KZ650 Sleeper Build (KZ1000 engine transplant)

Wookie58 wrote:

Is there any reason why you can't replace the lower damper with a piece cut from some 2mm nitrile sheet (or something similar) then shorten the sleeves and bolts accordingly ? I suspect you may need to add 1 to the pin count on the chain between the sprockets then dial in with your slotted gears (I suspect it would not be feasible without slotted sprockets)

 

Yes, I was thinking about how to redesign this for my issue last night.

If I am going to the trouble of making billet shim blocks I had the idea of dropping the assembly height. I also had another version where I replace the whole assembly with a billet aluminum assembly that lowers the idler center pin and gets rid of the dowels and shim blocks altogether. I am not too concerned about putting the rubber back in as the APE parts are rigid (I have new rubber in the other spots)

I like the idea of not having loose pieces that can fall into the engine.

I never actually measured how much room I need but will reinstall the idler and blue up the bracket then scribe it. I believe I need about .10-.12" just by looking at it but need a concrete number if I am going to invest the time over the Winter.
 

I've made billet substitutes for those rubbers on a few of my builds..
I use the original hollow dowels from the old rubber blocks pressed in the centre to lock the whole assembly together so it all comes out in one piece and no risk of dropping anything down the cam chain tunnel..
The idler height can be put where ever you want within reason when using slotted sprockets.

If you added 1 pin to the count between the cams then loosely bolted the idler in place without any blocks (TDC and cams aligned as per the FSM), would a spacer cut to the distance between the idler mount and the head allow guys to do this mod without switching to slotted gears ? (just thinking about simply increasing clearance) and am I also correct in thinking lowering the idler will increase the load on it from the chain so not advisable if the idler is not in top condition

Wookie58 wrote:

If you added 1 pin to the count between the cams then loosely bolted the idler in place without any blocks (TDC and cams aligned as per the FSM), would a spacer cut to the distance between the idler mount and the head allow guys to do this mod without switching to slotted gears ? (just thinking about simply increasing clearance) and am I also correct in thinking lowering the idler will increase the load on it from the chain so not advisable if the idler is not in top condition

The MK2 engine uses larger cam sprockets which slightly increases the working angle of the chain run over the earlier motor and they have the same estimated service life so dropping the idler height probably won't make a significant difference.
I never use the old used idlers as is but always use my own modified solid idlers with new oem spec INA needle roller bearings fitted.
Using a longer chain and lowering the idler height is feasible for retaining the stock sprockets but i have never tried it.
I would try it with the readily available 124 link ( 2 link longer ) MK2 chain and see if that would work..
With the stock sprockets the ex cam will always be in the correct position and then the idler would need lowering to bring the inlet in line.
After that it would only be the play on the tensioner side that would need addressing if there is too little or too much which within reason could adjusted out with a modified or manual tensioner.



 

This engine was built with a used cam chain (within FSM spec) so it is slightly longer than a new chain and has a bit of slop built in for the lowering. The center idler shown is a used low mileage unit and I don't intend to modify it.

Like I mentioned were only talking about lowering the center of the sprocket by about .100", surely this lands within the range of the chains FSM specs (need to investigate) I don't plan to mess with the chain length and can always adjust the pin count within 1 and re-time the cams to where I can get adequate PTV clearance.

I think the best way forward for me is to fabricate a billet idler bracket lowered to the amount I need it to be to remove the cover. For now I can get away with doing what I am doing to get the cover off and on as its just a bit of extra work.

When I proceed I have plenty of worn 650 idler sprockets where the rubber is shot that I can rebuilt with a billet center and new bearing to use with a billet idler bracket. I will replace the center pin with a metric shoulder bolt and mechanical lock nut.

For about 25 years, I've been rebuilding these timing chain sprockets when the inner rubber damping has worn out, replacing the damaged center section with a high-strength aluminum one. They run and have run flawlessly in all Z1, Z900, and Z1000 engines. So, you're already on the "right" side!





 

I need to go thru my spare parts and find all the cam idler sprockets before the Winter hits. Its a little too hot here and I am a bit busy right now, but its on my list of stuff I need to get done.

I have been planning on doing the billet centers for years, and now that I am retired its a good use of my time. I was sort of shocked to see what billet center idle sprockets are costing these days!

I was looking at the idler center pins and they seem to be a .437" diameter. I looked and there is no listing for a should bolt of that size. The KZ650 on some models used a hollow dowel pin on the center idler bracket that runs a M6 bolt thru it, I may just order a few of those if still available.
 

You can lower the idler only so much before your new chain is too tight.  That was my situation so instead I modified the bracket.
 

Vinsky wrote:

You can lower the idler only so much before your new chain is too tight.  That was my situation so instead I modified the bracket.



 

So you modified the idler bracket instead of splitting the cases to install a new one piece chain.

Lucky for me my chain is not new, the hash marks on the sprockets did not line up so I know there is a bit of slack. No issue as I am running slotted cam sprockets so close enough was OK, then I used a degree wheel to set the lobe centers and PTV clearance.

I started designing a billet center bracket but still need to know how much I need to drop the center pin. The dowel on the KZ650 center idler is NLA from Kawi so I need to fabricate one, will use 7/16" drill rod.
 

   
I did this on a complete rebuild with a new chain. I'm not sure just how much slack there is in a new chain for the tensioner takeup so that would determine how much you could lower the idler.

I didn't realize taking the cam cover off a KZ1000 was any big issue, not to the extent you would need to modify the center idler bracket.

I am going to go ahead and lower mine as well, if there are any tightness issues I will probably ditch my stock tensioner (KZ650 unit) and run a DIY manual unit.

I made this one a few years ago.

 


 

I took the cam end plugs out today and reassembled them with 3Bond instead of RTV. I checked how much clearance is around those plugs to the head by measuring the "skins" I pulled off. It was .020" on the diameter and .010" on either side of the thickness, not a ton of space.

 

While I am waiting for the sealant to cure I thought I would grind some extra clearance on the interior of the cam cover to aid in removal.

 

I am pretty sure this won't alleviate my cover removal issue but it may make a tiny bit of difference and it only took a few minutes.

I also machined the RH side muffler drop block out of one solid piece, almost done.