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Old 11-24-2012, 05:08 PM   #1
LanceR75 OP
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Got Her Running. First Ride. First Impression.

I'm used to riding old brits and this is my first time riding an Airhead. Maybe you guys are used to this and something I didn't consider or expect but, I can feel the boxer motor's horizontal (boxing) movement when riding and can see it when it's on it's center stand idling. I'm gonna assume that this calms down a bit at the right RPM but wanted to make sure from you guys that this is typical of this breed.

On another note, what a kick in the pants it is to ride. A different feel from what I'm used to but cool non the less. I can tell the forks need a rebuild and I need to check the timing and valve clearances. Starts on first or second kick with the right sequence of events prior... I think I ended up with a pretty solid but a little rusty /5.

Thanks for all of the help getting it to this point so far. This forum is awesome.
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Old 11-24-2012, 05:12 PM   #2
robtg
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Airheads have more handing quirks than a carload of circus clowns. When you get used to it you won't notice them until you ride something else.
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Old 11-24-2012, 05:27 PM   #3
disston
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Congratulations! What you describe sounds not exactly normal. Visible movement side to side is usually a couple of very out of balance carburetors. What have you done so far to get this far?

To try and answer one of your questions, there is a point from about 3500 to 4000 rpm that many of them vibrate the most in. I had this for a couple of years. But I have actually learned to balance my carbs better or it's worked it's way out. Mine still has some vibration but she is a strong runner and in 5th gear at highway speeds she's smooth.
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Old 11-24-2012, 05:53 PM   #4
LanceR75 OP
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Quote:
Originally Posted by disston View Post
Congratulations! What you describe sounds not exactly normal. Visible movement side to side is usually a couple of very out of balance carburetors. What have you done so far to get this far?

To try and answer one of your questions, there is a point from about 3500 to 4000 rpm that many of them vibrate the most in. I had this for a couple of years. But I have actually learned to balance my carbs better or it's worked it's way out. Mine still has some vibration but she is a strong runner and in 5th gear at highway speeds she's smooth.
Balancing, you say. I was thrilled to get both sides producing heat out of both tailpipes. I found I had installed one of the slides 180 degrees the wrong way but with that fixed. Just excited to get her to idle and ride. I have a Bing manual on the way and will work on that and other things next.

I've visually checked that both sides are opening the same time the throttle is opened and the idle screw is turned out the same on both sides. Nothing much else.

On a side note; the clutch doesn't disengage until the lever is almost all the way out. I'm assuming the bolt at the clutch arm needs to come out more as the lever adjuster is all the way in.

Cheers!
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Old 11-24-2012, 06:20 PM   #5
disston
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There is an actual measurement for the clutch arm free play at the back of the transmission and the free play at the clutch lever on the handlebar. I'm no good at explaining this one so let me just say: There should be free play at both ends. The arm on the trans and the lever on the handlebar.

Hopefully your new book might explain it better than I.
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Old 11-25-2012, 06:28 AM   #6
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Quote:
Originally Posted by LanceR75 View Post
On a side note; the clutch doesn't disengage until the lever is almost all the way out. I'm assuming the bolt at the clutch arm needs to come out more as the lever adjuster is all the way in.

Cheers!
Here is a procedure by Mr. Tom Cutter that was posted on the BMWOA forum.
It works good to set the freeplay and travel of the arm.

Do a complete, "from scratch" cable adjustment after replacement. To do this:

1) Replace cable, both ends now disconnected.

2) Loosen locknut at transmission lever, slacken adjuster screw several
turns out.

3) Insert top end of cable through adjuster, into the lever slot, pushing it
WAY in to the lever. Slip the greased barrel up onto the cable, and pull the
cable back to engage the barrel on the cable. Clean and examine all parts to
see that the barrel only goes in one way.

4) If the cable is routed properly, and the top barrel seated correctly, you
should be able to hook the barrel on the lower end into the forked clutch
arm at the transmission.

5) The first adjustment is made with the large threaded adjuster at the top,
lever end of the cable. You need to measure the cable dimension at the LOWER
end, and make the adjustment at the TOP end. The dimension should be EXACTLY 201 mm from the rear face of the transmission where the cable comes through, to the near edge of the cable barrel. You may need to turn the top adjuster out quite a ways to obtain that dimension. Squeeze the clutch lever and
remeasure, as that will seat everything. The easy way to measure the 201 mm is to cut a piece of coathanger to the exact length and use it as a guage. Put a piece of duct tape on the middle like a flag, write "BMW Clutch Adjustment 201mm" and you got a free BMW Special Tool.

