HI YALL, Possible carb problems

[Mag00]

I was just wandering the net looking for saddle bag covers when I decided to come to the MOA page. Then I noticed the forums looked pretty cool so I signed up. Gotta love the high tech.

Here's a brief overview of my problem. 91 R100GS. Hard starting when cold. 33 mpg. Idles to me rough. Pops sometimes on left bank. Chokes out coming to a stop when cold. Runs fine on highway, but under load seems to vibrate excessive.

I've taken it to two separate dealers and it is somewhat better,(it idles now) but still isn't right. Compression is 150 on both jugs and the valves were trippled checked. Float bowls have been cleaned etc. Throttle cables lubed etc. Timing was checked thrice also, but I find it to be a degree off, dealer say it's fine.

Anyway I would like all your help in diagnosing finding parts and repairing this myself. I'm just tired of shelling out the bucks and not having my beemer run right.

All help will be appreciated.
Dave

[sgborgstrom]

You didn't say what kind of work your trips to the dealer involved, so I'll just jump right in at the begining.


Part of the beauty of the airhead line is how simple they are to work on. Get yourself a Clymer and a Haynes manual (they attack the same job from slightly different angles, it's nice to be able get a second opinion with out leaving the garage) read up on basic tune-up procedures and get to work.

After 13 years you are probably well past due for a good carb cleaning and subsequent re-balancing. At the very least, pull the main jets and get them cleaned out, they get gummed up pretty good. Also check the air filter.

Steve

[Mag00]

Originally posted by sgborgstrom
You didn't say what kind of work your trips to the dealer involved, so I'll just jump right in at the begining.

Obviously not much, otherwise it would run good as requested them to fix when I took it in. Other than lubing the cables. (which I didn't think to do)


Part of the beauty of the airhead line is how simple they are to work on. Get yourself a Clymer and a Haynes manual (they attack the same job from slightly different angles, it's nice to be able get a second opinion with out leaving the garage) read up on basic tune-up procedures and get to work.

After 13 years you are probably well past due for a good carb cleaning and subsequent re-balancing. At the very least, pull the main jets and get them cleaned out, they get gummed up pretty good. Also check the air filter.

Steve

When I purchased this fine machine, in Colorado, the first thing I did when I got it back to CA was to go over it doing all maintanance etc. All fluid were changed new filters, greased the stearing head, polished and cleaned like any conscientious beemer owner would do.

It never would idle down and at time would run ok but other times coming to a light would idle high and rough. Also had a blown out gasket in the exhaust connections at the downpipes.

So I figure what the heck I'll just take it to the BMW dealer, they work on these all day long and should be able to fix her right up.

Boy was I wrong $300 later I still had the exhaust leak and it wouldn't idle, the two things I brought it in for. The service writer said that all that would be covered on the service. What a liar. Then when confronted about why it ran like crap and still had the exhaust leak, "well it must be something more involved lets keep it for a week and figure it out." Thankfully my ride had left and the bike was my only way home. I then took it to another BMW dealer and they at least were able to diagnose the sticky throttle cable, so now it will idle.

The idle is somewhat strained. Like it runs on one and half heartely on the other. Like it wants to fire properly but just can't. Today it was much worse.

I was on the Bing website and they sell and upgrade kit. Is this kit an improvement over stock? They claim better fuel efficiency. This is probably where I am inclined to spend my next money, that and a saddle bag.

For what I've already spent on dealer repair work I could have bought new carbs. :cry

How bullet proof is the ignition on the 91 r bikes? I'm pretty sure it is a carb problem, not just a simple adjust, as I or two dealers can't get it dialed proper. Considering I used to tune my Kawi H2 tripple, I don't see how two jugs could be so troubling.

The carbs have been off and cleaned and inpected by me, and only one thing seems to give me concern. The left carb seems to have some visible scratches in the slider. Not enough to hurt but maybe. All connections etc, tight and free of vacuum leaks. I've tried different blends and octane gas. Today it would idle on one only. the right bank. I always use the center stand for longer parking.

Any HelP? Hints? IdEas?http://www.smileys.ws/sm/speechless/00000003.gif
Dave

[nvbird]

Sounds like you have the problem figured out. My push rod tube seals leaked to the point and blew back around my neural switch to the point that I thought I had a seperate leak. Still waiting for parts to fix that problem. Take care

[nvbird]

whoops this was suppose to go to the neutral switch problem...Darn computer::dunno My screen has been locking up and doing weird things. Wish I was a computer guru!

[kbasa]

Just a thought here. You bought the bike in Colorado, which is, I presume, well above sea level and took it to CA, where I presume you're at something closer to sea level. Did the previous owner rejet the bike to run at altitude?

