Hard starting 1964 R69S

[Coolbreeze]

My 1964 R69S does not want to start -- whether hot or cold. It has gas, compression, spark, and timing. I have replaced carbs and coil more than once.

I am convinced the spark is weak because the magneto magnets are weak. If that is so, would rare earth magnets cure the problem? Where might I acquire such magnets?

[AFJ]

My 1964 R69S does not want to start -- whether hot or cold. It has gas, compression, spark, and timing. I have replaced carbs and coil more than once.

I am convinced the spark is weak because the magneto magnets are weak. If that is so, would rare earth magnets cure the problem? Where might I acquire such magnets?

The spark at the plugs should be 1/4" and blue in colour. If it is yellowish and much shorter it is possibly magnetism loss or a bad condenser. Can the magnets be re-magnetized?(usual on the British Lucas stuff, don't know about German equipment). Other possibilities which you may have already looked at are the ignition key switch circuit and wiring, too small a magneto safety gap (should be 1/2") or sticking advance unit.

Another thought - magneto systems do not like resistance wire, resistance plug caps, or resistance spark plugs. And since often the wire and caps these days are not marked as resistance types it is worthwhile using an ohm meter to check that there is a good, low resistance path from pick-up to plug gap.

AFJ

[Coolbreeze]

Thank you for the suggestions. I may ask Morris Mag if they will sell me a set of rare earth magnets cut to the correct dimensions.

[Rubone]

Just find an old tractor repair shop and get your magnets recharged.

[Somer]

My 1st suspicion on BMW /2's is the condenser. Get one with a pigtail from an auto supply. All condensers are the same. See if that helps.

[Coolbreeze]

A "BMW Powerdynamo 12 volt conversion kit" is offered on Ebay for $675. Has anybody tried this conversion? This may correct the temperamental starting R69S. I have tried all the tuning tricks, but have not re-energized the magneto magnet yet.

[Lyle Manheimer]

Wow, a bit pricey for me. My '65 R50 became hard to start and it was determined to be the mag coil. When the bike was warm it was hard to start due to expansion of the mag coil and the resulting "open" in the coil. Finally it failed and would not start even when cold. Replaced the mag coil and all is fine. Once again a true one kicker. I never had the magnets re-energized.

[PRG]

Howdy sir,

Not all condensers are the same, they are rated in microferads and this becomes very apparent/important at either end of the coil output scale. I'd be inclined to remagnetize and if not satisfactory go from there.

I did an early version of this latest conversion as depicted in the pics below. Admittedly this was the last one in a very small batch done by someone who primarily focused on Vincents, created this kit for his own use, then tried it on the BMW market which proved to be far tighter with their purse strings for the cost involved, and he subsequently abandoned the project. I cast no assertions on the effectiveness or lack there of but will say this. It includes a 100 watt alternator which would not keep up with a 50 watt halogen low beam in urban use. Prior to my purchase, my R69S had been ridden the entire time in locations with very low octane gas and therefore had rather low compression via cylinder base gaskets. When doing this conversion removed them reverting to the stock configuration with noticeably more compression. With this kit fitted my machine became more persnickety to start but the most annoying was plug dry fouling under high cylinder pressure, i.e., large throttle openings at low rpm under load. Was it a system ground problem, don't know, parked this machine over 5 years ago and never pursued remedy. Many of these kits now were/are modeled after mine, be sure to research before selecting one.

https://petergz.smugmug.com/Motorcyc...R69S/i-DFVgTwL

[Coolbreeze]

Wow, a bit pricey for me. My '65 R50 became hard to start and it was determined to be the mag coil. When the bike was warm it was hard to start due to expansion of the mag coil and the resulting "open" in the coil. Finally it failed and would not start even when cold. Replaced the mag coil and all is fine. Once again a true one kicker. I never had the magnets re-energized.

Thank you for your input. I have replaced my coil twice, with no improvement.

[jim d]

Have you checked out the Vintage BMW Owners Club website? There is a wealth of information on there. You can go on as a guest. Sometimes it is as simple as removing the mag. and cleaning everything to make sure of good grounding and contact areas. Over years of time resistance can build up in those areas that will affect the ignition. There was a discussion on that on the site. A 12 volt conversion will only affect the charging area, not starting which is controlled by the mag. coil, points and condenser. There is a download available by Don Rickles called Understanding and Maintaining The BMW /2 electrical System. It is 28 pages long and well worth being in your tech. library. Replacement condenser late 60s Ford NAPA # FA82.

[PRG]

Howdy sir,

View the last pic of the offering to which George is referring which is in the link below. Note there is nothing attached to the camshaft or any components of the mag remaining. Though touted as a 12 volt conversion far more significant is a hybrid adaption of CD (capacitive discharge) ignition - if similar to my BTH sourced version - which includes built in analogue auto advance. This latter feature is what he is focusing on.

CD ignition is known for its powerful spark at low starting cycle rpm and resistance to dry fouling at high cylinder pressures and was put on the mainstream map by Porsche in 1968 with the fitment of the American sourced Permatune to their 911 range for which the most powerful version, the 911S, had reached its ignition limit at roughly 90hp per liter. BTH's offerings absolutely transform the usability of a Vincents and Velocettes and I see no reason why this ignition, if indeed CD based, would not do the same for /2's. If nothing else it would get rid of the fiddly points, increasingly rare NOS replacement parts and sometimes wobbly points cam. I need to drag mine back out from the back of the shop and sort out what is likely a simple issue.

https://www.ebay.com/itm/BMW-Powerdy...tYjUbW&vxp=mtr

[Coolbreeze]

1. Joined Airheads
2. Found Dave Fahringer who volunteered to get my R69S to start like it should.
3. Dave found the magneto was time correctly as far as the points were concerned, but was not timed correctly as far as its orientation on the engine. It needed phase adjustment.
4. Now, it starts better than it ever has.

If I understand the problem correctly, the magneto was bolted on the engine block slightly crooked. I had no idea that was even possible.

[ryan]

Glad you got your bike running well. You have a nice collection!

[Coolbreeze]

Shortly after getting the R69S back from Dave Fahringer, it reverted to being almost impossible to start. Look at my posts this month on this forum to see how it was returned to the level of reliability one expects from a /2 BMW.

[PaulCDF]

Bummer!
Have you spoken with Dave Fahringer yet???