BMW R100RT choke frozen

I have only been able to fire up the bike a couple of times in the last 4
months. Both times the right choke actuator was frozen open. I sprayed the
exterior with WD-40, which did nothing, and then forced it to move with way
too much effort with my bare fingers. The second time I had to vibrate it a
bit with a rubber mallet. I know it should be ridden weekly, but that is
unlikely.

What can I do to prevent the sticky choke? If I'm not careful I'll break
the cable to the right side or both.

 

Lubricate the cable?

Leon

 

Sounds like you may have a frayed cable. When it gets sticky,
is it still sticky after you disconnect the cable from the carb ?
Most likely you've got broken strands of cable snagging on
the plastic liner of the cable housing.

The cable's really the only place I can imagine getting that
much mechanical resistance unless you've got something
really evil in your gasoline that might be reacting with
the aluminum. Just for laughs, you could also drain the tank
completely dry then refill with new gasoline.

You can buy carb rebuild kits starting from about $30.00.
That would get you a set of O rings and gaskets. If
it's really that stuck with the cable disconnected it'd
need to be carefully opened up to see what's going on.
Buy a new set of return springs while you're at it.

 

I don't think it's the cable, because after it is broken free, then it moves
fairly easily. I'm thinking I need to clean out the inside of the
carburetor, but don't really want to.

I'm wondering if I could spray some carb cleaner in the right hand
carburetor while it's running.

 

Instead of WD40, you might try Kroil, which is a way better lubricant.

http://www.kanolabs.com/

If you want a carb cleaner, Berrymans B12 is highly touted
by (who else) B12, who posts here regularly.

I'd also make sure you're not getting water in there via
the gas.

For a start, why not remove the float bowl and see what's
in it. Could be water or sludge. Either would be cause for
dumping and refilling the tank.

 

I'll see if my local parts shop has B-12, Kroil, or Kreen. Was really
hoping someone with an R100-RT had some pointers for injecting something
directly into the carburetor intake hose while the engine is running.
Sounds more active than adding it to the fuel tank, or spraying the
exterior.

 

Or the lever itself?

 

I'll see if my local parts shop has B-12, Kroil, or Kreen. Was really
hoping someone with an R100-RT had some pointers for injecting something
directly into the carburetor intake hose while the engine is running.
Sounds more active than adding it to the fuel tank, or spraying the
exterior.[/QUOTE]

For carb cleaners, people around here seem to think highly of the Yamaha
product, and Seafoam. IIRC, both products are poured into the carburetor
bowl and left to sit for approx. 30 min. then drained out. It's another
option, anyway. HTH

--
Later,
John



'indiana' is a 'nolnn' and 'hoosier' is a 'solkk'. Indiana doesn't solkk.

 

Oops! Reverb = Stumpy. I need to sync my home + work computers.

 

If "Kreen" means "Kreme", which is a gas tank liner, you
ought to use POR-15 instead, but I really don't think you'd
want to use either tank liner given your level of expertise.

Kroil is popular with gun owners as well as mechanics. POR-15
and other magic stuff are readily available via the internet.

BMW airheads are very similar to each other. I believe you've got
constant velocity Bing carbs, probably 40 mm. Some models use
a 32 mm carb.

Adding something to the tank or spraying the outside of the carb
is fine, so long as you're careful to do it by the light of a full moon
and sacrifice the requisite chickens at appropriate points in the
ceremony.

 

I stand corrected.

I'd continue to suggest though that anyone at the
OP's level of expertise should use tank sealers
with extreme caution. POR-15 and Kreme could
both be way messy to clean up if the job went badly.

I also don't think either one would fix a stuck choke.

 

The 'choke` on your air-head beemer is really a small "auxilliary
carb" on the
side of the main Bing carb body.
It's relatively easy to detatch it. If your problem is not the cable,
detach the air connections, swing the carb out, and four small screws
get you access to the little devil. See whats hanging it up.
Best get a Haynes manual first though.
MadDog
"R75/5 Forever!"

 

This is a picture of the little sucker.

http://www.xmission.com/~wendell/GS/node34.html

Some part numbers may be different, as this is likely a 32mm.

There's a gasket you need to replace if you open it.
Also some of those carb screws can be a real bear to unscrew
without damaging their slots. Make sure you have a well fitting
screwdriver and have the carb body held securely.

$30 or so would buy you a basic rebuild kit.

There's also a Bing carb manual available at

http://www.bingcarburetor.com/

and they're supposedly willing to answer owner's questions.

If it's really hanging up and it's not something on the outside
then my bet is somebody took it apart and put it back together
wrong.

 

My problem is not the cable, it works fine. I went out looking for B-12 or
equivalent, found inferior products. Bought CRC Clean-R-Carb spray which
says it can be sprayed into the carb as it is running. The air intake
connector is plastic, so I'll remove it before spraying the stuff. I can't
believe these solvents won't eat up gaskets, seals, etc.

I've got a garage full of toasters, clocks, and old projects that never got
fixed. Disassembling the unit is a last resort. A man has to know his
limitations. Should have time Sunday.

 

Kroil is a really good penetrating oil and worth having around
for all kinds of stuff. If you can find a can, spray the shaft
and lever too just to make sure they're not binding.

If it were me, I'd throw away the toasters, clocks and old
projects then fix the BMW motorcycle. A man's got to get
his priorities set right.

 

Stumpy,
A penetrating oil/ solvent might clear up the problem if it's on the
outside end ot that rotating part, but that part goes all the way in.
Look at R.K.s diagram.
Whatever you do - DON'T FORCE IT.
Best of luck,
MadDog

 

Good advise.

I put ~2oz of Techron fuel system cleaner into ~1gal of gas and fired it up.
Sprayed the carb cleaner stuff into the carburetor throat as it ran, had to
rev it a bit to keep it running. There was just normal looking black layer
of sooty film on all observable surfaces in interior. The spray cleanser
got it mostly off. I am curious about the little tube that hangs down into
the air intake connector. It had a drip of wet fuel on the end when I
opened up the intake. Closed it back up and rode the bike ~1mile to put in
2 gallons of gas, and then 2 more miles back home to make sure the additive
was diluted enough while the bike is parked.

I have come to the realization that my use of the bike fits the description
of "short term storage" and so have ordered Sta-Bil fuel stabilizer to treat
the fuel while it sits. Maybe I'll remember to exercise the choke next time
I'm rummaging around in the garage banging on toasters and clocks. Thanks
for teaching about the gummy stuff lurking in my fuel.

 

I'm not 100% certain what you're looking at but I think
you're probably talking about the crankcase vent system.

There's some very strange plumbing which runs the vent
tubing past the starter and into the air filter housing where
it goes to a tee fitting to two plastic tubes, one ending in each
of the air intake tubes for the carbs. If this is the one you're
looking at , it'd likely be a drip of oil rather than fuel.

In later model bikes, there's also a tube which leads
the fuel tank fumes into the crankcase. This is to meet
a late air quality regulation and is often found disabled.