Page 2 of 4 FirstFirst 1 2 3 4 LastLast
Results 16 to 30 of 58

Thread: Bing 32 (11/12) question

  1. #16
    Rally Rat 1074's Avatar
    Join Date
    Sep 2004
    Location
    Las Vegas, NV
    Posts
    322

    Chole assembly

    With the choke body removed from the carb, look at the inside and find a letter L or R stamped on the shaft. Left and right, simple enough. After inserting the shaft into the body, look at the outside of the shaft for a "dimple" on the end of the shaft. It will be to one side. Locate that dimple toward the part of the housing that protrudes somewhat like an ear.
    It's a good idea to pull the cables from the actuating assembly and clean all the junk out of there. It's somewhat tricky to reassemble the cables in the housing but the goal is for the cables to be installed evenly so that when you move the lever down to the full on position you can see the ends of the cables even and flush with the housing when looking through the two holes in the back of the housing (when placed on the bike). I use regular wheel bearing grease on the internal parts.
    Now that you have the actuator and cable assembly installed place the lever in the up position parallel to the ground and the lower cable ends through the carbs and into the carb lever assemblies. Push the levers on the carbs down to the stops. Some people pull the top lever down a bit so that when everything is tightened up there will be pressure down on the carb levers when the top actuating lever is pulled all the way up.
    Tighten the nuts that hold the threaded cable ends onto the top of the carb. Then tighten the clamp assembly on the carb lever and you're done.
    Having the shaft with the disc located left to right and indexed for the lever arethe spots where many people screw up.
    Boxerbruce

  2. #17
    Registered User
    Join Date
    Aug 2017
    Location
    Rhode Island
    Posts
    42
    Quote Originally Posted by 1074 View Post
    With the choke body removed from the carb, look at the inside and find a letter L or R stamped on the shaft. Left and right, simple enough. After inserting the shaft into the body, look at the outside of the shaft for a "dimple" on the end of the shaft. It will be to one side. Locate that dimple toward the part of the housing that protrudes somewhat like an ear.
    It's a good idea to pull the cables from the actuating assembly and clean all the junk out of there. It's somewhat tricky to reassemble the cables in the housing but the goal is for the cables to be installed evenly so that when you move the lever down to the full on position you can see the ends of the cables even and flush with the housing when looking through the two holes in the back of the housing (when placed on the bike). I use regular wheel bearing grease on the internal parts.
    Now that you have the actuator and cable assembly installed place the lever in the up position parallel to the ground and the lower cable ends through the carbs and into the carb lever assemblies. Push the levers on the carbs down to the stops. Some people pull the top lever down a bit so that when everything is tightened up there will be pressure down on the carb levers when the top actuating lever is pulled all the way up.
    Tighten the nuts that hold the threaded cable ends onto the top of the carb. Then tighten the clamp assembly on the carb lever and you're done.
    Having the shaft with the disc located left to right and indexed for the lever arethe spots where many people screw up.
    Perfect! This confirms that my choke levers were not set properly by the P.O.

    So per your comments above, this is where I stand:
    - L/R markings inside choke confirmed
    - dimple location on outside confirmed
    20170829_121431.jpg
    - choke levers pushed fully down with the hand choke lever up (or almost all the way up) will be confirmed shortly.

    Interesting, but with all the airhead info out there, I couldn't find this adjustment/set up. Thanks again.

  3. #18
    Registered User
    Join Date
    Aug 2017
    Location
    Rhode Island
    Posts
    42
    So now I've got the choke levers adjusted properly, but I still have one carb that won't drop the rpm when I turn the idle screw all the way in. In fact there is a slight increase when I go from 1/2 turn out to all the way in.

    As I mentioned above I replaced the gaskets and o-rings, adjusted the float levels to give me 24mm of gas in the bowls. My next thought is to go back through the carb again, starting by weighing the floats and then maybe replacing them along with the float needle.

    Any thoughts?

  4. #19
    Liaison 20774's Avatar
    Join Date
    Sep 2005
    Location
    San Antonio, TX
    Posts
    18,211
    Are you talking about the idle speed screw or the idle mixture screw? If it's the idle speed screw, then something is restricting the butterflies from closing. You could visually see that if you remove the air intake tubes and see what's going on looking down the throat. If it's the idle mixture screw, then gas is getting into the carb another way...the mixture screw controls a gas circuit, so shutting it off and it still runs means there's gas somewhere else. Did you remove the butterflies to replace the throttle shaft o-rings? If the butterfly isn't put on correctly, there will be gaps around the edges and air and gas will be able to get to the engine under the wrong circumstances.
    Kurt -- Forum Liaison ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  5. #20
    Rally Rat 1074's Avatar
    Join Date
    Sep 2004
    Location
    Las Vegas, NV
    Posts
    322

