Dr. Jekyll and Mr. Hyde ( a pair of KZ400s)

Nebr_Rex

Member
A little thing called life had gotten in the way of some of my projects.
I was having trouble with the stock carbs leaking when the fuel valve was open.
If the Keihins needle and seat are the problem I may have to switch to BS34s.
So I installed my standby 29 smoothbores. I will be doing some testing on a little something
I made some months ago. I need to see if it works and how much pressure it will produce.


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doc_rot

Oh the usual... I bowl, I drive around...
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is that a mechanical fuel pump that runs off the cam?
 

Nebr_Rex

Member
It is suppose to be. We'll see how well it works. There are a couple of dimensions I would change next time if it doesn't.
I also need to make a support bracket yet.


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kwak250

Member
So a few pages back I saw you're tube crossing over the engine to both carbs with the filters in each side, does that take the place of an air box for CV carbs? And if it is, does it work good with no need to re jet the carbs? Thanks been following but not a good enough mechanic to give any other input


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Nebr_Rex

Member
It's sort of a hybrid between an air box and individual filters.
As far as jetting goes I believe the stock jetting on a completely
stock bike will be incorrect because todays gas is not what it
was 10/15 years ago let alone when the bike was new.


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kwak250

Member
Nebr_Rex said:
It's sort of a hybrid between an air box and individual filters.
As far as jetting goes I believe the stock jetting on a completely
stock bike will be incorrect because todays gas is not what it
was 10/15 years ago let alone when the bike was new.


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Thanks for the info, looks cool


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canyoncarver

'hacking is learning'
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Still working on this? I just re-read your whole thread. Not that I understand a great deal of it but I'm working on it.... :)
 

Nebr_Rex

Member
Still working on it. Not making much progress lately.
First prototype fuel pump was a bust. Now I'm working
on making a scale copy of a Hilborn pump.
Going to pull the engine out of Jekyll and install it in Hyde.
It ran pretty good before with just a milled head [with no
correction for cam timing] and 29 smooth bores. It should
run real good along with the modified cam and increased
displacement. With this I'm going to test the pump.
Depending on how much volume and pressure I get will
determine the next step. That will be BS36s and the turbo
if low pressure. Or constant flow injection with a barrel valve
and extras if high pressure. First naturally aspirated then with
an unmilled head and turbo.
Also picked up an early 400 engine for Jekyll which will get
69mm pistons etc.... for about 40/45 hp at the tire.
Here is one of the gears for the pump. That end mill is .100 in.
in diameter.


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Nebr_Rex

Member
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.
 

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Nebr_Rex

Member
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.
 

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Nebr_Rex

Member
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.
 

Nebr_Rex

Member
Measured the 2 400 blocks I have, an early and a late.
The early 400 block is .015 of an inch shorter. This is
on what I have and I can not verify if this is typical
or not. The blocks do seem to be unaltered from the factory.


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Nebr_Rex

Member
Since my weekend head swap was a no show I dug out one of my spare engines
this afternoon. When I check compression no.2 exhaust valve is all carboned up and
did not hold any pressure, No.1 held 167 psi.. Since I have the parts on hand I'm going to
freshen up the top end. I'll do this so I can hold a 'class' on improving performance on
the KZ440 engine. This will start with a base line and will not involve milling or porting
the head. Just what the average person could do with basic tools.


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Nebr_Rex

Member
I was spraying down the valve with carb cleaner and PB Blaster while
doing the compression test the other day. But it wasn't working or so I
thought. When I checked again yesterday compression came up to 110
psi. So I sprayed some more and that resulted in 140 psi. After that the
cam was advanced 1 tooth which is 15.65 degrees. I checked valve
clearance by cranking down the adjustment screw 3 turns or about .095
inches with no contact. Compression jumped up to 180 psi. I will check
it again with a couple different gauges before I tear it down.


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Nebr_Rex

Member
The KZ440, rated at 40 h.p. at 8500 r.p.m. and 26 ft. lbs. at 7000 r.p.m.
is only 82% volumetric efficient at max power. That does not mean it is not
efficient at lower speeds. Intake port entrance measures 31.6mm compared
to 32.6 for the KZ1000J and 29.4mm for the KZ900/1000. Valve size is
35mm/intake and 31mm/exhaust. KZ900/1000s uses 36/30 valves.
Compared to the GPz1100 Unitrac head on bore and cylinder size it is just a
smaller version. Cam timing is 27/73 intake and 70/30 exhaust for a 113*
intake center line. Compared to the KZ900/1000 with 30/70 and 70/30 with
a 110* intake centerline the 400/440 intake is retarded 3 degrees. KZ650/750s
have a 105* centerline. These little engines have good port flow. They need some
help with cam timing and cylinder pressure.

As for carb size the most 440 are over carbureted. Cylinder volume of the 440
is 221.5cc compared to the 900 at 225.75cc which makes 20.5 hp/cylinder
with a 28mm carb vs. 20 hp w/ a 36mm carb for the 440. The 900 also has a smaller
port and compression ratio.

To advance the cam there are 4 options for the 440 that are strictly bolt on. One is
just advancing the stock sprocket 1 tooth for 15.65 degrees.

113-15.65 = 97.35*

98* is typically the farthest most people will advance an intake centerline. There is
probably some cam chain stretch to take it past 98*.

The other 3 options use the KZ750/4 cam gear for a guesstimated advance of 5, 7 and
13 degrees. The hole with the square is 5* and the white tooth next to the Z7EX will line
up the arrow on the stock sprocket. The octagon hole is 13* with the Z6EX tooth. The
round hole is 7* with the IN tooth. As for cranking compression with these settingsare as
follows on this engine, Measured with a different gauge than before because I think it is
more accurate. I was leary of freshening up and having the rings not sealing at first and
then breaking in throwing of the results. When I do a degree wheel will also be utilized to
document those specs.

Stock --- no. 1/2 165/155
5* ---- 163/170
7* ---- 160/172
13* --- 171/180
15.65* --- 180/187

Also note the end of the cam. I scribed a line for a reference. The notch will also work.
The more the cam is advanced the more those marks will rotate counterclockwise.

And don't let your advancer get this bad.



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