August 25, 2010

Linkert Float Replacement and Adjustment 1964 Harley

After my first ride, I was feeling pretty good about my ‘64 Duo-Glide.  The bike ran great and any problems that I had were due to operator error.  Being my first attempt at using a manual advance system, there were a couple “hiccups” along the way. 

Since I had one successful ride under my belt, I planned to ride the Duo-Glide to work the rest of the week.  The next day, I pushed the bike outside and began going through the start up procedure.  As I got ready to do the two prime kicks, I noticed that gas was pouring out of the carburetor.  Hoping for a stuck float or dirty needle, I started removing parts.  Soon a variety of brackets, oil lines, nuts and bolts lay in a pile next to my bike and I was holding the float bowl in my hands.  Nothing looked dirty and even the fuel filter was clean, so I gave everything a quick spray with carburetor cleaner and reassembled all the parts.  I reached up and turned on the fuel and once again was greeted with fuel freely flowing out of the carburetor and onto the ground.  I was already late for work, so the bike went back inside the garage and I drove the Jeep into work.

After work, I removed the float bowl again and took out the float.  Here was the culprit, the hollow brass float had filled with fuel.  I had read about drying these in the oven and resoldering the joints, but I opted for replacing it with something a little better.  A little poking around on the internet led me to Liberty Motorcycle Specialties where Cotten makes and sells his Durable Floats.  These floats are made to the same size and weight specifications as the original cork floats, but use a newer foam compound that is compatible with today’s fuels.  I mailed Cotten and soon my new float was on the way to NC.  Cotten was very helpful and even sent the float prior to my payment, just requesting I send a check when it arrived.  I thought that was very cool, I guess us classic motorcycle guys must be fairly trustworthy folks.

A few days later the new float arrived and I eagerly started  the installation process.  I pulled out the HD service manual, which came with the bike, and read over the directions.  Here is what my 1959 to 1969 HD Service Manual says on carburetor float adjustment: 

Turn assembled float bowl upside down.  Measure distance from lip of float bowl to top of float directly opposite float lever.  This distance should be exactly 1/4 in.  When adjusting the carburetor float, do not bend float lever while installed in bowl.  Adjusting in this manner bends and spreads fingers between which head of float needle fits and develops lash or lost motion between float and needle.  Float and lever assembly should be removed from bowl, and lever then bent as required.

Up until now, all the car and motorcycle carburetors which I have rebuilt and adjusted had one thing in common.  The all used a design in which the floats attached to the carburetor body.  You will see why this is important, but take note that the Linkert carburetors have their floats mounted in the fuel bowl.  Previously when adjusting carburetor floats, I would invert the carburetor and measure the distance from the carburetor body to the bottom of the float.  Old habits die hard, and so I used this same method on the Linkert floats, carefully setting the top of the float 1/4” from the top of the fuel bowl lip.

Upon reassembly, I opened the fuel line and stared at the old Linkert.  Five seconds passed, then ten, no leaks so far…  Just as I was getting ready to celebrate, fuel began pouring out of the carburetor and onto the floor.  It took two more disassembly and reassembly cycles before I realized my mistake.  There is no way that the float can even make it past the lip of the float bowl since the bottom of the carburetor is essentially flat.  This time I readjusted the float correctly at 1/4” below the float bowl lip and reassembled.

Again the bike spewed fuel all over the floor.  Bad needle, I thought.  Disassembled everything again and checked the needle.  Looked brand new, lightly tapped the top of it to make sure it was seating correctly and reassembled everything.  By this time I was getting pretty fast at the disassembly/reassembly process.  I carefully opened the fuel valve on the tank and watched the carburetor one more time.  As if on the cue, the fuel started pouring out of the carburetor at the 15 second mark.

Not to be outdone by a 45 year old carburetor, I started searching for solutions online.  I came across a post that mentioned the float should be set slightly off center or it will hang on the carburetor body.  At this point I was ready to try anything, off came the fuel bowl and associated parts.  The adjustment was made and everything was reassembled.  This time when I turned on the fuel, nothing happened.  I made it past the dreaded 15 seconds that the fuel bowl takes to fill and yet there was no gas pouring out of the sides and onto the floor.  Finally I had correctly adjusted my float!

I decided to take a quick test ride.  By the time a returned, I could smell raw gas, but this time it was dripping off my horn…  A quick inspection lead me to a leaky gasket where the fuel line connects to the filter.  Great, I thought,  how am I going to come up with a fuel line gasket.  Turns out the local dealer had four in stock (up in the attic no less) and the next day I purchased them all.  Once the new gasket was installed, everything was nice and dry and I was congratulating myself on getting everything figured out.  I also was a little irritated that the manual mentioned nothing of these very important float adjustments.  Couldn’t they at least put in a couple pictures…

Well later that night I was paging through the service manual and came to the page on float adjustment.  Then I did something that I had yet to do and that was turn the page.  Guess what was printed on the next page:

Maybe I am not as smart as I thought.  I guess the moral of this story is always turn the page…

Filed under Carburetors, Classic Motorcycle Maintenance, Panhead Jim's Blog by PanheadJim

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