Splitting cases/Reassembly

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I thought about posting this AFTER I'd already taken the motor apart, so this is the assembly. Teardown would simply be in reverse order.

*DISCLAIMER*: This info does not replace a manual for the bike. This is simply an order that I personally use on assembly and in no way saying it's the best or only way to do it. It's just some things that I've learned to look for when doing them, and along with these pics, might be helpful in conjunction with your manual.

In this case, we took it down to replace the crank bearings. This is the top half of the motor upside down. Remove all the old bearing halves. Make sure the case is clean and dry of oil before installing new bearings. A coating of oil on the back side of the bearings would change the clearances slightly.







When installing the new crank bearing halves, there is a notched area on the bearing that matches a notch in the case.





Just slide the notched bearing into it's matching notch and push the bearing into place. Try not to touch the actual bearing surface.





The 2nd bearing on the top side is where the saddle bearing goes. If the motor was right side up, it would sit on the top side between cylinders 3 and 4. This saddle bearing straddles the case and prevents sideways movement of the crank.









I use a wooden or plastic handle to gently tap the bearings to get them at the exact right height compared to the case.





*CRITICAL*: Make sure to inspect this O-ring. Make sure it's in good shape and there! This is the feed tube your oil pump attaches to. You want your oil going where it needs to be, not squirting out the sides back into your oil pan.





Make sure and lube the bearings up with some sort of pre-assembly oil or grease. I prefer white lithium grease, but STP oil treatment or Motor Honey works well also.





Next, pick the crank up by the main drive chain. Feed the smaller cam chain next to it through the cam chain galley. GENTLY set the crank into the bearings while feeding the piston rods through the holes in the top of the case.





If you don't get all the rods poked through the holes, they can get lodged under the case like this, and you'll have to raise the crank back up to get it out.





Next, take the starter clutch...





And set it into the main chain.





Make sure the main chain is situated correctly on the crank. This one is not on it all the way.





This is correct.





Next, take the starter clutch shaft and feed it through the starter clutch from right to the left as we are looking at the motor.









Install the gear.. don't forget this spacer that goes on first!





The gear will fit nearly flush, but not quite.





Install the washer, lock washer, and nut. Torque to spec. Don't forget to bend the lock washer up against the nut as a safety precaution.





Next, I set the top case of the engine aside and grab the bottom half. Clean and inspect... especially the dirt and oil from where the old bearing halves were.






To be continued....

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Install the other 5 bearing halves in this side and lube.







If you haven't addressed the gears before this point, it's time. Here's the gears from left to right. Middle drive gear, 1st gear, 4th gear, 3rd gear, 2nd gear, 5th gear.





With the problems many of these bikes have with 1st and 2nd gear, it's been suggested to move the washer seen here behind this circlip and on the front side of 2nd gear...





Remove the circlip and the washer beneath it.





After the circlip and the washer are removed, you can remove 2nd gear. When reinstalling, you'd put the washer on first, then 2nd gear. Sorry about this pic, but at this point on the shaft where the washer will now sit, it is a bit of a rounded joint where the arrow points. Some people will chamfer the washer's edge so this helps it sit more flush against the shoulder of this shaft. I don't do this, but you're welcome to. If you don't, 2nd gear spins a little bit tightly by hand, but will loosen up quickly after it's ridden.





Here's the washer now on the back side of 2nd gear.





And the circlip re-installed... Some people have a problem with the thought of 2nd gear now spinning against this circlip instead of a washer. I've had transmissions back apart after riding many thousands of miles with them this way, and there's virtually no wear on any of the circlips I've seen.





Next, flip the gears over to the middle drive gear side.





The middle drive gear and 1st gear will slide off the shaft. this will reveal a washer.





I tried an experiment once with this washer. Since moving 2nd towards 5th gear seemed to work so well, I thought that by moving 1st gear closer to 4th, it would help that problem also. I found a place that had this size washer exactly half the thickness of the original. I placed one of those washers where the original one is and placed the other one on the back side of 1st. This moved 1st gear towards 4th exactly half the distance of the stock washer. It was not good. While riding in 4th, the dogs of 4th gear would grind slightly against the lands of 1st gear. It quickly wiped out my 1st gear on the bike. Failed experiment.

Anyway, under that washer is a circlip. Remove this circlip and you can remove 4th gear.





The only reason you'd remove 1st or 4th gear, would be if you were touching them up with a Dremmel to get them squared back up again.





