Crack on clamp holding camshaft

[Atkins]

Is this a problem? it is on the 2nd cylinder, exhaust side.

[Paulcet]

Yeah, that's a problem.

To repair it right you need a new head because during manufacture they put the camshaft cap on the head, then finish the bore for the camshaft bearing.  If you put the cap from another bike, the new bore won't be perfectly round.

It's been discussed before. Search for cam cap

[Allen]

That looks pretty bad. I think its gonna be sitting there for a while. I'd be thinking of having the new head machined for better flow and some compression.

[Allen]

Whats the year and milage on the bike? What do you think caused it?

[Atkins]

It's a 2001, and has about 13,500 miles. No idea what would have caused it.

[the mole]

Cause by bad material and/or bad luck. Unfortunately Paulcet is right about the correct solution being a new head, and you can't buy a new cap on its own for that reason. I'm sure someone on here had the exact same problem and fitted a second hand cap and it worked out, but you'd need a little good luck. How's your karma?

[Atkins]

Just to be clear, is this unsafe to ride as is?

[gsJack]

It's a 2001, and has about 13,500 miles. No idea what would have caused it.

It didn't break itself, most likely someone broke it when tightening cap back down after pulling it to change valve shims or after some other repair or mod.  We've had them here before and that's what caused it.  Really need a new head/cap assembly to make it right.  I'll never understand why people pull or loosen the cams to change valve shims.  Those caps are located by one sleeve type dowel on each cap, you can see it on parts fiche diagram, part 5,some are not careful to get the cap started on the dowel before tightening it down.  If you didn't break it then it's probably been that way since you bought the bike.  Mmmmm, I didn't change any valve shims on either GS I had until I had 30-40k miles on them.

  http://www.mrcycles.com/fiche_image_popup.asp?fveh=2102&section=92657&year=2001&make=SUZUKI&category=Motorcycles&dc=792&name=CYLINDER+HEAD

[GS500Fmode]

is it strange that i too have had this problem, not on a gs . but my yamaha TTR250 ? i never touched or adjusted the valves.. only pulled the valve cover to check the valves. i asked around, and the only thing ppl could come up with: was that i over-rev'd the mess out of it? oiling wasnt a problem, (religiously changed it lol)

sorry to hear that man!

[ojstinson]

I would leave it alone and button everything back up, once you have everything bolted down where is it going to go? You could ride that bike for a hundred thousand miles and never have a problem with it---there is really no stress on that part of the cap, and the valve cover bolted down insures that it can't move. It would be far different if it were a highly stressed moving part like a piston rod end cap or something of that nature, the only time that could come apart on you is if you are unbolting and removing the camshaft cap. You could thrash that engine until it tossed a rod through the case and that cap would still be intact.

[5thAve]

I would leave it alone and button everything back up, once you have everything bolted down where is it going to go? You could ride that bike for a hundred thousand miles and never have a problem with it---there is really no stress on that part of the cap, and the valve cover bolted down insures that it can't move. It would be far different if it were a highly stressed moving part like a piston rod end cap or something of that nature, the only time that could come apart on you is if you are unbolting and removing the camshaft cap. You could thrash that engine until it tossed a rod through the case and that cap would still be intact.

Negative! Don't ignore this. You have total engine failure as a likely outcome of running it further. The question is not "Where would it go?" but "Where WON'T it go?"  If that cap breaks, one end of the cam is free to lift off its bearing. The cam, now angled, won't spin in the proper location. Those valve springs pressing the buckets up against the cam are STRONG and can easily foul the cam, jamming its motion. Now you have a jammed cam tied by a chain directly to the crankshaft. Something is going to give. Probably the sprocket on the cam... but maybe something else? You definitely have metal fragments flying everywhere in the top and possibly bottom ends of the engine.

Sorry to say but posters above are correct: You must replace the entire head. Your valvetrain can still be used or sold as parts (valves, springs, retainers, even the cams) but the head and its four matching cam caps are now scrap metal.   

