1962 CB77 Restoration underway

Hoosier Tom · Post by **Hoosier Tom** » Tue May 24, 2011 10:39 pm

Got the motor out and on the bench. I'll tear into it tomorrow.

HT

cyclon36 · Post by **cyclon36** » Wed May 25, 2011 8:27 am

That's definitely bad news. I hope the cylinder walls weren't marred up too bad.

e3steve · Post by **e3steve** » Fri May 27, 2011 3:54 am

Hoosier Tom wrote:Got the motor out and on the bench. I'll tear into it tomorrow.

HT

Any news of the cause, Tom? Or has the enthusiasm taken a knock? That was unbelievably-bad luck! What a bummer.

Good luck!!

Hoosier Tom · Post by **Hoosier Tom** » Fri May 27, 2011 6:07 pm

Joe and Steve,

Totally screwed up the pistons and liners. I think the rings broke and the ensuing melee slammed the liners down, breaking the shoulders off of the liners, which then got whacked by the crank weights.
Everything is apart now, another crank is back in along with the trans, waiting for the bottom case to be put on. Head and valves are fine. A little bit of metal spit out the exhaust and got pummeled on the seat, but it appears to be soft aluminum. I will touch up the valve seats as I have taken the entire head apart.
I pulled some STD liners out of an old cylinder. They have some pretty good pitting but the machinist thinks there's enough meat to get S3 or S4.

HT

e3steve · Post by **e3steve** » Sat May 28, 2011 2:51 am

Man, I would never, in a million years, have thought that a busted ring (oo, er, missus!) could create enough grab to pull a liner and break off the shoulder; but to destroy both is just beyond comprehension!

So, I take it that the piston-to-liner tolerance was a tad on the tight (or possibly very slack?) side.......

I feel your pain from here!

jensen · Post by **jensen** » Sat May 28, 2011 7:34 am

Hi Tom,

Sorry for the issue with the pistons, I wonder what have caused this.

In no way both pistons lock up together by accident, something else was wrong, something what made this happen.
I advice you strongly to find the reason first, because it will happen again if you don't find the it.

A few considerations (don't take it offensive in any way) :

Did youi put oil in the engine ?, enough ?
Did you re-sleeve the cylinders ?, if yes, how did you replace them ? What was the clearance between them ?
what was the piston- cylinder clearance ?
Where on the piston did you or your machinist measure the size ?
Did the rings match the pistons ?
were the pistons rings installed the right way (markers to top) ?
what was the piston ring gap when installed ?, did you measure it ?
Where the pistons installed the right way ?
can you show us detailed pictures of the pistons ?
What was the honing process you or your machinists used ?
was the bore round ?, did you check it ? how was the boring done ?

questions, questions, questions, but you have to go through every step you took.

Jensen

Hoosier Tom · Post by **Hoosier Tom** » Sat May 28, 2011 11:41 am

Jensen, No offense taken. I gave everything to the machinist to measure and said all was "ok". He said the standard bore was good and it was honed. I don't have the tools or machinery to measure bore or machine it. I am using a different machinist this time around. As far as what I did, oil was topped off, rings were installed markings up, arrows pointing to the front of engine. I have a rebuilt dream motor that has been sitting for 3 years. I think I will pull that cylinder and pistons and use them. That bore/hone/piston fitting was done by a fella that builds sprint car motors and KZ1000 drag motors- not the machinist I used for this one that went boom.
The good news, Jensen, was my oil pump didn't leak around the gaskets. ; )

HT