TOPIC:

I've been battling with a low rev misfire since I got my bike. I have tried everything I can think of the cure it. I'm not even sure whether it's ignition or carburation.

The bike is an '83 French A5 which was prepped by Godier Genoud from new. I think it had something done to the cam chain tensioner some years ago and the lump was taken down, though I'm not aware that this was anything other than to sort known issues. It has a K&N filter in place of the original air box, not pods. It has a Devil 6 into 1.

There is a 'bogging down' from 1-2 thousand revs, which makes slow riding a pain. As the engine gets hotter in urban riding situations it becomes more pronounced. I dumped the original coils and leads and fitted Dyna coils (the more compact ones)and Dyna Wires. I stripped out the carbs replacing all the jets etc and gave them a good swim in my ultrasonic tank. I got the impression that it was running weak on the pilot circuit so I upped the pilots jets a size given the adjusters were wide open already. This didn't cure the issue so I gave it a run on a dyno, which agreed with my hypothesis that the engine was weak at low revs. So I fitted the next size up of pilot jets, but there is little change. I had raised the needles a slot, but the dyno run suggested that they should be returned to their original position. At higher revs she was in perfect tune and produced 100horses at the back wheel, which the Dyna guy (a Kawasaki specialist) deemed to be good.

I'm running out of ideas. To me it seems unlikely that a pre-coils ignition issue would show like this, but I have no experience of the big size other than with my own bike. I have considered the carb diaphragms, but I would have thought that they were the cause that they would show up at higher in the rev range?

I could really do with some more ideas from folk with more experience of these bikes than me.

Cheers

Ralph:

With all of the coil and carb work done, I would take a close look at your ignition primary side of the ignition.

The Kaw shop manual provides thorough troubleshooting criteria at Ohm'ing out each component.

Pick up coils.
IC igniter.
Primary side of your new coils
Secondary side of the coils. (just to make sure)
Secondary coil wiring and resistors.
Also make sure the main and sub wiring harness's are intact, have no corrosion, and are have solid continuity.

With the age of our bikes, it's easy to overlook a corroded connection, a damaged wire, or degraded harness.

Check the main ground as well.

Keep us posted.

Todd.

Thanks for your help Todd.

I managed to pick up an ignition stator with the pick-ups for my bike and renewed the wiring with new silicon wire which should make it less susceptible to heat and oil than the original PVC. Went out on the bike and it was perfect to start with, but then as it got hotter the problem returned this however felt more like an HT issue so I get the hot bike on the bench and fitted an auxiliary fuel tank and used my ignition mate to measure the HT current and voltage as the bike got hotter. This found a problem with the new Dyna coil feeding one and six. I stuck on the original one and six coil back on and that was problem solved

Just come back from touring Scotland, North England and Wales and she has done best part of two thousand miles in perfect comfort Sadly I had a Minor slide thanks to an irresponsible farmer leaving a river of hydraulic oil on a road, but that's another story Looking for a new set of engine bars and Devil pipe

Great to have the engine running turbine smooth at long last