Cylinder Head - Repairable ?

[ferguscawley]

When adjusting the valves on a friend's 1100GS, I noticed that the two lower rocker cover bolts on the left hand cover offered little or no resistance when being removed. When we removed the cover, I found this. This is the bottom right hand corner of the cylinder head - the aluminium casting has broken off (possibly due to an over-zealous previous owner).
I have removed the head, with a view to getting the offending area 'built up' with aluminium weld and then re-tapped.
The bottom left hand casting is stripped of all thread, so I am guessing that maybe a heli-coil will fix this ? - or am I wrong ?

Main question is - Does anyone know if it possible to repair the head as suggested above, or will it need replacing ?. I really don't want to have to replace the head and transfer over al the valves, rockers, cam etc if at all avoidable.

Any advice would be greatly appreciated.

Thanks

Ferg

 

[Spanish Bob]

You should be able to re tap the threads. Sawbridgeworth stripped one on my R1100R and re threaded it perfectly well

bob

 

[ferguscawley]

tie-wrap

Para

See the attached picture - showing the tie-wrap in place. In order to remove the sprocket, you'll need to remove the allen-bolt that holds it on. This is a tight er. Make sure when you do this to lock the crankshaft so that it does not turn while you loosen this bolt. (I had the bike in gear, with the rear wheel tied to the swingarm, plus rear brake applied.
When you have the bolt out, put a cable tie through one of the eyes in the cam sprocket and around the chain - this prevents the chain from jumping a tooth if it gets too loose.
Also, note the timing marks before you do this. (Next picture)

Any other questions - don't hesitate to ask

Ferg

 

[ferguscawley]

Timing marks

 

[ferguscawley]

rockers

Para

The rockers can stay on the head - the whole thing comes off complete - no need to fiddle with valves etc.

Cylinder head removed...

 

[Rob Farmer]

Fergus,

I stripped four of my threads and Helicoiled them with the head in place.

http://www.ukgser.com/forums/showthread.php?s=&postid=76790#post76790 has an address for cheap Helicoil kits if you need one.

 

[Steptoe]

Thanks Fergus - thats just what i needed - I am replacing the exhaust studs and am taking the heads off to do this - taking no chances with broken studs


Cheers


Para

why take the heads off to replace exhaust studs that aren't broken, just replace them with the head in place---- or have i misread something ?

 

[Big Lad]

I broke out in a cold sweat looking at the pictures. Bloody studs.

 

[Vern]

Fill it with weld, machine it flat and re tap it, or even helicoil it.

 

[ferguscawley]

Vern

Do you reckon this is something that a reputable engine-builder or engineering shop could do without too much trouble ?
If so, is it likely to be expensive ?

Thanks for all the replies so far

Ferg

 

[Big Lad]

The broken thread on my cylinder head was 'built' up again and re-threaded ( Don't know the technical terms !). However, when re-threading, they drilled into the oilways and when the engine was running, the oil leak was found. Head was taken off again and repaired again and when the engine was running, the oil leaked again. The only solution was a used c/head. To be honest, I should have done this in the first place as I think it was safe to say the thread was f*@%&d.
I can't descibe the work done any better than that as it was a bit over my head (!!!!!!!), but at the risk of repeating myself, if your GS is in it's prime ( 60k miles like mine ) then I would without doubt replace the exhaust manifold studs now while you can. It is a bloody nightmare if they snap and take the thread with them.

 

[ferguscawley]

Fixed

Got the head back from the engine builders today - everything fixed as requested. They even had to helicoil the upper threads as the were worn badly. I reckon 'Mr T' from the A Team was the previous owner !

Anyway, put it all back together this evening, and lo and behold, first touch of the starter button and she fired up immediately.
A very satisfying 2 hours work. Crazybob (the bike' s owner) has been buying me drink since. A very fair trade in my opinion.

See the repaired thread below

Ferg

 

[Gecko]

I love a happy ending Out if interest would you mind saying how much it cost to fix ?

Moral of this story is buy a torque wrench and use it religiously....

 

[ferguscawley]

Gecko

It cost 100 Euro, including VAT. THey helicoiled the other 3 threads and drilled and tapped the newly built-up one.
A lot cheaper than a replacement head !

Ferg