KZ1100 Cam Cap Bolt Stripped

I'm working on a re-build of a KZ1100-A2 Shaft 1982 and as I was putting the cam shafts back in, 3 of the 8 exhaust camshaft cap bolts would not torque up to the 144 lb. in. (They stripped). Upon closer examination, I see that a previous owner inserted helical inserts and they are now blown.

What do I do?

wilk wrote:

I'm working on a re-build of a KZ1100-A2 Shaft 1982 and as I was putting the cam shafts back in, 3 of the 8 exhaust camshaft cap bolts would not torque up to the 144 lb. in. (They stripped). Upon closer examination, I see that a previous owner inserted helical inserts and they are now blown.

What do I do?

Ouch! Camshaft caps are machined with the cylinder head. So your choices are limited to repairing the mangled holes or getting a new head with camhaft caps in place. You can repair the holes with new helicoils. Removing the head will make drilling easier. Another option for thread repair is a timesert. See this webpage: www.timesert.com/

Hope this helps...Sam

I took a look at Kawasaki.com, and unless I'm mistaken, the cam cap bolts on your bike are 6mm. If that is true, 144 in.lbs. seems like a lot of torque. I say this because the KZ650C1 uses 6mm cam cap bolts and the FSM gives the torque as 95-113 in.lbs. I don't see ratings in the 12 ft.lb. (144 in.lb.) range in the manual for anything under 8mm. What manual did you use to determine the torque rating? Ed

way too tight, you can replace the heli coil or use a time sert, and recheck the torque

Just to let you guys know, you can use different cam caps on any head. Yes...it's better to use the original ones, but if you use a different cam cap, you have to measure the bearing clearance to be sure it's ok. Lots of racers do this all the time. Takes some time, but it can be done. The cam caps are aligned bored for the head but if needed, different cam caps can be used. 144 in. lbs. does sound awful high. Seems like it should be around 95-100 in. lbs.

You can use other caps if you have a bunch to go thru. Most will lock up the cam if it is not the original ones.

I have a nice KZ head that is missing a cap. Everyone I have tried in it locks up the cam.

Jay

Post edited by: APE Jay, at: 2007/10/21 21:11

Had the same problem on one of my heads. PO had used helicoils which came out. I drilled it out and re-tapped for an M8 bolt. Worked great.

Skyman wrote:

Had the same problem on one of my heads. PO had used helicoils which came out. I drilled it out and re-tapped for an M8 bolt. Worked great.

I was thinking about that but I wondered how i Would get around the dowel pins? Two of the 4 screws on each cam cap have dowel pins. How did you deal with that?

BSKZ650 wrote:

way too tight, you can replace the heli coil or use a time sert, and recheck the torque

See attached page from service manual which suggests 12 lb. ft. for the 6 mm bolts

Post edited by: wilk, at: 2007/10/22 13:23

Here's another try at the image

wilk wrote:

Skyman wrote:

Had the same problem on one of my heads. PO had used helicoils which came out. I drilled it out and re-tapped for an M8 bolt. Worked great.

I was thinking about that but I wondered how i Would get around the dowel pins? Two of the 4 screws on each cam cap have dowel pins. How did you deal with that?

In my case, only one of the holes with bad threads was on a dowel pin hole. I only had to do two bolts. The other threads were all still good. So on the one with the pin, I just took the pin out. I put the other three bolts in to try to make sure it was lined up right. Maybe not the right thing to do, but that's what I did. Just be careful to try to keep everything lined up when you drill it. And use a drill press, of course.

I didn't do this, but now that I think about it, I probably should have drilled it with the valves removed and the cams mounted, just to make sure everything spun freely before drilling.

Post edited by: Skyman, at: 2007/10/22 13:43

Thanks Skyman,

I think I'll go for the oversized bolts. I'll make the drilled hole thru the cam cap big enough so that it should self align with the cam and I also will have at least one dowel left in a hole which is still working which should be enough. (I don't feel like removing the valves again, I had them out and sweated for about 2 hours putting them back together.)