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Discussion in 'Thumpers' started by GB, Apr 24, 2008.
Does anyone have an X-Rack (Hot Rod Welding) for sale? I'd like to put one on my X-Challenge!
It seems to me that the countershaft sprocket is the worst known weakness on the X. To the people who have experienced this failure, what were the circumstances directly leading to the failure. Was there a heavy shock loading that preceded the failure?
My thought is the bolt and washer might not be tight enough and the spline fit too loose. Without good moly grease the two splines attack each other. I've heard it called fretting. If an aftermarket sprocket is used it may be much harder than the shaft and all the wear going to the shaft. When I mount a sprocket I check to see how tight the fit is. If loose at all I toss it. I then use Belray Moly grease. It's good stuff used on the splines of the Honda shaft drives. Then with the bike in first gear and the wheel on the ground I use the correct socket with a short extension to tight it to the correct torque value. I am hoping this will prevent the failure.
I do think you have a reasonable chance of success at welding it. A good welder that knows how to get proper penetration with a 175+ amp machine could make hot and deep beads with water cooling after each one. The end result would be a full pass all the way around the perimeter of the shaft. Those front steel sprockets can last a longtime with some daily lube. I do know a lot of bikes been repaired that way.
I replaced my engine this summer after a long and expensive hunt for the source of a bad engine knock. I had chased for a year it through head and valve gear. It kept getting worse so I bought a used engine off ebay from a 2013 G650GS. I was sceptical of compatibility but it went in perfectly with no issues. It should be the same with a Sertao engine. I have inspected the shaft on my two motors and they both seemed to have good splines. But they are definitely small and look very delicate. And they are only about half the width that they could be. Stupid BMW engineers!!
During my ownership they get at least biannual Belray Moly grease. So far so good. When I get some time I will dive into the old motor and learn what was causing the knock. It would start and run quietly when cold and then rapidly get worse as it warmed. I am guessing it is a rod causing the knock. I will keep you all posted.
Yeah, got users mixed up there, sorry about that
The grease is to provide lubrication. The retaining bolt does not prevent the sprocket from rotating on the shaft. It would require extremely high torque and a very tight spline with an interference fit if this was desired by the engineers. Something like the taper fit used for the flywheel attachment. Also consider the torque multiplication provided by the gear box. The splines need to be lubricated so the rotational movement (however small) doesn't promote wear.
Think about all the places splined shafts are used: automotive, truck and mc driveshafts, gearboxes, clutches, etc. And consider that the material used for the shaft and sprockets is not an issue. BWOE, a CV joint is extremely hard steel as it is bearing material. The CV axle shaft is not and in some cases may even be designed for some torsional give to absorb shock loads. Yet these two different materials slide past and against each other for thousands of miles. Or consider how some motorcycle engines (XR650R for example) use a lock ring or plate to retain the cs sprocket that doesn't provide any axial force on the sprocket. Lubrication is key to spline life.
ETA: The grease does provide rust resistance which is good since rust particles are abrasive and increase the wear rate. However you could use a silcone caulk if the only requirement was waterproofing.
https://www.amazon.com/dp/B001HWBSJ...olid=3EP9ELW3MA8LY&psc=1&ref_=lv_ov_lig_dp_it This should be enough for a lifetime of use except for the fleet owners go for the 16 0z tub.
This is what I use on my ST1300 drive splines also on the Husky TE630 counter shaft sprocket. If you really want to research this google Loctite 8012 spline lube, some good reading along the lines of best tires and oil.
Properly hardening the shaft would help too!
not my fault - I was drunk.....oh, never mind
Anyone have a Toura tech rear rack they want to part with?
I like it! Still laughing !
Now, that's what she said ......
Thats a sweet one. I just bought one and looking at what the "lite minded" have done for set up with all the bikes across this thread.
Paging @tester1 to the white courtesy phone.
I still in the room!!!
Hi, gang. Just happened to see this little blurb about a messed up front sprocket shaft.
I remember from XCo days of yore a problem worth mentioning here. There is a chance that someone tried to mount a sprocket from the F650 twin onto the G650 single engine which could result in a problem with the splines of the sprocket shaft.
BMW changed the naming nomenclature so many times that some sellers confused the parts of the BMW 650 between the Single-Cylinder 650 and the Twin-Cylinder 650 (actually an 800 re-named 650).
I remember ordering a sprocket once from a supplier and I specified the G650. The seller, apparently confused, thought all 650's were the same and shipped me the sprocket for the Twin instead of the Single. I did not readily catch the mistake from a casual look at the sprocket. Weeks later, when I went to install the sprocket, I easily saw the difference and realized I had the wrong part.
The Twin sprocket actually would fit on the Single's shaft but it was a loose fit. I thought then that someone could proceed with this faulty part and result in shearing off the shaft splines of the Single 650. There are other differences in these two sprockets but someone not paying close attention could possibly get in trouble.
If I recall correctly, I posted an old post here years ago showing pictures of this.
As someone else has already advised, when installing a drive sprocket, always check to be sure the splines fit accurately and snug.
For what it's worth, I used aftermarket sprockets and never found one that did not fit well IF I had the correct part number for the Single.
Yes ! I knew I'd seen it on here some years ago !
Glad you're still looking in Leafman !
By the way, anyone wanna hop-up your G650X for sure??
I still have a few parts in my stash from my XCo days.
I have an entire head, cams and valve cover from a Husky TR650 (made by BMW). These were revised from the standard 650 engine for the greater output of the Husky version.
I will make someone a helluva deal on all of it.
I also have an alternator from the 650GS that will replace the G650X unit and make more amps.
@leafman60 = Hopping up the motor would be a fun project for someone. Glad to see you still monitoring this thread! What are you riding these days?
Hi and thanks. These days, if I am not on pavement, I am most likely on my late-model R1200GSWC.
I also have a '91 airhead R100GSPD. I still have several H-D Big Twins and a few vintage bikes.
All in all, however, nothing matches the power to weight ratio that I enjoyed with my G650XCo. That was a running li'l sumbich and I have many fond memories of it.
I'd load it down with clothes and camping gear and run 500 miles warp speed on the Interstate to a destination, unload everything and then hit the curvy blacktop and the dirt single trails. It would do everything.
I don't think anyone is making a similar machine now. I am amazed that BMW discontinued the 650 singles.
From some of my favorite expeditions-
He's just like me, going places we shouldn't. Maybe if he had knobby tires, he wouldn't need the BIG rope!
SWM Superdual be like that; I own both SD and XCo and if I had to choose one SD would be obvious choice. Smoother engine with similar output, similar Sachs shock, same 45mm fork this time with adjustment and made by Fast Ace as marzocchi went out of business.