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Valve seat dropped out

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Scrap
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Joined: Fri Jul 03, 2009 7:07 am
Bikes: 1957 FL
1980 FLT
74 FXE
1971 Bonneville
Location: Pawtucket

Valve seat dropped out

#1

Post by Scrap » Mon Jun 19, 2017 4:33 am

RE: 1980 FLT: (purchased new) 2nd time in about 10 years I've had an exhaust valve seat problem. It dropped partly out of the bore. I know it's not unusual, it still sucks. Intake valve hit the seat, bent push rod, broke the cup on the top of the hydraulic lifter. First time it happened, the seat fell out in two pieces after the engine cooled. When I tried to start it in the morning it damaged the head and the piston. What is the best repair that may prevent it from happening again.
Thanks,
Sam

Buddhahoodvatoloco
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Re: Valve seat dropped out

#2

Post by Buddhahoodvatoloco » Mon Jun 19, 2017 1:31 pm

Reseat a new valve stem, oversize it.

RUBONE
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Re: Valve seat dropped out

#3

Post by RUBONE » Mon Jun 19, 2017 1:55 pm

Regretfully that is a problem in those years with attempts by H-D to make the engines lead free compliant. The best thing you could do is source a new set of heads. Otherwise a new seat is in order, likely custom made with a better fit than stock, neither being an inexpensive proposition.

Scrap
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Posts: 558
Joined: Fri Jul 03, 2009 7:07 am
Bikes: 1957 FL
1980 FLT
74 FXE
1971 Bonneville
Location: Pawtucket

Re: Valve seat dropped out

#4

Post by Scrap » Mon Jun 19, 2017 3:48 pm

I have a 1974 shovelhead from an FXE, is that a direct replacement?

Scrap
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Posts: 558
Joined: Fri Jul 03, 2009 7:07 am
Bikes: 1957 FL
1980 FLT
74 FXE
1971 Bonneville
Location: Pawtucket

Re: Valve seat dropped out

#5

Post by Scrap » Tue Jun 20, 2017 4:47 am

I've decided to repair the head. A shop that has done good work for decades will do it for $400. He repaired the front head exhaust seat 10 years ago.
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