Acceleration Noise/Vibration

I am getting concerned about a thumping/clunking noise coming from the rear and its either the drive shaft or the pumpkin. When i accelerate from a stop or a quick acceleration while rolling i hear and feel a thump/clunk. XJ 650's have that horrible hard shift noise at times and i dont know if this sound is normal. The rear pumpkin has oil... doesn't leak and seems ok.

Could the sound and feeling come from the engine and am feeling it in the rear??? Do the knuckles on the shaft go bad?

 

There is a ramp damper and when the spring gets older and weaker it will do that under harder launches my Xj750rl and xj650rjc do the same thing

 

I had the compression spring snap on mine ( located in the hub and connects to the driveshaft) and had a clunk and the frame vibrates when you turn the rear wheel by hand feels like a tight spot when rotating the rear wheel.

 

If is there any way to fix it or its just normal on an old bike? its a little unsettling when you merge onto the highway or take off at a redlight.

 

Yes its a cheap fix take the back wheel off remove the hub 4 17 mm nuts and replace the spring becare full with the hub it will leak oil if tilted the wrong way just over an hour to do the job .

 

Thanks for the info. I am guessing this is the spring 90501-16491-00. is there anything else i should pay attention to that might be the culprit?

 

Yes, that is the correct part number and only at the other end of the shaft is the UJ coupling if the spring doesn't do the job that will be the next thing to check for wear and removing the complete swinging arm to do so if you go that far you might as well replace the swinging arm bearings while it is off the bike.

 

we are getting ready to move out of Brooklyn and near goldens bridge. so this will be my first project in the new garage!

 

Bit of an update here chaps anyway replaced the compression spring and replaced the oil seal on the driveshaft and put it all back on the bike anyway set to go out on a ride went to take off and a bad noise from the driveshaft again a clinking sound, pushed it back in the garage and got round to stripping it today and guess what I found this time
The shaft between parts 10 and 11 had snapped not sure what you would call that shaft but the bike did still have drive my question now is can that shaft be removed or would it be just as easy to change the drive hub over and what hub to go for. Thanks for any help you can offer

 

I would get a used unit off E Bay.

 

Thanks for the reply are all the units the same my bike is a 1980 xj650 euro model.

 

I am not sure to be honest. Someone will know on this forum.

 

All the rear drive units the same on 650 and 750.

 

Thanks for the advice have managed to obtain a 650 turbo one over here off ❌b❌y for £30.00 hope to soon be back on the road before the bad weather gets here

 

the 650 Turbo unit may be different in some way. Virtually all the 650s and 750s including some 700 and 750 Virago models list 5G2-46101-01-00 as the part number for the whole "pumpkin" assembly; the Turbo shows a way different part number.

I have absolutely no idea what the difference might be, just be aware they are different than the others. One might suspect final drive gearing? Maybe ask Chacal?

 

they are painted black.

 

There is likely a bit more to it. Yamaha part numbers follow a distinct pattern; "finish" differences, such as black vs. polished or natural, etc., are covered by the last two digits of a part number; whereas the first three are the "family" of the bike the part originated with. So for instance, Yamaha used the same fender for the Seca 650 and Seca 550s, it carried a "4K0" part number prefix (the original Euro XJ650) all along, with only the final two digits in the part number indicating the color or finish.

In this case, the turbo pumpkin carries a 16G part number prefix (650 Turbo) whereas all of the naturally aspirated bikes use the 5G2 part. There is more to it than what color it is painted.

 

I may have found the difference, in an extensive review of the 650 Turbo when it came out: "the final drive now has a rubber shock cushion to ease the peak loads applied at the rear wheel." Whether this affects interchangeability I do not know. But it may explain the part number difference.

 

The Turbo has rubber cush drive parts in the rear wheel between the spline and the wheel.
The standard Seca is rigid here.
I have the RJ pumpkin on my Turbo now but I've only done 8 kms like this.

 

Although this shows the brake side, you can see the rubber inserts on the Turbo wheel on the left

 

Thank you all for the info you are a clever lot will go with the replacement drive and let you know if there is any problems with the unit, shame the postage is so much between the USA and the UK great prices over there for the same unit.

 

I am probably 3 sheets to the wind but, fark... what the hell am I looking at?
I know from my 750 and 900 that they both have a solid drive shaft that push into the final drive... what the hell is the little spigot and nutt and washer I am looking at?
Forgive my lack of understanding.

 

OK, here we go when you take the shaft out of the swinging arm you should end up with this,



When you pull the shaft from the hub you will find the compression spring that sits inside the 22mm spanner size nut that threads onto the middle shaft inside the hub(still don't know what is called) I take it this all keeps the shaft centralised and compressed you will know if the spring has snapped or the shaft broke its not a nice noise but you will still have the drive to the rear wheel


above the spring ,nut should be a 4mm washer and the broken thread off the drive. I am 4 sheets to the wind but I hope it helps.

 

FWIW the other part number differences on the final drives (across all Yamaha shafties) mostly have to do with the placement and type of rear shock mount. For example: the first-gen Viragos don't have a lug to mount a shock to, but instead have a bolt for the upper leg of the swingarm. The gearing an internals are otherwise identical to the final drives on the XJ series with just a few exceptions.

 

Ahh!
Yes in the light of day. Makes sense now! Thanks for the pics.