75/5 Maintenance and expectations for newbie

[8 Gauge]

Regards and thanks in advance for the tips!

I'm the guy that posted the thread about Mikuni carbs for my 75/5. Seems that shes running great now so I have a few questions before I put some miles on her.

In the last 10 years, very little miles were put on my machine. I swapped my bings with Mikunis because one of my enricheners was "goofy" which gave me a ton of problems. That seems to be sorted out now.

My biggest concern is maintenance with respect to the final drive and other things that aren't related to the motor. The rear end whines slightly when I take off and "clunks" a bit. Is this normal? It doesn't sound bad enough for a lot of concern, and I'd really like to chalk this up to "40+ year old bike" mechanics (shes a 1970). Also; taking off isn't as smooth as I'd like it to be. I think this is mostly due to me worrying and being afraid to slip the clutch too much. I, also, have no experience with a shaft driven bike. I'm an experienced wrench, but mostly on dirt machines that I wasn't afraid to beat the hell out of. (anyone ride a KX500?)

Bike seems to be remarkably tight, but I really do not know what to expect from this machine. Power and torque are SMOOTH and shes a blast to ride.

Another question that some might find silly: I'd like to make her a bit louder. I know people will disagree with my thoughts, but the people around here drive like idiots and I'd like to be heard. Would it be feasible to drill out the rivets in my mufflers, take out the baffles and wrap them in exhaust tape to render them "enloudeners?"

Thanks!

[Duane Ausherman]

You may have a grabby clutch, especially if it gets a bit worse when hot. You don't need to ask here, as everything that you wish to know has already been written up many times and is on the Internet. Just use Google and save the various websites devoted to your model.

[Deleted User 72]

It is not normal for the rear end to clunk or whine. I would begin the research by checking the play in the drive line. With the bike on the center stand rotate the rear wheel until the play is taken up in forward and reverse directions, and note how much rotational movement there is at the rim between these two positions. There are several things that could make up this play. Worn splines between the wheel and rear drive could account for play and possibly a clunk on startup. Misaligned ring and pinion gears (too much play) could cause a whine and also contribute to play and a clunk too, I suppose.

Can't rule out the transmission, either.

Report back.

[Major Softie]

Ya, rear splines were the first thing I thought of when you mentioned clunking rear-end. Whining is a different issue though.

[KauaiSlash5]

I'm no expert, but compared to other vintage non-direct drive motorcycles, I would say that a little clunk and a little whine is normal for these bikes. For a first time rider unfamiliar with these bikes, this can be a bit concerning. If you're used to the quirks of chain drive Import or British bikes, Airheads can take a little getting used to IMO. The clunking when shifting gears is well documented with these bikes, and a bit of mechanical whine is to be expected with a final drive. My guess is that you are hearing these things when "taking off", but that they are occurring at speed as well. This doesn't mean I wouldn't investigate things to make sure you don't have a serious problem, but these bikes have their own unique quirks just like any other make. See if you can pinpoint where the sounds are coming from (difficult to do with a full helmet on).

As far as wanting to make the bike louder, I hear you loud and clear I would recommend sourcing a pair of Hoske replica pipes. They have removable baffles, but many find them to be plenty loud with the baffles left in place.

[8 Gauge]

Thanks all! The whine is only when starting and the "clunk" isn't really bad at all. I'm pretty sure that this is just me being overly concerned.

That said, I'll probably end up taking it apart with the service manual in hand and check specs to be on the safe side. The tranny seems fine (I was actually impressed with the quality that it shifts)

Is there some sort of limited slip gizmo or slippy thing in between the final drive and business end of the transmission or it is strictly clutch+ direct drive?

As soon as I take off, its fine. No abnormal noise and It pulls smooth and hard.

Thanks again!

[chasbmw]

A standard 75/5 will have a direct drive between the gearbox and the rear wheel, a spring loaded Cush drive was introduced in or around 1978 as one of the changes thatmbmw introduced to improve the gear change,, and to reduce the possibility of locking the rear wheel with a clumsy change down from 1st to second gear.

The gear change was not really improved until the introduction of the ultra light flywheel from 1981.

It is possible that the PO of your bike has fitted a later swinging arm complete with the Cush drive. The swinging arm may be longer than stock if your bike was one of the short wheel base models.

BMW gear changes do take a bit of learning, and it helps if the clutch is properly adjusted by the method adopted for the later bikes.

[Zombie Master]

Clunking is usually caused by a rider who has no mechanical empathy. Shift them as they would like to be shifted, and there is no clunk. Whining is another matter, though a common Airhead rider characteristic.

[dougie]

Whining is another matter, though a common Airhead rider characteristic.

[SteveD]

Could the clunk be due to loose shaft drive bolts? The ones that connect the shaft to the trannie?

My R100RS had an unusual clunk recently. I fixed it easily when I put a nut to the right lower shock mount. D'oh! The old one must've fallen off. Not quite tight enough last time back on I'm guessin".