[Mag00]

Thanks, now there's a thought. The guy I bought it from told me it originally came from California so I didn't consider the rejet, if it was done. At least now I have a good reason to go back in and fix things. http://www.smileys.ws/sm/action/00000064.gif
After being to the dealers twice and them and their high tech equip, it's hard to justify tinkering, but I haven't tried since the cables been freed up. Maybe I'll have better results.

Any idea what the sea level jet sizes should be, I still haven't dug up my manual since my move.

[Wes]

Some resources to supplement clymer/haynes:

http://www.airheads.org/index.php?Technical%20Tips

http://home.jps.net/~snowbum/techindex.htm

http://w6rec.com/duane/bmw/bmw.html

http://www.ibmwr.org/r-tech/airheads/index.shtml

http://www.micapeak.com/lists/AIRHEADS/FAQ

[Wes]

Originally posted by Mag00

Any idea what the sea level jet sizes should be, I still haven't dug up my manual since my move.

My Bing manual says your bike would have carbs 64/32/357-358 and the jet size would be 135. If you want to check your carb numbers, I'll cross reference the manual.

[sgborgstrom]

Somebody once told me "90% of all carb problems are electrical"

That being said, you said you cleaned the carbs, did you also inspect/replace the assorted rubber bits? Diaphragms ok? How about the little o-rings that seal the throttle shaft? Does messing with the idle adjustment screw do anything? Is the "choke" mechanism shutting off? What do the plugs look like (black, brown,grey)? Spark plug cables go bad over time, are they original?

I'm just working through the assorted angles I'd use to trouble shoot this if it were in front of me.....

Steve

[Mag00]

Thanks for these grreat tips. I have the 64/32/357+8 carbs. The diaphrams are OK floats seem ok, needle seat ok, didn't check the shaft seals hmmm. Choke disengagine ok, I assume as it seems to do better with a partial choke---leads back to shaft seals hmmm. Spark plug wires? Cheap enough, that will go on the order list. Spark plugs are new, I'll check again, but seemed no odd stuff.

Also the other day while idling I did a quick check by pulling on the throttle cable at the left carb while idling. The left bank starts to fire and the r's go too high for idle. I sortof trust that the carbs have been syncronized properly, Acceleration good through all range, no hesitation etc. Runs well on the highway. http://www.smileys.ws/sm/sport/00000005.gif

[jgr451]

Speaking of scratching our heads over carb performance,what is the experience out there of buying the replacement(expensive)floats vs.the longevity of the originals?My carb ocassionally floods and I am thinking it is the floats saturated..84 R100 .

Sorry,not meaning to hijack this thread but to widen the discussion at hand!!


:p

[The_Veg]

The w6rec websitre mentioned in the list of online resources belongs to a chap named Duane Ausherman who was once the BMW dealer for the San Francisco area. Excellent info he has, although it is derived from knowledge of bikes up to the /5- after those he kind of lost interest, but is still interested in helping those who need to learn. You can talk with him and many other good helpful folks at www.boxerworks.com , a site at which I have really enjoyed being part of the forum community for about three years. it's as unmoderated as it gets and the humour runs way loose at times, but the folks there are very helpful and Airheads are what they talk about.
Good luck and keep us posted!

[Wes]

Originally posted by jgr451
Speaking of scratching our heads over carb performance,what is the experience out there of buying the replacement(expensive)floats vs.the longevity of the originals?My carb ocassionally floods and I am thinking it is the floats saturated..84 R100 .

Sorry,not meaning to hijack this thread but to widen the discussion at hand!!


:p

I don't have any direct experience but if you read

http://home.jps.net/~snowbum/bingcv.htm

there is a discussion of the Bing alcohol proof floats (the more expensive ones) and a recommendation against purchasing them. I offer this FWIW and with no personal opinion.

[jgr451]

Wow!!Some detailed article!!
Thanks for the tip.

[James.A]

Regarding vacuum leaks and bing carbs, here's a dirty little trick you can try. If you shoot a little starting fluid at the carbuerators when the bike is running, if there is a vacuum leak, the starting fluid will be sucked in and produce a temporary increase in RPM. Shoot a little at the throttle pivot and at the intake tubes.

[Mag00]

Originally posted by woodnsteel
Regarding vacuum leaks and bing carbs, here's a dirty little trick you can try. If you shoot a little starting fluid at the carbuerators when the bike is running, if there is a vacuum leak, the starting fluid will be sucked in and produce a temporary increase in RPM. Shoot a little at the throttle pivot and at the intake tubes.

Now that you mention it, I did that when I first started to troubleshoot. I found a couple probs and fixed them and it did improve some. I talked to yet another dealer and have come to the conclusion that I will just rebuild these carbs myself with the newer alcohol resistant floats etc. Also I can jet for sea level if needed. For what the dealers want I can almost buy a new carb. ($275 a piece, no gaurantee it will be fixed).

