Monday, August 26, 2019

The Tale of Two Carburetors

This could also be titled: Old Motorcycles Mean New Problems

My last post described getting the motorcycles home. 


With the help of my friend Doug Wothke, who stopped in on his way to Bonneville Speed Week, the Indian started right up. He said it ran, shifted, braked, and rode well. Yeah!

Note: Doug is a real round the world traveler, unlike those two movie posers.
Check out his site here for tales of his adventures.



Inspired, I got to work on the BMW after he left and immediately ran into a brick wall. The bike wouldn't start. A little exploration revealed that the carburetors were seized and wouldn't operate. Remember that this is a 76 year old bike from the country that lost the war. You don't just run down to the local auto parts store for replacements or parts.


It took a day of carb cleaner, CRC Power Lube, and hot water soaks to get the slide to separate from the left side body. The hot water bath is to get the aluminum body to expand faster than the steel slide and break the corrosion bond between them. One problem is that the slide is connected to the throttle cable but you can't pull too hard for fear of breaking it. Remember, no parts available.


The right carb was not so easy. Three more days of all of the above were required. This time the hot water soaks had a mixture of vinegar added. Vinegar is a weak acid that will eat into the corrosion but leave it to long and it will destroy the aluminum carb body. 

Soak, rinse, check, repeat, ...


Finally, they were both freed up. As you can see, some of the parts are missing and some are different. 


I turned to Craig "Vech" Vechorik at Bench Mark Works for help. He is to vintage BMWs what Bill Silver is to vintage Hondas, the very best and most knowledgeable! He helped with parts, service, and advice for my R69S but this time had only sad news. The carbs were not Bing but Graetzin and parts were NLA (No Longer Available). Not even on EBay. However, he said he could provide gaskets which would be a big help.


Luckily, Germany was on the metric system and I was able to dig around in my box of old Honda parts and make up substitutes for the lost pieces. Not perfectly but close enough for an old war horse.

Spark plugs were another challenge. Neither the local Honda nor Kawasaki shop had the right ones but Amazon came through with the correct NGK B8HS items. I'm sure that to be historically faithful I should have chosen Bosch plugs but I've never had a failure with NGK and always rely on them.



Putting it all together was rewarded on the 5th kick! It sputtered to life and coughed and kicked a bit but it ran! Some time fiddling with the adjustments resulted in a bike that ran and idled. Wow! Older than dirt but not dead yet. An inspiration for us all.



For a real test after I took it out into the local roads and tried some dirt trails. What a hoot! I could see trying the Trans America Trail on this and having a blast.


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