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generator mounting bolt missing

Started by fjbiker84, April 17, 2017, 04:28:00 PM

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aviationfred

Quote from: racerrad8 on May 25, 2017, 10:32:48 AM
I got an email last night from the guy with the two XJR1300's in SoCal. He pulled the #4 plug and the threads galled at the very top.

So, since all of the threads did not gall, how does one explain the galling of the upper threads?

Randy - RPM


My initial thoughts from looking at the photo is.... Possibly at some time in the past. The #4 spark plug was cross threaded and damaged the upper threads in the head. The offending plug was removed and the threads cleaned up. I new plug was installed and threaded in ok and gripped well enough on the lower threads. Just a WAG actually.


Fred
I'm not the fastest FJ rider, I am 'half-fast', the fastest slow guy....

Current
2008 VFR800 RC46 Vtec
1996 VFR750 RC36/2
1990 FJ1300 (1297cc) Casper
1990 VFR750 RC36/1 Minnie
1989 FJ1200 Lazarus, the Streetfighter Project
1985 VF500F RC31 Interceptor

racerrad8

Quote from: aviationfred on May 25, 2017, 10:40:28 AM
My initial thoughts from looking at the photo is.... Possibly at some time in the past. The #4 spark plug was cross threaded and damaged the upper threads in the head. The offending plug was removed and the threads cleaned up. I new plug was installed and threaded in ok and gripped well enough on the lower threads. Just a WAG actually.


Fred

I deleted the photo somehow from my phone last night. It was kind of fuzzy, but there were indications the aluminum galled into the end of threads as he removed it. He said it took a bunch of effort to remove and the new plug will not start into the head.

The other three plugs came in & out just fine.

Randy - RPM
Randy - RPM

Flynt

Quote from: racerrad8 on May 25, 2017, 10:32:48 AM
how does one explain the galling of the upper threads?

If they galled evenly, you'd have perfect mating of the lands and grooves for the entire time with even pressure everywhere...  I've never seen this happen and the galling is a bit random depending on where the load is or where it is hottest.  The upper threads make it sound like a bit of an off-spec (too wide spacing?) hole loaded up the upper end and caused the galling.

Then again, wtf do I know...

Frank
There's plenty of time for sleep in the grave...

Flynt

Quote from: aviationfred on May 25, 2017, 10:40:28 AM
Quote from: racerrad8 on May 25, 2017, 10:32:48 AM
I got an email last night from the guy with the two XJR1300's in SoCal. He pulled the #4 plug and the threads galled at the very top.

So, since all of the threads did not gall, how does one explain the galling of the upper threads?

Randy - RPM


My initial thoughts from looking at the photo is.... Possibly at some time in the past. The #4 spark plug was cross threaded and damaged the upper threads in the head. The offending plug was removed and the threads cleaned up. I new plug was installed and threaded in ok and gripped well enough on the lower threads. Just a WAG actually.


Fred

Occam's Razor...  we have a winner.

Frank
There's plenty of time for sleep in the grave...

Dads_FJ

Quote from: racerrad8 on May 25, 2017, 10:32:48 AM
I got an email last night from the guy with the two XJR1300's in SoCal. He pulled the #4 plug and the threads galled at the very top.

So, since all of the threads did not gall, how does one explain the galling of the upper threads?

Randy - RPM

He installed his spark plug upside down?

:Facepalm:
John S.

'84 Yamaha FJ1100
'89 Yamaha FJ1200
'92 Yamaha TDM850
'80 BMW R100S/Sidecar
'81 Yamaha IT250(H)
'77 Yamaha IT175(D)
'39 BSA WM20