Welcome. Very nice bike ! Some ideas...

• The number one issue is ALWAYS fuel related, especially when combined with storage. So your man installed the Bing kits, but did he blow out all the passages? Did the kit include new diaphragms? And what kind of a motorcycle shop doesn't have vacuum gauges? There are several rubber bits that must be replaced after long-term exposure to ethanol fuel: all the fuel line, the intake hoses, the diaphragms, the float needles... just to name a few. What fuel are you running and how old is the fuel in the tank?

• Secondly is the ignition system. These bikes have a mechanical ignition advance that has to be lubricated and serviced. Plug caps and wires should be replaced. (Your fancy plug wires are highly suspect. Are they metal core wires?) And exactly HOW was your ignition timing set? It should have been done at extremely high RPM, but some original manuals say "at idle". What spark plugs are you running? Was the heat sink compound renewed?

• Also, weird things happen to Airheads, like mice building nests in the airbox. Was the air intake system disassembled? Air filter replaced? 

• Due to 30 years of water exposure, you'll need to treat every electrical connection with an anti-oxidation compound, such as No-Ox-Id. Every connection, every relay, every battery cable, every terminal.

• Re-packing the head post will improve steering, but repacking the bearings in the starter motor can/will save you from having to buy a $300-$400 starter motor. So work on the starter motor comes first.

More tips here...  https://www.airheads.org/community/wrenching/new-owner-primer-tips-to-get-your-airhead-back-on-the-road/

Assuming the shop did a proper rebuild on your carbs, I am not going to insult them by implying otherwise, I would look for an ignition problem.  While I don't like changing parts to fix an issue until after I am sure the part needs changed, in this case order a set of new plug leads from BMW.  Don't mess around with after market or homemade leads but go to BMW, and get the right ones for your bike.  This is one of the times I will not mess with OM parts.  

A bad connection/ground can cause misfires, so as Richard says check the connections on the bike for the ignition system.  

You can pull the bean can ignition trigger off the front of the cam and spray some lubricant into the weight unit, but to do anymore work is a bit of a pain.  There were recent posts in the BMW Vintage forum as to how to do this.  Frankly the bean cans are very reliable with he Hall effect and not points.

Checking the steering head bearings is pretty easy, if you have the bike on the center stand (front wheel off the ground), gently turn the bars lock to lock feeling for bumpy or notchiness.  If it is smooth, requires little effort, the bearings are good.  As for adjustment, the bars should fall side to side with a tiny bit of resistance but not bang center to side.  Nor should they bind.  Frankly if the bike passes this test, ride it until it there is a problem.  Taking things apart to just lube is a royal big job and not worth it unless the bearings are shot.  LOL, even well lubricated steering head bearings go bad because the grease is not distributed around the bearing due to the fact the bearings are not really turning all that much and they are pounded rather than spun in use.  This is why when they go bad, they get notchy or bumpy rather than squeal like a wheel bearing.  Same thing happens to the swing arm bearings.

14 year old tires I would trash.  They may look fine but  I would not trust them, tires age from environmental issues.

I myself would look into changing seals particularly on a bike that has sat in storage for a long time on the other hand, I could very well just get it running and check for leaks and repair as they come up.   LOL, that depends upon how soon you want to ride.  The very worst that could happen is a seal is leaking.  None of the seals will blow out and cause catasrophic damage with the exception of the oil filter cover seal and o-ring.  

As for lubrication of the starter motor, yeah, they do need it from time to time.  I am frankly amused at the number of factory starters that get replaced for various reasons that could have just been looked at, lubricated and carried on.  That is another topic.

So there is a good chance if the bike were mine, I would put new tires on, new spark plug leads, change the oils, fuel it up ride it until there is a problem.   LOL, then again for a winter project, I would tear into things a bit more.  Good luck, St. 

So I have been thinking, LOL a sometimes bad thing, but it is raining.  Have you checked the color of the spark plugs after a long ride?  They should be tan color.  If white or very light, you could have a lean situation that is the cause of the misfire.  While I don't insult the shop that did the work I am assuming they set the rebuilt carbs up to factory settings for needle position.  

On the subject of a vacuum leak, get a spray bottle of water and while the bike is running spritz it on the rubber head to carb headers and the sides of the carb and such.  You will notice a change in idle RPM if there is a vacuum leak.  Perhaps you didn't get the clamp tight on the rubber header?  Or, it is broken down with time?  Also at the front of the heads, spritz there were the air injection tubes enter the head.  If there is a leak there it will cause problems.

