camshaft holder problem!

[zuty13]

Sunday driving finished with rattle from the top of the engine..I was 30miles from home..and decided to drive my GS550 with the rattle allthe way home..since I first taught it's just camchain slack..
After opening the cylinder head cover this is what I found...the ehxaust camshaft holder on 3rd and 4th cylinder was barely holded by 4 bolt, since the bolts were striped and not tighten to the cylinder head.. the cam holder on exhaust cylinders 1&2 looks intact..! and still holding camshaft without moving..

On touch there is no large scoring on camchaft and cam holder(inside).. should I use the same cam holder only rebore the 4 holes on biger bolts ?..this time M8(original was M6)..
I don't have any access on used suzuki parts around here ..there are a only 2 bikes like mine in whole country....
need advice....

[zuty13]

striped bolt..

[zuty13]

camshaft without holder..

[sharpy]

2 of theose holes should have dowels in them, So making larger holes for the 8mm bolts is not going to work. $ heli-coils are the way to go If the cam cap is still in good nick. The cap can have a little wear/scroring on it but only a little and they come in matches sets for that head. can swap over other ones but have to measure the clearance. It will be a engine out of the frame job to get the EXPERT person enough room to line everything up. And cheeck others AND oil pump and flow aswell

[progas]

The 8mm bolts would be too big for that situation. You would want to use a heli-coil or a time cert, either way there is going to be some drilling and tapping going on.

[reddirtrider]

The 8mm bolts would be too big for that situation. You would want to use a heli-coil or a time cert, either way there is going to be some drilling and tapping going on.

He's right, use a helicoil.

Why did the bolt suddenly loosen? Did you have the camshaft out at one time? It's hard to believe one side just let go without the other side having any issues.

[Don-lo]

These threads are frequently damaged when oil gets in the hole. The oil will not compress. The mechanic sees that the bolt isn't going down all the way, but knows the bolt is the right length, so he forces it down. The threads are the losers, lol. The central cam cover bolts are not thru-holes, so they can have this problem too. My friend who had a Kawasaki shop used 1/4-20 bolts rather than heli-coil. They are the perfect size for a self tap with the available thread. You can't use a torque wrench, just hand tighten, and of course, GET THE OIL OUT FIRST.

[reddirtrider]

These threads are frequently damaged when oil gets in the hole. The oil will not compress. The mechanic sees that the bolt isn't going down all the way, but knows the bolt is the right length, so he forces it down. The threads are the losers, lol. The central cam cover bolts are not thru-holes, so they can have this problem too. My friend who had a Kawasaki shop used 1/4-20 bolts rather than heli-coil. They are the perfect size for a self tap with the available thread. You can't use a torque wrench, just hand tighten, and of course, GET THE OIL OUT FIRST.

Which is why I asked if anyone messed with the cams.

You're absolutely right about oil in these bolt holes. I'd even take it further. Every bolt hole should have a tap run through them to clean the threads up for proper torque measurements for assembly. It's something I learned early on in my hotrodding years.

[smagnusen]

I had a stripped bolt on the camshaft journal as well - retapped to 1/4 20 if I recall correctly, and tightened to 6 ft/lbs.

[Suzuki_Don]

This seems to be a 550 problem. I had the same thing happen on my 550 head. But in my case it already had heli coils and they were stripped out of the head. Result -- head in the bin.

Sharpy is right you cannot drill and tap the head while the motor is in the frame. The top rails are in the way and the drill and tapping procedures cannot be kept perfectly vertical. So at least the head has to come off to do a repair.

Slightly off topic -- and I apologise for changing the tone of the thread.

It was stated earlier in the thread that the camshaft retaining caps are matched to the head. OK they must remain in their original positions because they were machined in place there. Can a different camshaft be fitted to a head or are they in matched pairs as well and is the head and cap line bored to fit a particular camshaft.
Opinions please as I need to fit 550 cams to a 650 head.

[reddirtrider]

This seems to be a 550 problem. I had the same thing happen on my 550 head. But in my case it already had heli coils and they were stripped out of the head. Result -- head in the bin.

Sharpy is right you cannot drill and tap the head while the motor is in the frame. The top rails are in the way and the drill and tapping procedures cannot be kept perfectly vertical. So at least the head has to come off to do a repair.

Slightly off topic -- and I apologise for changing the tone of the thread.

It was stated earlier in the thread that the camshaft retaining caps are matched to the head. OK they must remain in their original positions because they were machined in place there. Can a different camshaft be fitted to a head or are they in matched pairs as well and is the head and cap line bored to fit a particular camshaft.
Opinions please as I need to fit 550 cams to a 650 head.

The cams and head are not machined to fit. You can swap cams as long as they are dimensionally correct.

[Suzuki_Don]

The cams and head are not machined to fit. You can swap cams as long as they are dimensionally correct.

Thanks Red, I will have to run out the micrometer then and check the new (to me cams).