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1978 R100/7 Topend Overhaul

Still recovering from yesterday...hard work! I didn't take as many pictures as I hoped...I must have been in the "zone".

The first thing was to put assembly lube on the exposed camshaft and then I lubed the new cam followers and slid them into their holes. I put a very thin film of Permatex Ultra Grey on the engine case and on the outboard side of the compression reducing gasket. I made sure there was no buildup of sealant around the top studs. The gasket was 0.66mm thick. I made sure the small o-rings were on the upper studs...they fit into small recesses on the bottom of the cylinders. Here's a not so good picture of the sealant on the case.
 

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Next was to assemble the pistons on the rod. This turned out to be a real challenge with the internal snap rings...my thumbs are still very sensitive today. This picture shows the snap ring I installed fairly easily with the piston in my lap. I installed each of these rings so that the gap was pointing to the engine. Then I positioned the piston so I could slide the wrist pin in and installed the opposite side ring...that was what took some doing. Also shown is the left side piston all installed on the rod.
 

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The rings were installed using the orientation noted by Oak in his topend book. He suggested (left side) the following locations for compression/nose/oil control rings at 4:30/10:30/1:30. The right side is the mirror of that.

I applied oil to the exterior part of the pushrod tube seal and around the OD of the pushrod tube and slide the seal onto the tube in the proper orientation (goofed on the right side and had reversed the direction of the seal; had to pull back and reverse the seal). Used a ring compressor to slide the cylinder on the piston but because of the style of ring compressor and the shape of the piston, the compressor was bottoming out and I couldn't get the oil ring to slide in. Bill noticed that. I found two smaller hose clamps and tied them together and created a ring compressor for the oil ring and got the cylinder all the way on. Before sliding home, I put some assembly lube on the skirts of the pistons. According to Ted Porter, the rest of the topend was dry except for some lube on the wrist pin.

This picture shows the cylinder all the way on with the head gasket installed in the proper orientation.
 

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The cylinder will only go on so far before the pushrod tube seals hit their holes. When I tried to put the head on and the rocker arms, there wasn't enough purchase on the head bolts to draw the assembly to the block. So, I removed the rocker arms and used a washer and head bolt on just the lower head bolts. It was important to draw the assembly down evenly and that can be done with the two lower nuts. Once it was within about 2-3mm of the engine case, I could install the pushrods, rocker arms, nuts and complete the drawdown of the assembly. I also had to back off the valve clearance adjusters to avoid putting any pressure on the rods.

Torquing went in stages to 10, 15, 20, and 25 ft-lbs. I used the sequence of bolts at the 2, 8, 4, 10, 6, 12 clock position. Here's a shot of the left side all done up. I'll go back and recheck torque soon to see if things have settled in any.

The right side went a little faster, but those darn snap rings were troublesome again. Things still to do are: reinstall oil pickup with new gaskets, remount oil pan and fill with oil, spin the engine to ensure oil flow to rockers, exhaust, carbs, and general cleanup. I need to wait for the tips of my thumbs to feel better!
 

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I'm very envious of your very cool new hardware and the good work going on in your garage. Wish I could zip in those cylinders/pistons, but, it wouldn't be cost effective for my old bike. The fun part comes on start up. Easy as it goes, take plenty of time, congrats on the job.
 
Love what you're doing & sharing Kurt.

As I'm reading all the detail and care you're putting into re-assembly I had a thought about how the employees at BMW put the engines together - probably for them 1-2-3 next 1-2-3 next.

At any rate, looks like great progress Kurt.
 
Let's see if I can't bring this to a conclusion! The dynamic duo (w/ Bill) got to work again yesterday. I had already installed the oil pickup with blue loctite on the bolts and remounted the oil pan. I rechecked the head bolt torque after sitting for a week...some of the bolts need a bit more torque. I backed them off almost a quarter turn and ran them back up to 25 ft-lbs. I set the valve clearances at 0.15/0.25mm intake/exhaust...a little looser on exhaust until things settle in.

This was the critical point. I needed to spin the engine to ensure that I had oil flow to the rocker blocks. I secured each spark plug to the top of the cylinder using rope as shown. I wish I had binder clips like shown in another thread...I'll have to remember that...but the rope worked fine. I cranked for 3 days...OK, it was more like 30-40 seconds. Finally got some oil to both rockers. I didn't know what to expect, but it looked good enough. Once that was done, I could put on the valve covers and move on to the exhaust system.
 

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Got the headers all set up. Put the exhaust nut on first, then the compression ring and split ring. Coated the exhaust threads with anti-seize...I used the nickel variety which is good to 2400 deg F. The headers slipped in and the nuts screwed easily...put the rest of the exhaust system in place. Then went back to the front and began tightening all connections, tweaking things as we went. The clamp on the left side at the header/muffler connection was impacting the action of the sidestand, so I had to rotate it a bit for clearance.

Excuse the dirty valve cover! I'll clean those up the next time they're off for retorquing.
 

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We got everything place...mentally going over the steps and nothing seems to have been forgotten. Here's a picture of the new cylinder. Interesting color combon with the very bright cylinder, duller refurbed head, and dirty valve cover. I'm sure over time, the color will even out. She was ready to roll!
 

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She Lives!!

Initially, I hadn't planned on riding because the weather was supposed to be messy here (hey! we got some rain! :clap ) But we finished somewhat early, the sun was poking out. I'm going for a ride!!!

Got suited up. The next moment of truth!! She started, took some coaxing...the last time I rode the bike was in December. Finally got some throttle response and held the RPMs at around 3K for 60 seconds...a very long period of time! Smoke was roiling off the exhaust nuts. Kind of weird doing that. Threw a leg over and went for about 20-25 miles. Bill followed in the car as I made my way to a gas station.

I got to say, I've very pleased at this point. The bike sounded fine after the initial start. A little extra valve noise due to the wider exhaust clearance. I can really feel a change in power level. It accelerates very nice. It seems smoother, but I haven't done anything to the carbs and will have to resynch them. I tried not to dwell at any speed for very long, going up and down on the throttle and getting some back pressure in going downhill. Bill said he didn't notice any smoke when rolling off the throttle.

So, on with the break-in. I'll drop oil and change filter at 50 miles...a bit extreme but I just want to get that out of there. I'm running 10w40 right now and will switch to 20w50. I'll also check valves and head torque. I should also go over every nut/but that was removed just to be sure that everything is staying tight. I'll change/check everything at 500 miles...hopefully the settings will be stable.

Thanks for reading along. No real drama along the way. Having an extra pair of eyes didn't hurt either!
 
Congratulations, Kurt - you took this project one step at a time & I liked your decision process along the way - nice looking machine!
 
Thanks...I guess the proof of the pudding is in the eating! Or in this case, a nice ticking machine!!
 
Congrats on taking the dive for those trick new cylinders/pistons and the finished product. The thing I can never wrap my mind around when handling a piston before installation, is how can these slugs moving, what 3000 odd feet per minute?, come to two complete stops while changing direction, and going the other direction, without flying to bits? Or is it 3000 feet per hour? Anywho, it seems physically impossible.
 
Nothing like knowing the job was done right because you did it. Enjoy the many trouble free miles this will bring.

I probably won't be able to really relax for at least another couple of thousand miles! I always have this nagging wonder...what did I forget or not do right. Anyway, I'm loving it so far. :dance
 
I probably won't be able to really relax for at least another couple of thousand miles! I always have this nagging wonder...what did I forget or not do right. Anyway, I'm loving it so far. :dance

I feel ya... I did mine more than 7 years ago and I still get that nagging feeling...:huh

I'm sure it will work out great- nice pics of the job as well. :beer
 
Roll on Roll ON............Good job and just as expected from YOU it is running great.............God Bless.....lol.......HE is with you Bud........Dennis
 
I'm curious after reading your article on oil, what type are you going to be using?

I'm starting with BMW's petro 10w40...it was suggested by Ted Porter, probably more for what he thought might be colder temps. My first oil change I will go back to BMW 20w50. At some point in the future, I'll switch to Spectro 20w50.
 
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