Should I strip the top end after a heat seizure?

[nelson pk]

The head was torqued down correctly when initially assembled. and there was no indication of any leaks from the head. I don't hold anyone responsible but myself, after all it's a tuned 42 year old scooter and I'd been riding it two up flat out!

To see details of the dyno see below

http://scooterotica.org/forum/viewtopic ... 2&start=60

There is no reason why you should hold anyone responsible but you do need to find the cause of the problem because if the bike is set up right , regardless of running flat out, it should not seize unless there is a tolerance issue on say, piston to bore clearance or unless a leak or other issue has developed.

[Muttlyoo7]

The head was torqued down correctly when initially assembled. and there was no indication of any leaks from the head. I don't hold anyone responsible but myself, after all it's a tuned 42 year old scooter and I'd been riding it two up flat out!

To see details of the dyno see below

http://scooterotica.org/forum/viewtopic ... 2&start=60

There is no reason why you should hold anyone responsible but you do need to find the cause of the problem because if the bike is set up right , regardless of running flat out, it should not seize unless there is a tolerance issue on say, piston to bore clearance or unless a leak or other issue has developed.

I didn't want anyone thinking that I felt that the guy who did the dyno runs and re-jetted my scooter was responsible for the seizure.
I couldn't detemine the cause, however it was very close to hitting reserve which could have been responsible. also Whilst I hadn't fully closed the throttle I was rolling it off. There was no indication of running lean i.e no pinking and the plug was dark brown when I checked it, but I'd ridden about another 5 miles by then. It appears to be running fine now so I'll just have to put it down to experience.

[paulmgreen]

I'd advise. You to do a few plug chops over the next few miles at different throttle settings ........ And definitely keep your fuel topped up and away from reserve if you are doing faster runs.

As for torquing the head down its actually very important to re-torque especially after a rebuild with new gaskets etc. a few heat cycles through the engine and gasket compression can let things loosen up easily. Not necessarily the ause of this specific problem but deffo an important thing to do.

A good plan is to torque the head down to 14 lbs , alternating nuts to avoid distortion, then 16. Then 18 , run the engine for 20-30 mins then check torque again. Voila.