    Just another check

    OK. If you did both carbs alike then unless you missed the lack of slack in the throttle cables then you might want to re-check the valve clearance. Just a thought as a tight valve will show as this symptom.
    The /5s originally had brass bushings on the rocker arms unless changed to the later needle bearing assemblies. These bushings would wear to oval as well as wear out the actual steel rocker arm! I won't go into the theories for this event. That would be like starting an oil thread! But the point is that the bushings might rotate so that a valve adjustment might be spot on at first but then change when the worn bushing rotated.
    Boxerbruce

  6. #21
    Rally Rat 1074's Avatar
    Join Date
    Sep 2004
    Location
    Las Vegas, NV
    Posts
    322

    oops

    Forgot about the butterfly thing. Installing that disc is an art and must be done right!
    Boxerbruce

  7. #22
    Registered User
    Join Date
    Aug 2017
    Location
    Rhode Island
    Posts
    42
    Sorry for not being clearer with the correct part names.
    Here is what I did:
    - full cleaning of the carbs but I did not take the butterfly screws out. I recognized those were swaged from previous rebuilds of Mikuni carbs. I did inspect to see it they were installed correctly.
    - after the carbs were reinstalled I set the idle speed screw to just pinch a piece of paper.
    - then I set the idle mixture screws 1 full turn out.
    - had it running and made a few small adjustments of the idle mixture screws and the idle speed screws. It was better but clearly not running smoothly.
    - so I asked about the choke set up and adjusted them per the recommendations above. They were definitely set wrong by the P.O..

    - today was the first time I started the bike after the choke adjustment.
    - I readjusted the idle mixture screws back to 1-turn out and the idle speed screws with a piece of paper + 1 turn in to make it idle.

    After it was warmed up from a 20min ride, I started adjusting the idle mixture screws in small increments to balance the carbs and that's when I realized the left carb wouldn't drop rpm even all the way in.

    So...tomorrow I will recheck points gap, timing and valve clearance. And if anything is off I'll correct it. I'll also pull the bowls and weigh the floats.

    Not sure if this matters but when I first was checking the fuel level the reading I got from both bowls around 16mm. And in order to get it to 24mm I had to bend the float tang slightly past level, where before it was maybe 20 degrees in the other direction - it took a lot of bending to get the fuel level correct.

    And thanks for sticking with me...

  8. #23
    Registered User
    Join Date
    Aug 2017
    Location
    Rhode Island
    Posts
    42
    One more quick question - since I'll be looking at the valves again, should I reset the intake to .15mm? Currently it's set to .10mm, which I thought was the factory spec, but from what I'm reading it seems like a lot of recommendations for .15mm.

  9. #24
    Liaison 20774's Avatar
    Join Date
    Sep 2005
    Location
    San Antonio, TX
    Posts
    18,211
    The factory spec actually changed over time...it was 0.10 and 0.15mm at different points. Don't know if there's any consensus, but I would think that 0.15mm is better. The amount of heat subjected to the intake valve is less than the exhaust valve because inrush of fuel/air tends to cool the valve and seat. That said, it does get hot so having a wider setting might be better. It won't make any substantial difference in the way the bike runs. I suppose that with the clearance being bigger, the intake valve opens sooner and those a bit more fuel/air gets pushed into the combustion chamber. On the exhaust stroke, it will stay open a tad longer and more combustion products will get pushed out. But the differences are hardly noticeable.
    Kurt -- Forum Liaison ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  10. #25
    Registered User
    Join Date
    Aug 2017
    Location
    Rhode Island
    Posts
    42
    So two steps forward, one step back...

    - I replaced both float needles and floats and set them to be parallel with the carb body when they just start flowing gas when lowered. This gave me a fuel level of about 22mm. FWIW, the old floats weighed 13 grams, the new ones weighed 12 grams.

    - pulled both enrichers off the carbs and verified that the parts were assembled correctly - they matched the pics on the Airheads website, so all good there.

    - took the bike for a warm up ride and then spent some time trying to sync the carbs. The left carb will now slghtly drop the rpm when I turn the idle mixture screw all the way in. However, the smoothest balance was with it turned out 1/4 from fully seated. Doesn't seem quite right, but the bike does idle at 1000rpm and is "reasonably" smooth at higher rpm.

    So I moved on to re-checking points and timing.

    - points were at .4mm, so got out my DMM to check the static timing and here is were I'm confused. I assumed I was looking for a transition from closed to open somewhere close to when the "S" appears in the timing window.

    But with "S" set to the notch in the timing window no matter where I rotate the points carrier plate there is no change of state, the points simply stay open. In fact I need to rotate the engine 1/4 to 1/2 a revolution before I get to a point where phasing the carrier plate adjustment shows a changes of state.

    Maybe I'm confused?

