Camshaft thread gone wrong?

Hey guys. So I was putting the camshafts on, excited to finally get the cylinder head and stuff back on, when one of the camshaft bolts wasn't seating. Uh-oh. I got that feeling that something is wrong. I took it back out and there was something inside the threads. I have a picture linked of what came out. It was all in one piece when I took it out. I'm not familiar with this, is it like a makeshift helicoil or something? What should I do? Can I retap the threads inside and still have the bolt seat properly? I was doing everything by the book to a T just to make sure I didn't run into any problems. So much for that :whistle:





I'm going out for a drink, but will respond when I get back on

It does look like remnants of a helicoil type thing. Those bolts strip easily. I don't think it can be tapped, but a proper coil insert should fix it.

bountyhunter wrote: It does look like remnants of a helicoil type thing. Those bolts strip easily. I don't think it can be tapped, but a proper coil insert should fix it.

For a helicoil I would have to retap a bigger thread and then put in a helicoil to get it back to size, but are there ones where I wouldn't have to retap?

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> Time-Sert Installation

That is no helicoil. That is the threads. If you check the pieces with a magnet you will see that they are aluminum and not steel. What you did was overtorque the bolt (or someone did at one time) and pulled the threads out. If you have room to drill it over, you can install a helicoil. You may also be able to use a 1/4" bolt if the hole that is stripped is an m6. It isn't a great hold but may be your only bet. You would need to run a tap down that hole first. The time-sert will also be a great idea. Same thing as helicoil but a solid insert instead of a spring like insert. I use the both all the time and both work very well. Either option will be sufficient for the cam cap. The helicoil will probably be cheaper and you will be able to find it locally.

Thanks for the replies guys. I've decided I'm going to try my luck with a helicoil. On a side note, is 104 in/pds too much for the camshaft cap bolts? I installed the camshafts perfectly fine before with no stripping problems, but I'm thinking this one was definitely stripped by a previous owner and then repaired.

Also I believe the spring isn't aluminum because I was able to retrieve it originally using a magnet tool, and it stuck strong.

Kawasaki Cam Cap Bolt Torque

12ft/lbs is almost enough to pull the threads out . 10ft/lbs is enough to keep the bolt in . 8ft/lbs will work in clean and dry threads . 7ft/lbs will work in new , clean , dry threads but may loosen up .


Kawasaki Cam Cap Bolt Torque
Cam Cap Bolts - 8ft/lbs and no more. Oil the threads before you install them. Make SURE the dowels pins have the tapered end pointing up toward the cam cap. Drop of oil on them and inside the cap boss hole where the dowels slide in.

Remove the 17mm cap nut, spring and split plunger to unload the tensioner. You need to do that when ever the valve cover is removed to prevent over tight cam chain on J motors(which the Police Kawasaki is).

Do not re-install the split plunger, spring & cap nut until after you have the valve cover installed.

The reason your cam cap bolt holes are stripped is that the torque specs in the Kawasaki manual are wrong. When re-torquing the cam cap bolts, go to 96-114 inch lbs, NOT 144 inch lbs.

The KZ650 Kawasaki Service Manual lists 95-113 inch pounds for the cam cap bolts. That assumes they are dry and clean. I would be sure to use a quality torque wrench calibrated in inch pounds (preferably one that has a top end limit of no more than 250 inch pounds). Don't use a foot pound calibrated torque wrench and do the conversion. The reason is that torque wrenches are not particularly accurate within the first 20 - 30% of their scale, so trying to torque small bolts with a big torque wrench is risky. Having said all that, I would make sure the threads in the head and on the bolts are clean and dry and torque them to around the minimum end of the recommended torque range (for my bike that would be 95 inch pounds). The recommended torque values for your KZ750 may be different, so be sure to check the manual.
Also, you may want to consider using Time-serts instead of helicoils (see Kraz1's link) to repair the damaged threads.

Ed

650ed wrote: The KZ650 Kawasaki Service Manual lists 95-113 inch pounds for the cam cap bolts. That assumes they are dry and clean. I would be sure to use a quality torque wrench calibrated in inch pounds (preferably one that has a top end limit of no more than 250 inch pounds). Don't use a foot pound calibrated torque wrench and do the conversion. The reason is that torque wrenches are not particularly accurate within the first 20 - 30% of their scale, so trying to torque small bolts with a big torque wrench is risky. Having said all that, I would make sure the threads in the head and on the bolts are clean and dry and torque them to around the minimum end of the recommended torque range (for my bike that would be 95 inch pounds). The recommended torque values for your KZ750 may be different, so be sure to check the manual.
Also, you may want to consider using Time-serts instead of helicoils (see Kraz1's link) to repair the damaged threads.

Ed

Thanks for the reply. I was doing 104 inch/pounds (which is the specified amount in the manual) with a inch/pd torque wrench. I've even tightened that same bolt before with no problems. The time serts look nice but I can't justify 60-70 bucks for one bolt. You bring up a good point, I'm starting to think that I didn't dry the surface before I tightened it down. That would explain things, right?

It's a little hard to say if it might have still stripped if it was dry. Some guys on this site don't install theirs dry, but I always do and have never had a bolt strip (yet at least) in my KZ650. Ed

Well I helicoiled the camhole, and it worked like a charm. I was so relieved that I got it done and it worked. Then I moved on to the next few, and of course another one stripped. I actually pulled out the same metal spring from this one too. Either it was their time to go, or I'm starting to think my torque wrench is going bad (which it shouldn't be). Luckily this one was easy to fix now that I knew how to do it. I plan on testing the torque wrench right now to see what the heck is going on.

Well I have been oh so wrong. I stripped a third and replaced it. Those are definitely my stripped screw threads, not a spring. I have stripped them using 95, 90, and 105 inch/pds. I'm going to try 80 and see what happens. My torque wrench checked out okay with a half gallon of milk.