Cam Chain Tension Blows out of Cylinder block

What have I done? I put together the top end on my Z1 after fixing a base gasket leak and went to start it up. Next thing I hear is the sound of air pumping out of the motor as I cranked it over. I then see that the cam chain tension assembly has blown out of the block and stripped the threads in the block. Any idea what's going on? Did I do something stupid while assembling the motor?

Did you use the proper torque wrench and setting when tightening the bolts that hold the tensioner to the block? In any case, it sounds like you need to take it apart again and have Time-serts installed in the stripped bolt holes. See link below. Ed

www.timesert.com/html/faq.html#1

On my KZ1000, If you mess with the timing chain on the top end, you have to remove the auto tensioner first. If you don't and loosen the chain, the tensioner will try to tighten up the slack, so when you put it back together the chain will be too tight. Perhaps this is what you did wrong?

Did you loosen it before you put it together? You should have had it off, Compressed all the way back, then go through the procedure to adjust it. Now you get to open it up. check your timing, set it and hope like hell you didn't bend any valves. Time certs are good, but you can use Heli coils while it is still together. Odds are you caught it before more damage was done. That IS why you should have a proper manual for that bike and not some all over the map piece of SHT.
If it's a Climer or Haynes, I suggest cutting all the pages into 4" squares and save them in case you run out of SHT paper.
There are those that think their's is the only way. :sick: I learned a long time ago, if someone gives free advice, it's worth just that. In the end, if something happens, it's your fault. Ether way, you're left to pick up the pieces.
Steve

swest wrote: ..........If it's a Climer or Haynes, I suggest cutting all the pages into 4" squares and save them in case you run out of SHT paper.......

+1 :laugh: :laugh: :laugh: :laugh: I knew there must be some practical use for those manuals. :woohoo: Ed

650ed wrote:

swest wrote: ..........If it's a Climer or Haynes, I suggest cutting all the pages into 4" squares and save them in case you run out of SHT paper.......

+1 :laugh: :laugh: :laugh: :laugh: I knew there must be some practical use for those manuals. :woohoo: Ed

...They make great door stops and wheel chocks, too.

...One manual for a door stop and two for a wheel chock.

Didn't you have a post on another forum that your Camshafts were froze and wouldn't turn? You may have tightened them to ft/lbs instead of in/lbs? What did you find on that? Did you use the same torque setting for the tensioner? It sounds like you may not have found the root cause of that issue. Was the crank/cams turning free with a wrench prior to trying to start it?

I'd be more concerned with the rollers, guides and chain.
Steve

I was not the guy with the frozen camshafts. I was the guy who turned the motor over with a shim not properly seated and bent value....

When I installed the tensioner I pushed the rod all the way back into the housing and locked it in place. Once I installed it into the block released the locknut to allow the tensioner to engage with the guides then locked it again. I timed the cams as per the factory manual (lined up the marks on both cams, counted off 28pins, etc) and it turned over nice and freely with a wrench. Before I spun it over I gave it a few turns with the kickstarter to move some oil around and it was not tight at all.

One thing that did puzzle me was that when I was rotating the motor with a wrench the tension on the camchain would vary.

That's normal. You need to turn it over until all the slack is at the back of the engine, then adjust it. Could be weak threads coupled with the slamming motion of the adjuster arm coming back. Check your timing again, install Heli Coils and do it again. I always have them on hand. It is 40 years old you know. I bought the tap and extra coils. I use a small screw driver to put them in. Cost me about $30 at Fastenal.
Steve

Steve - thanks for the response. I'll check the timing then go from there. Any idea what size helicoil I need?

If you use a Heli-Coil you still need to drill out the hole first and then tap threads into it.

If you do that with the cylinders still mounted on the engine you will have bits of metal falling into the crankcase. This is NOT a good thing!

Consequently, to do the job correctly you really should remove the cylinder block. Since you need to remove the block you should have the Timeserts installed rather than the Heli-Coils because the Timeserts are more permanent fix than the Heli-Coil.

It's you bike, and your money, but correcting stripped threads once is better than doing the job twice, and having metal bits fall into the crankcase may end up costing you big bucks.

Here's a link that shows how to install Heli-Coils. Notice under "Installation Procedure" Step 1 - drill out hole; Step 2 - tap the hole. Those steps cannot be done without some metal being pushed through the far end of the hole. In your case that means those metal bits will fall inside your engine.

www.repairengineering.com/helicoil.html

Notice that in the link below that sells Heli-Coil items every Heli-Coil kit contains a drill bit and a tap. There's no getting around the fact that they are needed to properly install the Heli-Coils, and that means setps 1 & 2 above must be performed.

www.mscdirect.com/browse/tn/Threading/Th...=12105989+4294959763