To split or not to split? That is my question.

[Chuckwagon]

I'm well into a rebuild of my '77 D engine. I had rebuilt the top end 4 years ago and about 6000 miles on it. The oil slick it left behind everywhere we went became an embarissing let down to what is an otherwise great running engine. I've lived with leaky bikes, but this was ridiculous, especially since it was my hands that did the rebuild. Granted it was my first engine rebuild, and I've learned and improved my methods since then. The only high point of this scenario (besides that the bike always got me where I wanted to go, no problems), was I never ever had to worry about oiling my drive chain!

One of the multiple leaks was under the clutch cover. It was a mess under there, so it was hard to tell exactly which seal it was... could be all three. During the first rebuild, I replaced the countershaft seal and the clutch push rod seal and the push rod bushing as well. I followed the directions as posted on this site and with the bushing that came from mike's xs. I did my best at the time to make sure the seals were evenly seated and used a bit of three bond on the outer edge of the seals.

A friend and sometime mechanical adviser to me who is a retired motorcycle mechanic and mechanic instructor for Honda just shook his head and laughed when I told him that I had replaced the seals without splitting the cases... as we know, these seals were inserted in between the case halves prior to assembly, the shift shaft seal being the exception in that area.

I also know that many on the board and otherwise have had success in installing these seals without splitting the cases.

Since my first rebuild of the XS engine, I've successfully built leak free british engines... split the cases and all. I know... you think I'm lying. ALL BRITISH BIKES LEAK is a commonly held belief. Anyway, point is, splitting the cases isn't as daunting to me as it once was.

I do have some worries with splitting the cases on this engine though.
1) I don't see the cases just lifting apart magically as the manual shows... That yamabond they used at the factory works really well. I had a tough time getting the valve cover off that was glued on with the stuff.
2) I don't see a good place to pry the two halves apart once the previous statement comes true
3) I'm afraid of goobering-up a really nice paint job I did on the cases on the last rebuild that has lasted the past couple years. To add to my theory of point 1, I painted the cases, and now that paint is adding to the "glued shut" phenomenon I fear.
4) The big end bearings and crank "feel fine" from manipulating the con-rods and other indications. The engine has 17k total on the bottom end, and is quiet and the transmission shifts well. Really not much motivation for me to split the cases besides ensuring I don't have to screw around with these seals again for a long time.

I've pulled engines apart by using ratchet straps mounted to fixed points to apply gentle and steady pulling pressure and letting time do some of the work. That method worked, but again, I don't see any good attachment points or pry points. That's not to say they don't exist... I'm just not seeing them. If I'm ignorant, please enlighten me.

So what do you guys think. Split them, or try again with the method that I failed at executing on a previous attempt?

Thanks -
Mark

[Chuckwagon]

Zzz... This once bustling wagon stop has become a ghost town. So much so I have resorted to replying to my own posts. Just kidding guys... You must have lives or something.

Anyway I found this on "the other board" (yikes!)

"If after all the bolts are removed and they are still stuck together...this is what I did to split my cases.

I used ratcheting tie down staps and attached one to the lower mount and one tie down to the front and upper rear mounts (I used nylon webbing and the stock bolts for the rig) put the engine between two solid posts and slow ratchet to split them. You will want to allign the rig so that is separates straight across."

So I will save you all the hassle and judge myself as both ignorant and blind regarding part of my previous question as to points to attach ratchet straps to. (Easy cowpoke, Put that flamethrower down)

As of writing this I am feeling motivated to split the cases for reasons including charting a course through previously unseen territory (for me at least). And ensuring my seals don't leak. Maybe my seals won't leak but my cases will. Mr. Murphy lurks at every corner to uphold the law in these here parts but I was born free and stupid, so catch me if you can, Irish Lawman. One way or another, a lesson will be learned.
One other motivator is that Ive also noticed a "tight" spot when I rotate the countershaft that piques my curiosity. If my Yamaha were a Norton, that would likely mean a bent main shaft as typical of that fine British marque. What does it mean on a Yamaha? No reason to suspect issues with the transmission otherwise... Never a hickup in the miles I've traveled.

[preston]

Thanks for your posts and insight....
.. hope it works out OK for you and you enjoy the ride.
preston

[Chuckwagon]

Hey, Preston... hope you have been well. Have you been to the VJMC show at WRMC in recent years? I moved down to Delaware, so it isn't too far, but apparently far enough that I haven't gone in 3-4 years. However, I have been to the AAMC show in Oley, PA... usually held in April, and a very worthwhile place to visit. Lots of american bikes and other origins, and many that are pre WWII. Y
I was reminded this summer of our meeting at the VJMC show... I once again got stung on my hand by insects. I unwisely decided to do battle with a large nest of baldfaced hornets that I felt was too close to set of stairs; the hornets, on the other hand, thought I was too close to their nest. I lost that battle, but won the war by calling in the professional exterminator.

