THROTTLE BODY BUTTER FLY LEAKING NORMAL?

[chrisstroh]

Trying to find the surge in my 02 RT. If I spray starting fluid around the left TB butterfly shaft opposite the TP sensor, I get a change in idle. Should the butterfly shaft bushing absolutely positively not leak at all? Starting fluid is pretty thin. Should I be using something else?

[Hedge36]

Trying to find the surge in my 02 RT. If I spray starting fluid around the left TB butterfly shaft opposite the TP sensor, I get a change in idle. Should the butterfly shaft bushing absolutely positively not leak at all? Starting fluid is pretty thin. Should I be using something else?

 

Told ya. Not very often on the left side though

[Hedge36]

One thing you can do to see how bad it effects (or doesn't) the overall synch: smear some good heavy axle grease all over the bushing end to try to seal it. It'll hold up to repeated throttle movements for a while before the air finds it's way through again.

 

You may find the effect to be fairly minimal overall.

[smiller]

Starting fluid would make for a pretty drastic test as even the most minute amount getting in would probably affect idle. I would follow the suggestion in the prior post and just temporarily seal the shaft with grease and see if it causes a change. No change = no worries.

[chrisstroh]

GREASE? But wait...doesn't that mean I'll get my hands dirty? No way!! I probably won't have time to do that test until you look at it Hedge.

[Hedge36]

GREASE? But wait...doesn't that mean I'll get my hands dirty? No way!! I probably won't have time to do that test until you look at it Hedge.

 

Sounds good. We'll put mine next to yours and see if we get the same result with the ether... my guess is that we will.

[DEF]

Starting fluid is VERY volatile. It fills the nearby air with volatile vapors. A such, your BMW may be aspirating these vapors and thus changing the idle slightly.

 

The best way to detect leaking TBs is to remove them and test them for leaks with air pressure and submerging them in water, kind of like checking an old inner tube for leaks in the water trough.

[tomk99r11]

Is it time for one of those BMWO group hugs? Gee, can you feel the love!

[chrisstroh]

ok it's a love fest! No, but seriously, Hedge has been very helpful to me and my surging problem, walking me through the diagnosis. By LUCKY coincidence, we both happen to live in Petaluma, Cal. and he's willing to take a look at it this weekend. Couldn't ask for more!Thx Hedge!

[lithoman]

Just don't hit any cow's on your way to his house

 

(Petaluma has Lot's a dairys out there!!)

[Joe Frickin' Friday]

I haven't tested mine, but at 110K miles, I'd imagine they're leaking by now. If I get bored this winter, is there a way to fix them, or is just a matter of replacing the whole TB?

[tomk99r11]

I think there is a kit available, don't know what it includes. Can't be very hard to do the rebuild I would guess.

[DEF]

I have had my TBs off the bike several times to cure vacuum leaks and inspect intake runners, O-rings and joints. However, I have not dissassembled the TB butterflies, shafts, etc. There has been no need...mine are not leaking.

 

Prior to reinstalling, I usually soak the area in and around the TB shaft where it enters the TB casting with copius sprays of WD-40 to remove grit, etc. Also, I then add a bit of silicone spray to this area to lube the seal (I assume it is an O-ring) inside the shaft bore.

 

Reassembling the butterflies in carbs or FI systems requires that you very carefully position and orient the butterflies onto the throttle shaft. Otherwise, you may end up with different air flow patterns in each TB. And while TB sync will take care of some of it, there may still exist non-linearity in the two TBs. Very carefully align the butterflies when reassembling your TBs.

[tomk99r11]

I periodically test my tb's with WD40, and they are fine. No intention of taking them apart, but if and when I do think it a good idea, your comments will be helpful. Thx.

[smiller]

Due to some of the reasons DEF noted and others, unless you are experiencing an actual running problem that is definitely attributable to TB wear it is probably best to just leave them alone rather than go off on a search for perfection by frequent inspection and cleaning. In fact I've noticed that several automobile manufacturers specifically recommend against attempting to clean TB unless the action is clearly indicated by some sort of problem.

 

There is such a thing as too much preventative maintenance.

[Joe Frickin' Friday]

There is such a thing as too much preventative maintenance.

 

Pilgrim refers to this as "wearing the bike out with a wrench instead of the throttle."

[RFW]

Trying to find the surge in my 02 RT. If I spray starting fluid around the left TB butterfly shaft opposite the TP sensor, I get a change in idle. Should the butterfly shaft bushing absolutely positively not leak at all? Starting fluid is pretty thin. Should I be using something else?

The fact that anything gets in there at all, and also that it only occurs on one butterfly, but not the other, tells me you have a sealing problem.

 

But for heavens sake, DON'T use starting fluid! One wrong move and you have an inferno! Try a light oil like WD40. If the idle is still affected, then you have a leakage problem that the fluid is temporarily sealing. This should be fixed.

[ShovelStrokeEd]

Yeah, and Pilgrim is right.

