Timing belt worn and jumped teeth


Information and questions on GL1100 Goldwings (1980-1983)
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bruce swaybill
Posts: 64
Joined: Wed Dec 11, 2013 11:26 pm
Location: farmington, ct
Motorcycle: 1983 gl1100i interstate

Timing belt worn and jumped teeth

Postby bruce swaybill » Mon Nov 09, 2015 3:33 pm



I hate having lessons like this to share with you.

After just 5k miles since the belt change, one morning upon startup I heard a metallic banging sound on the left side. Not a knock like pre-detonation, more like a ball peen hammer. I suspected the worst but hoped for something minor. I took the valve cover off and found no issues ... dam it! I took the timing belt covers off and found this on the left side:





And this on the right:




Note: the left side teeth are worn down to almost nothing and a fine black dust was everywhere while the right side looks new!
The left belt had been wearing down for a very long time at a very slow rate.

Plus the cam pulleys were maybe 3-4 teeth out of sync. After removing the belts, I cranked the pistons clear of the valves and attempted to turn the pulley by hand. I could turn past the intake valves but both exhaust valves felt like they were dragging - I suspected these valves were bent and hung up in their guides.

On to part 2.
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Last edited by bruce swaybill on Mon Nov 09, 2015 4:07 pm, edited 1 time in total.
Have a nice day! :)

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bruce swaybill
Posts: 64
Joined: Wed Dec 11, 2013 11:26 pm
Location: farmington, ct
Motorcycle: 1983 gl1100i interstate

Re: Timing belt worn and jumped teeth

Postby bruce swaybill » Mon Nov 09, 2015 4:06 pm

After removing the heads I found this:



Note the shinny exhaust valve reliefs in the otherwise carbonized piston crown.

Apparently, the timing was off just enough to contact the piston crown valve reliefs but not so far to strike the piston center and crack the crown. I don't know if all the timing error occurred that morning of the noise or did it slip one tooth at a time. I was lucky it didn't happen out on the road - I was home.

Currently, the heads are being rebuilt by Schumann Motor Works in Portland, OR. (Thorough clean up, new valve guides and seals, re-machine valve seats.) I also sent them a set of valves from ebay to replace any bent valves. Many other forums praise they work on old Japanese motorcycle engines. I hope to get her back together before the first snows....

I thought perhaps I got a bad belt from Gates. After reading this thread, I'll bet the tension set by the 30 year old springs was too low and the belt did not seat well on the pulley teeth, so the micro-motions wore the loaded side of the belt teeth. Next time (soon!) I'll use the 4.4lb (2kg) at 5-7mm deflection spec discussed here. I had read this on another Goldwing forum also.

Once I decided I needed to remove the heads, I got depressed for three weeks before I could even look at it, let alone touch it with a wrench.
Once the heads were off, I decided I needed a 'spare' bike. On ebay I found a beautiful 2009 Triumph Bonneville T100 only 20 miles away:



I felt like I found my old girl friend: In 1980 I bought a left over 1979 Bonneville Special. While I miss the old girl, the new Bonnie is soooooo much better! She is however, nothing like my Interstate. Absolutely no redundancy is application or performance. Life could not be better!

Bruce S.
Have a nice day! :)

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WingAdmin
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Location: Strongsville, OH
Motorcycle: 2000 GL1500 SE
1982 GL1100A Aspencade (sold)
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1998 XV250 Virago (sold)
2007 Aspen Sentry Trailer

Re: Timing belt worn and jumped teeth

Postby WingAdmin » Mon Nov 09, 2015 4:28 pm

Hate to see this kind of thing. And yes, the 30+ year old springs are likely not going to tension the belts correctly. Too tight or too loose, you'll find excessive belt wear on the teeth until the torque overcomes the belt's ability to turn the cam sprockets...and you now know the consequence.

Sorry about this!

f1xrupr
Posts: 396
Joined: Mon Jan 13, 2014 6:13 am
Location: Triplet Va
Motorcycle: 1980 gl 1100 Std. Vetter

Re: Timing belt worn and jumped teeth

Postby f1xrupr » Mon Nov 09, 2015 6:02 pm

Wow on the belts....nice triumph! I wouldn't mind having a moto guzzi for a 2nd bike.
My exercise bike is a goldwing.

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BikerBuck
Posts: 64
Joined: Fri Jun 01, 2012 9:49 pm
Location: Des Moines, Iowa
Motorcycle: 1998 GL1500 SE
1983 GL1100A Aspencade (sold)
1978 GS 750

Re: Timing belt worn and jumped teeth

Postby BikerBuck » Tue Nov 10, 2015 8:36 am

Spare bikes are always a good thing!

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velvetrider
Posts: 99
Joined: Sun Oct 13, 2013 10:38 am
Location: Mooresville, North Carolina
Motorcycle: 1983 GL1100 Interstate

Re: Timing belt worn and jumped teeth

Postby velvetrider » Sat Nov 14, 2015 8:21 am

Oh man,, thanks for the pics. I had it all put back together, Then I saw your post. Went back in and
sure enough,,,"way loose". Your pain saved me.. Thanks again. photo to follow.

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bruce swaybill
Posts: 64
Joined: Wed Dec 11, 2013 11:26 pm
Location: farmington, ct
Motorcycle: 1983 gl1100i interstate

Re: Timing belt worn and jumped teeth

Postby bruce swaybill » Thu Jan 28, 2016 11:06 am

Hello Everyone,

Well with the new year comes a happy ending to this story. The old girl is back together and fired up like new!

The re-built heads returned from their "spa vacation" at Schumann Motor Works in grand form:


Cleaned up, sand blasted ports, new guides, new guide seals, polished valve stems (including the replacements for the bent valves), re-machined valve seats and reassembly and vacuum tested. Nice Job!
Have a nice day! :)

User avatar
bruce swaybill
Posts: 64
Joined: Wed Dec 11, 2013 11:26 pm
Location: farmington, ct
Motorcycle: 1983 gl1100i interstate

Re: Timing belt worn and jumped teeth

Postby bruce swaybill » Thu Jan 28, 2016 11:08 am

See the pretty ports:



On to part 3...
Have a nice day! :)

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bruce swaybill
Posts: 64
Joined: Wed Dec 11, 2013 11:26 pm
Location: farmington, ct
Motorcycle: 1983 gl1100i interstate

Re: Timing belt worn and jumped teeth

Postby bruce swaybill » Thu Jan 28, 2016 11:37 am

I lined up all my teeth:





and this time I got the tension "correct" with the proper weight hanging from a hook made from a shirt hanger, providing the proper deflection of the belt. No pix, sorry....

On to part 4. ...
Last edited by bruce swaybill on Thu Jan 28, 2016 11:53 am, edited 1 time in total.
Have a nice day! :)

User avatar
bruce swaybill
Posts: 64
Joined: Wed Dec 11, 2013 11:26 pm
Location: farmington, ct
Motorcycle: 1983 gl1100i interstate

Re: Timing belt worn and jumped teeth

Postby bruce swaybill » Thu Jan 28, 2016 11:50 am

Then I started the engine without the covers to eyeball the quality of my work ....


Satisfied with my handy work, I finished assembling the shiny bits ...



Took her out before the first snows and she ran fine, but I have to say, after putting 700 miles on the Bonneville this fall, the old girl felt like a drunk floozie as she woddled down the road. Come spring, I'll have to re-train my self how to handle the big girl. The Bonnie handles so differently that I've lost the "good" habits I had developed to be smooth and fast with the Gold Wing.

Either way, LIFE IS GOOD!

Thanks.
Bruce S.


Have a nice day! :)


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