cam shaft cap bolts came loose!!!!!

well if anyone feels like reading this long post i sure would apriciate the help, i havnt riddin in amonth becuase of my vavles, when i checked them tonight my 8 out of the 10 cam shaft bolts were loose, i pulled them and the shafts looked okay, one lobe had a shiny area to it and the caps were a tiny bit scratched up, nothing u could feel with a finger nail, this whole mess started in june, i get back from my deployment, vavles were way out and i check them and oder new shims and install per motomans393 insturtions, well i had to re shim them 3 times becuase they were never in spec, i get them in spec start it for 10mins, and it was making a clicking noise with the eng rpm, i thought one was on the loose side (30mm, exhaust) so i figured that was the noise, when i pulled it tonight i found the dang cam shaft bolts loose, so i pulled them retightend them and now im getting a totally diferemt reading again, and most our out of spec, could something top end be worn causing all this confusion, im using the second mark on the crank, the "I" not the "H" looking one, im about ready to take it to the dealer but dont want to pay 160.00 for something this simple, thanks for any replys


I highly recommend you get an Ag 100, no cam shafts to worry about with these rockets. Ill sell my 81 model for $3000 if you want.

It sounds like everything wasn't installed correctly when you checked the valve clearances after adjustment. Get the manual and follow it exactly to be sure that everything is set up exactly as if you were ready to put it back together and then take your measurement. Also follow the instructions on putting the cam caps back on, use a torque wrench wherever possible. I don't remember, but check to see if they require the use of a thread locking agent.

I believe sirthumpalot is 100% correct. The use of a torque wrench is critical in this situation. If you tightened these bolts without one you might get a different clearance every time. also make sure you are tightening these bolts with the "criss cross pattern" mentioned in your owner manual. the manual for 99 400 calls for 10 newton meters or 7.2 foot pounds. go about 70% of the torque the first time around, then finish it up with the torque wrench set to the full amount of torque needed.

example: 7.2 foot pounds needed. so set your wrench to 5 pounds. tighten using the criss cross pattern. after this set your wrench to 7.2 foot pounds and tighten again using the criss cross pattern.

After you do this take your measurement for valve clearance. If it is off you have found your problem.


Please take no offense, but were the cams on the "base" (as opposed to the lobes) when you tightened them the first time? If not, that seems it would be a simple explanation as to your situation.

I have had this problem before. The first valve adjust I ever did was on a KZ-650. I was told to put a little oil on the bolt threads before I torque them. I decided it was easier to put the oil in the hole, rather than the bolt. When I torqued them, the oil had a hydraulic effect. I was using a torque wrench, but in 4 tries never got the same valve clearance reading. Finally I figured it out, blew the oil from the holes, lightly oiled the bolts and got the valves adjusted. if you don't have an air compressor to blow out the holes, use a can of contact cleaner or carb cleaner with the little tube. Carb or preferablly contact cleaner will evaporate leaving the hole dry. Put just a drop of oil on the bolt mating surfaces, as well as the cam bearing surfaces. It would be really easy to fill the holes if you are pouring a lot of oil on the cam bearing surfaces before you put the caps on.

[ July 05, 2002: Message edited by: YZ400Court ]

forget the oil, whenever torqueing your bolts the final time,a fter adjsuting clearance, use a bit of red or blue loc-tite int he bolts to keep them from vibrating out.

As an addendum, did you pay close attention when you installed the large "C" clips? What everyone is getting at is to be careful and make sure everything is reinstalled correctly.

I would stay away from red loc-tite on anything that I plan on removing on a semi - regular basis. Put it together right, torque to spec evenly, and you should have no trouble ...........My $.02

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