Again I am assuming the shop did the job properly, but even a good shop can make mistakes or miss things. St.

Right on, lots of good stuff,  thanks Guys!

The "Fixing one thing and then testing" ship has sailed I am afraid.

I wanted to get the broken speedo of to Terry in Oregon asap, sounds like it might take a while so tore into it.   While I have this end opened up I can sort it out as well:

• Put in Race Tech emulator and springs.
• Repack steering head bearings, old brown grease did not look all that bad, kind of soft but…..
• Put a Conti TKC 70 on the front, like these tires good road manners and decent grip for the few times I am on gravel.
• Chk/ repack front brg’s.
• Install OEM heated grips.
• Paint the front sliders/ replace broken reflector.
• Go over all of the electrical connections in that rats nest of wires.

Yes it is hard to say where things are at with those carbs, my mechanic will have a Vacum gage but why he did it this way?  So a good clean along with a rebuild, may do this myself, not sure, those things are a mystery to me but if I am not in over my head where is the fun.

The plugs are clean and close to black, not sure what this means. I replaced them with iridium plugs just before it came in for the winter but they made no difference.

Plugs that came with bike.

I did spray some ether at both ends of the carb with no reaction from the motor so that seems ok but will change out the old rubber. I will put in new.

I did replace the air filter and will check for restriction upstream. Also freshen up the starter motor/bean can.

I am enjoying this.   Any idea what make the shock is?

Thanks again.  Al

LOL, Sorry Allan, I thought you had not torn apart the front end yet.  One of the deficiencies of communication of forums is lack of communication.  LOL, in a five minute phone call, I bet that would have been sorted and I would not have written a book telling you what to do, forgive me.

Really with your last post, you have done a lot more than perhaps I would have done, but what I would have done, if you get my confusing drift.  All good things to do especially if the history of the bike is not known.  

So spraying ether didn't show any change in engine RPM at idle, that is good, it means there are no vacuum leaks.  I have looked at your picture of the spark plug and I am wondering if perhaps you are running just a bit lean.  

So the shop that rebuilt your carbs is it close by, do you feel confident working on the carbs yourself?  

The reason I ask is it is possible to change the mid range mixture by adjusting the needles in the carb slides one notch richer.  If you want to do that yourself I will try to dig up a description of how to go about it or you can do a web search.  

Nice ride, enjoy it.  St.

🙂 yes maybe I am getting a little to excited but I do like this bike, it will not be a silk purse when it is done but will a nice pleather purse with a hole in the bottom I can pour loonies through.

I am probably not the best person to full on tackle the carb but I did replace the needle jet and jet needle on this one, mechanic said they did not come with the kit, the needle clip is at the #2 position per the Bing book. Of course that tweaking is a next spring thing now so I should get the carbs sorted out to be a known know. That means sending them out to a proper carb spa, south for a winter vacation I guess.

Allen, my local restoration/repair shop owner turned down two bikes this past fall for restoration due to the cost versus worth of the bike when finished.  He is VERY good about making sure that owners know how big a bill they may end up with.

That aside, in my case I have thousands of dollars into keeping a 84 R80RT running despite the fact that it is probably worth $1000 on the market because of mileage.   Why? because I love the bike, it is as I have said in other forums the almost perfect bike for me.  LOL I will never reach perfection but it is pretty near it.  Also, I love having winter projects and the few times I have done ground up restorations on it makes me happy. I also take pride that when I am done I have a bike that with the exception of worn finish around the clock and voltmeter dials and the choke horn lever, with some other spots, looks like brand new.  Not show bike quality but solid rider bike.

I don't have the bing book at hand but I believe you are correct with number two notch.  Also, it is not all that difficult to change a notch and see what you get.   

A well sorted airhead is a joy to ride.  Yeah, they can cost some loonies and maybe the owners are loonie, but what the heck!  

I take it you are in Canada?  So like me you are buckling down for winter.  Enjoy the restoration, keep us updated on your progress, St.

Posted by: @14724

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Assuming the shop did a proper rebuild on your carbs, I am not going to insult them by implying otherwise....

I will. Based on Allan's comment about the shop setting the carb balance by ear, either 1) the shop does not own a carb balancing tool, or 2) they don't know how to use it on an Airhead. Just in my personal garage, I own 2 carb balancing tools. So setting the carbs by ear sets off huge alarm bells for me. They are either under-equipped, or they don't work on Airheads and lied about their level of expertise. 