In this case, Jamie has been kind enough to spring for brand new gears, so no Dremmel work for me on this one. New 1st and 4th.... as well as 2nd and 5th. I've never seen a problem with 3rd on these. The dogs on 4th gear that engage 3rd gear are beveled correctly already.





Slide 5th gear off the shaft, and install the shaft into the case from the bottom side as shown.





Set the shaft into the bearing on the case half and install 5th gear.





This gear shaft is held tight against the case by a washer headed bolt. This bolt goes into the shaft on the clutch side (Middle drive and 1st gear side). this bolt has a tendency to back out and get eaten by the gear on the back of the clutch basket, so be sure and use lock -tite of some sort on this bolt after you clean and dry it. Torque the bolt to spec.





Next, take the shift fork gear shaft. You'll notice a dowel pin behind a circlip next to the small gear. The shaft is also notched to make room for the middle drive gear on the set of gears you just installed.




As you slide this shift fork shaft through the motor, the dowel pin will sit in a notch in the case shown here.





Before sliding the shift fork shaft through the motor, locate your shift forks. You will see them numbered 1, 2, and 3 shown here.





As you are looking into the motor here, from left to right the shift forks will be in order 1-3. You will install the shift fork shaft from the right side, so the first fork you'd install will be #3. Situate the fork so that the forks go around 4th gear, and the nipple on the back side of the fork goes into the race/groove on the shift cam behind it.. shown with the arrow here.





Next is shift fork #2. It's fork is situated up out of the gears between 2nd and 3rd gear. I repeat.... this fork is situated up with the nipple on the back in the groove of the shift cam behind it as well. It operates another set of gears, not these.





Finally, shift fork #1 is installed onto the shaft. It's fork goes around 5th gear with the nipple in the back in it's groove on the shift cam.





I then install the two circlips on the shift fork shaft so it can't back out and I don't lose them. At this point, the dowel pin next to the gear will be sitting in that notch cut in the case on the clutch side.





To be continued...

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When you reinstall this middle driven gear, you might think you're missing one of the half-moon clips. The front side has two as you can see, but the back side only has one. You are supposed to install this so it sits half in the lower case and half in the upper case as shown.






Next, install the main gear shaft that your pinion gears are on and that your clutch basket will be mounted to. Notice this dowel pin on this bearing. Situate it against the case here. The notch for it is in the other case half. *Note* The last '78 motor I took apart didn't have this dowel pin, so I think it was added later to keep the bearing from spinning in the cases.





After you clean up the mating surfaces of the two cases well, making them clean from dirt and oil, you are ready to use something to seal the case halves. Some like the Yamabond, but I prefer the Threebond 1194. Either will work.





You have to work fairly quickly here. Run a bead all around the UPPER case half and smear the sealant evenly with your finger. You want enough to cover, but not copious amounts. just a nice even layer that will squish and seal nicely. You want to do this to the upper half since the crank is in the lower half and getting this sealant around that is a PITA.





*CRITICAL*: Make sure, when running the sealant around the crank bearing lobes, that you leave a bit of a gap by the edge of the bearing. You need to get around this hole to seal it, but if any of the sealant squishes into the bearing, it will likely ruin it on startup.





After the sealant skins over for @ a minute, pick up that half and set it on top of the other. At this point, you need to pay attention to that shift fork #2 (Shown with this arrow) that faced a different direction than the others. It needs to go down into the groove of the pinion gear below it. You may need to spin the gears a bit to get them all meshed right and the case halves will drop together.





I like to tap around on the case with a rubber mallet to make sure the halves are mated and together good.





When I disassembled the motor, I took a piece of cardboard and punched a bunch of holes in it, then numbered them 1-34. You'll actually need 35 holes though since there's two number elevens.





Where every bolt goes on the cases, it has a number next to it. Just stick the bolts in the appropriate holes and torque them down in order. I run all of them down until they just touch the case, then go back and torque them. This side of the cases will take bolts 1-22.

Flip the engine over, and the rest of the bolts from 23-34 will be used. Don't forget the one bolt under the breather cover. Torque to spec in order. *NOTE* When disassembling the motor, you'd start at #34 and work your way backwards.





Under the shifter cover, the bearing for the gear shaft and an oil nozzle were originally held in place by a torx head screw. I hate these and always replace them with a matching phillips head screw. My local True Value Hardware store carries them. You are welcome to re-use the torx screws. The factory manual recommends locktite on these.





Here's the bearing...





And here's the oil nozzle. Make sure this O-ring is there and in good shape.