6) The second adjustment is made at the rear of the transmission, using the
adjuster screw and locknut on the clutch arm. Turn the adjuster bolt in until
there is NO free play on the cable, determined by lightly pulling the lever
with one finger and looking at the gap at the hand lever where the cable
passes through. Once you have removed all free play, back out the adjuster
just enough to give 2-4 mm freeplay at the hand lever. To hold the adjustment
while securing the locknut, just pull and hold the clutch in with your left hand
while snugging the locknut with your right hand.


Cheers
Steve
01 GS
78 S
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Old 11-25-2012, 06:42 AM   #7
Bill Harris
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Quote:
Airheads have more handing quirks than a carload of circus clowns.
That they do. I've gotten so used to it (and/or my riding has mellowed so much) that I don't even notice it.

You did get a manual for the bike, didn't ya?

--Bill
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Old 11-25-2012, 08:16 AM   #8
Big Bamboo
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Quote:
Originally Posted by LanceR75 View Post
I can feel the boxer motor's horizontal (boxing) movement when riding and can see it when it's on it's center stand idling. A different feel from what I'm used to but cool non the less. I can tell the forks need a rebuild and I need to check the timing and valve clearances.
Definitely adjust the valves and timing before attempting to adjust the carbs. If you have vacuum ports on the carbs, consider making a cheap manometer to aid balancing them. With a well tuned BMW you should be able to read the license plate of the car behind you in your mirror. These are some of the smoothest running engines when set up right...
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Old 11-25-2012, 08:37 AM   #9
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Quote:
Originally Posted by Big Bamboo View Post
Definitely adjust the valves and timing before attempting to adjust the carbs. If you have vacuum ports on the carbs, consider making a cheap manometer to aid balancing them. With a well tuned BMW you should be able to read the license plate of the car behind you in your mirror. These are some of the smoothest running engines when set up right...
It's hard to make guys who ride Britbikes understand this on their first airhead.
You don't have to just settle for "yay! It runs." You can tweak it til it runs very very well.

And keep your fingers out of the diode board.
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Old 11-25-2012, 08:50 AM   #10
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Cool2 Do NOT...

Please search for more information, concerning my next 2 points!
Try to NOT USE THE KICKSTARTER MECHANISM.
Do NOT idle for more than a FEW MINUTES, Without a BOX FAN blowing on your cylinders.
Good luck....
LOVE /5 machines!
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Old 11-25-2012, 09:23 AM   #11
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Thanks for all of the awesome advice. Have both manuals and will work out the kinks in the next few days. Will keep y'all posted.
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Old 11-25-2012, 10:57 AM   #12
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Keep at it, there WILL be a lot of little things to work out.

The carbs may or may not have vacuum ports and may or may not have places to add the ports, being a 1971. You can get the vacuum fittings from Bing (and maybe from BMW). The fittings (or places for the fittings) should be on the bottom, on the "cylinder side" of the throttle plate. Does anyone have a photo of the carb with the vacuum fittings to show?

--Bill
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Old 11-25-2012, 11:28 AM   #13
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Bill,

You should know , you have a /5. But I thought the carbs with vacuum ports on the bottom were all the newer models. Aren't /5 vacuum ports on the outside of the carb, on the side, away from the engine?



Here is a picture of the 64/32/10 carb on the right side of a /5. There were other models, they had different numbers, but they looked the same, as far as I know, to most people. The right in the picture on the cylinder intake side of the carb you can see several screws. The two screws on the bottom that look clean are the intake rubber clamp screws. The smaller rusty looking screw above that is the vacuum plugging screw that is removed to connect a vacuum gauge or manometer or some other tool that reads vacuum.

This screw goes into a short stem. You can almost make it out in the picture. If you don't have this stem with a screw in it but have a hollow spot like the one above it then you can add a vacuum port and the directions and the kit are available from Bing.

Of course you may not have original /5 carbs? What are the numbers on the sides of the carbs? Do you have vacuum ports? Be careful with the tiny gaskets under the screw head. If they get lost or damaged the screw will work with out them but I think it's nice to have them.
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Old 11-25-2012, 11:52 AM   #14
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I found this picture of a carburetor with bottom vacuum ports. (A little hard to see. I haven't figured out how to resize photos.) The blue arrow points to the vacuum port. This is a more modern carb and I believe the nose is hooked up to the vacuum port because it is part of the emission system. Notice dimples where the older carbs have the vacuum ports.
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Old 11-25-2012, 12:17 PM   #15
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On something that "new" in the (/5) model production, and something that physically old with beaucoup owners, no telling where or what the vacuum ports are. Maybe the best thing would be to get a photo of Lance's carbs.

--Bill
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