Saturday, October 6, 2012

Roadside Knucklehead Ignition Points Repair

Last Sunday, Steve and I left bright and early to head up to the Southern Coalition AMCA Road Run in Maggie Valley, NC.  I was riding my 1964 Panhead and Steve was astride his 1947 Knucklehead.  We had about 250 miles to ride  and wanted to get an early start just in case we ran into any problems.

Since we didn't need to reach Maggie Valley until 5:00, we took our time and rode the first couple hours on secondary highways, passing through small towns and scenic countryside.  Our first gas stop was only 10 miles from the interstate, so we decided to give it a try.  What with it being a Sunday morning and all, we figured traffic would be light and plus it was a more direct route to Maggie Valley.  

After about an hour riding down the interstate, Steve's bike backfired a couple times and shut off.  We rolled over to the shoulder and I started digging out my tool roll as Steve began troubleshooting his Knucklehead.  Steve soon discovered that the rubbing block on his points had broken off.

In case your not familiar with how ignition points operate, the rubbing block is what rides against the cam, opening and closing the points.  Without it, the points stay closed and there is no spark sent to the plugs.  See the diagram below.

After scratching our heads for a while, I started digging through my saddlebag looking for something that could replace the rubbing block.  A quick search yielded a fork terminal from my electrical spare parts bag.  Since the rubbing block is attached with a rivet, I thought that we could slide the fork terminal under the rivet and then cut it to the same length as the original rubbing block.

Within a few minutes, Steve had the rest of the original rubbing block removed and we slid the fork terminal under the rivet.  A couple good hits with an improvised metal punch on the backside of the rivet tightened the fork terminal down nicely.

Steve re-installed the points and made a couple adjustments to the length of the fork terminal until the points could open and close properly.

The last step was to keep the new metal rubbing block from grounding out to the cam.  Rubbing blocks are usually made out of stiff plastic or other non-conductive material and the fork terminal we used was definitely conductive.  Steve found a plastic drink cup on the side of the road and trimmed it into an insulator.  A little electrical tape was used to hold it in place and then he set the points gap.

Once the gap was set, the cover was placed back over the points and Steve kicked the Knucklehead back to life.  We eased back onto the interstate with about 75 miles left to Maggie Valley.  Believe it or not, the bike ran fine all the way there.  Just goes to show you that with a little ingenuity, you can fix an old bike in a jam.  Try doing that with a modern twin cam or evolution motor...


Lonnie C. said...

Pure genius.

Michel Guillemin said...

Too cool !

It was not raining !!!

The last time I rode on my DuoGlide I had seven failures and six repairs in only 120 miles from the seashore to Paris.

The top three was:
3 - the inner upper front brake spring broke on a collision with a piece of wood fallen from a truck > front brake "off" > inverse the springs and replace the broken spring with a piece of iron hanger (see forward) just to stabilize the mounting
2 - the clutch lever rein broke > repaired with a very tightenned adjustable strap for child bike.
1 - the choke string fell on the highway (!!!) and the choke shutter just closed when it wanted while running > a iron hanger found in the highway gutter, cut and folded in "V" then inserted in the carb to keep the shutter unshut.

Thanks to my Leatherman "Wave", to the hazard, to the luck, to the ancient knowledge we have all of true life on old H-Ds !


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