Coil wiring mod...engine noise?

This past week I replaced my fuse box with the blade type. My old box was blowing the main fuse on a regular basis. Upon removal and disassembly of the old box I found the wiring inside the fuse box was very corroded and melted in places. The replacement went well. While I was at it, since my new fuse box had a spare fuse location, I decided to do WiredGeorge's coil mod as well. I didn't check the coil voltage beforehand but I did have some issues with difficult starting.

Anyway, did the coil mod and the bike started right up. Seems to start easier than before. However, the engine is also noiser than before. It seemed so noisy when I first started it that I thought I had cracked an exhaust header. Turned it back off and visually checked everything I could think of (exhaust, intake manifold, oil level) and all appeared OK. Started back up and went for a short drive. Starts good and runs fine, but is still noisy--particulary from 2k-3k RPM while under load. Seems to be hitting on all four cylinders as the exhaust pipes are all hot to the touch.

Its hard to describe a noise in a post but its definately loudest when I put my ear near the top part of the engine. My thoughts are: 1) blown exhaust gasket or cracked header, but there is no visual indication of this, 2) cam chain guide or tensioner, 3) timing somehow thrown off due to coil mod, 4) pre-ignition happening somehow due to coil mod, 5) the coils themselves somehow become noisy due to the higher voltage.

Bike is a 1983 KZ1100-A. Coils are original. Ignitor box was replaced by previous owner but replacement is same as original. Valve clearance was checked and adjusted <500 miles ago. Noise was not there before the coil mod.

Any thoughts? Could this noise possibly be related to the coil mod or is it just a coincidence?

NormZ-

Just a thought- could one or both of your coils loosened while you were doing the mod? Mine did and afterward I got an awful noise. I took off the tank, tightened the coils and the sound went away.

Also, you may want to unwrap your main wire harness under your tank. I also used to blow my main fuse often. I unwrapped the wiring harness from the left side under my tank and found a shorted wire touching my frame.

Hope this helps:)

bigkaw815 wrote:

Just a thought- could one or both of your coils loosened while you were doing the mod? Mine did and afterward I got an awful noise. I took off the tank, tightened the coils and the sound went away.

Good idea. That would be great if it turns out to be the problem. Thanks!

I did find a few spare minutes last night to pull the relay from the socket and jumpered together terminals 86 (in from ignition) & 87 (out to coil). This essentially put it back to the old wiring. Started up and noise was still there--so that eliminates my idea of timing change, etc. I'll check the coil mounting bolts tonight & make sure they're tight.

Post edited by: NormZ, at: 2007/02/27 11:10

Well, after more diagnosing & closer listening, I fear that the noise is comming from the cam chain. Maybe a broken or rubbed through guide. Still seems a rather strange coincidene that the noise started at the exact same time I completed the coil mod. However, all indications at this time point to the cam chain. Sound is from top of engine and the best I can describe it like a bunch of marbles rolling around in a plastic bucket. I guess I'll start by removing the valve cover to see if I can see the front/rear guides from there.

maybe the extra juice was all it needed to self-destruct?

At least you found out at 0mph, and not 70