 

At your milage, Mitch, I would not think it out of line to at least inspect the TB's. Remove from bike, open WFO and try to wiggle the shaft. There should be little or no play, maybe a thou or so. To my knowledge, BMW does not offer any form of kit for rebuilding the things. Wouldn't be too difficult to do given access to a small, precise lathe, and a vertical mill, you could rebush the bodies and then ream the bushings to fit the shaft. A little bit of creativity might incorporate a small seal into each bushing to help with the vacuum thingy. Even a new throttle shaft would not be all that much trouble. Throttle blades are a real PITA unless you make a fixture.

[smiller]

Wouldn't be too difficult to do given access to a small, precise lathe, and a vertical mill, you could rebush the bodies and then ream the bushings to fit the shaft. A little bit of creativity might incorporate a small seal into each bushing to help with the vacuum thingy. Even a new throttle shaft would not be all that much trouble. Throttle blades are a real PITA unless you make a fixture.

Sounds like your next project Mitch!

[Hedge36]

Somebody - PLEASE make a kit for this.

[Dr Klawn]

Why not just replace the TB if it's leaking or has high mileage? There's plenty of low mileage used ones out there.

 

Just a thought.

[Hedge36]

I'd rather fix it than replace it with another that'll probably be just as worn not too long after.

 

Besides, a repair kit could use more durable materials.

[mikefigielski]

Bing ( www.bingcarburetor.com )sells replacement shaft assemblies and bushings etc for these throttle bodies. See their add in the BMW MOA mag for the phone #. I just ordered the parts to redo my left TB. I have been having a hard time getting a consistant synch lately even after replacing throttle cable, rubber intact manifolds and TB o-rings, etc. The right TB I replaced with a new one I got in a dealer buyout. The butterfly shaft and bushings, etc were about $50 and a new early '94 R1100RS left side TB is over $500 new!! Hard to find low mileage early model TBs............. even for me!!! I'll let everyone know how it goes when I get to it later this week.

Mike

[tomk99r11]

Thx Mike, I thought there was a kit available. Pls post how it goes and the results. Ride safely.

[smiller]

Bing ( www.bingcarburetor.com )sells replacement shaft assemblies and bushings etc for these throttle bodies. See their add in the BMW MOA mag for the phone #. I just ordered the parts to redo my left TB. I have been having a hard time getting a consistant synch lately even after replacing throttle cable, rubber intact manifolds and TB o-rings, etc. The right TB I replaced with a new one I got in a dealer buyout. The butterfly shaft and bushings, etc were about $50 and a new early '94 R1100RS left side TB is over $500 new!! Hard to find low mileage early model TBs............. even for me!!! I'll let everyone know how it goes when I get to it later this week.

Please do Mike, we'd all love to know what you find. Do they discuss the TB replacement parts on the web site you mentioned above? I can't seem to find mention of it anywhere...

[chrisstroh]

But isn't a thousandth or so going to let starter fluid in? I've found on car carbs the shafts almost never seal that well. My 02 RT has 48 k on it. Do a lot of these shafts where out by then? If I hold my throttle at 2500 rpm in neutral, it wanders all over within say 300 rpm. It's NEVER steady. I hope this syncing does the trick.

[Hedge36]

But isn't a thousandth or so going to let starter fluid in? I've found on car carbs the shafts almost never seal that well. My 02 RT has 48 k on it. Do a lot of these shafts where out by then? If I hold my throttle at 2500 rpm in neutral, it wanders all over within say 300 rpm. It's NEVER steady. I hope this syncing does the trick.

 

Yeah, ether is the fussy man's method of looking for leaks... not that there's anything wrong with that, but I wouldn't lose sleep over it.

[mikefigielski]

I think they deal mostly with Airhead carb parts, but when I called they knew exactly what I needed and had the parts in stock. Phone is best with them I think. Hoping to do the job this weekend.

Mike

[Yeeha! Stephen]

Trying to find the surge in my 02 RT. If I spray starting fluid around the left TB butterfly shaft opposite the TP sensor, I get a change in idle. Should the butterfly shaft bushing absolutely positively not leak at all? Starting fluid is pretty thin. Should I be using something else?

 

But for heavens sake, DON'T use starting fluid! One wrong move and you have an inferno! Try a light oil like WD40.

 

I've always used an unlit, hand held propane torch... Not as messy as WD-40.

[chrisstroh]

Now why the hell didn't I think of that? Good idea! Thx!

[Hedge36]

Update: Chris now knows what the 259 motor is SUPPOSED to feel like. Nice bike, too.

[chrisstroh]

UPDATE: Hedge is right. Good work! I want to ride my bike again.

[SWB]

UPDATE: Hedge is right. Good work! I want to ride my bike again.

 

So, what did you guys do? Replace "O" rings, or just slab grease all over the butterfly shaft to seal the air leaks? Or, did you actually replace the throttlebodies??

[chrisstroh]

Hedge came to my house with his twinmax and meter. We changed spark plugs to autolites,set the tps,synced the throttle bodies, and reset the motronic. I didn't set the valves because they were done recently. Now I haven't ridden it more than about 5 miles, but from when I first got on it I knew it was running lots better than ever before. Now at 5000rpm it purrs.(handles don't buzz)

Surging is just about gone (90%, the other ten may just be a charactoristic). I was thinking Techlusion but as Hedge said, every boxer he's seen with surging is fixable with careful tuning and he's right. I'll have to put some more miles on it on INDEPEDENCE Day but I'm already impressed. I was thinking about selling it because of the surging but now it's a resounding NOT! I'll give a further update after INDEPENDENCE Day.

[mikefigielski]

Did the TB rebuild yesterday. It wasn't too bad. The shaft may have been a little worn, but it didn't look horrible at 74K miles. The little rubber seal was a little ragged, maybe thats where the real problem was. Not a very confidence inspiring sealing arrangement on the shaft. The only real PIA is when removing the TPS. After you pull off the TPS, there is an E-clip that holds the end of the shaft. In BMW's (or maybe Bing's) infinite wisdom they did not leave enough room between the shaft and the TB body to easily get the clip out!! Not too bad getting it out, just have to wiggle and pry, wiggle and pry. Putting it in is anoother story. Very difficult to get it in without bending or breaking the clip, believe me I know! Of course I did not order another clip with the shaft and seals. Good thing I have a dozen TBs around that I could steal one from. Seems to me that a D-ring would be better. Just spread the ring with the special pliers and lower it on. Anyway, got it back together and it does seem easier to synch now. I decided to do a zero-zero adjustment since I had the TPS off (actually replaced it with a low mileage one I had here). Kept getting too high of an idle and had to lower the TPS to .320 to get the idle low enough. Synched the throttle stop screws and did the high RPM synch, then reset the TPS to .380. RUns great and very smooth. All in all, rebuilding seems like a good deal at approx $60 vs $400-$500 for a new TB.

Mike

[smiller]

Hi Mike,

 

So it is the throttle shaft that wears and not the TB casing itself? I had always assumed the latter and thought that a rebuild kit would include some new bushings or something... but I guess not. Apparently you can transfer the throttle plates from the old shaft to the new? (if I am understanding you correctly) And the TPS just pulls off of the shaft?

 

Lastly, is there any special way to identify the TB to the Bing folks, or will a simple 'it came off a BMW R1100' do?

 

Thanks for the tip about th e-clip, will be sure to order one or many. After all some of us don't have a dozen throttle bodies and a bunch of extra TPS units lying around...

[chrisstroh]

Thx Mike,

 

I've ridden my bike 100 miles and it still hunts around at idle but otherwise is much better than before. I think we broke the golden rule by NOT checking the valves beforehand. Well I'm going to check them now to see if they're out and see how she runs. If it isn't perfect, then it's TB sync time again.....geez.

[Hedge36]

Thx Mike,

 

I've ridden my bike 100 miles and it still hunts around at idle but otherwise is much better than before. I think we broke the golden rule by NOT checking the valves beforehand. Well I'm going to check them now to see if they're out and see how she runs. If it isn't perfect, then it's TB sync time again.....geez.

 

 

Time for another wrench session?

[mikefigielski]

The throttle shaft comes with the throttle plate pressed on it. The shaft is brass and the sleeves in the throttle body are steel I believe (or some metal harder than brass anyway) so the shaft wears first. The TPS just pulls off the shaft (after you remove the two screws holding it on) revealing the stupid E-clip. Once the clip is removed the shaft/throttle plate unit pulls out (unhook the throttle return spring first. The TB has a number stamped on the ridge in the top of the TB casting. It will be something like 101 or 102 if it is an early model or 103 or 104, etc. They will know what you have by that #. See examples of the differnt models and years they fit here: http://www.beemerboneyard.com/thboin.html (shameless plug)

 

Oh yeah, just so anyone wanting to order the parts knows, there is not a kit per se, I just asked him for all of the seals, the shaft, etc to redo the TB. Kinda hard without a parts diagram showing everything which is why I didn't get the E-clip.

[chrisstroh]

Thx Scott, I appreciate that. Would you like me to contact you before or after I attack the valves?

[wolcott]

Mikefigielski: you wrote about that dastardly e-clip "Just spread the ring with the special pliers and lower it on".

1)What special pliers are required for these e-rings?

Thanks for your tips. This was a good thread with helpful info.

[Davis]

If you read Mike's post carefully, he complains about getting the e-clip off and states a d-clip would be easier since there is a tool (the "special pliers") to remove them even when in a recess. There isn't a tool (other than a screwdriver) that I know of for removing e-clips when in a recess (there is a tool designed to push them off, but it isn't much help unless you have clearance).

 

E-Clip

 

D-clip