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1971 Yamaha RT1B Transmission Replacement

And Then, Godzilla Stumbled

 

yamaha-transmission-replacement

Shortly after writing about how remarkably reliable Godzilla, my 1971 Yamaha RT1B 360 was, the old girl developed a persistent, chest-rattling cough. I fancy myself something of a motorcycle-whisperer, so I count hunches as valid trouble-shooting methods. Paranormal signs indicated a spark issue.

I never liked Godzilla’s ignition system. After a rash of broken legs following the RT1’s debut in 1970, Yamaha doubled-down for 1971 with a decompression valve and a sloppy, centrifugal spark-retard device on the flywheel. The decompression valve alone worked so well that subsequent 360s could ditch the hokey spark-retard flywheel entirely.

So Godzilla had an orphan ignition. After checking every wire in the harness, cleaning grounds and installing a new battery to no avail, I sent a 1972 stator off to Dr. Enduro for a full-body makeover. A quick survey of eBay turned up a fixed timing flywheel from a 1972 model and in no time, I had Godzilla purring like a wounded cat trapped inside a cinderblock cage.

This edited narrative sounds nice and tidy, but real lives do not happen in the time-space vacuum of Motorcyclist’s blogosphere: over a year passed between sputter and spark. And during that year off, Godzilla’s clutch plates managed to fuse themselves together.

When I say fuse, I’m not joking. I rode the bike for 10 miles, clutch lever pulled in, revving the engine, stomping on the rear brake and banging gears. The plates just would not release. I resigned myself to pulling the clutch apart and turned Godzilla’s noble head towards home. And that’s when it happened. Riding at 50 miles per hour the rear wheel locked up. Thinking the engine had seized, I pulled in the useless clutch lever as the bike skidded to a stop. Hmm, no rod hanging out of the case, but the clutch was finally free.

Pulling the ignition cover revealed a loose flywheel, and removing the flywheel revealed a sheared woodruff key. Better call in the troops, or should I say, troop: the wife. She arrived in my truck a half hour later. From the bed of my junk-filled truck I sourced a scrap of iron and fabbed up a new woodruff key. Road-side repairs done, the bike started but had only first and third gear.  Godzilla limped home, battered but not bowed.

All of this is kind of long and rambling for a video introduction, no? But you really need to understand where the transmission failure started. Follow the trail of destruction and you can see that I was the root cause of Godzilla’s problems. So I have to be the one to right these wrongs.

Episode 1 depicts the teardown and splitting of Godzilla’s cases. I’m almost sure this is the first time the bike has been apart since it left the Yamaha factory 42 years ago. Nothing was held back. You see it all.

Episode 2 covers the installation of a used, $30 eBay transmission and the reassembly of Godzilla. The climatic test run scene bumped this video into Oscar contention. Only the fact that The Studio System refuses to consider films shorter than 10 minutes kept Godzilla from walking away with the little gold man. Enjoy.

 

 

Categories: Editorial, Yamaha  
 

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