R60/6 '75 backfiring issues.

[Deleted User 72]

I believe Duane has a page on static timing. If not, he still has a ton of stuff you'll want to know.

http://w6rec.com/duane/bmw/index.htm

Also on Duane's site is a link to someone who sells a little tool that greatly simplifies setting the points gap. Its a sleeve that slips over the cam in place of the advance mechanism which is a bother if not removed, and when removed no longer opens the points. Sounds worse than it is. Get the tool. You won't regret it.

[Kurt in S.A.]

Yes, Duane's link is http://w6rec.com/duane/bmw/points/index.htm

Kurt in S.A.

[Lasse]

Yes, Duane's link is http://w6rec.com/duane/bmw/points/index.htm

Kurt in S.A.

Can you be more specific please? I read that page twice already, not having found any detail on actually doing the static timing.

I see the gap part and then a long description of the various parts and testing of those.

Regards, Lasse

[Kurt in S.A.]

Turn the engine (plugs out using an allen wrench in the alternator bolt, or engine in gear and turning the rear wheel), find the point at which the points open the widest. The rubbing block of the points rides on a cam that changes dimensions as it turns. Once at the highest spot, slip a flat feeler gage of 0.016" between the points. Basically, you'll need to change the gap to equal 0.016"

Point gap is changed using one screw (IIRC)...not the two screws around the edge of the points plate. The advance unit has to be removed to make this adjustment. Take care with the 10mm nut that holds the advance unit on. Loosen the single screw, use the tip of a screwdriver to change the gap, replace the advance unit, remeasure the gap. There are other nifty ways to do this...this is the classic way.

After getting the gap to around 0.016", now hook a multimeter to the points, preferably one that has a buzz feature of continuity. One side of the meter is ground the other side is on one of the points...the arm I belive, but you'll have to figure it out. Turn the motor again. Mostly the multimeter will be buzzing. When it stops buzzing, stop turning the motor. Look at the timing hole. You're looking for the S-mark...probably a series or 2 or 3 lines. If 3 lines, try to get the get the middle line in the middle of the window.

If no S-mark, you have to figure out where it is and what to do next. Two ways to then adjust the timing. 1) Loosen the two outside screws and turn the whole timing plate. Tighten the screws and recheck where the buzzing stops by turning the engine again. If you run out of screw slot with this method, you need to go to #2. 2) Change your gap, either narrower or more open. Think about what's happening with advance unit cam and points rubbing block. Then make a change to the points gap.

It may take several iterations to see what happens when you move the point gap one direction or the other. When you do that, the light bulb will come on and you can hone in on the correct gap and rotational position of the points plate.

Beyond that, you may need a local Airhead to come by and help you out. It's not difficult but it's fiddly and you have to understand what you're changing as well as the responses from the timing when you make a change.

Kurt in S.A.

[Airbear]

G’day Lasse, and welcome to the forum.
I had much the same trouble shortly after my 90/6 came into my life. While checking the source of misfiring I found that the little felt oiler was completely gone and the fibre points cam-follower had worn down such that the points were near enough to closed. The points surfaces were also very lumpy – mountains and valleys reminiscent of the Himalayas. Everything in there was pretty buggered.

I priced a new cam plate – yikes - $220 here in Australia. Bought some new points and condenser and made a new ‘felt’ by pop-riveting a strip of suede leather over the arm. I saturate this with some marine grease. This arrangement is still working well after 10 years and 60k kms.



I urge you to get yourself one of these to do the static timing – about $6



The screw-on cover for the tip wedges nicely into the cylinder fins for convenience. Carry it with you, along with a points file, feeler gauge with a bent end, and some spare points and you are covered. Here is the relevant stuff from the Clymer manual (to my mind the best book to get).




Note that the ‘buzz box’ shown can be replaced with an ohmmeter, continuity tester or test lamp hooked up the same way.

Ah, I see Kurt has written a description of the static timing procedure while I’ve been writing this. For setting the points gap, I use a 0.016” feeler gauge with a 45 degree bend about 10mm (3/8”) from the tip. This allows me to (just) be able to set the gap without removing the advance unit each time.

Good luck with it all. In a way, this little difficulty you are having is a good introduction to old airhead ownership. Getting intimate with every part of your bike gives a nice sense of security, especially if you go adventuring.

I'll add that it is good to see a young fella here getting down and dirty with a fine old machine.

[Lasse]

It is not my first oldie

My MZ TS250 (2stroke), taken in Switzerland this summer


AJS Model 18 1952


Honda CB500 Four K3


Thank you guys for a nice welcoming

[Deleted User 72]

That AJS is a beauty, Lasse. Did you do the custom work to it?

[Airbear]

Wow, what Native said.

This was me in 1974 - 1954 AJS. I had a '51 Matchless before that.


I much prefer Bosch electrics to Lucas.

Back to the /6, I've just picked up an Omega electronic ignition to fit to my old girl -

http://www.omegaignitions.com/

It is crank mounted, so there are no problems with each side being out-of-sync, and I get to retain the points as a backup. And there's a bunch of advance curves to play with. Yay!

Any progress with your timing?

[Lasse]

I bought it as seen there, what a sh!t example I got, very bad put together, lots of stainless "custom" parts that weren't up to the original measurements, so nothing would fit properly.

The Omega system looks neat, however it looks to be more than I can handle at the moment. I am not good with electrics.

Did consider the Boyer though.

Edit:

Upon further reading, the Omega seems quite neat actually!

Btw. tried to set the timing today. F came up at 1000 RPM, which of course has changed so much because of the faulty gap. So I am going to rotate the pointsplate counterclockwise to retard the ignition. If only some prick didn't tighten the screws so much. I think I am going to have to drill them out.

[Airbear]

If only some prick didn't tighten the screws so much. I think I am going to have to drill them out.

Lasse, I think all Previous Owners everywhere should be lined up against the wall and shot. (er, me included. I've done some terrible things to bikes along the way and I now regret parting with any of them.) One of my backing plate screws has stripped, the one that the Previous Owner replaced with a huge self-tapper. Fixing that is on the list.

It'll be a nasty little job drilling those screws out - maybe try an overnight soaking with WD40 and that One Good Hit with a favourite hammer on an impact driver with a well fitting bit. Some german expletives might come in handy. Good luck.

ps: Lasse, just between you and me, things on AJs and Matchies did not fit in the first place. The primary chain enclosure still makes me laugh. It's likely that your temporary fear of things electric appeared when you came in contact with that AJS. Hopefully you will embrace the simple but quirky Bosch electrics. There's lots of stuff in the Boxerworks Archives and Duane's and Snowbum's sites and others that you will blunder across. The Clymer manual is a worthwhile investment. You've got a great bike there for the highway, the twisties and the dirt. I'm sure she's got some education planned for you, and you are going to love riding her when any catchup repairs and maintenance are done.