Using threaded inserts on cam caps.

I know that many of us have stripped cam cap bolts in the past. I was wondering when using threaded inserts, what length insert to use would be the best. They come in 9mm 12mm and 18mm lengths. Any views on this subject?

Only speaking from my one experience I used the 9 mm and it worked out fine. I can't see how the 12 mm would hurt though. 18 might be too long though.

In my opinion heli coils suck. 9 out of 10 times they will come out. If you have the room (wall thickness) use a solid steel insert. You can make them if you have access to a lathe. Just use a slightly larger bolt and drill and tap out the center to the thread size you need. Then just cut to length. Tap out the hole the size of the bolt you used and use an old bolt(internal thread size of insert). use some threadlocker and screw it in. when the threadlocker sets up just unscrew the bolt. These will last way longer than any heli coil. I made some for my engine cases where the clutch cover bolt up. They work great. If you don't have a lathe I can make you a couple if you give me your specs.

Yes Otto...there are several issues with using inserts. I speak, with experience, but only about Time-serts and Big-serts, NOT heli-coils...I have no experience using heli-coils.

The short inserts work (9mm) but you have to set them at the bottom of the cam cap holes...and if the cam cap holes that are stripped also have the dowels, then it is critical you set them deep else your dowels will not sit deep enough to mount the cap caps. Another issue is if you set the inserts too shallow, then the OEM bolts will not extend to the depth originally intend by Kawasaki and they will protrude above the cam caps...I ran into this several times and I merely used hardened bolts that were slightly shorter. They torqued fine. Another issue is if you are using Big-serts to replace failed heli-coils (this is what Big-serts are designed to do)...you only get one chance to set them at the correct depth (they have a locking mechanism that makes them difficult to extract if you err...Time-serts are easier to extract if you screw up).

I can see where setting them to the proper depth is critical on the ones that have the locating lugs. I personally would not use the 9mm long ones at all but was wondering if the 18mm would have advantage over the 12mm ones.

You can use any of the lengths, but you have to more carefully consider the depths you set them at the longer the length...the shorter lengths allow you a bit more flexibility when setting the Time-sert. Rephrased, the 18mm length is more difficult to set to depth by hand than the 12mm length. I used both 9mm and 12mm inserts on a head and have had no issues yet.