My Ongoing '78 KZ1000 LTD Project - Engine Thread (Lots of Disassembly Pics)

Here is the bike that I've been documenting on this forum in this thread:

kzrider.com/index.php?option=com_kunena&...=11&id=212650#212650

Here are my plugs in the electrical thread:

kzrider.com/index.php?option=com_kunena&...d=3&id=212647#212647

#1 and #3 are running hot, so I thought I'd check the valves quick-like.
I figured I'd post some nice pictures of my valve check..

Step 1: Get Underpants..

Step 1: open 'er up! Yup there's good healthy oil up there.

#1 intake valve - .0015 / .038mm

#1 exhaust valve .005 /.127mm

After thoroughly measuring the valves (and *not* taking pictures) I got:

Exhaust:

---

Intake:
1) .005/.127mm .0015/.038mm
2) .002/.051mm .002/.051mm
3) .002/.051mm .002/.051mm
4) .002/.051mm .002/.051mm

So is it worth shimming?

What would the effects be of this? I'm wondering why my engine is getting progressively hotter in cylinders #1 and #3??


Here's the chart I made so I would get lost, cuz I tend to have scatterbrain days...

FYI -- Correct clearance per FSM is 0.05-0.10 mm.

Seems to me that #1 Intake at .038 is out of spec (too tight).

Don't believe the existing gaps would cause any overheating on Cyl #1 and #3. But please await better advice on this.

What are compression readings? Overheating can possibly be caused by carbon build-up in combustion chamber. If compression figures look okay, may then be time to address carbs.

Good Luck!

Compression tested last year with an automotive tester was over 100lbs per cylinder and within 1 PSI for all four cylinders.

I'm addressing the carbs right now... Posting a few pics in 'Carbs'

tight valve will hang open

Beatpoet wrote:

Compression tested last year with an automotive tester was over 100lbs per cylinder and within 1 PSI for all four cylinders.

I'm addressing the carbs right now... Posting a few pics in 'Carbs'

100 psi is low. Do you have a lot of black fuzzy on your plugs? Mine was at around 110 at each cyl. and I was fouling plugs after about an hour of riding.

Looks like #1 is too tight and the others are within spec according to the book. I personally would bump up the clearence to .004 at least. Some guys on here go as loose as .006.

donthekawguy wrote:

100 psi is low. Do you have a lot of black fuzzy on your plugs? Mine was at around 110 at each cyl. and I was fouling plugs after about an hour of riding.

Last year it ran great. I tested with an automotive tester, and I had to put an extension on it to get the right fitting also.

I'm guessing I could add a few pounds for pressure lost in the hose. Maybe it needs rings in the next year or so, but it still ran really strong last year, pulling through the whole acceleration and keeping the plugs nice and brown...

After
1) getting new points and adjusting timing to *perfection*
2) Changing the oil

It is running too hot - the plug tips are white after 3-4 minutes of normal riding.

I then:

3) disassembled and cleaned carbs, hi-temp silicon'd the entire intake and exhaust manifold system

It made no changes on the plugs... Still too hot.

I'm wondering if I should change the jet size or 'shim' the needles!

Beatpoet wrote:

...Last year it ran great... ran really strong last year, pulling through the whole acceleration and keeping the plugs nice and brown...running too hot - the plug tips are white after 3-4 minutes of normal riding...wondering if I should change the jet size or 'shim' the needles!

wondering if I should change the jet size or 'shim' the needles -- No, because the jet size and needle position are still the same as last year when running so well with good plug readings.

the plug tips are white after 3-4 minutes of normal riding -- seem to recall the plugs are indeed fresh NGKB8ES as per factory specs. So heat range is correct. What about plug gaps? -- And don't recall whether already assured proper operation of ignition advancer unit by viewing with a strobe-type timing light and watching it move backward and forward with rpm changes.

ignition timing is perfect -- so that's not the reason (but would double-check anyhow to assure using the F marks for ignition timing, and NOT the T marks).

Let's say the overheating isn't because of: carbon build-up; clutch slippage; oil level too high or too low; wrong viscosity oil; brake drag. So carbs may be the culprit.

Carb-related causes for overheating include: main jets clogged; fuel level too low; carb holders loose; air filter poorly sealed or missing; air cleaner duct poorly sealed.

Intrusion of outside air into fuel mixture may cause ultra-lean fuel mixture resulting in over-heating. Such leaks may arise from several places, such as old hard cracked worn-out poorly sealing vacuum caps on the vacuum nipples, but more often arise from old hard cracked worn-out carb holders, such as the example depicted in the following thread (which looks pretty horrible):
Beatpoet's carb thread

To my knowledge, there's no feasible way to refurbish worn-out carb holders, so would urge adding these Z1E items to the wish list:

Carb Holders
and
Vacuum Caps
and 1/4" or 3/16" in-line fuel filter(s) - in better fitting size --
1/4" Filter
or
3/16" Filter

Such air leaks in carb holders are also a common reason underlying other maladies such as unstable idle, unexplained increases in idle rpm, etc. Even perfect carbs and perfect everything else can't compensate for air leaks.

Sorry about the budget constraints, and realize these large classic bikes are not the cheapest form of transportation, but recalling this bike is the principal mode of transportation, and remembering it's fuel savings at over twice the typical car's mpg.

Bottom line -- am thinking the overheating is resulting from air leaks in the carb holders.

Good Luck!