The hard plastic tube that goes from the air filter housing to the carb. Which end does the rubber adapter with two hose clamps go to, at the carb or or the filter housing. I have seen images with it both ways. Mine is at the carb. At the housing where the o-ring is, does the plastic tube fit over the o-ring and the single hose clamp directly on the tube or should there be a rubber fitting there as well. My plastic tube does not appear to be fully square at the air filter housing. It is not off much, but it is off. I know I have the left one on the left and the right on the right. It is not possible to have the tube round the wrong way is it?
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Air intake tube 78 r100/7
- Thread starter 79woodsie
- Start date
Here's a picture of the right intake tube on my /7. As you seem to realize, there is a left and right and that's because the carbs are different distances from the clam shell housing because of the offset in the crankshaft. Yes, the tubes can be flipped around on each given side. I didn't realize that until one time many years ago, I was in St. Louis and happened to stop by the dealer. The service manager saw right away that I had them upside down. It's noticeable in that the intake tube wasn't turning straight into the carb inlet as it should be. If you're wondering if you have it right, try it both ways...only one way will look right.
At the housing the big rubber grommet fits over the housing...of course the housing will have a small o-ring which you should put some silicon grease on. Then the air intake tube fits into the opening of the rubber grommet.
At the housing the big rubber grommet fits over the housing...of course the housing will have a small o-ring which you should put some silicon grease on. Then the air intake tube fits into the opening of the rubber grommet.
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If your pic is correct, then mine are on wrong too!
I'm pretty confident mine are right. Basically the tube should exit the air filter housing in a direct line and the same for how it enters into the inlet of the carb. I've tried to illustrate that with this picture. When they're on wrong, it's quite evident that these alignments are not followed.
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Hey Kurt, my air tubes on my / 5 are the opposite, with the rubber sleeve at the carbs. I will try to post a pic tomorrow. My take is that the O-ring on the air box is there to seal up the intake tube on the air box flange, and the rubber sleeve belongs between the carb and the tube. I am confident that the intakes can be assembled either way. More to follow.
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gr8ridn2
Tourmeister
And here is the BMW parts fiche from BMW for my R90/6. At least in the case of the R90/6 it appears the rubber connector along with the two clamps attached to the carburetor. I consider this credible evidence in the case of my bike. Like said before, this also justifys the use of an O ring on the air cleaner housing.
Best to check the parts diagram for your specific model.
The key detail is to ensure the alignment of the tube with the air cleaner and carburetor is true to the alignment of both items as Kurt shows in his photo.
Best to check the parts diagram for your specific model.
The key detail is to ensure the alignment of the tube with the air cleaner and carburetor is true to the alignment of both items as Kurt shows in his photo.
g48ridn2 -
Interesting! Good point, too...I wonder what the reason for the change is for an R90/6 and the R100/7. They both have the same clam shell housing and both have CV carbs. I could see the difference if it was the slide carbs or Dell Ortos or something. Hmmm...
Interesting! Good point, too...I wonder what the reason for the change is for an R90/6 and the R100/7. They both have the same clam shell housing and both have CV carbs. I could see the difference if it was the slide carbs or Dell Ortos or something. Hmmm...
Only thing I can think of that is different is the crank case vent tubing is changed from /6 to /7, with the /6 and earlier motors venting into the right side carb tube only and the later having the longer hose system and dropping into both carbs. In these pictures we can see the placement on my /5 and my mono-shock RS.
Note that the rubber sleeve must be installed at the top of the air tube on the late style, flat, air filter assembly. I think 79woodsie should go with the assembly order Kurt has described since it seems to work on Kurt's bike which is the same model and year. We want these things to be as correct as possible, y'know.
Note that the rubber sleeve must be installed at the top of the air tube on the late style, flat, air filter assembly. I think 79woodsie should go with the assembly order Kurt has described since it seems to work on Kurt's bike which is the same model and year. We want these things to be as correct as possible, y'know.
My '78 /7 only has the one drain into the right carb. So, that can't be the difference between the /6 and /7. I would agree that the flat filter arrangement changed things, though.
In your picture of the /5 arrangement, the 2 clamps at the bottom really look crammed in there with more than enough room for an additional clamp by the air filter. I wonder if someone had a "D'oh" moment at some point and moved things around.
In your picture of the /5 arrangement, the 2 clamps at the bottom really look crammed in there with more than enough room for an additional clamp by the air filter. I wonder if someone had a "D'oh" moment at some point and moved things around.
Yeah, it's a pretty tight fit in there, and not the best picture by a long shot. Maybe the rubber sleeves are narrower on /5's. Hmmm....
I remember picking up a '78 R80/7 parts bike several years ago that had the long "y" hose routed for the crank case ventilation. Maybe the "78" model run was when the change-over occurred.
I remember picking up a '78 R80/7 parts bike several years ago that had the long "y" hose routed for the crank case ventilation. Maybe the "78" model run was when the change-over occurred.
toooldtocare
Active member
To be honest, I have always thought that Kurt's arrangement was wrong, however I could be wrong as well.
It does, however, seem to me that the two clamps and the rubber tubes should be at the carb end and the plastic end should go up and seal by the o-ring.
Anyway, that is how both of my airheads have been when I purchased them. A '74 R90/6 and my '78 R100/7.
Also, I had mine to a old bike repair shop a few months ago, and the two mechs have been working on airheads for years. Rubber tubes were installed to the carb end.
Hmmm.
Usually I really trust Kurt as he is very well studied and knowledgeable.
But...I am keeping mine the way I have had it!! Too bad Kurt, you lose this one!!!
It does, however, seem to me that the two clamps and the rubber tubes should be at the carb end and the plastic end should go up and seal by the o-ring.
Anyway, that is how both of my airheads have been when I purchased them. A '74 R90/6 and my '78 R100/7.
Also, I had mine to a old bike repair shop a few months ago, and the two mechs have been working on airheads for years. Rubber tubes were installed to the carb end.
Hmmm.
Usually I really trust Kurt as he is very well studied and knowledgeable.
But...I am keeping mine the way I have had it!! Too bad Kurt, you lose this one!!!
m_stock10506
Well-known member
I had to look twice to confirm it - my 1974 R60/6 has the sleeve and two clamps at the carbs, my 1984 R100 has it the other way with two clamps and sleeve at the air box connection.
toooldtocare
Active member
Not sure we'll ever really know what's correct. This is from the link to the '78 brochures. It shows an R100S in the foreground with two clamps up by the air box while the R80/7 appears to have two clamps down by the carb.
The R100RS has two clamps by the air box...can't see the R100/7. But one rule of thumb is to not trust what BMW shows in their photos...sometimes things are done cosmetically and only for the shoot.
We know that what works for you, you should keep doing!
The R100RS has two clamps by the air box...can't see the R100/7. But one rule of thumb is to not trust what BMW shows in their photos...sometimes things are done cosmetically and only for the shoot.
We know that what works for you, you should keep doing!