[Mag00]

Well I just got off of the phone with Bing Carbs after ordering the float upgrade and full rebuild with new jets. Seems the r80's and r100's were jetted the same and many r100's needed to be rejetted to run right. If that is the case I may have to go back to the dealers to get some money back, as they should be well aware of this fact, if it is true that is.

The float upgrade has been redesigned and I guess works great and have reported to increase mpgs. We'll see.

[widebmw]

With the dual float kit it is possible to put the bowls on the wrong side. If you do the choke will not work.
Check to be sure. There is a jet in the bowl. The tube must go it that hole.

[Mag00]

So my float kit etc. came and this weekend was the time to fixhttp://www.smileys.ws/sm/action/00000064.gif

After tearing down and cleaning I'm in the assembly stage and stuck at how to set the float level. With the floats in the bowl, how do you set the level? Bing was supposed to send that info with and didn't. They are closed until Monday, but I would like to finish today and it is not looking good. I'm considering drilling a hole and putting a fitting in the new bowls so I can watch the fuel level through a clear hose. Just don't see why should have to do this after spending almost $300 bucks.

Any suggestions apreciated.
Thankshttp://www.smileys.ws/sm/sport/00000005.gif

[widebmw]

With both the stock floats and the dual floats the standard to start it to have the floats shut off the gas when the "Y" piece or the part that holds the float is parallel with the bottom of the body of the carb. Put a bowl under the carb and raise and lower the floats or the "Y" piece to shut the gas flow on and off.
To adjust the level bend the tab that hits the bottom of the float needle. It should shut off when the bar the floats hits is parallel to the bottom of the carb. I found that if I put a small wrench on its side up to the bottom of the carb where the float bowl sits it is easer to gauge when it is parallel.
Does any of this make sense ?

[Wes]

The floats should be parallel to the lower body of the carb - they usually come such that you need not adjust them - better that they are a hair (0.02" max) below than above. You adjust by bending the tab that the float needle and wire clip attach to with a small screwdriver. Just be careful when bending.

[gambrinus]

Hey MaGOO, Just for giggles, which L.A. area dealers did you take the bike to for service?

[Mag00]

So here is a couple of pics of the new float setup.
http://bunnylandranch.com/bingfloats.jpg http://bunnylandranch.com/floatbowl.jpg

The trouble with this setup is that the floats stay with the bowl. I did initial install with the lever (attatched to needle valve) as it was shipped. With the needle seated the lever itself (no floats) it is just lower than parallel on both carbs, so I would rather err on the low side. I will still call bing in the morning to verify this before I turn the fuel on.

I took the old overflow pipe out of the old bowls and drilled out the new bowls to accomodate the overflow pipe. If I can get a measurement of where the fuel level should be, I will use the overflow pipe to hook a clear hose to. To do this I will have to tap the overflow pipe to lower than the operating level and then tap it back when finished. A little more work than I want to do, but should be well worth it.

Acording to bing, with the dual floats, the fuel level will stay closer to optimum when cornering etc, thus improving performance.

I also rejetted to 145's (had 135's)

Here's a before after type shot.
http://bunnylandranch.com/bingcarbs.jpg

The left carb (dirty one) was pretty bad inside also. In the needle jet area alot of carbon or gunk like carbon. Both enrichment valve gaskets were blown out. The richness screw was all the way in on the left carb.

I can't wait to spark it up tomorrow, It's gonna run sa weet, at least I hope so. Got all the cables adjusted and starting with some preliminary adjustments. I do have an airflow meter and will try that if I have difficulty by ear.

I'd say sorry for the long winded post NOT I'm just so anxious to see if it will run like a Beemer should, it hasn't since the day I got it, and trust me, it isn't as much fun especially pulling up to a light and it's not idling proper, how embarassing.

Now I can imagine the nice pup-pup-pup-pup all even and sexy wooo hooo. :D

[Mag00]

Originally posted by gambrinus
Hey MaGOO, Just for giggles, which L.A. area dealers did you take the bike to for service?

I'm not saying, but what I can say is it was Orange County, was the worst, and Long Beach/Carson did accomplish better performance but have moved and really didn't fix it either. Do you have a quality dealership to recomend?

I figure a guy who works day in and day out on BMW's, should only have to hear it for about 35 seconds to know what to do. Sorry, I just don't believe in trial and error from a dealership.

Needless to say I will do all my own wrenching on it from now on. I don't mind supporting the local dealer, but just can't give them money for sevice not rendered. I'll run to San Diego and get the parts to do the rear main. It's a nice drive. http://www.smileys.ws/sm/sport/00000005.gif