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markrider
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Rockaway NJ
Joined: 08/20/2013
Posts: 2

Recently a purchase a 1970 BMW R50/5 with less than 16,000 miles. The bike is unrestored, complete, with minimal signs of wear.
The bike looks like it was stored indoors.

The person I bought it from was the second owner, he only owned it for a few weeks, apparently the original owner owned it all these years. The second owner said he did a "tune up" including all fluid changes.

Upon receiving the bike, I experienced great difficulty starting the engine when it is cold. I tickled each carb for two seconds and pushed the electric starter. The engine spins strongly with the starter but it takes 5 or 6 long start attempts to start the engine. Once the bike starts it takes several minutes for the bike to reach a consistent RPM to idle without constant tweaking of the throttle.

Once the bike warms up, the engine runs strong and accelerates well. Warm restarts are no problem.

I have just begun to go over the bike mechanically. I found that the second owner replaced the Bosch plugs with NGK BP7ES plugs, and installed a Chinese Battery. I plan to install Bosch plugs and a sealed quality battery.

The clutch was adjusted incorrectly, I read the owners manual and corrected this issue.
I ordered a shop manual in order to do a more complete tune-up. My thinking is that the idle jets are clogged or the valves are not adjusted correctly. Please, if anyone has any suggestions about how to correct R50/5's cold start difficulties, I would really appreciate your expertise/recommendations. This looks to be a great forum. I will post pictures after I detail the bike. Thanks
Mark

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Markrider2

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 6900
Mark - Sounds like a nice

Mark -

Sounds like a nice find! You certainly need to do some of the basics. One thing you should do fairly soon before tearing in too far is to check the valve clearances. That could make for starting and/or idling problems. Certainly, you need to consider at least a minimum carb cleaning.

I've never owned a /5 which requires tickling, but I have to tickle my R69S. While I don't have the advantage of an electric start, for me it's a matter of finding the right amount of tickling. Tickling consists of holding the button down, not stabbing at it. So, you might experiment with longer periods like maybe up to 4 seconds or so. Too, long and you'll flood it. Or it could be the bike wants less tickle time...I doubt it though.

What do you do with the throttle while cranking? You could experiment with cracking it slightly or maybe a quick twist and then closed to help with the air-fuel mixture.

Nothing wrong with NGK plugs...those and Bosch seems to be the choice. Be sure they're gapped correctly. You might have a weak spark due to corrosion in the coil towers...or a breakdown in the spark plug wire or cap. At some point, try measuring the resistance from one spark plug cap to the other one. The coils should be 5K each and the caps should be around 1K each. So, you should see something around 12-14K. That might tell you something as well.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

R.D.Green
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Joined: 12/04/2008
Posts: 281
Mark - - Here's the drill on

Mark - - Here's the drill on my 1971 R60/5 which may be applicable to your R50:

1) Turn fuel on.
2) As Kurt suggested, hold each tickler down for 3-4 seconds. Don't stab at them.
3) Open and close the throttle twice. This will activate the accelerator pumps (a tip the Bing Agency folks gave me years ago).
4) Turn ignition on.
5) Hit the starter button while holding the throttle open about one quarter or one third.
6) If the bike coughs and sputters but does not start and run, just keep working the throttle while hitting the starter button.

Make sure you have fresh fuel and a good condensor and, yes, make sure your valves are adjusted correctly. Once the bike is in tune, the more it's ridden, the easier it will start.

markrider
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Rockaway NJ
Joined: 08/20/2013
Posts: 2
Thanks for the Information-My Bike is up and running!

Thank you again for the great advice. I cleaned the carbs and found dirt in the left carb float bowl, main jet, and idle jet. Once the carbs were cleaned I checked the valves. the Right Cylinder valves were within spec, but the left cylinder exhaust valve was so tight that I could not insert any feeler gauge. I checked the head bolt torque values and found that the exhaust side left cylinder head bolts were not torqued properly. I followed the owner's manual head bolt torque sequence procedure, then I was able to set the left exhaust valve clearance properly. I replaced the covers and the bike started up with just one quick push of the starter button.

Thanks again. I am so happy! This classic 1970 BMW starts more easily than my other bike which is a 2006 Modern Triumph Bonneville! I plan to begin the detailing process, then I will post pictures.

Mark

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Markrider2

spo123
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VBMWMO #7819
north of Boston
Joined: 09/08/2010
Posts: 38
Retorquing the cylinders and

Retorquing the cylinders and heads can cause trouble......Cylinder torque needs to be 25lbs OR LESS, as the engine block (aluminum) threads can (tear) out and strip.....Just ensure that they are tight.
Have FUN and ride that bike a lot!

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spo123 '73 LWB R75/5

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