[preston]

Hope i do not get yelled at...
YES i go each Friday and Sat to White Rose PA, VM swap meet ( 3rd weekend in August ?)
This year saw several 650's and 650 parts,,, only got gloves,, last year my nice saddle bags, and when you were, your exhaust system, which is still on the 75 ride.
You still riding the green 650 ? we rode last day of the year,, fingers still numb.
preston

[Chuckwagon]

Yes, still riding the green '77, "The Hulk"... that is the bike/engine I'm currently working on. My only XS, which is actually really my wife's bike. She rides it, but I put more miles on it. I'm working on convincing a coworker of hers that has what looks like a '75 stashed in his barn for the last 30 years. claims "he's gonna fix it" and won't let it go.
I always have fun at the VJMC swap meet. I got two decent side covers for my XS, but I think that was all I ever bought there. Just never find what I'm looking for. I always took a pile of stuff to sell.
I picked up a free (really) Benelli 650S recently. Engine was disassembled due to a broken shift fork, then never put back together. So most likely I'll be looking for parts for that... so of course, if you have any leads on Benelli stuff please let me know. Kind of rare in the US, so I'm casting the net far and wide.

[preston]

hey Mark,,, i do not know much about these 650 Yamaha's , let alone a Benelli. ( i may send you a PM, about someone who may know )
and... I do know your gauges are still on my 77 ride, so all is good there.
preston

[Chuckwagon]

I was able to rig up the engine on the workbench with a few ratchet straps looped underneath the bench and the engine mounted in the engine stand I bought off ebay several years ago. The engine was attached to the stand only by the bottom, and I also tried to balance the pull by adding rope looped around the ends of the crank and tied to the stand, since there is only one engine mount on the bottom case. The stand makes a more stable platform, and also gives you something solid and safe to whack with a mallet.

I put a lot of pull into the straps, but nothing gave. I put more pull... more nothing. A bit more and I'm getting scared something is going to give and take out my head. I hit the stand with a mallet. nothing. carefully hit some of the through studs with a drift and hammer... still nothing. I decided to go eat dinner and let things happen on their own. About 45 minutes later, I hear this thud come from the basement. Aha... I think my engine came apart. Fortunately no damage, but that was lucky. I should have backed down the tension a bit before I left. Ideally, I wanted to be there to guide the process, but no harm no foul.

[motormike]

Can we assume the clutch rod bushing isn't a issue.. if it's worn.. even a new seal may not solve the oil leak... I'd try seals again... I take the sharp edge off the case seal entrance... for the clutch rod seal...I'll insert the road..it centers the seal...then with the flat side of a socket.. hammer it home. PCV pipes has diameters that work well for the sprocket seal.
I helped a buddy and we discovered a small nick on the push rod that created a leaky seal. I have split cases before.. crank replacement .. and I used a hard rubber mallet... with a wood stick on inside of the case near the sides... I slowly worked it around and around...top and bottom, both sides...and it separated no problem...

[grizld1]

Yep. A little impaction with a wood drift is all it takes, if you just want to get the cases apart. But the goal here was to to do the job without marring those nicely painted cases, and the solution shown is elegant. Good work!

Mike, why would you fool around with chamfering edges, driving seals, etc., with the cases split and waiting for the seals to be laid in? Right, if the clutch rod bushing is worn a new seal will get wallowed out in a hurry.

[Chuckwagon]

Jan 22, 2015 10:41:05 GMT -5 motormike said:

Can we assume the clutch rod bushing isn't a issue..

Yes. I replaced the push rod seal and bushing as mentioned in my original post, but thanks.

[5twins]

Something not mentioned and what could have very well been your problem is that the countershaft sprocket nut needs to be very, very tight or you'll have a very bad leak in that area. It's actually not the seal that's leaking though. There's a sleeve that fits into the seal and presses against the inner race of a bearing inside the cases. You can see this at the bottom right in your last photo. If the nut isn't really tight, the sleeve won't be tight enough against the bearing race to seal. Oil will flow out between the shaft and sleeve.

[Chuckwagon]

Jan 26, 2015 12:30:27 GMT -5 5twins said:

If the nut isn't really tight, the sleeve won't be tight enough against the bearing race to seal. Oil will flow out between the shaft and sleeve.

