1983 r80/7 cuts out when put into gear

[HaYnMogli]

Hello new to forum and first time airhead owner. Ill try to give the most pertinent information I can.

Primary Problem:
I can start the bike in neutral.When I put the bike in first gear while running with clutch lever pulled in on two wheels the bike cuts out and dies.

Pertinent Info:
New(not OEM) clutch lever installed and clutch cable. No clutch lever switch. Never touched neutral switch under the gearbox and it's not connected to anything at the moment. Bike on the stand while running can be put into first and second without cutting out.Tire spins fine in both. It still spins when I pull clutch in and in neutral(quicker than it should be spinning).While the bike is off I can pull in the clutch lever and go through gears. But with it in gear and lever pulled in the tire won't spin. I got the bike after it has been sitting for 18months to two years. I do have it wired to M-unit.

Any suggestions are greatly appreciated. I plan on taking the gearbox off and inspecting the clutch assembly. but before I do Id like to know what to look out for more or maybe its a switch issue?

Thanks ahead of time.

[schrader7032]

Welcome to the forum!

It was my understanding that the clutch lever switch and the neutral switch at the transmission were part of a safety circuit to not allow the starter to engage when the engine was running while in gear. Quite possibly, if those two circuits are not in place, it cuts off all power to the engine, not just the starter.

Seems simple enough to correct at least one of those circuits, probably the neutral switch would be the easiest. With it connected, retry putting the bike in gear.

[HaYnMogli]

Thanks for the reply. I guess I need to figure out what to connect it to as its not the original wiring and I could only think of connecting to the speedometer for the neutral and oil pressure light.

[srankin]

I would not bother with the work needed to take out the gear box, unless you feel the clutch is worn or you have a leaking main seal or shot input shaft.

Your problem is wholly electrical. Something is not connected that should be connected and it happened when things were removed for whatever reason. Not to be a jerk, but when replacing OEM parts with non OEM parts, care must be taken they play well with the whole system. I don't have a schematic in front of me but I can pretty much figure if you don't have a clutch lever switch in the system, things aren't going to work properly. Something will have to be done to make up for the lack of the switch.

You mention something about Neutral light and oil pressure light connection. A tip to you is to make sure, you have a charging light for the electrical system or at least you have bypassed the red charging light. If you have not, your charging system will not work as well.

Good luck, St.

[HaYnMogli]

I have the switches from oil pressure and the neutral switch. But Im not sure what to run it to. I have the wiring diagram however, I have the m-unit installed. I have the OEM throttle assemble and switches also.

[srankin]

Hello, perhaps we are confusing each other?

Are you building a custom BMW motorcycle and replacing/substituting parts to do so?

Are you working with a stock BMW bike and trying to repair it?

The reason I ask the questions is because of your comment about replacing the clutch lever: "New(not OEM) clutch lever installed and clutch cable. No clutch lever switch". If you have done this, you have broken the circuit, and you will need to figure out a way to bridge or make up for the missing switch. The schematic will tell you if the absent clutch switch is normally open or closed.

I am not understanding the point you make about the neutral and oil pressure switches? Are you saying they are still on the bike? Each of them has a place in the bike's wiring.

Are you rewiring the bike? Are you using the stock wiring harness?

What am I missing here? St.

[schrader7032]

I'm glad you asked, Steven, as I'm confused, too. Note that he is installing an "m-unit" which I believe is a Motogadget M-Unit. I've not heard much from people on using that.

[srankin]

OKAY, I see from earlier posts, one of my questions has been answered, I apologize for not reading the note properly.

You do not have the original wiring on the bike and you are wondering how to wire in the neutral light and now missing clutch lever so everything works, is this correct?

Is this bike a custom cafe style bike?

On a custom made bike, you do not have to have any kind of neutral light or oil pressure, so long as you have the ability to engage the starter motor to turn the engine over and the ignition circuit is intact to provide spark. A bike will run fine without the neutral switch and its lights and the clutch cut out switch IF a patch is made in the starter motor circuit and perhaps in the ignition circuit.

A wiring schematic for the bike will only tell you how the energy flows in the system, by looking at it, for example, I can look to see just how the neutral switch/light/clutch switch is tied into the starter system to prevent the bike from being started in gear. Since I can see by the schematic how the system is supposed to work when properly wired and everything is in place, I can also figure out what parts of the system can be removed to eliminate the circuit altogether and still get the bike to start regardless if it is neutral or not.

One of the attributes of custom or cafe bike building it the elimination of "stuff" on the bike. Everything on the bike except the ignition, and charging system can be taken off the bike and the bike will run. Now, unless you are going to kick start the bike, you need a starter motor circuit in place. This circuit does not need clutch interlock switches nor does it need a neutral light in order to function these things can be taken out/bypassed to complete the needed working circuit.
I mentioned one thing in one of my previous notes and that was to include a charging indicator light in the charging system. I will say this, IF the charging system wiring is stock, you must have the charging light in place or bypassed in order for the system to work properly. IF the system is not stock wiring, then you have your hands full figuring out with the aid of a schematic or design plan what is needed to make the system work.

As I have said, I don't want to be a jerk here nor do I want to insult you, I want to help you get your bike running. A schematic or circuit design plan done in advance to the build or changes can help you greatly in figuring out what parts can be taken off the bike or bypassed to still make the bike run.

I am afraid when it comes to building custom or cafe bikes and doing the wiring, I am not able to "tell" you exactly how to hook up a circuit in order to make it work. IF I were there in person, I could do it but it is very difficult to do by forum.
All I can do sitting here at my home is look at the schematic I have for the stock bike and tell you what stock color wire to hook to what stock terminal. Beyond that, I am confused and not much help.

I don't want to be insulting or rude as a result of my confusion and ignorance. Cheers, St.

[HaYnMogli]

Thanks srankin for the feedback and I do not feel insulted. Im here to learn from knowledge of others.

Yes I do not have the original wiring of the bike. I have the Motogadget M-unit installed. Everything starts up fine however when I put it in gear with the clutch pulled in the bike would shut off. Since then I have pulled out the clutch and did find the friction disc was frozen to the pressure plate due to sitting for extended period of time (I assume). new parts have been ordered to fix that problem.

However, I am not sure if that is why the bike was shutting off. Could that be the reason? Or is it electrical?

[srankin]

So it was a mechanical problem after all. If things are locked up or frozen, the bike could stall when the clutch is let out.

IF it is not a mechanical problem, and you are still having problems, I suspect, the problem is with the wiring and the addition of the motogadget M, unit and the removal of the clutch switch in the handle bar.

I have not idea how or what the motogadget M unit is or does, so I can't comment on it's wiring or how it ties into the wiring.

I do know on the stock bike, the neutral switch, and clutch switch are wired into the starter system to prevent the bike from starting in gear. Changing the circuit by removing a part,(the clutch switch) can mess up this system and things won't work.

In reality you only need an ignition circuit to run the bike. A charging circuit to top off the battery and provide power for a headlight taillight and brake light. All other circuits are not needed and can be removed.

The fact is, before you start making major changes to circuits, you need to know how they work and how they interact with other circuits on the bike. By the proper reading of the wiring schematic, is this possible.

Is it possible to contact the motogadget M company to see if they can help? Did the unit come with any kind of instructions for installing it? Does it in fact work on your bike?

It is great to be able to build a custom bike just for yourself. I am happy you are asking for help and I am happy to try to help you along with others in the forum. Good Luck. St.