Tuesday, May 29, 2012

Migoto returns! Brakes, carbs, and electrical maintenance

The K3 made an appearance over memorial day. She came back to have a new starter solenoid installed and because of a squealing noise coming from the front wheel, and bearing grease everywhere.
It turns out that water and cable lube had run down into the speedo drive and made a mess all over the wheel. That was a simple fix; just remove wheel/disc/speedo drive, wipe clean, and replace grease. I also took the time to clean the speedo cable with kerosene and re-lube. While I had the kerosene out I cleaned and re-lubed the drive chain as well.
The squeal was the result of a bad rotor. I swapped it for another one and all was well.
Then the new starter solenoid went on (with some different mounting hardware than the original) and the bike looked good to go.

This took all of about 2 hours to diagnose and repair, but I had all day off so I of course had a bad case of "while I'm in there."
I pulled and cleaned out the new petcock. There was a bit of rust in it from the tank but nothing too bad.
After this, I decided to take it for a test run to see if the new rotor was good to go. There was a problem though, the bike would NOT start. Actually it wouldn't even turn on. After checking everything I could I finally determined the ignition cylinder must be faulty. I pulled it and sure enough it was melted: completely fried. So I cut the wiring harness of of it and made a new "key" from the old wires by splicing the black to red and brown/white to brown, thereby emulating the ignition cylinder's "on" position when it is plugged in.

Not a key in the traditional sense, but it works.
In order to make the new "key" easily accessible I had to relocate the harness plug, so off came the tank and headlight, out came the coils and the front of the wiring harness. I wish I had taken pictures of the whole process but I was on a roll, it was hot, and I didn't want to halt progress. The sooner I finished, the sooner I could take refuge from the heat.

After relocating everything I figured I'd shorten up the spark plug wires a bit since they were a touch long. I removed the NGK resistor caps and wire sleeve to reveal... electrical tape? Fuck, electrical tape on spark plug wires is not a good sign.

Sure enough the wires had an additional foot of wire spliced onto each of them. I have no idea why, but I'm glad it's taken care of. The downside however, is that the bike now has an AWESOMELY powerful ignition spark. Why is this a problem? Well...

After a test ride that spark plug was looking a bit roasted. Meaning that the bike is running a touch rich. Hooray awesome ignition, boo poor carburetion.

Luckily main jet changes on the Keihin CR29 specials are stupidly easy. Remove the float bowl drain plug and boom, there are your main jets peeking out at you.

Not so luckily, for some reason I have 2 sets of #120 mains and no #125, #128, or #130 jets. I have no idea what happened to them, but I only had #110 and of course #120's which were already in there.

Oh well, I had to let her go home like this. She was running strong and there's no lean condition at all above 1/4 throttle. Even up to 1/2 throttle the plugs looked fine. 3/4-full throttle was where it was an issue with being overly lean but the owner has been instructed to take her easy until she returns next week for an oil change.


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