Aha. That is a very good piece of information. In fact, my countershaft sprocket nut was very loose when I removed it. In looking at the oil seal, sleeve, shaft and bearing, I thought to myself... "how the hell is this setup supposed to seal oil in the crankcase? What prevents oil from passing through the bearing and then inside the sleeve along the shaft to the sprocket to the outside of my cases?" Indeed, I noticed that there was a lot of oil being thrown off the sprocket, and my chain was always nice and oily... I never needed to oil it. I was confused by what I saw, and thought I may have assembled things wrong or missed a part, so I looked at the parts diagrams, but everything that was on the diagram was on my bike and in the correct sequence. So I surmised that I had just poorly installed a seal (which could also still be true) that was causing a leak. But this new information (new to me) regarding CS nut torque is correlating with what I saw and was confused by. I'm sure this key factor has been pointed out somewhere on the forum, but I never took notice of it or paid enough attention. It is too long ago to remember how I torqued down the CS nut, and I never thought it was loose, so I never rechecked it after putting things together. Thanks for pointing it out! I sure would be upset with myself if I had gone through all this work, just to have another trail of oily pavement following me around. However, I did take note of the loose sprocket I found during disassembly and was planning to make sure I addressed that when putting it back together... more for the sake of preventing damage to the sprocket and the shaft, without understanding the implications on sealing the oil in the case. Thank you!

So the next question is, what is the best method to ensure a tight CS nut? I believe I have the right size socket in the garage, sized to be fitted to a 1/2" breaker bar. I was planning on putting the bike in 5th gear, locking the rear brake and also tying a strap around the wheel to hold it to my bike lift (for good measure) then torquing it with the breaker/checking with a ft/lb torque wrench.

Also, new light has been shed (literally) on the poor state of the head, which also appeared to be leaking between the head and cylinder. Since building the XS650 engine 4 years ago, I've spent a lot of time building a BSA 650 engine and dealing with similar head leaks. I learned a lot through working on the BSA, specifically how to spot and fix a warped head.

Applying what I learned to the XS650, I found that the head was warped. I could tell this from the appearance of the head's mating surface (to the cylinder) as well as by dry fitting the head to the cylinders... I could rock the head back and forth. I could also see light passing between them when I would illuminate with a flashlight. Same goes for using a straight edge and flashlight on the head itself.

The solution that worked very well on the BSA, and which I used on the XS650 is to hand plane the head. I did this by taking a large sheet of 800 grit sandpaper and taping it against a piece of plate glass. I then clamp the glass to my workbench, lay the head on the sandpaper and move the head across the sandpaper with a figure 8 pattern. I had to remove the lower exhaust studs from the head first. I work the head until I can see an even surface - you can see this by eye... the sheen of the aluminum changes as it makes contact with the sandpaper. When you first start the process, you can easily see which portions of the head surface are making contact with the paper and which are not.
I took some photos, which are just ok... will try to get some posted.

Also, while I had the head apart, I worked on the valves. I first turned the head upside down and poured gas in the combustion chambers. no gas leaked through, so that was a good indicaiton. I carefully scraped all the carbon off the heads. I removed the valve springs and I checked for valve guide wear by wiggling the valves to see if there was a lot of play, but didn't take any measurements (don't have the tools). I replaced the valve guide seals, though I had no reason to suspect they were bad... cheap insurance. I also lapped the valves using sticks and grinding paste. I reassembled after cleaning everything, and put assembly lube on the valve stems. Plan on re-checking with gas to make sure I didn't somehow make the valve seats leak with my work.

[5twins]

To tighten the countershaft nut, I put the bike in gear (usually 2nd), sit on it, apply the rear brake, then reach down and tighten the nut. The torque value is one of those specs that changed frequently over the years, I don't know why. The early models had the highest spec, about 13.1 m-kg (94.75 ft/lbs). Some of the later Specials speced it as low as 36 ft/lbs. Common practice is to use the higher early value (or close to it). That seals the best. Remember, you're trying to seal a steel sleeve against a steel inner bearing race. It has to be very tight.

To test for valve leaks after filling the combustion chamber with liquid, I blow compressed air into the intake and exhaust ports, and watch for streams of air bubbles emanating from around the edges of the valves where they seat into the head. Liquid just sitting in the head will show you big leaks but not the tiny ones.

[Chuckwagon]

Thanks for the torque spec... sounds right. I had in my head at least 80 ft/lb. I will probably ask my lovely assistant (the wife) to sit on the bike while I use two hands on the wrench. Trying to to read 95 ft/lb while pulling a wrench to that torque with one hand at the same time as sitting on the bike and pressing hard on the rear brake sounds like a recipe for a rounded off nut, bloody knuckles and broken teeth on the garage floor with my luck!