When you pay for "professional" repairs on any vehicle, tools and knowledge are the 2 things you should be getting at a minimum. Watching YouTube vids does not constitute vehicle competence.

Additionally, do the math. Anyone who worked on Airheads then, would be in their 60's today. Did you see any 60 year-olds ?

All this is why the owner needs to become the "local Airhead expert". This is why you need to attend your local Tech Days so that you can gain that knowledge. Even if you find someone qualified, if/when something goes wrong on the road, if you haven't been making yourself familiar with the machine, then chances are you're in for a lot of expense and frustration rather than an afternoon of fun.

Here's the truth about motorcycle diagnosis and repair... When you have a complicated, multi-variable problem the only way to fix it is to take 1 variable (the carbs) and fix them so well that you can rule it 100% out. THEN, and only then, can you can start on the second variable (the ignition). From your description, I'm not 100% sure about the carbs. 

Consequently everything mentioned thereafter, no matter how well-intentioned, is really just guessing. You might as well get yourself a Ouiji board, some Tarot cards, or consult a palm reader.

This is why I stopped at fuel. And I can't really continue until you answer all my questions.

All the best.

Let me say, my original BMW dealer/mechanic ran his shop and NEVER used anything other than his ears.  He could balance an engine like no other.   

Until I lost hearing in one ear and can't sound locate from one side of the bike to the other, I never used any kind of gauges. 

The fancy vacuum gauges that are on the market now didn't exist back in the day when I learned to set carbs.  Yeah, I suppose I could have bought Mercury or fluid sticks but frankly never needed them.

IF you look, you can set cable adjustment for equal pull off visually before you even start the bike.  Same goes for idle speed.  

If you set the mixture for Bing recommendations and the carbs are working as they should be, the most adjustment needed to fine tune will be 1/4 of a turn.

All this can be done without a gauge, just proper set up and a good sense of hearing using finesse on adjustments.  

Frankly I am peeved I had to purchase a gauge because it sits in the tool box more than it is used.   Once I set carbs they stay set for a very long time until the cables wear out or at a 100K miles the needles wear out.  My old dealer/mechanic told me "carbs are very reliable once set they stay set for a long time. Too many people start to fiddle with them when in fact they need only to do a valve adjustment and get themselves into trouble".    And you know what, he is spot on.  Yesterday I noticed my bike wasn't idling smooth and when I got home and looked at my Maintenance log I found it is time to adjust the valves.  I will bet good money one is slightly out.  St.

Posted by: @14724

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Frankly I am peeved I had to purchase a gauge because it sits in the tool box more than it is used.   Once I set carbs they stay set for a very long time until the cables wear out or at a 100K miles the needles wear out.  My old dealer/mechanic told me "carbs are very reliable once set they stay set for a long time. Too many people start to fiddle with them when in fact they need only to do a valve adjustment and get themselves into trouble".   

Here's the difference, my friend...

• Any good mechanic can set the carb balance by ear at idle. But you also need to set the balance by cable pull at ~2000 RPM. And for that you need the carb balance tool. I have the tool and you have the tool, but that is not the topic. The discussion is why the OP's mechanic seems not to have that same tool. A shop would be using that tool 2 or 3 times a week. 

• "Your dear old mechanic" was proabably remembering his dear old gasoline. I too have fond memories of those days and leaded gasoline. But gasoline has gone through numerous changes since the good old days. And the topic under discussion is the OP's present issue with today's gasoline. Please keep your comments germane.

• The OP has already told us that the throttle cable was replaced. So by your own admission, use of the tool does apply. 

Posted by: @14724

↑

Allen, my local restoration/repair shop owner turned down two bikes this past fall for restoration due to the cost versus worth of the bike when finished.  He is VERY good about making sure that owners know how big a bill they may end up with.

That aside, in my case I have thousands of dollars into keeping a 84 R80RT running despite the fact that it is probably worth $1000 on the market because of mileage.   Why? because I love the bike, it is as I have said in other forums the almost perfect bike for me.  LOL I will never reach perfection but it is pretty near it.  Also, I love having winter projects and the few times I have done ground up restorations on it makes me happy. I also take pride that when I am done I have a bike that with the exception of worn finish around the clock and voltmeter dials and the choke horn lever, with some other spots, looks like brand new.  Not show bike quality but solid rider bike.

