Timing advancer too tight?

Just a quick question, has anyone had to reduce the tension on the timing advancer springs?

I say this because since I've owned this bike I've been chasing my tail with off idle hesitation at exactly before 3k. After trying everything a friend suggested messing with the mechanical advancer as a last resort. We tried tightening the springs via preloading them more by bending the hooks closed. Made the issue 5 times worse. We then reduced the preload until it was just enough to keep the rubber pads and weights in place and viola the issue of the pre 3k hesitation was finally solved.

But honestly, have I covered up another issue by shifting the advance curve down a bit? Should I be looking at something else? The hesitation was between 1.5k and 3k and if this wouldn't have worked I'd literally be selling the bike, since everything else has been meticulously gone through.

Hi thatfiveohtho,
On Z-1's we've found that the decades-old factory grease between the inside of the advancer cam and advancer body becomes more like thick paste than grease. We've even seen one stuck at partial advance because of old, sticky grease. Careful disassembly, cleaning and reassembly with fresh high-temp grease has solved every weird spark advance problem we've ever had on Z-1's.


Good Ridin'
slmjim & Z1BEBE

Thanks for the reply. Thing is, I already did that long before readjusting the springs. Maybe a Polish is needed as well? Its by no means rusty or in bad shape.

Should I be looking at something else? The hesitation was between 1.5k and 3k and if this wouldn't have worked I'd literally be selling the bike, since everything else has been meticulously gone through.

Have you looked at the pilot bypass outlet in the carbs ?

I have a 1980 KZ750 E1 with Keihin CV34 carbs and am thinking your carbs are the same. When I bought the bike in 2003 I had what sounds to be the same problem, a hesitation between 2000 and 3000rpm which varied from a stutter to severe coughing and spluttering. It took several months to find that the issue was dirt at #3 in the diagram below.

The pilot bypass consists of 3 tiny holes and you have to open the throttle butterflies to see them. A fine pin with the tip bent at 90 degrees or a guitar string can be used to poke them out. Patton has a great schematic showing how to spray carb cleaner in the pilot jet at #4 or $8 while blocking #6 or #7 and watching for the cleaner exiting at the bypass. Use eye protection when doing this.
When finished poking blow everything out with compressed air.

A fuel filter if not fitted could be a good thing.

I have read this in my first searches of this site, and done so, about 4 times now I think since the start of this little project. The pilot bypass was my first culprit with off idle performance. Which is what threw me off, since I've known the carbs to be clean.I've had some problems with float levels but those have since been corrected, helping the stutter slightly but not by much.

And to put this thread to a premature death, I borrowed my dad's timing light and found that the mechanical advance is working as it should, and that the timing was advanced all over by a few mm due to some slop in the pickup bracket. Since adjusting the bracket, the ride home was quite good, no noticeable stutter at all.

Any more input is certainly welcomed. Maybe the springs were work hardened? :silly: