Failed XS750 Final Drive (Images and video link)

[WMarshy]

I doubt if it does.... what you should be comparing is torque. The 750 (which is what this FD was designed for) only put out 45.6 ft-lbs. The 1100 on the other hand puts out 66.6 ft-lbs, a increase of 46%. Add in the 20% higher weight of the 1100 vs the 750, you're asking a lot of that FD....

I agree, the torque value is what matters here... would be nice to know what the load ratings are for the different bearings in each. I doubt they over engineered the 750 FD that much, probably not much margin left in the design when the eleven is at full power... after reading all this, I'm not sure the 750/850 FD will be a good choice for a punched out XS!

[BA80]

Tod has one in his XJ.

[3Phase]

You're bored again, aren't you, Greg. Is this going to be a five minute argument or the full half hour?

Yes, John, the oil failed. Big time. Along with the drive. It definitely overheated on its last trip but it was dying before I left for Colorado and the oil was never burned at any time when I changed it. I would have noticed that so I think it was the hot slowride through Telluride and back that did it in. A whole town filled with beautiful women and we were forced to go past all of them, twice, and then ... hang on a minute! That was me not the drive!

The drive didn't start to fail until 8,000 ~ 5,000 miles ago. Before that the oil was clean so it ran for a good while before it showed any debris in the oil. It's really not a good sign that it was still running quiet and smooth when I changed it out at 40,000 even though it had started running a little hot since somewhere around Sweet Home, Idaho and sustained 75 MPH speeds.

The fresh 75W-90 synthetic masked some noises I should have been hearing but there wasn't a lot I could do about it besides buy a Labrador retriever and rent a U-Haul truck to Harley the XS back home to Davidsonville.

All in all it's probably one of the better $50 I've spent: $15 plus tax for the drive, $15 for shipping, $15 plus tax for a new crush washer. I'm totally devastated that it only ran for a couple of years.


Marshy, a 750/850 drive should work okay in a bored out XS. It won't last anywhere near as long as the stock drive and if you get too radical it will wear out/break but the stock final or middle drive could do that, too, if you pump up the engine. I suppose that it entirely depends on how you ride along with when and where it happened if it would be more than an annoyance to swap in another drive or if you had to ride out the big skid when the middle or final drive 'sploded or locked up.

Keep a spare middle and final drive in the garage, watch the oil and change it. Frequently. From looking at how the 750 drive failed on my XS I'd say change the middle and final drive oil when you put on a new rear tire and grease the splines. Don't try any extended drain interval tricks even if you use synthetic oil.

If you want to be totally paranoid like I was at first you can remove the Phillips screw from the pinion assembly and take it out to have a look at the ring and pinion gears when you change the rear tire. I did that for the first and second oil changes, then I quit looking and just rode it like an XS11 until it started to give up the ghost.


Oh, and my grandmother, God rest her soul, drove like a little old lady from NASCAR!

[Toolmaker Tim]

Final Drive Failure

I have heard about what happens when the middle drive fails and locks up, but I can't recall hearing anything about a total final drive failure. Is it as disasterous as a middle drive failure? Also Scott, were there any other signs of failure prior to the appearance of metal chips and shavings and the rise in temperature? I guess since you are going to reinstall another 750/850 final drive you were not too bothered by what happened. Heck of an experiment though.

[cywelchjr]

Thanks for correctly assigning 'credit'....

But I have to admit that I agree with Scott. Yamaha went to the trouble and expense of redesigning the 750 drive for the 1100, putting in stronger bearings in the two places they would be needed to prevent this sort of issue and beefing up some other areas as well. This would make the rumor that Yamaha originally was going to use the 750 drive plausible, but the change IMO was made not so much in search of 1/4 miles times but due to durability issues found in pre-production testing. After all, this was their flagship performance model and you know they figured that many owners would beat the hell out of the bike. Get even a few reports of failed FDs, and the bike's reputation would have gone in the toilet...

Does that mean that every swap will fail? No, of course not. But I'd be willing to bet that the factory found that a certain percentage would fail, leading to the 'upgraded' unit that ended up in the production bikes.

The quote I saw from XS11 heaven didn't say it was supposed to get the 750 FD, it said it was supposed to get the same final drive ratio. I expect it would have been a beefed up FD with the same ratio. I am just a little surprised that they didn't have a touring variant that was geared just a tad higher though, as that would have made it a much better goldwind killer.

[cywelchjr]

I agree, the torque value is what matters here... would be nice to know what the load ratings are for the different bearings in each. I doubt they over engineered the 750 FD that much, probably not much margin left in the design when the eleven is at full power... after reading all this, I'm not sure the 750/850 FD will be a good choice for a punched out XS!

I figure if I only get 40,000 out of mine the way I ride, I'm doing something wrong, but then if I do, another $30 will get me another (I may even get another in advance just to be ready plus a spare stocker (or fix my original with a new seal)) and a second one should take about 15 minutes to install after the prep time which all can be done in advance so the replacement is ready in advance.

[James England]

My main concern isn't the cost or effort (both not much) of replacing the 750FD. It's what would happen if it exploded or locked up at, say 70mph.

I'll keep checking the oil etc and report back. I really do not want to have to go back to the OEM FD!

[BA80]

You're bored again, aren't you, Greg. Is this going to be a five minute argument or the full half hour?

No arguement Scott, just stating facts from the real world. .

Tod tore one up in his XJ too but that boy could destroy an anvil with a rubber hammer. He has broken parts you and I don't even think about.

[3Phase]

James, don't worry too much. About the best you can do besides giving up motorcycling and selling your XS to buy a giant inflatable ball to walk around in when you're not driving your Prius cocoon is to look carefully for debris in the oil or on the magnetic drain plug and trust your nose if you think you smell overheated or burned gear oil. Check the lash in the final and middle drive when you change the rear tire and grease the splines.


Tim, there wasn't really any sign of anything going wrong with the final drive or the middle drive except for the debris in the oil and on the magnetic drain plug. The final drive didn't start to burn the oil until sometime during its final 4,000 miles. The middle drive was still okay but it was starting to wear out and put a little more metal than usual on the magnetic drain plug and in the oil.

The small amount of extra lash that crept into the drive train wasn't really noticeable when riding until I put on the low-mileage XJ final and middle drives. That made a very noticeable difference!

The drive does get hot when you run it fast and hard but the extra heat really only started to show up when checking it with my hand when I was in Idaho ~ 2,000 miles from the end of its last ride.

After I first installed the 750 drive there were a couple of extra slow-growing thousandths of an inch of lash in the final drive after the third oil change but nothing really unusual in the oil.

That had grown to a few tenths of an inch of lash with an evil gray streak of worn bearings and a rainbow trout cavorting in the oil in the drain pan by the time I replaced the drive but it happened gradually. I kept track of the wear by checking the final and middle drive lash when I greased the splines during tire changes. No, I did not keep a written lash log or make a spreadsheet with a giraffe, err, graph!

I did turn the rear wheel back and forth by hand, then spun it forward and then backward after draining the oil before I removed the 750 drive. I couldn't really hear the bad carrier bearing clicking until I tore down the drive and washed off all of the heavy gear oil and sludge but the extra tenths in the lash and the gear wear was audible.

Special Ed had a final drive fail and lock up the rear wheel of his '79 Special at street speed in Santa Cruz. The drain plug came loose on the final drive and the oil drained out while he was riding. It could have been worse at highway speed and locked up when the teeth started to break or the teeth could have just sheered off at speed and put the final drive into permanent neutral until the bearings seized up.


Okay, Greg, I'll bite but I refuse to swallow the hook!

The easiest way to describe the difference the extra 16 HP will make is to have you go outside and try to push your XS up to 15 MPH, then try to lift it up off of the ground. You might be a little winded after trying to run 15 MPH while pushing an XS11 so it'll be okay if you try to lift your bike before you try to push it.

Try it again with one horse to pull your XS.

Try not to be surprised that one horse will be able to pull your XS faster than you will be able to run. Be careful and don't trip and let the horse run away with your scoot.

Try again it with sixteen horses.

Try to get sixteen horses to all go in the same direction at the same rate at the same time.

Okay, sixteen horses won't be able to hold out for very long even at a pokey 15 MPH but they will get you into town and back so you can stop by the feed store to pick up a few sixpacks carrot juice and a couple of cartons of grain for each horse.

I think you will also discover that it's a lot easier for you if you just use one horse to lift the XS up off the ground but sixteen of them can literally make an XS11 fly! Briefly.

So, now you have at least a rough idea of how a mere 16 HP works in the real world but you still scoff at the completely absurd idea that the engine and drive train has to supply more force to a 750 final drive to turn the rear wheel than it does to turn the rear wheel with the stock final drive and that the smaller gears and bearings in the 750 final drive are no big deal.


Dust off your trusty hydraulic floor jack and use it to lift your XS up off the ground.

That was almost too easy, wasn't it? At least it's a lot easier than trying to use a horse, or a mere sixteen horses! to do the work.

Okay, now put the bike back down on the floor and then try to lift it again with the floor jack but this time don't use the 4' long jack handle, use a screwdriver.

Put the handle of the screwdriver into the hole for the jack handle and press down on the business end of the screwdriver to work the floor jack.

Huh?! What's going on here in the real world?! It will always take exactly the same amount of force to lift your XS11 up off the floor with or without the floor jack.

Of course you could barely feel the amount force you had to use with the stock 4' long, wide-diameter jack handle that came from the factory with the floor jack and you probably lifted your XS with just one finger on the end of the jack handle!

You had to use a lot more force to push down on the screwdriver. The business end of the screwdriver is so thin that it left a visible mark on the palm of your hand that would slowly fade away after a few minutes. If you kept using the screwdriver over and over and over that mark would start to turn into a bruise and eventually cut into the meat of your hand.

Your hand will heal.

Small marks on gears do not fade away after a few minutes and bruised, cut, metal can not heal.

The ridiculously small, minuscule, a mere 16 HP of extra umph from the XS1100 engine is delivered along with the rest of the HP to the thinner gears with their proportionally smaller gear contact faces in the 750 final drive.

The engine will also have to supply the extra force that is required to turn the rear wheel using the shorter lever provided by the smaller-diameter gears and the smaller bearings in the 750 final drive.

Go figure. It's almost as if the the final drives were intentionally designed and installed at the factory on different motorcycles!

[James England]

I checked my FD oil and plug. The oil is clean and the drain plug had a very very thin smear of uniformly grey/black slime.... hardly anything. That's only after about 700 miles though. It looks pretty normal to me. Mind you, I couldn't actually see or hear anything too well though my cotton-wool body lagging...

[3Phase]

James, it looks like your 750 drive is doing just fine!

A small amount of gray metal on the drain plug is normal and so is a small amount of sludge.

There will always be a few flakes in the oil but too many of them is bad. Flakes come from the hardened surfaces of the gears, bearings and races fracturing and coming off so if you see a drain pan full of shiny stuff in the oil that's not a good sign.

If there is a lot of black sludge there is either too much water in the final drive and/or the oil is overheating and failing.

Other than normal condensation you might get some extra water in the final drive by riding in the rain. It could also happen if you were a little too enthusiastic with a pressure washer or if you tried to check the ballast resistor by riding your XS through the Channel to France and back.

[BA80]

OK, now I'm trying to understand why I got this rather lengthy kindergarten explanation.

Okay, Greg, I'll bite but I refuse to swallow the hook!

The easiest way to describe the difference the extra 16 HP will make is to have you go outside and try to push your XS up to 15 MPH, then try to lift it up off of the ground. You might be a little winded after trying to run 15 MPH while pushing an XS11 so it'll be okay if you try to lift your bike before you try to push it.

Try it again with one horse to pull your XS.

Try not to be surprised that one horse will be able to pull your XS faster than you will be able to run. Be careful and don't trip and let the horse run away with your scoot.

Try again it with sixteen horses.

Try to get sixteen horses to all go in the same direction at the same rate at the same time.

Okay, sixteen horses won't be able to hold out for very long even at a pokey 15 MPH but they will get you into town and back so you can stop by the feed store to pick up a few sixpacks carrot juice and a couple of cartons of grain for each horse.

I think you will also discover that it's a lot easier for you if you just use one horse to lift the XS up off the ground but sixteen of them can literally make an XS11 fly! Briefly.

So, now you have at least a rough idea of how a mere 16 HP works in the real world but you still scoff at the completely absurd idea that the engine and drive train has to supply more force to a 750 final drive to turn the rear wheel than it does to turn the rear wheel with the stock final drive and that the smaller gears and bearings in the 750 final drive are no big deal.


Dust off your trusty hydraulic floor jack and use it to lift your XS up off the ground.

That was almost too easy, wasn't it? At least it's a lot easier than trying to use a horse, or a mere sixteen horses! to do the work.

Okay, now put the bike back down on the floor and then try to lift it again with the floor jack but this time don't use the 4' long jack handle, use a screwdriver.

Put the handle of the screwdriver into the hole for the jack handle and press down on the business end of the screwdriver to work the floor jack.

Huh?! What's going on here in the real world?! It will always take exactly the same amount of force to lift your XS11 up off the floor with or without the floor jack.

Of course you could barely feel the amount force you had to use with the stock 4' long, wide-diameter jack handle that came from the factory with the floor jack and you probably lifted your XS with just one finger on the end of the jack handle!

You had to use a lot more force to push down on the screwdriver. The business end of the screwdriver is so thin that it left a visible mark on the palm of your hand that would slowly fade away after a few minutes. If you kept using the screwdriver over and over and over that mark would start to turn into a bruise and eventually cut into the meat of your hand.

Your hand will heal.

Small marks on gears do not fade away after a few minutes and bruised, cut, metal can not heal.

The ridiculously small, minuscule, a mere 16 HP of extra umph from the XS1100 engine is delivered along with the rest of the HP to the thinner gears with their proportionally smaller gear contact faces in the 750 final drive.

The engine will also have to supply the extra force that is required to turn the rear wheel using the shorter lever provided by the smaller-diameter gears and the smaller bearings in the 750 final drive.

Go figure. It's almost as if the the final drives were intentionally designed and installed at the factory on different motorcycles!

In retort to this;

No arguement Scott, just stating facts from the real world.

We'll see. I've had mine in for between 20 and 30K now. I'm not sure because I didn't note my miles when I installed it and I also switched speedometers about 14K ago.

It's been to the Ozarks 2 or 3 times now and in about 10 days it will make it's second trip up north to the Lost Rally in Minnesota, not to mention several trips to Texas, and Kansas. And I NEVER do wheelies or speed shift.

[b.walker5]

Just a thought... but it seems to me that if you ride your 30+ year old motorcycle like a 30+ year old motorcycle then the 750 drive is going to hold up just fine, if however, you ride your 30+ year old motorcycle like a 2 year old production R1 or somesuch then the swap probably isnt for you, and the drive wont be the only thing that breaks.

Personally i'm in the 30+ camp and will be swapping drives later this year once winter is over, and it's warm enough to work in the garage again. (now that I dont have to sell it)

If (when) i want to ride like a lunatic i take the XJR

Very informative thread btw.

[3Phase]

OK, now I'm trying to understand why I got this rather lengthy kindergarten explanation.

Well, Greg, because you're just trolling, that's why.

After seeing the pictures and reading the explanations written by some pretty sharp individuals the best you could come up with was that the real world is different for you. You're not actually interested in the answers or the pictures except to amuse yourself and only small children or childlike adults do that so you were given an answer appropriate for small child or a childlike adult.

On the totally off chance that you are actually interested in the subject and you have been woefully misunderstood all along then do yourself a favor and do your own research. Post your results with pictures.

The pinion assembly will slide right out of the final drive and there are only ten nuts and washers holding on the right side cover and ring gear. The next time you change the rear tire on your XS and pull the final drive to grease the splines, take a look at the bearings and the gears. Be careful when you put it all back together. If you cut the lip of the seal on the ring gear the final drive will leak oil all over the place and you will be doomed (DOOMED!) when the back tire spins up in its own oil slick and tries to slide out from underneath you.

Oh, and it would also help your credibility if you had some pictures of the inner workings of the drive from before you installed it on your bike. "I don't remember the mileage when I installed the drive ..." simply isn't believable.

Unless you have detailed before and after pictures that you posted well before you actually completed the 750 mod that won't cut the mustard with any serious art critic.

So I'm sorry if I woke you up now go back to sleep and finish your nap or you'll be fussy and cranky for the rest of the day!

[3Phase]

So, Brian, I'm not only a stupid liar but I ride like a lunatic? "Thank you, sir, may I have another!"

Man, this just keeps getting better and better! I should have just Photoshopped everything and then sat back and had a few beers and a larf.