    Engine rotated to "S" position.
    20170902_195345.jpg

    Points cam position with engine at "S" position - phasing points carrier plate makes no difference...
    20170902_182130.jpg

    Points cam position with the engine rotated to a location where phasing the points carrier plate transitions the point from open to closed:
    20170902_195022.jpg

  11. #26
    Liaison 20774's Avatar
    Join Date
    Sep 2005
    Location
    San Antonio, TX
    Posts
    18,211
    Yes, the points should open when the S-mark is in the window. Remember you have two adjustments for points timing - the gap and the rotation of the points backing plate. And the 0.4mm (or 0.016") points gap is not mandatory. The gap can be vary on either side of that and the engine will be just fine with that. The points are "working" when closed allowing current to flow to the coils to saturate the windings. When they open, the field collapses and the spark happens. On a 2-cylinder system, the points will be closed plenty long with a gap from say 0.012 to 0.022". And also, a small points gap change makes a big difference in where the S-mark falls.

    Be sure you're setting the gap with the points rubbing block on the high point of the points cam. Then try changing the gap to see how that affects where the S-mark is when the points open. Don't fall into the trap of elongating the slots in the points backing plate...absolutely not necessary...just change the points gap.
    Kurt -- Forum Liaison ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  12. #27
    Registered User
    Join Date
    Aug 2017
    Location
    Rhode Island
    Posts
    42
    Ok, that's what I thought was correct - that I should be looking for the transition from closed to open at the "S" mark.

    (Btw, thanks for confirming how the system works, because it's been two years since my last rebuild and laying on my back last night in the dark trying to sort this out was making me doubt myself)


    As to your other comments:

    - I'm certain I adjusted the gap while I was on the high point of the points cam lobe. The first time I did it was with the advance mechanism/cam lobe installed. The second time (last night) I used the points tool that everyone seems use and the gap was the same.

    - I'll pull it apart again as soon as I get a free minute and adjust the gap per your recommendation and see what happens to the "S" mark as I vary the gap.


    One more question, if you don't mind - More searching last night uncovered the Chinese points with the long rubbing block. I assume when I get things apart if I discover they are installed I should replace them before I do anything else?

  13. #28
    Liaison 20774's Avatar
    Join Date
    Sep 2005
    Location
    San Antonio, TX
    Posts
    18,211
    The points setting tool is very handy. However, it doesn't allow you to set to a gap bigger or smaller than that. Once must actually find the high point on the cam and then make manual adjustments.

    Yes, if you have the Chinese points, you might as well stop until you get a replacement. As has been shown, the rubbing block is way too big and the gap can't be set. I suppose if there was a way to precisely shave off the offending part of the rubbing block, it could be reused. But that's likely difficult to do...easier just to install correct points.
    Kurt -- Forum Liaison ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  14. #29
    Registered User
    Join Date
    Aug 2017
    Location
    Rhode Island
    Posts
    42
    Ok, first I'll sort out what I have for points then focus on the gap.


    Not sure I understand why I couldn't use the points tool to vary the gap, though? All it does is simulate the high point on the cam lobe, but without the advance mechanism in the way. Unless you mean I'd just need a different feeler gage (which I have)?

  15. #30
    Airmarshal-IL James.A's Avatar
    Join Date
    Sep 2013
    Location
    central Illinois
    Posts
    356
    Quote Originally Posted by 20774 View Post
    The points setting tool is very handy. However, it doesn't allow you to set to a gap bigger or smaller than that. Once must actually find the high point on the cam and then make manual adjustments.

    Yes, if you have the Chinese points, you might as well stop until you get a replacement. As has been shown, the rubbing block is way too big and the gap can't be set. I suppose if there was a way to precisely shave off the offending part of the rubbing block, it could be reused. But that's likely difficult to do...easier just to install correct points.
    Kurt, I almost always agree with you, but I want you to re-think the first part of your response. The point setting tool (sleeve) simply gives the user the equivalent of the high point of the cam without the obstruction of the advance mechanism. A person should be able to set the point gap at any value, using a feeler gauge set with graduated leaves like the kind we might use to set valve clearance. A narrower than specified gap will cause the spark to occur sooner as the shoulder of the cam rotates clockwise to then contact the following block and kick the points open. The China made points with the oversized following block would blow the setting out of the water as you correctly noted.
    1973 R75/5

Similar Threads

  1. Bing diaphragm replacement question
    By rolyak in forum Airheads
    Replies: 2
    Last Post: 08-19-2013, 07:56 PM
  2. Bing Type 53 Carb Question(s)
    By kentuvman in forum Airheads
    Replies: 17
    Last Post: 06-07-2013, 09:36 PM
  3. bing carb. question
    By rayfwms in forum Airheads
    Replies: 3
    Last Post: 10-15-2009, 02:33 AM
  4. Dumb Bing Question
    By BreadMan in forum Airheads
    Replies: 4
    Last Post: 10-26-2008, 11:56 PM
  5. Bing diaphragm change question
    By 535IS in forum Airheads
    Replies: 9
    Last Post: 08-23-2008, 10:09 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •