Forum bmwbike.com

I have a 1966 R50/2. I have no power in 4th gear. I can top out in 3rd at about 60-65 MPH; 4th can barely hold that speed.

I note that for the life of me, I cannot set the timing on this motorcycle. What I did was hook up a Ohmmeter to the points, and adjust them that way, to the best of my (admittedly limited) ability. Any tips?

Lack of power could be due to low compression or to very bad timing. It would help to know more about the history of the bike and your expertise.

Static timing is OK for the initial setting to get the bike running, but you need a strobe timing light to see what is actually happening.

Before timing, it is important to set the S on it mark and then make sure the magneto on the V mark when vertical. This alignment is called abrisz and lets the magneto make the strongest spark. It the magneto is not on its mark, you must pop its rotor magnet off its conical shaft using a special bolt tool, and reposition it.
Then set the points, and then rotate the points plate to set the timing (clockwise is advance). You can read an article on this at .

Do not rotate the magneto body to set initial timing, because that will upset the abrisz setting. After timing has been set pefectly, it may change slightly, and it is OK to make small adjustments rotating the magneto body.

I will need to email you the site for the article on timing; URLs are not displayed here.

"...and then rotate the points plate to set the timing (clockwise is advance)."

Setting the timing with the points plate is a laborious, trial-and-error process. Remove advance unit, adjust points plate, replace advance unit, start engine, use timing light to see what is happening, stop engine, and repeat. It may take a few tries if you are practiced at it, or it may take a dozen tries.

This is why people like to set timing by rotating the magneto body. Sometimes they twist it so far that it reaches its stops and still the timing is off. And they have also weakened their spark.

There is a points plate conversion that allows you to adjust the timing with the engine running, as you watch the timing marks. The Pentacomm points plate costs $90 and is widely available (Bobs BMW, Bench Mark Works, MotoElektrik, etc.)

I tried it, but don't use it because I like using the original parts.

...You can read an article on this at .

The URL I inserted after the word "at" did not show.
This is a test to see if this forum will accept an indirect link to the website that did not display in the message above.

...You can read an article on the abrisz alignment
here.

Another test, this time I checked the button to show my own html tags.
The article on magneto timing should show here

Another test. It has been hard to post the proper kind of photo to this forum, but maybe I can put a reference tag to a photo on another site here

In addition to timing, the most common fault of low power at higher rpm is carbs set too rich. I said most common, there are many faults, beginning with timing too advanced or retarded, poor quality fuel, valves improperly adjusted, bad or improper plugs , bad wires, low compression, incorrect fuel mixture, going up big hill, heavy passenger and dragging your feet.

Thanks for all of your help. I never did see your last posting, but it just came thru.

As far as the history of the bike, it was a basket case that had been crashed in the 1970's and left to rot.

I have new carbs on the bike. The cans were honed, and the original pistons were still in spec. I put new rings on the pistons. The shop that did much of the work is a honda shop owned by the relative of a co-worker.

The valve clearances are correct, and frankly, I may have to break down and go to the local BMW shop; they refuse to work on any pre-/5 MCs, but they agreed to do a "tune up". . .

I almost forgot- I have a new advnce unit on the MC as well.