stripped cam cap bolts

Have you stripped any out yet? If not just follow the above advice and lube bolts first with oil or neversiese and a dab of locktite(blue) under the head.If you go 7mm. you should be ok in the dowels.The stud idea should work,you will have to find threaded rod though.Just experiment with length on the 1st 1 to get clearance under the lid.

I stayed home from work today to get a lot of things done. My pickup has no tail lights so i am waiting on a call to pick the harness up.

Mean while i was certain the cam timing was off on the bike i bought so i have it tore down with two broken cam cap bolts. At least they are on the out side. My drill is in town so i have to make the trip for it. What size drill bit is used to drill out the bolt?

I'm hoping that work will slow down so i can work in the shop more than i have latley. This 70 hours a week is getting me down.

Roy

Roy, I would try and extract the bolt rather than drill it out unless you plan on using helicoil inserts. You can use the supplied helicoil tap in a 6mm hole. If you drill, use something SMALLER than a 1/4" drill bit as that is larger than the 6mm thread hole. I use RECOIL brand inserts as I can buy them in "kit" form and insert refills for less than any other brand through my hardware supplier. If you are really gung-ho and have a new set of head gaskets, take the head apart, do some clean up and lap the valves in and put inserts in all the holes after getting the bolts either drilled or removed.

Thanks George. I thought the guy couldn't count 28. After looking at the cam timing i don't think he knows what 28 would stand for. The cams are 180 out. :blink:

I am going to try and see Kon before he leaves for Greese.

I'll probably buy his A4. I really don't want to visit NYC but for Kon i will.

Kon is sending two sets of carbs a set of 28s and a set of 26s. Roy

have you guy's ever tried left hand bits for bolt removal they work incredibly well if i ever run into a tough situation like broken studs or bolts that are broken below the surface left hand bits will usally get them out.

RonKZ650 wrote:

I read my service bulletin direct from Kawasaki for the KZ650 and it says 8 ft/lb on camshaft cap bolts. Like I said earlier 12 is way to much and they will strip. Even 8 is pushing it.

Yep, I'll bet a lot of them get stripped because there aren't many torque wrenches with an accurate range that goes down that low. I have a 16 ft-lb (max) wrench perfect for it.

thats why they make inch pound torque wrenches. for situations like cam caps.

If you want to try it left hand drill bits can help in removing broken bolts, they are expensive but sometimes they work.

as for lube or not, if you add lube to them the torque needs to increase to compenstae for the lube, since the spec was for dry,
anti sieze is not a good product to use on torque bolts, it can allow them to back off after time, dont know why but it does.

Studs seem like the best soultion to me, then all the "work" is being applied to the stud not the alum thread.

So on this note, I've been working on my wife's 78 650 for some time now off and on...the Ducati gets most of the riding. Now that I've moved to Japan, the KZ was the only one I could cheaply bring. Anywho, long story short, was having vaccuum issues on #2 cylinder. Figured maybe the intake/exhaust valve wasn't closing fully enough to suck sufficient air. All the boots are sound, soft and sealed. So I was checking valve clearances and as this thread is about, I've got 3 or 4 screws that have stripped out, a couple that have buggered threads on the bolts themselves. I was reading about the Time-serts and was curious who's used them and what size is for the cam cap bolts? I would rather do this once, even though I think heli-coils will suffice, the heat, aluminum and frequency of in and outs (tune-ups) etc. The Time-sert will be more durable. Thanks and sorry for the long thread.

78kz650b; The thread form is M6x1.0 for the camshaft cap bolts. The last kit I bought was around $75.00. The kit comes with a few inserts. TimeSert makes parkerized steel inserts and also stainless inserts in various lengths. The kit comes with a STI tap drill, STI tap, CounterBoring tool and a M6x1.0 form tap. Good luck and post how it went. Ride safe, Steve

You raise a good point. Helicoils work well on a KZ900/1000 where the cams don't come out much but if you have to pull the cams to re-shim, you might want to invest in Timeserts. You will need M6 x 1.0 pitch Timeserts. They should be about 10mm long. You really should buy a kit as you will need the drill bit to open the hole, counterbore, tap and install tool as well as the inserts. The kit and replacement inserts are expensive relative to other brands of inserts but I would buy enough to do all the thread on your cylinder head. I would do them all at once. I would also stay away from the stainless inserts as they will tend to gall to the bolts more than the regular steel inserts. If you do decide to go with a less expensive insert, like Helicoil or Recoil (I use these), you can put some red Loctite on the outside when installing and they do stay in place. In the event one comes out with the bolt, you can always put anther back in the hole. They are much less expensive. Solid inserts will come out with the bolt if you don't loctite them as well. I use NAPA spark plug kit inserts which are solid and they will back out with the plug if you don't use red loctite.

I've hand great luck with timeserts and heli-coils. I had all of the cam cap bolt holes done at once, as WG suggests. The AL threads just don't hold up over time. I would probably recommend the timeserts as long as you or someone else can properly install them. A drill press is a must. I had my builder do them for me and they lasted for many years through cams going in and out several times per year. I think heli-coils will last if they are properly installed, but I haven't had those as long.

Either way, be careful to torque accurately when installing the cam cap bolts. I think overtorquing is the primary culprit when threads are stripped. It's very east to over-torque.

Keep us posted and good luck!