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Magneto stuff - help with R60US

ahdoman
Posts: 15
Joined: Thu Aug 30, 2007 11:05 pm

Magneto stuff - help with R60US

Post by ahdoman »

be a good idea to listen to your kicker foot before you set out running amok again

good luck

The problem is I haven't had this bike long enough to feel the difference. Besides, running amok means I'm learning about all of the details of the bike.

EuroIron
Posts: 367
Joined: Mon Apr 23, 2007 12:38 pm

Magneto stuff - help with R60US

Post by EuroIron »

sounds like it, have fun

figured out if valves or rings yet?

often when they sit for long periods of time

a valve or two can need un-keying for a dance in the seat with some lapping compound...... very easy job and once you've done it a time or two..... 30 to 45 minutes start to finish

and some I've found the oil settled to the bottom most part of the cylinder has turned to a pleasant glue, easy enough to cut with modern solvents

maybe you just have a valve adjusted tight

but I am going to tell you again

you have excessive resistance in the ignition secondary regardless the culprit responsible for the low compression

low compression will have the exact opposite effect on what's happening with the arcing across the safety gap

so it seems your bike has multiple culprits

tackle them one at a time and get the compression right first

ahdoman
Posts: 15
Joined: Thu Aug 30, 2007 11:05 pm

Magneto stuff - help with R60US

Post by ahdoman »

sounds like it, have fun

figured out if valves or rings yet?

often when they sit for long periods of time

a valve or two can need un-keying for a dance in the seat with some lapping compound...... very easy job and once you've done it a time or two..... 30 to 45 minutes start to finish

and some I've found the oil settled to the bottom most part of the cylinder has turned to a pleasant glue, easy enough to cut with modern solvents

maybe you just have a valve adjusted tight

but I am going to tell you again

you have excessive resistance in the ignition secondary regardless the culprit responsible for the low compression

low compression will have the exact opposite effect on what's happening with the arcing across the safety gap

so it seems your bike has multiple culprits

tackle them one at a time and get the compression right first

The bike did set for awhile before I got it so that's a great tip. The excessive resistance thing seems to be solved with the magnet re-alignment since when I did manage to get the bike running the safety gap was no longer arcing.

BTW - how much PSI should I be getting in each cylinder? I can't find that spec anywhere.

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schrader7032
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Magneto stuff - help with R60US

Post by schrader7032 »

BTW - how much PSI should I be getting in each cylinder? I can't find that spec anywhere.

Some information on how to test for pressure and some range of numbers here:

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

Kurt in S.A.
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.

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VBMWMO
Posts: 1322
Joined: Sun Aug 23, 2009 7:49 pm

Magneto stuff - help with R60US

Post by VBMWMO »

Bike is an R60US. It was running OK but not right (see previous threads by me). One of the main problems was that a previous owner severly rounded out the advance tab channel on the magneto magnet shaft. Being the a-retententive person that I am I had to make it right. Yesterday I had a friend weld up the damage (MIG welder) and we re-installed the magneto (new points, plugs and condensor also. All gaped properly). I lined up the whole assembly per Vech's "Magneto Blues" paper and now it barely runs (if at all). If I get it started and hold it to about 2000 RPM it backfires and pops through the exhaust. I have confirmed fuel and jetting so we're OK there. Also spark is nice and bright blue at the points and plugs. Just because I know better I went back and replaced all of the old hdwe; same problem. Here's a couple of questions;

1) Is there a chance that welding the tip of the magnet shaft changed the magnet?
2) How often should I see sparks jump across the safety gap terminals? Or should I at all?
3) Is the advance collar (not the plate) supposed to move parallel along the magneto magnet shaft as well as rotate with advance?
Dedicated to the Preservation of Classic and Antique BMW Motorcycles.

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