4980095 9/74 DO Basket Case

[macfly]

So great to see you bringing this one back to its former glory, you are a braver man than I for taking on such a serious undertaking!

[lazyjake]

BMW trashed pistons.jpg

Here's an interesting photo of a pair of R90S 9.5:1 pistons. Or, at least, they used to be 9.5:1. The one on the left was that way when I got the bike. When the piston is seized fast in the cylinder you can't get the cylinder off the block unless the piston decides to let go or, you go through the piston, remove the connecting rod bolts, and take the cylinder off with piston and connecting rod attached. The previous owner mangled the piston and the cylinder trying to get it off. I soaked the remaining piston in Marvel Mystery Oil and automatic transmission fluid for three days and it wouldn't budge. I finally went through the top of the piston with a hole saw and you can see the end result. I think mine looks a little better but, they work about the same now.
I have a good set of R90/6 pistons (9.0:1 CR) and cylinders that I can use. This will lower the compression by 1/2 point but, with todays fuel quality and my mellow age, that might not be a bad thing. The R90S cylinders are black and I believe I can remedy that on the R90/6 cylinders with some flat black, hi temp, rattle can paint.
Did I mention that these pistons are expensive? You can buy a balanced small block Chevrolet stroker crank, rods, pistons, rings, wrist pins, and keepers from Northern Auto Parts for less than the price of these two pieces of jewelry. Ah well.

[lazyjake]

I looked at the Siebenrock "Power Kit" on their website thinking that would be the way to go. The kit is beautiful and would solve a myriad of problems however, my "early" '75 has the same 97mm crankcase opening as your '74. You wouldn't think that two silly little millimeters would make much difference. Maybe I could beat them in with a hammer?

Dale

[macfly]

Wow, that is some serious work. Did you notice this rather wonderful kit on EBay, I would have bought it but my early bike doesn't have the 99mm crankcase opening.
http://cgi.ebay.com/ebaymotors/19048791 ... _508wt_941

[Darryl.Richman]

4980095 stopping by to visit USS Razorback in Little Rock, AR. We are on our way home to Mississippi from Tulsa, OK.

Hello All. I would like to start by thanking Macfly for starting this message board and making it available to those of us that love this bike. A little background. My Son, Jerry, in Tulsa had acquired a Honda ST-1300 and wanted to give it a little test ride. He blasted his way down here to South Mississippi for a short visit. I have ridden bikes of all make and marque for most of my adult life. I was, at the time, without bike. In conversation I mentioned to him that a bike I had always wanted was an R90S. Long story short, he rode back to Tulsa, found 4980095 on the Tulsa CraigsList, and E-mailed me the link. You can guess the rest.

You can see from this one picture that the bike is rough. It was last registered in '95 and was let set out in the weather all that time. The gentleman I bought the bike from had purchased it to restore but was forced by outside circumstances to change plans and sell the project. He couldn't give any history on the bike. It truly is a basket case albeit, a complete one with matching numbers.

Major issues: The pistons were seized in the cylinders and had to be destroyed to get them out. At $360 apiece that was bad news. Good news, the engine inside (crank; rods; cam etc.) are spotless and turn over with two fingers. The instruments are pretty much trash. I have the bike pretty much apart and there was not one seized cap screw, nut or bolt. I believe that speaks to the high standard of quality to which these bikes are built. The fuel tank is rusted through the bottom and will have to be cut out, repaired and welded back. I'm not sure I have the skill to pull that off. Maybe.

That's enough for starters. I have many more pictures to resize and post. I'll work on that.

I do want to mention that it is my intention to "restore" 4980095 to my personal Specs. I believe Mr. Macfly can relate. It will get aftermarket upgrades, some visible, some not so much. It will be DO but, I may attempt to body work and paint it myself. And, it will take time because time and money are at a premium. I hope to make steady progress and keep you posted.

TKS

Dale