NOOB-1st Post, Timing Advance question

So I pickup my first KZ, an '82 750 Twin that had not been ridden since 1990. But the price was right and I've been working my through the bike for about a month and so far no major problems. Popped the timing cover off and the thing was a rusted mess- which would explain why it wouldn't rev above 2500 without bogging down- there was no advance timing, everything was rusted solid. So i broke everything loose and now I think it advances to quickly because it won't hardly idle now at all, like the springs are weak because of the rust being knocked off. Which brings me to the question, a lot of the KZ era timing advance assemblies I see for sale in the aftermarket look similar if not exactly alike. Are the interchangeable? is there an online resource for parts swapping?

Pic? I don't know if they are interchangeable. If not and you can't find one for the bike, you might be able to get one for a more common one and switch springs if that is the problem.
Steve

The inline fours and twins turn their cranks in opposite directions so you can't swap advancers between twins and fours even if the advance curves were the same, and they probably are not.

The KZ400/KZ440 twins advancer might swap, but I'm not sure.

The springs, obviously can swap as long as they are the same rate etc.

You can tighten up your spring a tiny bit by very very carefully closing up the loop on one end. It only takes a tiny bit to make the advance start later. I would just do one spring first. Sometimes tightening up both springs is too much.

conundrum wrote: So I pickup my first KZ, an '82 750 Twin that had not been ridden since 1990. But the price was right and I've been working my through the bike for about a month and so far no major problems. Popped the timing cover off and the thing was a rusted mess- which would explain why it wouldn't rev above 2500 without bogging down- there was no advance timing, everything was rusted solid. So i broke everything loose and now I think it advances to quickly because it won't hardly idle now at all, like the springs are weak because of the rust being knocked off. Which brings me to the question, a lot of the KZ era timing advance assemblies I see for sale in the aftermarket look similar if not exactly alike. Are the interchangeable? is there an online resource for parts swapping?

The problem on my 750 twin was that the wear loosens up the advancer over time and mine would only advance a range of about 15 degrees instead of the 30 required so either you set it way too advanced at idle or way too retarded at high RPM.

I made a thread about cutting new springs for mine a couple of years back. It's a royal PITA, but my bike runs way better now with new springs.

I peeked at Partzilla and the advancer fits all 1980-83 750 twins.

The 1980 750-G had points ignition.

Interesting. I wonder if they use the same advancer or if the folks at Partzilla made a booboo? I wish the Kawasaki site. Had that info still....

martin_csr wrote: The 1980 750-G had points ignition.

It's possible the advance unit can work for both points and electronic, but it would mean swapping out the rotor part. It's been a long time. but I thought I recall someone swapping them. It would take some measurements to confirm.

Obviously, as you point out, the part numbers wouldn't be the same, but I think that is a case of the parts fiche containing both numbers, and the parts-list compiler just listing the fiches containing the part number, even though that part number may not be used on the particular bike.

Am thinking it doesn't matter to the advancer whether the ignition is points or electronic, so long as the advancer's F mark aligns with the case timing mark at idle rpm.
The advancer is of course a mechanical component, with no electrical function.

If the advancer springs are strong enough to hold the advancer in closed position at idle rpm, the engine may be correctly timed at idle rpm.

If the springs have weakened for whatever reason, the advancer with begin opening sooner as rpm is increased, thereby advancing the timing sooner at a lower rpm (a quicker advance curve).

For reference from the FSM for '77~'79 KZ1000:


Perhaps the poor performance at idle isn't due to the advancer, but may be resulting from clogged carb pilot circuits.

Good Fortune!




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Unfortunately no one sells replacement advancer springs for these bikes that I have found or heard of. I know someone on here replaced them with advance springs from a Chevy 350 with success. If I recall correctly, it was a 4 cylinder not a twin. Make sure the pads are well lubed on the advancer. It may have been tuned to run with sticky advance. There shouldn't be much advance if any at idle anyway.

Might get lucky on Ebay but don't see much right now ?

kaw-a-holic wrote: There shouldn't be much advance if any at idle anyway.

That was the problem on mine. When they get old and have wear on the metal posts, there is play. The springs don't hold the wings in at idle anymore and you get about 15 degrees of advance at idle. That means the total range of advance from idle to full is only 15 degrees which is way too small. New springs hold the weights in at idle and give the full 30 degree range.