noise from the drive shaft when bike is in gear

Hi everyone, i am new to the forum, and i have a question. I have a 1982 xj 750 maxim, the bike is a u.s import. My question is this: When riding along the road, i keep hearing a kind of metallic whirring sound, it sounds like the starter motor is spinning, but i can't be sure, this noise is not always present, it is intermittent, and it comes and goes. When i got home, i put the bike on the centre stand, started her up, and put her in gear, to see if i could hear this whirring sound. I didn't hear that particular noise, but there was a lot of knocking coming from the drive shaft. I listened to various parts of the engine (through a screwdriver), but the noise was loudest when i listened to the drive shaft where it joins the swingarm, and enters the crankcase. The bike has sufficient oil in both the engine, and the drive shaft. I was just wondering if anyone out there could help me with this problem, as i am new to the xj's, i would be most grateful for any solutions / advice etc, thanks, Jim. p.s the noise is only evident when the bike is in gear, when in neutral, the bike is a lot quieter.

 

And only when in motion? Or at least the tire spinning?

 

Is it as simple as you hearing middle gear whine?

 

When I put my 81 XJ on it's center stand and shift into first, there is clunking/ knocking.
I perceive it as normal because the rear end is free wheeling without any load on it. If I twist the throttle the knocking goes away.

I have not noticed any type of whirring/ starter motor sound when on the road. Then again I wear a full faced helmet and it may be muffling what may very well be 'normal' driving sounds.

Sit tight and some of the more experienced people here will most likely provide you with a better answer to your concerns.

 

the first noise is most likely what KrS14 said, middle gear whine, it has to do with the drivetrain making a 90 degree turn in the engine, don't worry about it.
the second noise might be from play in the driveline, if you would put some drag on the wheel (touch the brake or adjust some drag in the brake) and listen again.
with the bike off and in first gear, how far can you turn the wheel back and forth ?

 

its almost a deafening sound? gets right into yer head ?mine does the same thing same bike out on the highway its like somone whistleing loud in yer ear until ya shift down or somthing, drives ya nutz

 

Mike, look up "middle gear servicing" in the factory book. if there's too much play in the middle gear it'll whine like a old chevy pickup

 

Thanks Polock I will do that asap.The Haynes manual?I would have to get a new one think mine burnt in the fire at the shop

 

Thanks for all your feedback guys, yes, the noise is only there when the bike is in gear, with the wheel spinning. When the bike is on the centre stand, and i put her in gear (ignition off), there is maybe around 1 - 1.5 inches of play, moving the rear wheel back and forth. Thanks again for all your advice guys. Jim.

 

This noise of which you speak is probably the same noise I was rather concerned about my self when I first got my XJ750 and it use to drive me nuts as well. Once I pulled the clutch apart and saw the straight cut gears between the clutch basket and the drive shaft I could see why the bike made the noise, straight cut gears are noisy but strong, that's why they are probably used in the primary drive of these bikes. Automotive gearboxes and diffs have gears cut on an angle to overcome this whine but gears cut on an angle are not as strong. Some bikes use a chain drive in the primary drive probability to overcome this whine. Its just an XJ thing.

 

I love my whine! I'll have to check my play, I'm sure it's way ore than an inch.