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

I'm hoping to get some boots from Z1 and a new front mag, but it's going to take a while on my budget. Sadly, after all this time and money trying to get 'er ready for spring, she's gonna be parked in favor of my Suzuki gs550

I called the local Kaw guy today.. He theorised that:

1) The old points were so bad you had weak ignition.. Someone probably tuned it into the ground rather than replacing parts. I'd tend to agree, judging by the fact that someone would rather cut the chain short than replace it.

2) The stock jets (#105) might be too small for the 4:1 Jardine with no baffle and free-flow K&N paper intakes..

So I had a set of #115 Jets laying around.. I also trimmed each idle mixture screw 1/2 turn counter-clockwise.

The plugs are still white, but much less so... The thing moves like a bat-outta-hell now... But due to the badly clearanced valve on #1 (I think) and the new, richer mixture #1 doesn't fire at idle anymore, only at medium throttle.

I found a short in the plug caps for both #1 and #4 (you move them and you get 'Open Loop' resistance on the meter) but #4 still fires OK...

Next step: Valve Job.

If one plug cap was bad, would the timing be thrown off causing hotter running?

Beatpoet wrote:

...stock jets (#105) might be too small for the 4:1 Jardine with no baffle and free-flow K&N paper intakes..set of #115 Jets laying around...trimmed each idle mixture screw 1/2 turn counter-clockwise...plugs are still white, but much less so...due to the badly clearanced valve on #1 (I think) and the new, richer mixture #1 doesn't fire at idle anymore, only at medium throttle. I found a short in the plug caps for both #1 and #4 (you move them and you get 'Open Loop' resistance on the meter) but #4 still fires OK...Next step: Valve Job...If one plug cap was bad, would the timing be thrown off causing hotter running? [/b]

Larger main jet may be preferable with freer flowing intake and exhaust, but will have most effect at wide open throttle where it determines the fuel mixture.

Pilot mixture screws are usually set where they most enhance idle.

Using a thinner shim to increase clearance in #1 intake valve should avoid any loss of compression at normal operating temperature.

Would not expect a faulty plug cap to affect ignition timing or contribute to overheating.

The hard truth is that until air leaks, #1 intake valve clearance, and any remaining ignition faults are corrected, carb adjustments are futile and often counter-productive.

Good Luck!

www.dansmc.com/valveclearence.htm

Beatpoet wrote:

www.dansmc.com/valveclearence.htm

As Uncle Dan says:
So what happens if there is too little clearance? Well, for one thing the valve loses most of it's heat through the valve seat. If the valve doesn't seat fully it will start to get hotter and hotter. Sooner or later the valve starts to melt or burn. Not good!

Am thinking #1 intake valve has not yet suffered any damage, especially since compression tested okay.

I glued the manifolds - the bike started running rich immediately with the 115 jets so I switched back to 105 mains.

Switched out my .270 valve shim for a .265, bringing clearance back into spec.

Check out the valve tools I made out of high carbon knife stock. If anyone wants a set like this, let me know. The hook compresses the bucket, and the little hockey stick taps it out from the back side of the lobe.

After fixing the valves and getting new plug caps

...It turns out that I have burned the rings down in cylinder 1 after a compression test.

I guess it didn't pay to not fix immediately.. Running cylinder one with an intake valve hanging is going to merit a re-hone and new rings.

Well... Pics of total disassembly coming soon.

Beatpoet wrote:

...burned the rings down in cylinder 1 after a compression test... Running cylinder one with an intake valve hanging is going to merit a re-hone and new rings....

IMO the overheating more likely resulted from excessively lean mixture created by outside air leaking through old cracked worn-out carb-holders, which aren't repairable with silicone or anything else, and regardless of being glued to the head when installed.

Good Luck!

I'm skeptical of the new rubber - the guy at the shop I frequent (long-time kaw guy!) says that the new rubber SUCKS! He suggested that they are probably from some compound that is short-living as to save production costs. Anyone got an opinion on this? Does anyone even read my long winded threads?

The old rubber is not in that bad of a condition, it was really dirty and oily though. once I cleaned them up they looked and flexed like new.

As I am on a rock-bottom budget, I'll be riding these ones for a little while anyway.

After all, I'm going to pay someone else (read: more experience) to mic and bore/hone the cylinders and pick my new rings.

Patton wrote:

IMO the overheating more likely resulted from excessively lean mixture created by outside air leaking through old cracked worn-out carb-holders, which aren't repairable with silicone or anything else, and regardless of being glued to the head when installed.

Good Luck!

Sorry if already posted, but here's the link to new carb holders available from Z1E.

Z1E Carb Holders

Would like to assure the over-heating issue has been resolved before risking damage to the fresh new engine work.

Good Luck!

Well, here we go again...