Vibration

[Suzie750]

I have a 1982 gs750t, when riding and shutting the throttle off get bad vibrations, pull the clutch in and it goes away. Thinking of looking at the clutch hub nut? Also when in top gear doing about 35mph and opening the throttle takes a long time to pick up, cleaned carbs and balanced them.

[salty_monk]

If the carbs really are clean & in balance then yes the clutch hub nut could be a good place to look. The threads stretch and they loosen. An upgraded nut from APE or an 1150 model nut is worthwhile.

A top gear roll-on at 35mph isn't really what these bikes were made for.... Especially as your speedo probably over reads so you are likely going closer to 30...

[Rich82GS750TZ]

35 in 5th gear should be barely possible. I’ll get to 35 in 1st before I shift to 2nd. Is this your first bike? First time riding? You’re lugging the engine. That will cause the bike to shudder.

I don’t mean to sound critical or harsh. We all start somewhere. And the above 0-35 in 1st gear would be a hard pull. Put another way, if I’m riding along at 35 mph, I’m in no higher than 3rd gear. And I’d speed up a bit to maybe 40-45 before shifting up to 4th.

[Redman]

I have a 1982 gs750t, when riding and shutting the throttle off get bad vibrations, pull the clutch in and it goes away. Thinking of looking at the clutch hub nut?. . . . . .
...

THis would be during decleration, when pull in clutch, then are coasting. Is the "vibration" the handlebars shaking? Learn about steering bearings and check for if they are loose.
I myself would not suspect clutch hub for this, but dont have any arguement against it either.

. . . . .
Also when in top gear doing about 35mph and opening the throttle takes a long time to pick up, . . . . .

Top gear & 35 mph would be very low engine rpm.
Learn about the horsepower & torque curve of the engine.
For more acceleration you want to be more like 4k rpm and higher.
35mph for some acceleration you want to be in 3rd gear (not 4 or 5), for more acceleration you will want to be in 2nd gear (or 1st).

Welcome to THeGSR. Do introduce yourself in the "owners" section. Pic of bike would be goodtoo.

[grcamna2]

How old is your drive chain ? Do you think all the links move freely? That's the first place I would look as a dried-out chain can have links that will seize-up and cause what you describe.

[LAB3]

35 in 5th gear should be barely possible. I’ll get to 35 in 1st before I shift to 2nd. Is this your first bike? First time riding? You’re lugging the engine. That will cause the bike to shudder.

Having ridden big torque monster V-Twins this was something I had to learn to get past, that engine in your bike is made to REV and you shouldn't worry too much about running it in the 5k rpm range a good part of the time!

[Rob S.]

Revving too low is called lugging, and guess what? It can be worse for an engine than going past redline.

If you follow the shift points in your owner's manual, you'll be lugging.

[Suzie750]

Hi Rodman, thanks for your response, engine vibration when decelerating. Pull clutch in goes away? Have two gs750 ts both 1982, this one I have just got has 9000 miles on clock. Tightened all engine bolts new wheel bearings new chain cleaned and balanced carbs, compression 125psi hot on all cylinders. Throttle full open. I am comparing the new bike with my old one, doing about 35mph on old bike in 5 gear and it pulls away, new one takes longer to get going, but if I go through the gears lots of throttle it's ok, not new to bikes just Japanese ones. Aways had British bikes still got a 1974 triumph trident t150, regards Kevin.

[Rich82GS750TZ]

In the OP's defense, and contrary to my previous statements, I found this in the 750T owner's manual. And it supports his riding at 35mph in 5th gear. I just can not imagine attempting to ride my bike at these low speeds, in the recommended gear.