New member and owner!

[Made2care]

Hello everyone!
Just purchased a running 1978 R100/7.
Po went through engine and the bike runs great!
Few questions though
1- can’t shift down without shifting up while riding
2- front end bounces when gaining speed

Thoughts??

[Kurt in S.A.]

Welcome! 1) -- transmission input splines might need lubing. Also be sure you're clutch cable is properly adjusted. 2) -- how is the balance on the tires? How old are they? Is the bead of the tire properly seated.

Kurt in S.A.

[Made2care]

Thanks for the input

[Made2care]

Is there a service manual on here?

[melville]

Welcome! I'm working on a 1978 R100/7 myself right now. See the Idiot v. Motorbikes thread for the gory details.

I like the bike a lot, even though I haven't ridden it that much yet.

[Kurt in S.A.]

Look for manuals by Haynes and Clymers. Probably should get both to bounce things off each other.

You can look around the library on the Vintage BMW website...search for R100/7:

https://vintagebmw.org/library/

Kurt in S.A.

[SteveD]

This is a doc I've saved from Tom Cutter Kurt in SA tells me. Thanks Kurt.
No need to add a new cable unless yours is frayed at the handlebar. That's the usual snap point.

AIRHEAD CLUTCH CABLE REPLACEMENT AND ADJUSTMENT
CLUTCH CABLE ENDS- FITTING AND LUBRICATION

1) The inner clutch cable does NOT get lubricant of any kind. The cable sheath
has a Teflon sleeve that provides that function. (Non-OEM cables do not have
that sheath, do whatever you want with them, they will wear out rapidly. Lube is a
BAD thing for the inside of BMW cables, not a "what could it hurt?" thing. The
lube attracts and holds abrasive dirt in the bends of the cable sheath.

2) Lubrication of the upper cable barrel is necessary, but cleaning of the lever
pivot holes is necessary first. Take the lever off, clean and inspect the teflon
bushing for close fit to the pivot pin, and for the presence of the anti-vibration
wave washer. The washer is important to reduce lateral play in the assembly that
causes wear. The cable barrel should be CLEAN and lubricated with light grease
or non-petroleum lubricant like Gun Snot (my favorite because it repels dirt.)
2a) Prior to reinstalling the lever, bench-check the fit of the barrel with cable
inserted as if in use. If you have one of the newer cables, with the hexagonal
swaged part on the nipple, dress that hex portion where it travels through the
lever slot. Clean up any debris from filing the swaged nipple. I don't recommend
widening the slot in the lever, as the nipple needs to be smooth as well as proper
dimension. See more on this topic at the end of this article.
3) The lower cable barrel fitting on the clutch lever arm should be CLEAN, should
FIT the u-shaped lever arm fingers smoothly and easily, and be lubricated with
light grease on the barrel OD, the ID of the arc of the "fingers."
4) The rubber accordion boot at the lower cable end should be clean, wiped with
Armoral to extend the rubber life, and fitted snugly onto the end of the outer
sheath nipple where it projects rearward from the attachment point in the
transmission housing.

CLUTCH CABLE ROUTING, ADJUSTMENT AND MAINTENENCE
There should be ONE tie wrap on the clutch cable, midway down the right-side
frame down tube. This should be snug, not tight. Route the cable so that there
are no severe bends, and you may need to loosen the motor mount nuts to fit
the cable in below the pushrod tubes. Torque the nuts to 55 foot pounds
afterward. If the old cable is the OEM part, it may be routed correctly, just
follow the routing. It's easiest if you use some masking tape to attach the new
cable to the old one and pull it through. Just handle the cable gently. They
can be damaged by rough handling on installation.
The cable should NEVER be lubricated, but it IS necessary to lube the
barrels on each end annually. Also check that the hole in the hand lever is clean
and free of dirt.

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
PRECISELY 201 mm (7-15/16”) 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 re-measure, as that will seat everything.
The easy way to measure the 201 mm is to cut a piece of coat hanger to the
exact length and use it as a gauge. 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.
Test ride the bike, and recheck the two dimensions after the bike cools off.
You will note that the freeplay will change slightly when the bike heats up.
Don't readjust when hot. If you have the cold play adjusted correctly, there
will be adequate freeplay to accommodate the change when hot.
This works with all airheads after 1970. The factory first defined this procedure
with the introduction of the 1981 models with the new clutch/transmission design,
but the procedure was well known to BMW dealers for years before. I learned it
in Service School in 1973.

The problem with new BMW clutch cables is NOT lubrication. BMW changed
suppliers or vendors of the control cables a while back. There have
been myriad cable fitment and quality issues since that time. The issue with the
clutch cable premature failures (very common, BTW) is that the upper swaged
nipple is now crimped with a hexagonal die instead of a round die, as was used
on the original cables. The hex-shaped part of the swaged nipple is too large in
cross-section to pass through the slot in the clutch lever as the lever is pulled and
the barrel rotates through its range. Look closely and you will see where the
nipple is hanging up and causing the cable to bend right at the end of the nipple.
That bending will cause a very rapid failure of the cable. The fix is to carefully file
the hex-shaped part of the nipple round so that it passes freely in the slot in the
clutch lever.

[Made2care]

Thanks mate!

[Kurt in S.A.]

SteveD -

That's from Tom Cutter at the Rubber Chicken Racing Garage. Link is here:

http://www.rubberchickenracinggarage.co ... stment.pdf

Kurt in S.A.

[SteveD]

SteveD -

That's from Tom Cutter at the Rubber Chicken Racing Garage. Link is here:

http://www.rubberchickenracinggarage.co ... stment.pdf

Kurt in S.A.

Thanks Kurt...I'll add that to it. Cheers