I don't have the bing book at hand but I believe you are correct with number two notch.  Also, it is not all that difficult to change a notch and see what you get.   

A well sorted airhead is a joy to ride.  Yeah, they can cost some loonies and maybe the owners are loonie, but what the heck!  

I take it you are in Canada?  So like me you are buckling down for winter.  Enjoy the restoration, keep us updated on your progress, St.

Well put ST.     I have put a lot of $ into motorcycles over the years, making them ride better/look prettier only to take a $ loss on them when it is time to move on. It is the satisfaction and pride you get out of the work that is the payment, it is nice to have the next owner walk into the shop and fall in love.  Geez that sound corny!   Luckily Cheryl gets this and is happy to have me busy and out of the house :).   I used to keep 4 or 5 bikes around but they did not get used, collected dust and ate batteries so now it is two bikes, a project and a for sure runner. Having said that the for sure runner (87 Transalp) just pooped the bed, a sucker for basket cases I guess LOL.

Allan -

What say we stop yapping and start focusing on your problem?

Despite all the rambling, your issue is most likely fuel/ carb related. BUT, there's also an outside chance it could be ignition. This leaves you with a 2 variable problem and just like in Math, the only way to solve the problem is rule out one of the variables. 

The carbs were just apart and had many pieces replaced, so it should be easy to quickly go through and 'double check' rather than assume anything. I have found that the biggest time wasters all start with assumptions. So my personal method is to assume nothing and check everything. 

Fuel/ Carbs

• Again, I need to know 1) what grade of fuel you have and 2) how old it is. Modern fuels will age and go "bad" (research "phase separation") in a matter of weeks. So this information is critical. 

• Your issue's RPM range is mid-needle. So you need to look at the needle and needle jet. These parts should be clean, shiny, new parts with zero corrosion or build up. And all jet numbers and measurements should be exactly the same on both carbs. The needle jet is held in place by the main jet. The needle is inspected by removing the top of the carb, which allows you to check the 1) needle condition, 2) diaphragm condition and 3) needle extension distance (clip setting).

• The float setting needs to be checked. Hold the carb at 45° and the molded seam should be parallel to the carb body.

• Set both the pilot screws at 1-1/2 turns out. 

• The inside of the float bowl should be spotless. 

• I understand you bought new rubber intake hoses and this is good. Ethanol fuel attacks all "rubber" parts, and even "ethanol-proof" parts develop cracks or just get hard... and thus need replacing. One thing to check is the metal spigots screwed into the cyl head at the intake. Those can and will get loose. Make sure they are screwed tightly into the cyl head  before installing the new hose. 

• As a check, clear the air intake tract. Mice love to build nests in the air box, which can starve the engine for air.

• Finally, you can build your own carb balancing tool following the instructions here:

http://powerchutes.com/manometer.asp

I suggest filling the tubes with red ATF making the reading much easier to see.

► Yes, the carbs need to be balanced at idle (950-1000 RPM). That's done with the Idle Speed screws.

► But they also need the cable pull balanced at ~2000 RPM. This is accomplished with the cable length adjusters on the sides of the carb tops. This is really where it becomes mandatory you have the carb balance tool.

When you do all that, I'll be back with suggestions for the ignition. 

Richard

I am using this thread to keep track of this problem, so let's buckle down, here is what I have done to date on the list.

   -  PROBLEM  The problem I would like to run by you is the bike bucking/missing usually between 3000 to 4000          rpm with the throttle just open and motor warmed up.  

   -  I have run two tanks of 91 octane no alcohol fuel with Seafoam through the bike, before that ? Bike sat                  through one winter with some fuel stabilizer in it.  

    -  Carbs are   40mm  94/40  123&124

   -  at sealevel here, 1100ft where I found the bike

   - Mechanic installed a Bing CV#4 40mm kit,  he said there was no needle/needle jet in the kit.                                 Problem still there.

   -  Bing sent me the needle/needle jet, no cost.  jet needle 'new style T-94', needle jet 'T-64,84,94', matching              numbers.

