My Hand Went to Sleep

mooney1el · Post by **mooney1el** » Fri Sep 17, 2010 4:10 pm

I now have my '67 Scrambler back on the road and have put about 60-75 miles on it since its rebirth. While the thrill is there, I am very annoyed with the vibration in the bars, especially the right side. While riding this afternoon, my right hand felt like it had "gone to sleep" from the vibration after a short 4-5 miles. BTW, it has stock, 43 year old grips :)

For the experts: What could cause this, what I consider, excessive vibration? This is definately RPM related and is independent of the gear I am in. The engine mounting fasteners are tight. The carbs have been rebuilt. The ignition has been "gone through"; setting the point gap (static) for the right side and setting the timing both with a on-off lamp as well as using an automotive strobe. Both sets of points are set for the F marks and do not exceed the maximum upon revving the engine. Spark plugs are new. The timing chain, while original, has been set for tension. Valve lash is set at .004" for intake and exhaust. I have not checked compression, but both cylinders give basically equivalent temps at the exhaust pipes measure with a non-contact temp gun.

This engine has a "337" or "350" (can't remember which now) kit that I put in back in '67 or '68 and I recall installing what were called mild cams back then too. The vibration I remember increased after these mods, but nothing like this.

Any ideas about where to look first...second etc?

Thanks in advance,

Richard

Snakeoil · Post by **Snakeoil** » Mon Sep 20, 2010 7:56 pm

Well I'm no expert on these things for sure, but an engine is an engine.

First, if you have not ridden it in awhile and have been riding modern bikes, the vibes might seem excessive. Depending on the temps that day and if I have not been riding in a while, my hands can go to sleep and it's not a vibes thing.

Are the rubber isolators for the bars original or new. If they are original, they are probably hard as a rock. It could be as simple as that.

Vibes come from motor imbalance. Some is just the nature of the design. If you think it is excessive, maybe something has moved, like a rotor magnet?

You did not mention if you rebuilt the engine or just got it running again. If you just got it running, it's anyone's guess what it looks like inside. You also did not say how long it sat.
regards,
Rob

mooney1el · Post by **mooney1el** » Tue Sep 21, 2010 7:58 am

Thanks Rob. The bike was brought back to life after 37 years of garage storage with no rebuild except for the things mentioned above. It is a Scrambler, so I don't think there are any bar isolators, they mount directly to the triple tree upper; or maybe I am missing something?

I think over the cooler months I will pull the engine and check everything out carefully.

davomoto · Post by **davomoto** » Tue Sep 21, 2010 9:01 am

These bike tend to vibrate a lot. I just did a 337, 3mm overbore, and it vibrates even more than a standard. After 37 years, the memory fades, maybe even gets a bit romantisized on how that bike performed. Best thing is if you have an opportunity to ride someone elses, and compare.

Hotshoe · Post by **Hotshoe** » Tue Sep 21, 2010 9:13 am

This falls into treating the sympton rather than the (possible) cause but I started wearing my bicycling gloves that have foam pads in the palms with excellent results.

davomoto · Post by **davomoto** » Tue Sep 21, 2010 9:16 am

Hotshoe, I think the problem is that were older than we used to be, and these bikes vibrate so much more than a modern bike, or even a CB or CA. I think the full frame of the CL, as opposed to the CB and CA frames using the engine as a stressed member has a lot to do with the excessive vibration. JMHO

Snakeoil · Post by **Snakeoil** » Tue Sep 21, 2010 1:18 pm

It's funny how some preceive the bikes to vibrate a lot while others do not. Back in '73 I bought a brand new 650 Yamaha. That thing would loosen your fillings if you kept it at speed for any length of time. When I got my first Harley I thought that the vibes (that everyone says are horrible) were rather soothing and more therapeutic than annoying. Now, many years later I get my first vintage Triumph and expect horrendous vibes. Not the case. And the same on my Scrambler. Sure it vibrates, but still no where near as bad as that 650 Yam. I think it's all personal perception.

Of course I would not want to go touring on any of these old twins. But that's more a butt endurance thing than a vibration thing.

I will say this, though, after riding these vertical twins, my balanced TC88B engine in my Harley feels like an electric motor when I ride it.
regards,
Rob