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KZ440 rich symptoms 03 Apr 2024 08:59 #897217

  • Michi
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Hi guys. Went for a long-ish ride yesterday on my KZ440. It was running great. However, on my way home, I noticed the bike lacked power. Then my ears told me one of the cylinders was firing intermittently at high speed. The problem got worse and worse until the bike was running like, to put it frankly, absolute doo-doo. I could only keep it running smoothly at 40-50mph. It sounded really bad, as you might expect. Got a few funny looks from pedestrians, so outside the helmet was probably even worse. This is a rebuilt engine but it's got 700 miles (all good) post-rebuild, plus had the head retorqued post-reassembly, plus I had just changed the oil.

I removed the spark plugs and they were sooty. One side completely covered in carbon deposits. Even though the engine was hot, I was curious so I put spare spark plugs in. It was still bad. Would barely idle, sounded terrible, cut out when throttle on, etc. Decided to turn it off and leave it. 

I came back to it today to go through it with a fine-toothed comb (because I know the carb settings are fine - spent ages on them). Cold engine - checked compression on both cylinders and it was fine (about 150psi each). Checked the valve clearances and one side's exhaust valve was tight but it had clearance. So I adjusted it to within spec (0.2mm). However, this wasn't the side with the (even) more sooty plug. I removed and checked the (single) carb and everything was fine - all jets and passages clear. Cleaned it anyway, removed air filter, inspected and cleaned that as well. So the carb hadn't any issues. Then I looked at the ignition timing (it has contact breaker points). This is what shocked me: the timing had moved way off - massively. Now I know points have to be maintained and adjusted from time to time. But 700 miles and the thing was massively retarded. They aren't an old set of points either - they had been replaced not long before the engine rebuild. So I reset them. 

Reassembled everything, started the bike and it was perfect. Idle smooth, plenty of power, etc. Faultless. Took it for a ride around the block - didn't baby it - and it was fine. But do I trust it? Hell no.

What's niggling me is the ignition timing (points). I actually had to remove the screws holding in the points to reset them (i.e. the timing was so far off that it couldn't be done by just wiggling the backing plate), and this suggests a LOT of wear on the asbestos/fibre bit that comes into contact with the ATU cam. Why should there be so much wear? What caused this? Any ideas? Thanks
 
KZ440A LTD (1980)

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KZ440 rich symptoms 03 Apr 2024 09:26 #897219

  • sf4t7
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maybe it's time for electronic ignition such as the dyna conversion, don't know if there is one for the KZ440.
Scotty

1974 Z1A
1015
welded Z1 crank
Andrews 1X Cams
Delkevic 4 into 1
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KZ440 rich symptoms 03 Apr 2024 09:56 #897221

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maybe it's time for electronic ignition such as the dyna conversion, don't know if there is one for the KZ440.
 

I wouldn't think so: 1980 was the only year the 440 came with points. 81 and up came from the factory with electronic ignitions; OEM parts for those are rather rare these days. I have read about people who have taken half of a Dyna kit and used it on the 440 - not sure of details. There is also a mod that uses parts from the General Motors HEI but I know even less about that.

There is a company called 7th Gear Designs that makes aftermarket electronic ignitions for the KZ400s/440s but he's had some issues with parts availability. I bought a couple of his kits two years or so ago but haven't gotten around to installing mine. A nephew has the other one and has made some progress, so he can help me when his is done.
1979 KZ400 Gifted to a couple of nephews
1967 Yamaha YCS1 Bonanza
1980 KZ440B
1981 Yamaha XT250H
1981 KZ440 LTD project bike
1981 GPz550
2013 Yamaha FZ6R
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KZ440 rich symptoms 03 Apr 2024 10:01 #897222

  • F64
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Mark the points plate and the points housing with a paint marker to see if it rotates and loses registration.

Nerdy, I use the GM HEI mod. It only replaces the igniter. The trigger would have to be addressed as well. The link for the HEI mod is in my signature. Lou Dudzik was the expert on that mod.
81-KZ440-D2.
Louis Dudzik's GM HEI ignitor conversion installed 2015 s3.amazonaws.com/gpzweb/Ignition/GPZgmHEImod.html
Motogadget m-unit blue installed 2017.
LIC, NY
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