Page 15 – Airheads Beemer Club

Discussion of ‘Tank Slappers’–Part 1

Discussion of Tank Slappers–Part 1 (Snowbum) Since the original publishing of the discussion about tank slappers”, I finished writing an extensive article on that and allied subjects. This was after accumulating a very large number of tests on a large number of BMW Airheads, mine, and customer’s bikes. The article is on my website. Here […]

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Type V Fork Rebuild Tips

When I did research on rebuilding the forks on my 88 R100 RT, I found very little information regarding the “Type V” forks on the monoshock RT and RS’s. And, what little I found turned out to have a significant amount of incorrect information. I’m writing this to be used in companion with other information. Clymer indicates the wrong damper rod assembly for the Type V forks. In addition, the exploded views of the forks by both BMW and in the Clymer book are missing an O ring on the damper rod assembly. The BMW fiche indicates only one O ring located on the damper rod; however, there is an O ring on the valve, which is not shown. This O ring on the valve is the same O ring that is on the damper rod, so just double the order. Since I had a hard time trying to figure out what parts to order, I have included a parts list at the end of this article.

Throwout Bearing Maintenance

Sure… The reason I suggest doing this, is due to the nature of the layout of the rollers in the bearing. Before the ’74’s (/5 and earlier), BMW used a ball bearing throw-out assembly. They went back to this after 1984. If you referrence a price list, you will see that the ’74 to’84 roller set up is a LOT cheaper. The rollors are laid out radially in a circle.This insure that as the rollers attempt to roll, one end will go faster than the other and will scrape on the two “thrust pieces” on each side.

Flywheel Removal Warning

seal..etc., it is CRITICAL that the crankshaft be BLOCKED from moving forward. If you do NOT block the crankshaft, you run the risk of the crankshaft moving forward a small amount. This can result in a HIDDEN thrust washer moving downwards and off its two locating pegs. If that happens, the washer will not align back on those two pegs as you tighten the 5 flywheel (or clutch carrier) bolts, and you run the risk of MAJOR DAMAGE to the thrust washer….and even MAJOR damage to the engine casting. The crankshaft will begin to freeze up as you tighten those 5 bolts. There is another similar thrust washer located rearward of the engine casting, and it can also come off its pegs. I install it oiled, which acts like mild glue when installing the flywheel (clutch carrier) You REALLY do NOT want any of these problems happening. If you forgot or did not know about blocking the crankshaft, and you want to know IF the crankshaft has moved, there is a link near the end of this article, which will give you the information. The dimensions need to be as shown, in order to know that the crankshaft has not moved. The only way to see and get the hidden thrust washer back in place, if it has moved off the pegs,

Fuel system. Tank cleaning & protection. Premium vs. Regular. Fuel additives. Fitting other tanks/seats. Rusted/frozen seat hinge screws. Throttle & choke cables. Fuel hoses. Tank sealants/liners.

Tank cleaning & protection methods. Premium vs. regular. Fuel additives.
Fitting other tanks…seats & fitment with various tanks. Pesky
rusted/frozen screws on seat hinges. Throttle & choke cables.
FUEL HOSES. Tank sealants & liners.

No Spark on a /7

I have a ’78 R100/7. It’s my first BMW. It broke down a few weeks ago and I never got it started again. The problem is I have no spark. The local shop is no help unless you bring the bike in and I don’t trust them. I don’t think it would be a coil because there’s no spark on either side.

Double Row Timing Chains for Dummies

YOU CAN DO IT. You will want to replace everything. Don’t do a rinky dink job that will need to be redone sooner rather than later. Replace the chain $35, crankshaft nose bearing $10 and sprocket $65. Also replace the tensioner $10 and spring $2, and all gaskets and seals $17. These are 2003 prices. I got everything from Motobins and Eurotech. I found that the most worn piece was the crankshaft sprocket. The chain and bearing actually do not wear that much, but that sprocket is half the size of the cam sprocket and made of some soft stuff. The teeth get narrow and pointy. The gap between the teeth gets really wide as the sprocket wears. That’s where most of the slop in the old chain comes from.

Cylinders, case stud threads, heads, top-end, intake spigots, break-in procedures

If you are installing a camshaft and/or followers, READ http://bmwmotorcycletech.info/cams.htm regarding assembly pre-lubrication.

You may think that pulling off a jug is major surgery & frightening to contemplate. Once you do it, perhaps at a TechDay; or, from the information in this article, you should no longer have much apprehension about doing it yourself.

CAUTION-1: Every year comes questions about removing a head, perhaps for a simple de-coking (and not pushrod tube seals), & whether it is possible or not….to keep the cylinder sealed at the bottom. In order to do this, you would have to very securely wrap bungees …or via some other means, …around the cylinder fins, across the motor, & all-around the motor. Or some such. You would have to keep the cylinders from moving off the base area in the slightest. This method has been done when I only needed to work on the heads & was being done ‘in the field’, such as at a Rally, or a TechDay, & no O-rings and no piston ring compressor were on hand, etc. But, in order to do it, the bungees must be super-tight & evenly surrounding the cylinder, fore & aft. I recommend you not try it. Chances are high that you will not be fully successful & your cylinders will leak oil.

CAUTION-2: Never reuse a head gasket unless it is a real emergency. While it is possible to leave the two head-to-barrel nuts in place (the ones located at 12:00 and 6:00), & to reuse the gasket by never separating the head from the barrel, this is a poor idea. It MIGHT result in distortion of the assembly. I have not seen that distortion, if the assembly is done fairly quickly, within minutes. Pure speculation anyway. These 2 head nuts (located at 12:00 & 6:00) are supposed to be the first to be loosened, the last to be tightened (in the usual cross-staging).

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Cylinders (iron, steel, Nikasil, Galnikal). Boring, honing, cylinder shims, plates, gaskets, o-rings.

BMW has used both Galnikal & Nikasil in describing their late cylinders, & never explained the difference. BMW used at least two companies in producing these cylinders for them. They are basically the same process. Nikasil is a registered trademark of Mahle Gesellshaft (yes, the piston and filter makers). Coated cylinders are done via a plasma process, in Stuttgart, & is a blend of nickel & silicon carbide. Galnikal is a trademarked name for the process used by Kolben Schmidt, which is a major German foundry & castings maker. They also make pistons. If you have Kolben Schmidt cylinders, or other products, they use a symbol which is a letter “K” on top of a letter “S”, and it looks like this:

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Changing a Timing Chain

Getting started: I, having done this a number of times, budget about three to four hours to do this task. I’ve done it in two hours with everything going well. Sometimes you find the exhaust nuts are frozen on. Sometimes the universe is just not going to let you get that keeper/clip on the timing chain until you have REALLY demonstrated you want it. And so on. First time? Four hours: minimum. I would place this in the “advanced intermediate” catagory of dificulty.

Change oil if it is nearing that time. Turn engine to Top-Dead-Center. You have to clear away obstructing parts first: namely the front wheel, fender and exhasut system. Drop the exhaust pipes and headers, pull the front wheel and remove the fender/lower sliders, after draining fork oil (now might be a great time to do fork seals too…). It helps to have the bike on the center stand and a couple of 2X4s to get the front end up. Now remove the tank, disconnect the battery ground cable, loosen the carbs and remove the air cleaner assembly. Remove the starter motor cover, this is the cast aluminium piece on top of the engine block, you may have to undo the coils and move them out of the way to accomplish this.

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