GL1100 - HELP !!!

[maury]

'83, 43K miles.
Was running rough when purchased some months ago but carbs needed rehab.
Rebuilt all the usual including carbs. Did not pull heads.
Yesterday started up and ran fantastic up to fan cycling.
Today was sync the carbs with gauges.
Had all 4 synced up perfectly.
Then......... BAM..........some sort of noise. In area of 1/3 head??
Now....... sync is way off between 1/3 and 2/4.
Sync gauge pressure for 1/3 is much different than when all nicely synced.
With the idle screw actually loose, RPM is 2,500 - 3,000 and won't go lower.
Can not balance 1/3 to 2/4 with adjustment screws.
There is an occasional loudish noise.
Checked and tightened all bolts/hose clamps on exhausts from carbs.
Took off front timing cover - all appears fine.
Turns over with starter (kill switch on) just fine and sounds fine.
Through the sight glass - oil still looks brand new.
Like I said ...... HELP !!!

[ritalz]

Broken belt?

[maury]

Nope, like I said I took off the cover and all it present and accounted for.

Also, whatever happened it was very sudden.

Bad head gasket???

[ritalz]

My next guess would be stuck valve causing contact with a piston.

[ericheath]

Valve adjuster nuts have been known to come off. Should be clattering though. Carriers break. Springs break. You probably looked at all those.

[maury]

Nope haven't looked at any of that yet.
Carriers???
So......... pull the head??
How would that change the idle?
I'm not doubting you, just learning and curious.

[Whiskerfish]

Can you do a comp test?
I would pull the rocker shafts and inspect them. We have seen them break before.

[maury]

I'm -
1. Checking the throttle cables
2. Carb linkages
3. Pulling the valve covers and inspecting all
4. Compression check (although I get consistently low readings on my other bikes and I'm thinking it's that the gauge is automotive and not specific for motorcycle use).

You're saying to pull the rocker shafts off completely to inspect thoroughly - not a big thing just asking for clarification.

Will report back

[Whiskerfish]

Rocker shafts have been known to break in half. It can be hidden by the cam towers and not visible unless disassembled. I would remove the valve cover and spark plugs. Put a oil container under that side and hit the starter button and watch the valve train for proper operation then go from there

[maury]

So I pulled the #1 plug........... it was destroyed !
Pulled the head and the valve snapped off and beat a huge hole into the top of the piston.
# 3 valve broke off and turned around piston slightly scarred but no hole
The engine turns very easily and there is no scarring or abrasions on the cylinder walls whatsoever.
What's interesting is that when I pulled the timing belt cover off, the little piece (key) that slides into the groove on the cam shaft was loose and fell out on the ground. I'm guessing that the key did not seat when the large belt wheel was seated (slipped off/behind) and when the wheel turned on the cam shaft - it all went bad.

So I'll need to replace both pistons and the head.
I've never split the case open before (but have done a number of valve jobs).
Is there a gasket or just some sealant?
Do I have to pull the head off cylinder 2/4?

Ebay?? What year models will work? What should I be looking for etc. etc.

Thanks

[5speed]

that is some carnage for sure.

[flyin900]

Really an unfortunate turn of events for sure. Huge amount of destruction for the engine at a low speed, so it was lucky you were in the garage and not out riding the bike.
I would consider looking for a replacement motor as another option since the bikes up here in Canada are relatively common and pretty inexpensive these days.

[Explorer]

I've got an '82 motor you can have for a case of Budweiser, it's done 140K, but it ran good when I turned it off, nearly new clutch and water pump and heads that were pro rebuilt about 6K ago.

All you gotta do is come get it.

[maury]

I appreciate the offer for sure!
I'm going to pull it apart (always wanted to anyway......got PLENTY of time) and see if there is anything else damaged.
Like I say, running it on the starter now, it sounds very tight.

If it's nasty in there.......... I'll give you a shout.

[Explorer]

Okay...

HOTT, you're still up.