      I installed the parts, needle clip at position 2,carb looks good, to my nooby eyes, clean new gaskets/diaphragm. There are no other jets or rubber seals in the #4 kit.   The carb bowls look clean a stain in the bottom of of one points to past grunge.  After the install I vacuum balanced the carbs with my Syncromate. At idle first, right idle mixture screw was out 3.5 turns ! left out 2 turns, put both back to 1.5 had to pull balance left a little and got balance at 1200 rpm, could go no lower. Balanced with cables at 5000 rpm and it sounded and idled good, the test drive was great for 20 min or so and then the problem returned.   Problem still there.

   -  I did check the float bowls while on the bike. Floats up no leaking, as you let the floats drop the fuel starts to          flow when the floats are parallel to the base of the carb, both sides.

   -  Checked airbox and piping to carbs and all clear.

This is where I am at now, to continue on the carb track I am going to have the carbs properly cleaned/blown out, replace rubber and all fittings except the needle jet and needle which are new.

The position of that idle jet screw says alot about my mechanic, I do have to talk about him so that there is a litle more knowledge here and less assuming.  

No he is not in his 60's, just into his 40s I would guess, Licenced trained Red Seal (can work nation wide).  He is locally respected, busy, and the shop is in a commercial mall on main street. The shop is well set up he does his own machining/fabing. He works on all brands, his vacuum gauge will probably do a CBX. He is a serious fellow, I can get him to smile but it takes a bit of work. I still trust him though maybe not on Bing carbs any longer.

Pulled the plug wires last night, found corrosion on the coil end of both, ordered new OEMs.

You've said and answered a lot above. It's too complicated to Cut & Paste so if the responses are simply bulleted in order, I hope you can follow. Here goes...

• Fuel octane rating varies because it's calculated differently in different places. Also "winter mix" may lower the number, but you should always be using the highest octane grade possible. And because most cars don't use it, you should only be buying it at stations that sell a LOT of gas. (The gasoline/ethanol not only separates in your tank, but ALSO in the tanks of the station !)

It may also help you to read and learn about Top Tier Fuels. HERE

• My only experience with Seafoam is that is SEEMS to have eaten the O-rings out of the carbs on another bike. I do not have scientific, conclusive laboratory evidence of this. However, it was echoed by other users on another forum. I would highly suggest StarTron, which is a stabilizer AND cleaner. 

• I have a personal issue setting needles in the same position for both Bing carbs. I grew up on Mikuni and Amal, where you can visibly see the needle notch. So I use the depth portion of a caliper to check the installed needle heights. Apparently others have this same problem because I have found needles in different positions on customer bikes. Just check.

• Needle jets should have had a number like "2,66" on them. By 1991, EPA was making them lean the bikes out for pollution, but they never ran as good. So you want the largest jet that a GS ever used. So if you encounter a 2,64 then that may be part of the issue. Just check.

• "Carb bowls look clean". Good, any muck or corrosion would start first in the bottom of the bowl and then move into the jets. None is a good sign.

• "Balance at 1200 RPM, could go no lower". That's because there was no slack (free play) in the throttle cables at the top, bottom or both. The engine then had to be slowed by using an incorrect Pilot setting. Set the Pilot to 1.5 turns out and that should be very close. Back off the throttle cable adjuster at the carb tops until the bike will idle at 1000 RPM. Then use your carb tool to match the balance at 2000 RPM by using your twist grip cruise control. 

You should end up with 3 things happening concurrently: 1000 RPM balanced idle, balance at 2000 RPM, AND 2-3mm of slack in both outer throttle cables when the throttle is completely rolled forward and shut. When all 3 things happen, then your carb adjustments are good. (Be Aware: Carb adjustments can change if/when we set the ignition timing.)

• Glad to hear your mechanic has some age. All I see around here is 20-somethings that are "experts", but don't know the 4 strokes of a 4 cycle engine. Sounds good in that department.

• On the plug wires, I'm more concerned that they are leaking due to extreme age, or may have been replaced with resistance wires from a car. However, the corrosion proves my point that water goes everywhere !! That same corrosion then is also present (in smaller portions) in the 12V wiring. Get some of the recommended No-Ox-Id and put a tiny dab on any electrical connector, relay, battery cable or fuse you ever unplug. It will also help exclude water from places like the sparkplug wire socket in the coil too. 

• Recently NGK stopped making non-resister sparkplugs. That means only resistor type are generally available. So if you are running NGK you will NOT want an "R" in the plug number. Should be BP7ES, not BPR7ES. This because there is already a resistor in the plug cap, you do not want a second resistor in the spark plug or in the plug wire. 

All the best.