And here they are installed with the new phillips screws.





Next is the shift shaft assembly with the shifter spring.





Make sure to install the spring legs around this post.





Next is the shift lever.





Remove the outside circlip you've installed on the shift fork shaft and install this. The spring loaded arm goes over the shift cam. In 2nd gear, all these dots and lines will line up if installed correctly.





Next, the starter clutch shaft bearing. Check these O-rings and install. This bearing is a tight fit and might need a light tapping with a rubber mallet.





When I install the screws for this, I leave them hand tight. Once you attach the starter to the motor, it fits in with this bearing cover and you can perfectly align them to match before snugging down the bolts.





Next comes the clutch. Install the correct washer that goes behind the clutch basket.





If you've taken apart the clutch basket (Or someone else may have) there's a similar washer inside the clutch basket that will interchange with this one, except it is slightly bigger. Make sure that when the washer is installed against the bearing, you can still see the bearings past the washer. The other washer will cover the bearings completely and eventually starve the bearing of oil, causing it to fail.





Next comes the clutch basket and it's bushing. Sometimes getting the clutch basket on all the way can be a chore, but when you're done, the shaft should be close to flush with the basket surface as shown. *Note* Some people add an extra steel disc into the clutch basket. This will cause this basket to stick out the thickness of that one disc further than what you see here.





Put on the washer, lock washer, and torque the nut. Don't forget to bend the edge of the lock washer over against the nut.





Install the springs....





Then install the star plate and 6 bolts. Tighten the bolts evenly a turn or two at a time to make sure the star plate goes on evenly. These break easily if you don't do this.





To torque these 6 bolts, locate a notch at the top right of the clutch basket shown here...





Install a screwdriver between the gear and the notch, and you can easily hold the basket still to torque the bolts.





Next, inspect your oil pump O-ring.





Install the oil pump so that the oil pump gear meshes with the small gear that is on the end of the shift fork shaft.





*CRITICAL*: Clean and dry the allen bolts used to attach the oil pump as well as up inside the motor where they go. Apply some Loc-tite or similar to these bolts. These are the three bolts that Bob Embry had back out enough so that the oil pump wasn't being driven by the small gear. Zero oil pressure is not a good thing.







Install your oil pan before moving the motor around. The oil pump hangs down lower than the case halves and you will damage it if you don't.


Continued...

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Next, I replace the crank seals. I prefer this brand. They are a double lipped seal and seem to work better than most others that are single lipped.











One seal is 45mm across and the other side is 48mm across, so you can't mess them up. A little more lithium grease on the seal to install it...





Tap it in with a rubber mallet...





Then make sure it's fully seated with a tap on a proper sized socket.





Do the same on the other side....





Make sure and clean off the engine case sealant where the engine covers need to seal against the engine. You still have the external things to instal like the pistons, cylinders, head, alternator, and pickup coil stuff, but this will get you to and from the cases being split. Hope this helps someone.

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I was asked about costs...

Cost is a crap-shoot. I've scored full sets of bearings off Ebay for $50, and I've seen them selling (Or trying to) for $250. My closest Yamaha store still has the crank bearings for $12.50 for each half, so that's $112.50 (x9 halves) and @ $20 for the one saddle bearing for a total of $132.50.

The connecting rod bearings are now unobtainium, so your only resource there will be Ebay. Luckily, these rarely go bad, and probably why they quit making them. The conrod bearings are the same on XS/XJ1100 as the XS750 & 850.

New gears are another ??? if you go that route. Most just re-grind what they have, so there's no cost there if you already have a Dremmel (Or similar) tool. Seems like I found the crank seals for @ $6 a piece, but I stocked up on several of them at the time.

A tube of Threebond or Yamabond is 12-14 bucks most places and the replacement screws I use for the torx head.. a couple bucks.

The only other big price item that you'd need would be a gasket set, and you can figure roughly $100 for that depending on where you buy it. Even if you don't use any gaskets on the sidecovers and such and just use a liquid gasket of some sort, it will give you a new head gasket, the big orange O-rings that go on the base of the cylinders, and the new valve seals that are a good idea to replace. Buying them all seperately costs more than just getting a complete gasket set. One thing I've seen though, is some gasket sets include a gasket for the middle drive and some don't. I don't worry about that personally, as I quit using gaskets there long ago and just use the Threebond or Yamabond. Many prefer a paper gasket.

There's always costs you don't count in, like carb cleaner, lube, etc..., but I've always just got that stuff around anyway.