Motorcycle Restoration BMW R75/6 Motorcycles & Other Musings Page 2

30 Апр 2015 | Author: | Комментарии к записи Motorcycle Restoration BMW R75/6 Motorcycles & Other Musings Page 2 отключены
BMW R75/6

Grey Ghost Restoration-Part 17 Rebuild, The Good The Bad The Ugly

the Memorial Day weekend, I took on the of rebuilding the carburetors.  The right carb had a broken float pin and I had to get a used R75/5 carb 5 years ago to get it running again.  The side has not been happy and the heads and valves were the right side exhaust was in shape than the left are signs of lean running on the side.

  With 103,000 and 35 the left side carb, and no rebuild in that time floats and float needles of but no rebuild) it was time to get them in condition.

To keep parts prevent confusing the parts the left with those the right side and to always a correctly assembled carb to to, I rebuilt them one at a time with the right side.  I was going to reinstall the original right side carb, I be stripping all parts off the old 75/5 body, replacing with new in the rebuild kit, and reusing the parts.  The R75/6 body had sent to the Bing Agency to the broken float boss.

  are the before and after pictures.

Bing cleaned the carb, I it up a bit more with aluminum steel wool and metal while I waited for parts to in solvent.

The first step was to remove the from the R75/5 body out the 4 machine screws.  As you can see in the picture, is the Bad part — as in dirty.  But it gets

Next, I took off the float … and now you can see the Ugly part … a nice of glop in the bottom … not a good of a healthy carb by any means.  I’m that the float was starting to which can happen with our laced fuels.  Corrosion is clearly evident on the washer the main jet in the center of the carb and the between the float bowl and body is complete toast.

I on the enricher rebuild first.  I it, and took pictures of the parts so I wouldn’t make a mistake.  I have the Bing Agency book with full view diagrams which is helpful.

  I’ll refer to numbers in this diagram in the material.

I removed the old O-ring cracked) (#26) and soaked in washer solvent for several cleaned up the housing and lever a wire wheel, aluminum and then metal polish.  I some masking tape to the threads of the disk (#47) to it easier to get the O-ring (#49) on and not it in the process.  I have some picks, one of which has a “C” shaped end I hooked under the O-ring so I pull it over the threads and the slot.

I found details in Snowbum’s BMW reference material on how to ensure the is assembled correctly.  There are two as well as another on the R75/5 carburetor.  As is the case with his read slowly and carefully and be to be told the same thing times in different places and ways.

  The right side has the curved passage on the right.

You confirm you have the correct The inside of the shaft is stamped “R” for right and “W” for wrong … :-), it’s “L” for left.

Then the is inserted as shown, with the at the 8:00 position and the little at the 1:00 position.

Then I the housing putting the new gasket between it and the carb body.  I put a amount of silicone grease on the and a tiny amount of antiseize on the of each of the screws (#51).  there is a dimple on one side of the

  This should be closer to side on the right carburator.

The handle goes on the shaft the nut (#52d) to attach the choke facing you. The shaft goes between the two verticle and the shaft should be pointing to the spigot on the carb.

I put a tiny bit of on the brass threads of the shaft and tightended up the nut.

The next was to remove the throttle linkage #28), spring (#35) and linkeage bracket (#31).

remove the throttle plate (#23) and shaft (#24).  The screws holding the throttle plate to the are peened over and are hard to I was not able to remove one of them.  So, I off the end of the screw on the back side of the plate with a grinding on the end of a Dremel tool, and drilled a hole for my smallest easy out and it.

  The carb rebuild kit comes new screws, so no worrries.

I soaked the in solvent for several hours and cleaned them.  I polished the linkage parts and springs a wire wheel, steel aluminium cleaner and then them off with metal I replaced the O-ring on the throttle using tape over the and put a bit of silicone grease on the O-ring.

  I pushed the shaft back the throttle body.  It took a of tries to get the throttle plate the slot in the shaft, so be patient and force it.  I found the throttle linkage bracket the groove on the throttle shaft and tightening the bracket screws to the body ensured the shaft not bind.  I didn’t do that the time and it bound up as there is laterial play in the throttle

BMW R75/6

  I used lock tight on the plate screws to ensure wouldn’t come loose … if do, they go right into the :-(  I also put a tiny bit of grease on the in the throttle shaft to keep turning smoothly.

Next I the top, pulled out the slide the jet needle and removed the metal (#17) holding the rubber to the top of the slide.  There is a new jet needle in the rebuild kit and a new needle jet (#4).  The vibrates and wearing the needle jet and the

  I could see grooves in the needle.

I took out all the jets from the of the carb.  When I reassembled the jet, it cracked in two.  It had a crack in it before

  I suspect a cracked main jet help carburetion any  :-(   I have extra jets, so no problem.

Each of the jets I removed #5, #1, #2, #3, #10) was very dirty.  is the crud that was inside the jet (#3) and the atomizer (#2).

I had on Snowbum’s posting that B-12 Chemtool was very at removing crud and fuel but extremely nasty stuff.  I some and wore my nitrile when handling it.  I fished the parts out of the container, the started to wrinkle … the next the finger parts had completely … nasty indeed.

After all the jets were cleaned, I put new on them again using the tape trick and “C” shaped pick to pull them the groove on the jets.  I broke one but my handy Ace hardware had a metric :-).  I put a tiny bit of antiseize on the jet as they are brass and screw pot metal threads.   I installed the new jet (#3) and atomizer (#2).

  The exploded view diagram and the I took helped me make these went together in the order.  I installed the new float float needle (#4) and float pin (#1  from the rebuild kit and then put in the new gasket (#46) into the groove in the of the float bowl.

I reassembled the slide (#13) the new diaphram (#16) from the kit putting a dab of antiseize on the screws.  I the internal spring (#22) was not part of the original carb supplied these and said them would improve gas

Then, I put the top (#20) back on and put a amount of antiseize on the four (#21) that secure it to the carb

Now for the Good part.  Here are and “after” pictures showing the right side carb and the yet to be left side carb.  night and day.

I did it all one more on the left carb.  Both in need of attention, so I am very they will operate better and the bike run a lot smoother.

BMW R75/6
BMW R75/6
BMW R75/6


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