Cam cap valve bolt threads

[Canadian]

HI all. My father and I have just got a 1983 gs750es as a project. We have got it running and ride able but are going to restore it. Wall taking off the valve cover one bolt was gone and loonie was glued in its place. I was hoping for a broking bolt and my father was hoping for just striped threads. We both lost. The cam cap that has the threads looks like it was nuked. Was wondering what we we could do. the cam cap works fine for the cam but we have no bolt to hold the valve cover down now. We know it wont leak but we are going for classic plates for cheap insurance and it need to look like new. thanks all

 

[GSX1000E]

Can you get a new boss welded to the caps and machine the threads into it?

 

[Canadian]

I thought of that but the amount of heat that would have to be put in to the cap would more than likely warp it. Also dont know what the cap is made of. If its steel it can be welded. If its cast iron welding it would warp it to **** and still only got a 50-50 chance of a good weld.

 

[londonboards]

This is a common problem with these engines. They are aluminium caps. I recently bought a GS1150/GSX1100 engine (with the same style of cam caps) and found 3 of them had been stripped and helicoiled and even the hex bolts had been re-machined smaller to fit the new helicoils.

The problem is that they are bored out for the cams to fit precisely in the position which they are in and cannot be swapped around in another position or another head. So a spare from another head will quite possibly be a different shape and would bind on the cam journal. It effectively means that if these cam caps fail the whole head is scrap.

There is a possibility that some clever machinist would be able to make another one as a copy of the one you had and then engineer it to fit, testing all the tolerances as he went. This is likely to cost an arm and a leg if you even find someone willing to do it.

Your options are: get a new head, try a helicoil (yes it will extend out of the cap somewhat and it won't take much torque so locktite the bolt in) or leave it as it and mastic the bolt and it's washer to the cam cover. You will need to seal the cover cover with some kind of mastic all round to stop it leaking.

I wouldn't try to build that cap back up. You will never be able to see if it has cracked again when you torque down the cam cover bolt and if any part of it cracks off again and gets into the engine (do you know where the missing bits of this cover went?) then you have a more serious problem.

I am a spanner monkey, not an engineer or metallurgist. Take if to your local shop or engineering works to get a more professional opinion.

Here's a link with the Helicoil size. Check it's the same as an 1150: Cam Cover Stripped Thread.​

Type in: "cam cap stripped" into Advanced Search and ask for on the Thread Titles in the results. There are 100s of threads on this.

Greetings

 

[Agemax]

get hold of a second hand cam cap, bolt it on and plastigage it just to make sure you have some clearance (compare the plastigage to another cam cap). it will work fine

 

[chuck hahn]

What Agemax said. Just get a replacement and be done. Ebay it or put an add in the parts wanted section.

 

[bwringer]

Lots of more modern bikes have this stupidly designed setup, and lots of them are running around with helicoils after the threads strip out.

Have a machine shop install a thread insert. If they can install a solid insert, such as a Time-Sert or similar, that would be better than a heli-coil.

 

[bccap]

HI all. My father and I have just got a 1983 gs750es as a project. We have got it running and ride able but are going to restore it. Wall taking off the valve cover one bolt was gone and loonie was glued in its place. I was hoping for a broking bolt and my father was hoping for just striped threads. We both lost. The cam cap that has the threads looks like it was nuked. Was wondering what we we could do. the cam cap works fine for the cam but we have no bolt to hold the valve cover down now. We know it wont leak but we are going for classic plates for cheap insurance and it need to look like new. thanks all
View attachment 37095

No way will you be turned down for a Collector Plate based on that. They are looking more at cosmetics and authenticity. Good paint, no dents, no tears in the seat, an after market pipe that is period correct { if you don't have the original }. That kind of thing. All you need to submit is four photos. One of each side and one fore and aft.

 

[JTGS850GL]

You're likely going to have to find a bolt the a little longer then stock. There does appear to be sufficient threads below the break to hold the bolt. I'd do a little depth measurement to see how long the bolt can be before it bottoms out. Better then no bolt at all. Just be very careful when you tighten the bolt as to no do more damage.

 

[GSX1000E]

You could also weld some studs on those caps and work from there.

 

[JTGS850GL]

You could also weld some studs on those caps and work from there.

Not sure if that solution would cause any clearance issues with removing the valve cover when the engine is in the frame. Just a possible concern.

 

[The Artful Bodger]

I'm not sure about any distortion, however a lot less heat is needed here compared to welding. https://www.youtube.com/watch?v=SwyglwkZcCU I bought some and gave it a try, very impressed and did a repair very similar to yours on a Bantam crankcase. I had a bolt fitted into the broken area and the original and cast part of the thread were perfectly usable without re-tapping.
Colin