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1994 R1100RSL. Do Throttle-body cleaners with Acetone also dissolve the TPS insides?

D

davidanderson327

New member
1994 R1100RSL. Do throttle-body cleaners with acetone also dissolve the TPS plastic insides?

While replacing my wet head gaskets, I see my throttle-bodies' venturis are stained with carbon. The auto parts store brands have acetone and toluene to dissolve that varnish. A YouTub video showed liberally rinsing the venturi with spray can cleaner, scrubbing with a brush along the butterfly for a good seal.
Will getting the Throttle Position Sensor pivot there inside the venturi, getting it wet with these powerful solvents, also dissolve the plastic inside the TPS mechanism?
Have you rinsed your venturi, wetting the TPS pivot, without disturbing the TPS?

David Anderson 228147
Escondido CA
 
Acetone or toluene will absolutely destroy "SOME" plastics - use alcohol or gasoline.

And welcome to the Forum!
 
davidanderson327 said:
1994 R1100RSL. Do throttle-body cleaners with acetone also dissolve the TPS plastic insides?

Will getting the Throttle Position Sensor pivot there inside the venturi, getting it wet with these powerful solvents, also dissolve the plastic inside the TPS mechanism?
Have you rinsed your venturi, wetting the TPS pivot, without disturbing the TPS?

David Anderson 228147
Escondido CA
Click to expand...

The throttle position sensor (TPS) is on the outside of the left throttle body. The TPS is rotated by the throttle plate shaft as it comes through the side of the throttle body. There's an o-ring at the point where the shaft exits the TB and connects with the TPS. You would have to submerge the throttle body in cleaner for it to get into TPS.
 
True, IFF the O-ring is acetone/toluene/solvent resistant... :scratch
Just because it survives a little gas and some air (as in "fuel") is not an indication.
 
Pauls1150 said:
True, IFF the O-ring is acetone/toluene/solvent resistant... :scratch
Just because it survives a little gas and some air (as in "fuel") is not an indication.
Click to expand...

I have used Gumout brand spray carburetor cleaner on R1100RS and R1150R throttle bodies on several occasions. I have not had any issues with the TPS on either bike. Keep in mind this is a quick spray with the cleaner followed by some compressed air.
 
Agreed, a "quick spray" followed by a cleanup (air or wipe) ought to be OK. I've used various cleaners on individual parts, but I never saturate the area. If there's significant buildup of crapitation, I'll use alcohol or gas to wipe it off. (The tips of our Big Brass Screws are a good example.)
Note that the MSDS for Gumout's spray carb cleaner does say it has acetone and toluene, so wear gloves and eye protection. I definitely would NOT use it near the O-rings of the BBSs.
 
Best throttle body/carb cleaner/cylinder de-carbonizer/valve cleaner, Bon Ami.

I don't know if they sell it anymore and you used it wide open throttle and made sure pets, children, adults, clean cars, your freshly painted house wasn't in the same postal code.

After you were done, a bucket of water and an extra pair of gitch got you home.

Dead serious, the stuff was wonderful, from the land beyond though.
 
When I cleaned the throttle bodies on my R850R (which were full of carbon gunk like yours), I pulled them out entirely and removed the TPS and everything rubber so that I could spray the nasty cleaner all over them with reckless abandon.

As long as you unplug the bike's battery and precisely mark where the TPS was set before you remove it, and reinstall it in the exact same spot, I don't see why complete disassembly is an issue.

My left throttle body was so weathered from sitting out in the sun for 3 years (previous owner neglect) that the TPS mount screws and washers left nice precise bright spots for reassembly.
 
senseamidmadness said:
When I cleaned the throttle bodies on my R850R (which were full of carbon gunk like yours), I pulled them out entirely and removed the TPS and everything rubber so that I could spray the nasty cleaner all over them with reckless abandon.

As long as you unplug the bike's battery and precisely mark where the TPS was set before you remove it, and reinstall it in the exact same spot, I don't see why complete disassembly is an issue.

My left throttle body was so weathered from sitting out in the sun for 3 years (previous owner neglect) that the TPS mount screws and washers left nice precise bright spots for reassembly.
Click to expand...

The TPS setting is in micro-volts. A TINY movement of the TPS location gives a substantial change in the TPS voltage reading. Installing the TPS where it was previously marked could still give you a significant change in the TPS idle voltage. Setting the TPS requires an accurate voltmeter reading the TPS pins.

Original (brown) Pine-Sol makes an excellent throttle body cleaner if you're going to remove it from the bike and scrub it clean. Yes, remove the TPS off the left TB. Rinse the Pine-Sol off when done. And no acetone or other caustics that would eat up o-rings.
 
senseamidmadness said:
Sounds to me like it'd be fine to take it all apart, get the throttle bodies ultra-clean (or ultrasonic clean if available!), and then reset the TPS voltage to the correct spot after reassembly.
Click to expand...