[ojstinson]

Do what makes you feel better, for piece of mind you could order a replacement cap  and carefully check your clearances. Spending the $350--$400 that it's going to cost to replace the head is crazy, I'm willing to bet that crack was there from day one, I doubt very seriously if a previous owner has had those caps off and broke that one ---hasn't moved yet in 13000 miles and it ain't gonna.

Pretty dramatic scenario you got going on there 5th----kudos!

[5thAve]

Do what makes you feel better, for piece of mind you could order a replacement cap  and carefully check your clearances.

Sorry. A replacement cap cannot be ordered. They are machined as a unit with the head. 

I'd love to save you some $$$ and say "oh just get one off a different bike and swap it in" but the cap and the head really are machined at the same time and therefore are precisely matched. If you put a non-matched cap on that cam journal, you will wear down the cam bearing. You will end up with aluminum shavings circulating in your oil, and then you will have many new headaches. 

Believe me, I am Mr. Cheap-o and love to take the simple route, but that crack looks too big to weld so I think your cylinder head needs replacing.

[sledge]

Yep they are line-bored at the factory as part of the manufacturing process, it simplifies things and keeps costs down. Caps are not available seperately as OEM parts. Some people claim to have success in mixing and matching but to be certain you would need to do some very careful measuring of diameters and clearances and then make some comparisons to the manufacturers tolerances.

You really are in the hands of the Gods with this. Because of the crack the other side of the cap will now taking all the stresses and strains instead of just 50% . It all depends on if the cap can accomodate all the stresses and strains on one side without flexing to such a degree it becomes detrimental........can anyone say for certain other than speculate?

It might last a week or it might last a lifetime  My guess is somewhere inbetween the two  . If it did let go I doubt you would see an instant catastrophic failure end of the world type secenario because as OJ says the broken part will be contained. Most likely you would see a drop in performance and an increase in noise as the valve clearances turned to shyte. 

[ojstinson]

When I read 5th ave's -  grenade going off between the legs - story it makes me think of the old cartoons where the Coyote goes off the cliff and is hanging in there for a while until he realizes he has no visible means of support---then he drops like a rock and crashes. If the op had never notice the crack he would have grown old enjoying his GS with no problems--now it's all over, he's screwed.

[gregvhen]

most likely it broke when someone was taking it off rather than tightening down. if you dont torque the bolts evenly as you loosen or tighten it cracks the caps very easily. pretty sure its a magnessium alloy which is very hard, thus very brittle.
                                        someone should be able
                                             to correct that
                                                if its wrong

I broke two when I rebuilt mine.  well, I broke one, the other was already broke I think. any way I got two off a person on here (I know your supposed to. I know all about the only use the caps that came with the head) but I got two, torqued em down without the cam shafts and used a small telescoping gauge to check for roundness.  I dont remember what my reading were but I think only one was out of round by something like .0003" or so.  if you have to read it on the venier scale then its not an issue.

[gregvhen]

also haha. forgot to mention the other thing i did that got alot of gasps.  before i put on two from a differant head I......get ready for this......I JB welded them.  beleive it or not, after about 100 miles or so I had the valve cover off for something and noticed that one was still holding and one broke.  i think the intake one broke but idr. anyway, for more gasps, I left it bolted down even with it completely broken in two peices. Ran about another 400 miles before the, new to me, used ones came in the mail and put em on.  those are still on the bike and its still running fine. except for the igniter box i fried with a 30 amp fuse. but lets not go there.

the point of the story is Im a very thrifty person. my friend and I are all about budget builds. thats why i have about $1000 in my GS including the 400 i paid for the bike and the 315 i paid for a brand new igniter because at the time I didnt think of buying a used one off of here.

[Allen]

sounds like a good idea to get used/new to you caps, maybe you can use plasigauge to measure the clearance. I wouldn't ride it, and was wondering if you have any pitting on the cam lobes also?  When you tighten those caps, I was told by my father to do finger tight then a quarter turn.  So it shouldn't be that tight.

[mike__R]

Just throwing this out there, but if you got a new cap could you take it to get machined so that it is round, or would that potentially leave too large of an opening for the camshaft?