Clutch's 1982 KZ750 E3 Cafe

Checked out fuel system, and all looked good today. All four float levels were within spec and the rubber fuel line looked to be in good condition, so I don't think it's a fuel issue anymore. I was going to take the bike out for a ride after checking all that, so I had it warming up in the driveway for a few minutes. All seemed well until I walked back into the garage to grab a helmet. The bike died! Started it back up and it had dropped 2 cylinder again. So now I'm fairly certain the Dyna-S is failing due to heat. If I recall correctly, that is a common issue with the stock electronic ignition, so I would assume the Dyna-S can have that problem as well. Anyone know for sure?

I emailed the guys at Dyna since this seems to be a common problem one that I may still have I hope they get back with me with a reasonable explalnation or at least some other cause for us to look for incase they wont own up to the abnormal intermittant brakdown of signal

clutch wrote: Checked out fuel system, and all looked good today. All four float levels were within spec and the rubber fuel line looked to be in good condition, so I don't think it's a fuel issue anymore. I was going to take the bike out for a ride after checking all that, so I had it warming up in the driveway for a few minutes. All seemed well until I walked back into the garage to grab a helmet. The bike died! Started it back up and it had dropped 2 cylinder again. So now I'm fairly certain the Dyna-S is failing due to heat. If I recall correctly, that is a common issue with the stock electronic ignition, so I would assume the Dyna-S can have that problem as well. Anyone know for sure?

This may result from plug fouling during warm-up due to over-rich mixture from whatever cause such as too rich pilot circuit or prolonged choke application, and is especially apparent where battery charge is questionable or full voltage isn't reaching the coils for whatever reason.

Have many times experienced dropped cylinders as the ride begins, then ride for a while with the headlight clicked OFF to give the battery a chance to recuperate, and when cylinders resume combustion, turn the headlight back on, and boom-shakalaka, no more problems for duration of the ride.

Would try more quickly eliminating choke, and using the throttle to keep engine running during warm-up.

Good Fortune!

I had already removed choke several minutes before it died on me. Idle mixture should be fine as I had leaned it down a few months ago from being slightly rich. Also, it was idling with headlight off, so I don't think the battery is the issue. Plugs, coils, coil wires, Dyna-S and every wire on the bike are all new. I checked all wiring in the ignition circuit and replaced anything questionable, so I don't think it's that. Anyone know of a bench test for the Dyna-S? I would love to be able to measure it somehow.

clutch wrote: ...was idling with headlight off, so I don't think the battery is the issue....

Battery condition doesn't particularly matter during warm-up.
And it doesn't matter whether headlight is off or on during warm-up.

Where there's tendency to fuel-foul, battery condition matters mostly after warm-up. And if charge is marginal, may cause dropped cylinders.

While sitting there warming up at choked fast idle, the plugs are exposed to fuel fouling, and when the cylinder drops, the inadequate spark from the low battery is insufficient in the non-firing cylinder.

It's just that in my experience this is a more common experience than a failed Dyna-S. Not to say it's not a faulty Dyna-S in this particular instance.

Good Fortune!

Got a reply back from Dyns I really didnt expect them to condemn there product but was hoping for a little more info


(from Dynatek)
Hello Aaron.
The issues you report are not common with the Dyna-S. To cite my own
experiences, I had a Dyna-S on a motor for over 19 years and 45,000 plus miles
with no problem at all. Keep in mind that this was many years before I came to
work at Dynatek. Having installed too many to recount over the last 25 years,
I had never seen failures and this is why I continued to use them, up to and
including today.
The majority of Dyna-S failures we have seen are the result of either using
the incorrect coils (wrong ohm rating), charging system issues (under and over
charging) or loose connections within the Dyna-S system and electrical system,
including the battery positive and negative. It is relatively rare to see a
Dyna-S fail for no reason. In all fairness, the Dyna-S is a man made,
electronic part and a failure may randomly occure, but not very often. The
actual return rate is just under 4 of every 100 sold.
When you do replace your coils, be sure they are rated at no lower than 3.0
ohms.
Thank you,
Larry Nelson
Technical Support
Dynatek
1-800-928-DYNA (3962)

I decided to give the "blipping the throttle to warm it up rather than using choke to long" method a try today to see if I was fouling out a plug or two. It ran well for a few minutes, and then the same thing happened. I watched the fuel closely though. It appears that fuel flows (trickles really) ONLY when the bike is running. This is with a manual petcock in the on or res setting, and with or without the tank cap open. It appears fuel flow really is the issue, and I'm stumped as to why it won't fill up the filter like it used to. Should I drain the tank, pull the petcock and inspect it? This is a new petcock (few hundred miles), so I don't think it's gone bad already. What do you guys think?

EDIT: Could it be that crappy clear plastic fuel line from the tank to the filter? I know they cause issues, but I didn't think flow was one of them.

sounds like your petcock is plugged up clutch.

i would pull it from the tank and insure it was clear.

leon

I will check that out next time I get motivated to do something with it. What would clog it so quick? Crappy gas? Foreign object in the tank (where ever it may have come from)?

you should be able to pull the hose off your petcock and turn it on and the gas should flow freely from it.


leon

Could also open the float bowl drain screw to see whether fuel flows and keeps flowing freely from the bowl. As this assures flow from inside tank on through everything and into the float bowl.

Good Fortune!

Hey guys...haven't been on lately. I pulled the gas tank yesterday and after a few minutes of checking the "little things", discovered that the problem (hopefully the only one) is a clogged/faulty fuel filter. Got a couple on the way from Z1, but am hoping to find one locally so I can ride and test it out tomorrow.