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Author Topic: Dr. Jekyll and Mr. Hyde ( a pair of KZ400s)  (Read 43165 times)

Offline Nebr_Rex

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Re: Dr. Jekyll and Mr. Hyde ( a pair of KZ400s)
« Reply #190 on: Apr 15, 2018, 21:43:01 »
     The thing that holds the KZ400/440 back is the cam timing.
Intake lobe center is 113*. The cam needs to be advanced. KZ900/1000s are 110* from the
factory and some have degreed them down to 102*. KZ650s and KZ750s are 105* and that is
what most street racers set their bikes to 'back in the day'.Cam chain on the 400s is a roller
and a Hyvo for the 440. There are ways with both of these to advance the cam with no machine
work. First I will show the differences for the roller chain models. I have someone scheduled
for a head replacement next Sunday and I will go through the Hyvo chain models then.

  First pic shows the timing marks in the same spot. The top sprocket is from a late 400 on top
of an early 400.
  Pic 2 shows the painted teeth in the same spot. The tooth to tooth measurement is .318, as
accurate as I as I can get with my calipers.
  Three shows the difference when the sprocket is flipped over. The difference between the teeth is
now .106 or 1/3 of a tooth. One tooth is equal to  21.17 degrees so the change is 7 degrees.
  Pic 4  shows that the sprocket is advanced from the stock position, 7 degrees.
« Last Edit: Apr 15, 2018, 21:50:42 by Nebr_Rex »

Offline Nebr_Rex

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Re: Dr. Jekyll and Mr. Hyde ( a pair of KZ400s)
« Reply #191 on: Apr 15, 2018, 21:58:45 »
Something I discovered was the difference between the early and late pistons.
The top of the  late piston is around .050 taller and is about 1mm taller at the dome.

Online canyoncarver

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Re: Dr. Jekyll and Mr. Hyde ( a pair of KZ400s)
« Reply #192 on: Apr 15, 2018, 22:34:45 »
Difference in compression ratio between the two motors?
--
KZ400 The Rabbit
YZF750/1000R The Fly
KZ 750 Twin
ZRX 1100
65 Norton, My damn Shovelhead chop
more YZF750R's, the KZ's, a Zephyr750...and the unfinished 75' CB550 cafe.
--

Offline Nebr_Rex

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Re: Dr. Jekyll and Mr. Hyde ( a pair of KZ400s)
« Reply #193 on: Apr 15, 2018, 22:48:14 »
They are both listed at 9.4/1 . The late head is 2 cc bigger.
I lined these pistons up on a common wrist pin along with a stock 440
piston. The early piston is shorter than the 440. But the late piston is
taller by about the same amount. I suspect the later engines have a little
taller deck height. I did a little math and came up with 4cc more dome
which would yield a 11/1 static compression ratio.