SPII, handlebar vibration

[JayDee24ca]

Our grand daughter has been visiting this weekend, and at 7 years old she is tall enough to reach the pegs, so I have given her her first bike rides on the SP, and we have had a ball riding the back country roads.
All that aside, I noticed for the first time a very bad vibration in the bars, that is very apparent on hard acceleration. There is zero vibration in the foot pegs, thus my first inclination is to eliminate the drive line as a source. I also wondered if perhaps the head pipes were touching the frame, but they are not. The vibration almost ceases at a steady rpm, but gets so bad on acceleration that my hands are still tingling as I write this.  The tone or sound of the engine on acceleration also seems a fair bit more hard or harsh.
I don't think it is any way related, but I notice the tach seems sluggish as well.
Anyone have some helpful ideas as to its source?
JD

[Denis]

I have an SP II that I bought new and it now has almost 75,000 miles on it but have never experienced such a vibration. If you've eliminated the drivetrain, I'd check out the front end, specifically the tire and wheel. If yours still has the 16" wheel, I'd imagine that any flaw in that tire would be exaggerated because of the small diameter.

Perhaps it's out of round, has bad or especially uneven wear or is out of balance.

[pehayes]

Check the various mount brackets for the upper and lower fairings. My /2 did some strange vibrating with cracked brackets.
Patrick Hayes
Fremont CA

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[RinkRat II]

When was the last time the carbs were sync'd. Plugs? Wires?

    Paul B

[JayDee24ca]

nothing wrong with the front wheel and the fairing mounts are secure. I believe I am going to pursue the car balance and tune avenue, as it almost feels like the cylinders are "fighting" each other, if you know what I mean. I'll check the timing, although there is no reason to believe it has moved out of time, then slap the Harmonizer on the carbs to see what they are doing.
I'll post back what I find.
John D.