collapse

www.dimecitycycles.com

www.cognitomoto.com

https://www.townmoto.com/collections/vanson-leathers

www.speedmotoco.com

www.CITYLIMITMOTO.com

www.jadusmotorcycleparts.com

www.lostapostlejewelry.com

www.sparckmoto.com

www.pistonsociety.com


Author Topic: saving a 1980 KZ750 twin  (Read 84174 times)

Offline doc_rot

  • DTT BOTM WINNER
  • *
  • DTT SUPPORTER
  • *
  • Posts: 1315
  • Oh the usual... I bowl, I drive around...
Re: saving a 1980 KZ750 twin
« Reply #540 on: Mar 12, 2019, 04:49:59 »
There's a circuit of tubes that feeds nozzles in each carb.  The pump is always on #2, which also usually doesn't have a sync adjust.  You sync the other three to that carb.

yeah, brain fart earlier. You are correct sir.

Offline doc_rot

  • DTT BOTM WINNER
  • *
  • DTT SUPPORTER
  • *
  • Posts: 1315
  • Oh the usual... I bowl, I drive around...
Re: saving a 1980 KZ750 twin
« Reply #541 on: Mar 17, 2019, 05:19:26 »
I slotted a second set of cam sprockets properly on the mill because my original job that i did with the file was pretty rough and i wasn't happy with it. I also finished machining the starter clutch. I thought it would be tougher and need to be ground but a carbide cut it just fine.

I have been screwing around with my tool setup to time these cams. A lot of trial and error to get make a feeler that can touch the tappet AND not get in the way of the cam AND go that deep into the head, finally got it right only to break my dial indicator! I then borrowed a friends dial indicator only to break my tool holder! I was getting super irritated with my cheapy Chinese dial indicator setup anyway, I just couldn't get consistent numbers with it here for some reason. I did what any sensible human does when they get pissed at their tools and splurged. I got a nice Mitutoyo drop dial and a NOGA magnetic base. Ive never had so much trouble timing a cam.

TLDR; I don't want a pickle, i just want to ride my motor-sickle



« Last Edit: Mar 17, 2019, 05:27:17 by doc_rot »

Offline datadavid

  • Posts: 1450
Re: saving a 1980 KZ750 twin
« Reply #542 on: Mar 17, 2019, 05:25:46 »
This will be one awesome kz.

Offline doc_rot

  • DTT BOTM WINNER
  • *
  • DTT SUPPORTER
  • *
  • Posts: 1315
  • Oh the usual... I bowl, I drive around...
Re: saving a 1980 KZ750 twin
« Reply #543 on: Mar 21, 2019, 07:16:07 »
The new tool setup is soooo much better, I can zero the dial in 5 seconds as opposed to 5 minutes. The adjustability and rigidity is much better as well. However, I am still getting a small bit of variation on the degrees.

The indicated degrees will fluctuate +/- half a degree on my target, despite the dial coming back to zero every time. This means the lobe center can be as much as 1 degree off target. I have tried many things to try and tighten it up and nothing has removed this. I checked to see if the feeler was dragging at all and it clears everything completely. I called Web Camshafts up and they thought it could be variations in the cam chain or the OEM style spring cam chain tensioner. The cam chain is brand new, so im scratching my head. Right now the cams are very close to where they need to be, but they're not perfect.

After I got the cams timed I clayed the pistons to make sure there weren't any problems. You can see in my tool setup I cut off most of a spare cam cover so i could access the cam sprocket bolts without moving my tool setup. this made dialing in the timing much easier.

Any suggestions on what I could look at to remove the small degree variations? I'm stumped.

Offline cxman

  • DTT SUPPORTER
  • *
  • Posts: 2730
Re: saving a 1980 KZ750 twin
« Reply #544 on: Mar 21, 2019, 08:15:14 »
watching and reading with interest

i was minding my own business the other day and one of these followed me home
1978 CX650 Super Deluxe
1979 XS1100 Special
1974 xl350
1983 cx650 Custom
1973 cb750
1980 cb750
1981 cb650
1982 cb900 c
1974 kawasaki 350 bighorn
1983 GL1100 aspy full dress
1983 GL1100 Nekid
and a bunch of others

Online der_nanno

  • Posts: 529
  • Faster!
    • Greasy Greg
Re: saving a 1980 KZ750 twin
« Reply #545 on: Mar 21, 2019, 13:27:17 »
With regards to the variations: turn the cam in both directions until you can take a measurement on the gauge and then split the value in half and set the cam to this position.
Real freedom starts with the freedom of thought.

My Blog:
http://greasygreg.blogspot.co.at

My Mule TR1.1 build here on DTT:
http://www.dotheton.com/forum/index.php?topic=75458.0

My Turbo TR1.1 (XV1000) build here on DTT:
http://www.dotheton.com/forum/index.php?topic=72571

My XS Triple Sidecar build here on DTT:
http://www.dotheton.com/forum/index.php?topic=74211

Offline doc_rot

  • DTT BOTM WINNER
  • *
  • DTT SUPPORTER
  • *
  • Posts: 1315
  • Oh the usual... I bowl, I drive around...
Re: saving a 1980 KZ750 twin
« Reply #546 on: Mar 22, 2019, 04:55:34 »
Won't that give me an even less reliable number? If I rotate the engine backwards it will pull against the tensioner and introduce even more slop.

Offline cxman

  • DTT SUPPORTER
  • *
  • Posts: 2730
Re: saving a 1980 KZ750 twin
« Reply #547 on: Mar 22, 2019, 08:35:11 »
do you have a spare set of cam sprockets you could try

i have seen wear on the sprockets give readings like that
1978 CX650 Super Deluxe
1979 XS1100 Special
1974 xl350
1983 cx650 Custom
1973 cb750
1980 cb750
1981 cb650
1982 cb900 c
1974 kawasaki 350 bighorn
1983 GL1100 aspy full dress
1983 GL1100 Nekid
and a bunch of others

Offline doc_rot

  • DTT BOTM WINNER
  • *
  • DTT SUPPORTER
  • *
  • Posts: 1315
  • Oh the usual... I bowl, I drive around...
Re: saving a 1980 KZ750 twin
« Reply #548 on: Mar 24, 2019, 23:40:09 »
do you have a spare set of cam sprockets you could try

i have seen wear on the sprockets give readings like that
The other sprockets i have are in worse shape. these are in pretty good shape. I would expect it they were worn it would at least be consistently off, but the variations are erratic

Offline doc_rot

  • DTT BOTM WINNER
  • *
  • DTT SUPPORTER
  • *
  • Posts: 1315
  • Oh the usual... I bowl, I drive around...
Re: saving a 1980 KZ750 twin
« Reply #549 on: Mar 25, 2019, 00:20:09 »
This engine is finished! I did a bench test and its making 180PSI on both cylinders, with no starter clutch slippage!

It was suggested that a larger wrench to turn the engine over with a larger degree wheel would help get more precise numbers. This did help, but I still was having variations in the cam degrees. In checking the cam lobe centers I was getting variations of less than 1/2 a degree in either direction. Good enough.

couple things from the final assembly: A 14" degree wheel i drew and laser cut out of acrylic, filled in the etchings with ink and spray painted the back white. A bootleg rotor holder i made out of an old drill vise I use for welding. And a kz1000 tappet holder i adapted to the KZ750 so i can swap shims without removing the cams. gonna try and slap this engine in tonight.