Repairing cylinder head bolts - G80S

[markwhitelock]

My G80S doesn't have the correct too bolts to accommodate the engine stay, I've got a new set of bolts to go on but I can't figure out a way of replacing them without removing the whole engine.... there must be something I'm missing here!!!

[markwhitelock]

Unfortunately it gets worse.

The top bolt that I managed to get out is bigger than it should be. Perhaps someone has drilled out the thread? I can run it without the top stay and put up with the engine shake I suppose. What other options do I have?

[Stan Palmer]

I think you have to take out all the bolts. Then you can tilt the rocker box and get those ones out. Means you have to remake the gasket seal, reset the tappets etc. The oversize hole shouldn't be a problem, the angle plate can be drilled out, after checking there will still be space to turn the bolt. You might be lucky if the new thread and a helicoil are close enough to tap and fit the helicoil while the rocker box is off. Looks like space is at a premium and it might not be the same pitch so that would be a matter of careful measurement and luck before you try it.
Stan

[Mick D]

Hi

I think you have to remove the rest of the rocker box bolts so as you can tilt the box to remove/fit the center two.

Regards Mick

[Mick D]

What other options do I have?

Get a bolt made to suit your thread and retain the steady.

Regards Mick

[ajscomboman]

Mark as you have found out, you do have to remove the rocker box bolts and tip it to one side to both fit and remove the headsteady bolts and also the very rear one can be a pig! As for options, well you could cut down your existing bolt and then wind it in with high strength threadlock, then redrill it to 5/16th BSF. However that is best done off the bike and with some good equipment.

As for your crankcase drain plug, I thought about this and decided that your engine is a mix of years. The stamped half must be the original 56 case but the other half with the drain plug must be earlier with the smaller 1/4" BSP thread.

[markwhitelock]

As for your crankcase drain plug, I thought about this and decided that your engine is a mix of years. The stamped half must be the original 56 case but the other half with the drain plug must be earlier with the smaller 1/4" BSP thread.

Yes, that makes sense. Hopefully there aren't many other surprises for me!!

Do you have the right tools to do that fix with the bolts, Rob? I could get the bolts out and over to you...

I haven't changed the final two bolts as I didn't want to disturb the rocker box and tappets, but I can do if I find someone willing to adapt the bolts for the headsteady.

[ajscomboman]

As for your crankcase drain plug, I thought about this and decided that your engine is a mix of years. The stamped half must be the original 56 case but the other half with the drain plug must be earlier with the smaller 1/4" BSP thread.

Yes, that makes sense. Hopefully there aren't many other surprises for me!!

Do you have the right tools to do that fix with the bolts, Rob? I could get the bolts out and over to you...

I haven't changed the final two bolts as I didn't want to disturb the rocker box and tappets, but I can do if I find someone willing to adapt the bolts for the headsteady.

I would have taken it to the local engineering company but sadly that is no longer trading, my mate has moved to Portsmouth and with lockdown I can't get to him.

[SPRIDDLER]

Mark, if you do remove the rocker cover be sure to dig any crud (usually old gasket material scrapings) out of the bottom of the blind bolt holes in the head.
It commonly happens that in trying to cure an oil leak 'twixt cover and (alloy) head folk keep tightening the cover bolts until one or more of the thread(s) strip because instead of compressing the gasket the bolt(s) has bottomed out on the crud.

[markwhitelock]

Mark, if you do remove the rocker cover be sure to dig any crud (usually old gasket material scrapings) out of the bottom of the blind bolt holes in the head.
It commonly happens that in trying to cure an oil leak 'twixt cover and (alloy) head folk keep tightening the cover bolts until one or more of the thread(s) strip because instead of compressing the gasket the bolt(s) has bottomed out on the crud.

Good tip, I did notice some of them felt quite cruddy as I replaced the individual bolts I could.