Boxerworks.com

Those big springs under the top - should they be replaced once in a while?
My Haynes manual has no specs for them, or any method for checking them.
The Motobins website has a picture (PN 60305) in which they appear to be 12.5cm long. Mine are only 11cm.

some Bings don't have springs on the diaphram

and I would not worry about it, gravity and lack of intake drops them well

Early CVs up to I think /7 had no springs. In the mid to late 80s the spring rate was incresaed.

The springs imrpove throttle response by slowing the rise of the pistons when the throttle is opened. The incresed air velosity through the venturi sucks up more fuel through the main jet causing a tempoary rich mixture like an acelorater pump.

As airheads matured and emision standards tightened the jetting was leaned to meet imposed standards. These lean settings made the bikes stumble off the line. The solution was to add the piston springs and later to change to stifer spings. This allowed decent throtle responce with a leaner midrange.

Doug, are your Bings 32 or 40s? The above story was about 32s but the spring theroy is the same for 40s.

Weak springs won't cause your red pipes.

BTW way, was the Loctite you used red? If so switch to blue and your pipes will just turn blue.

Garnet wrote: BTW way, was the Loctite you used red? If so switch to blue and your pipes will just turn blue.

And that's the colour they should be!

More info on the springs...
http://jhau.maliwi.de/mot/r100tic.html#carb

Garnet wrote:Doug, are your Bings 32 or 40s? The above story was about 32s but the spring theroy is the same for 40s.
Weak springs won't cause your red pipes.
BTW way, was the Loctite you used red? If so switch to blue and your pipes will just turn blue.

Mine are 32mm.
Red Loctite !!! I will never hear the end of that one.
Maybe if I use 243 - it's purple ya know.

SteveD wrote:

Garnet wrote: BTW way, was the Loctite you used red? If so switch to blue and your pipes will just turn blue.

And that's the colour they should be!

Quite so!

If I were ever to do a 100 point restoration, and didn't want to spoil my hard work by actually riding it on the road, I would flame the head ends of the, well, headers with a propane torch. With that nice lustrous blue now in place I would carefully attach the pipes to the heads in order to avoid blemishing the blue.

The scary thing is, if I were to restore the R90S of my dreams, I would be tempted to do just that! I have a vision of a Daytona Orange R90S, mounted on a turntable, in my living room. I would regularly rotate the turntable a bit so's I could admire it from a new angle. To my credit (I think) I would also want another R90S in my garage to ride along with my other airheads.

Until then I'm thinking that my '82 RS would look pretty good in my living room. (Anybody got any plans for a good turntable?)


Ken, speaking tongue in cheek in Oklahoma

Be a lot easier to just move into your shop.

Ken in Oklahoma wrote: I have a vision of a Daytona Orange R90S, mounted on a turntable, in my living room.

That would be one BIG Lazy Susan.
I wonder if it could be done with steering head bearings (properly adjusted of course)?

dougie wrote:I wonder if it could be done with steering head bearings (properly adjusted of course)?

It could be, yes, but it's not a good solution. a heavy weight lazy susan bearing for the center pivot, with some type of roller bearings (such as casters) further out on the circle.