Yes, if they are really, really dirty. But this is not needed usually.
 
I hesitate to ask more questions on this thread, should I start another?

image.jpg

Here’s the TPS left side pictured, same gasoline wash and I rubbed that dark carbon line with carb cleaner on a cotton swab.
I didn’t get much of the carbon residue off on the cotton swab, however, when I hold the throat to the light, I see a thin white line all around the butterfly.

This left side hasn’t the blue paint, the right side did have the blue paint from the factory on the butterfly stop screw. Because both sides thin white line is identical to me, I believe both are still factory adjusted.

I hesitate to ask more questions on this thread, should I start another? What’s customary? My next question is where might I buy a Three Prong Male Connector to plug into the diagnostic port, eventually to check the TPS trigger point is adjusted for moving off.
 
The thin white line is appropriate if I recall from when I rebuilt my throttle bodies from my 2004 R1150RT about 6 years ago. I believe the BBS is a controllable supplement to the airflow allowed by the small clearance between the housing and butterfly. Regarding the TPS voltage monitoring I believe you will need the harness connected to get power to the sensor. What I did was to use maybe 4-6" of a single (one) strand or copper wire from a typical home appliance electrical cord. I laid these 2 wires into the harness connector and then carefully connected it back onto the TPS. IIRC it was the two outer most connectors pins of the connector. Then I used a DMV with alligator clips which clipped onto the two single strands of copper wire. Worded like champ. Just have to be patient and careful with "setting" the wires into the harness connector so that they stay in place while you connect it to the TPS. Careful and deliberate positioning or preforming of the wire is the key. The other option would be to have a very fine pin or needle and pierce the wire insulation just outside of the harness connector and then again use alligator clip to hook up to the DVM. I do not recall the two wire colors, but you should be able to find those on various resources. it may be brown/gray stripe or just brown for one and white/red strip for the other. Also be careful to not let the 2 wires touch each other once the ignition is turned on. Not sure it would cause a problem, but why find out...

Thanks,
 
The thin white line (small gap) between the throttle body bore and the throttle plate is the bulk of the air required at idle. The bleed screws just fine tune that to obtain the correct idle speed and balance. The actual position of the throttle plates is set with a very sensitive airflow meter at the factory - thus the blue paint on the adjusting screw.
 
David327 (Chevy?) - if further questions are related to what's going on here, stay in this thread; if they're a completely different topic, start a new thread.

I sometimes have access to other folks' "junk", so I was able to make this handy little gizmo for TPS measurements:
PC270001.JPG
Pin 1 - the white wire with a red runner, topmost in the photo and rearmost on the bike - is the TPS measurement point; use the brown wire attached to the throttle body as your ground/return.
 
Last edited:
Yes, that pictured patch cord is ideal.

Yes, that pictured patch cord is ideal. Beemer Boneyard says he hasn't any suitable connectors for me to solder together as you pictured.
I'm considering Mr. BewareBoy's idea of using a sliver of lamp cord wire in the TPS connector, as above.
Or Mick McKinnon's post,
k11og.org/forum/viewtopic.php?t=2110&postdays=0&postorder=asc&start=0.
Mr. McKinnon says all R1100 bikes with 2.2 Motronics can use the diagnostic connector and an LED...

I am delighted by y'all's ideas: the feeling of expert teamwork, the empowerment.
And I'm delighted how my posted question brought machine-generated archived thread suggestions I couldn't find manually when I searched. Advertising automatically spams me related products, now that automation worked in my benefit!
 
davidanderson327 said:
Yes, that pictured patch cord is ideal. Beemer Boneyard says he hasn't any suitable connectors for me to solder together as you pictured.
I'm considering Mr. BewareBoy's idea of using a sliver of lamp cord wire in the TPS connector, as above.
Or Mick McKinnon's post,
k11og.org/forum/viewtopic.php?t=2110&postdays=0&postorder=asc&start=0.
Mr. McKinnon says all R1100 bikes with 2.2 Motronics can use the diagnostic connector and an LED...
Click to expand...

I just want to emphasize that the TPS Adjustment Test via the diagnostic connector is just a pass/fail test. It shows that the TPS at idle is in the acceptable range, it doesn't show the voltage.

That connector pictured is a neat piece of work. I take a single wire from a four-wire telephone cord, strip off the insulation at each end and slip one twisted end into the TPS pin 1 slot and close the connector again. The wire is thin enough that it will conform to the closed connection and still allow it to close. I then attach a voltmeter to the end of the wire sticking out from the TPS connector and measure the voltage on pin 1. At idle, I shoot for 380-385 mv.
 
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