R100RT Neutral Switch

[casper_zip]

Hey there:

Can anyone tell me where the neutral switch is located on the R100RT bikes ? My neutral green lite is not coming on, and bike will not start even tho it's in neutral. However, pulling in the clutch, the bike will start and run. So, this is telling me the problem is not in the light itself, but the switch is not closing to light the light telling me I am in neutral.

I've looked and looked, so far, have found nothing about this switch. I hope someone can help me. I don't care to pull in the clutch every time I need to start up.

Thanks in advance. Also really don't know how to change my bulbs in the instrument panel when that becomes necessary. This R100RT has the full fairing on it.

Thanks so much,

Casper_zip

[alkoivisto]

You'll find neutral light switch up and behind rear engine mount thru bolt at bottom of transmission. Block up motor, remove nut one side, pull bolt out 'till you can remove spacer sleeve. R&R switch. Don't forget to drain trans lube first! Moisture finding it's way into swich innards causes contacts to self destruct. Not repairable. Kind of a pain to hook wire backup if you have big mitts like me.

[20774]

Bottom of the engine...atually, it's tapped into the bottom of the transmission. Look at the underside towards the rear of the engine. You should see an electrical plug, probably with a single wire going to it. All the wire does is create a path to ground with the switch is closed. If you find the switch and wire, pull the wire off and find a way to touch the inside of the connector to ground...use a paper clip or something. If the light comes on with the ignition turned on but not started, then the problem is the neutral switch. If the light doesn't come on, then at least one problem is the wire and/or the bulb in the instrument pod.

[alkoivisto]

Oops! Forgot about neutral light bulb. If instrument cluster same as '81 R100RT, disconnect speedo cable, remove three #3 Phillips screws holding cluster to bracket, remove #1 screw holding elec plug to cluster, set cluster face down, remove screws holding back cover on. You'll eventually see flexible printed circuit ribbon at center with series of black plastic bulb holders behind display. Remove black plastic bulb holder to access neutral indicator bulb. Probably good time to change all bulbs as this procedure is a PITR if you re-assemble and neighboring bulb decides to fry. Be carefull not to deform copper contacts where they contact circuit ribbon. Don't drop small fasteners into instrument assembly! Assembly reverse. Then hope all bulbs light up when complete!!

[CTellman]

If you do decide to replace the bulbs in the instrument pod be very careful when removing the big soft plug with the single phillips head screw. That big plug has about a dozen male aluminum contacts that fit in the s/s receptors in the pod.
My bike had no lube on them (dielectric grease) and self destructed. This means a full wiring harness replacement as there is no way to just buy the big plug and splice it in.
Wiring harness is $340. and it took me a couple days of cleaning and adjusting when I replaced it. I went through and greased all contacts for the future.
Go to autoillumination.com and check out their cool led replacement bulbs. Much better light.
Good Luck,
Campbell Tellman II
'93 R100RT
:thumb

[alkoivisto]

With regard to rear engine mount bolt, once you have partially removed it, assuming you're replacing neutral switch of course, you may find steel spacer sleeve between lugs on engine difficult to remove as aluminum has slightly mushroomed around spacer sleeve. It may be wedged in so tight you may think it's part of casting. Take care and don't use wrecking bar to pry it out!! In my case I had to gently tap sleeve forward with plastic mallet, file off mushroomed aluminum, then pull out sleeve to rear. Not much room to work. Much easier job if you have or have access to bike lift.

[MRHALL]

I also had a bad neutral light (77R100S) and changed the bulb. Old bulb wasn't burned out. I then changed the neutral switch, again no help. I checked the pig-tail wiring and was found okay.
Now what?

Bad ground somewhere?
I also re-checked the bulb, no help!

Seems when things start happening they COME. Just before I started the switch job I noticed fluid under the bike. Thought it was oil, traced to leaking master cyl, coming from around the plunger behind the snap-ring. Brake-clean and couple hrs cleaning. I just bled the F brake about a week ago, makes you wonder!
Can I buy a overhaul kit for the MC?

[20774]

I also had a bad neutral light (77R100S) and changed the bulb. Old bulb wasn't burned out. I then changed the neutral switch, again no help. I checked the pig-tail wiring and was found okay.
Now what?

Bad ground somewhere?
I also re-checked the bulb, no help!

If you ground the wire at the switch end to the engine case, the bulb should light with the ignition key turned on. If not then you have something wrong with the wire, but instrument pod circuit, or the bulb. You say the bulb is OK. Must be the wire or the circuit. Can you ohm out the wire from the switch end to where the connection shows up in the pod? As for the circuit in the pod, there is a delicate strip of plastic that contains the circuit. It is easy for this to break in critical locations. You must be careful removing and pushing in new bulbs as the circuit can tear.

Can I buy a overhaul kit for the MC?

Yes. But I remember that getting the o-rings on the MC pistion can be a biyotch!

What may have happened while bleeding the brakes is overextending the hand lever, moving the piston and o-rings into "uncharted" areas of hte piston bore. Be sure and check the bore of the MC for rust/pitting. That may have cut the o-ring. If you have rust/pitting, find a wooden dowel and use some sandpaper to lightly ream out the bore and see if you can remove the pitting. If not, then continued use of that MC will cut o-rings. A replacement will be necessary. There are companies that can resleeve the bore...might be a cheaper alternative.

[sumran]

You can verify that the switch is the culprit with test lead fitted with alligator clips. As mentioned, the switch is on the bottom of the tranny. Mine has two wires going to it and the switch breaks the ground in the circuit. Other years may have a different design. If you attach an alligator clip to both tangs of the neutral switch, it will bypass the switch. If the light still doesn't come on you need to look for trouble somewhere else in the electrical system.

Warning: This has the potential of activating the starter circuit even though the bike is in gear. If you push the button you will have a campfire story for you next airhead tech day.

If the light comes on with the jumper wire in place, the switch needs to be replaced. You need to drain the transmission oil, unless you want to go to a lot of trouble to save a few bucks. Pull the tranny, do a spline lube, replace the switch, and reinstall the tranny. The terminals on the neutral switch are easily broken. Take great care not to bend them when installing the slide terminals. I have installed the wires with the tranny installed but it is much easier to install the wiring before you put the tranny in place.

Let us know what you find and how it turns out. Not a bad job if you take your time and you end up with a spline lube and fresh tranny oil as a bonus. Getting someone that has done it before alongside is a big help. The spline lube procedure is well documented. Search the forums and the web and you will find many explainations (and much spirited discussion) of proper methods.

[casper_zip]

Hello again:

Many thanks for all the info/advice, and help on this switch. I tackled it, and all went pretty good. It is time consuming, I ended up pulling the back two motor mounts, drove the threaded rod thru the hollow alum tube, and gently tapped the tube out of the way. I did get the old switch off, and wasted a day trying to replace this switch by just trying to screw it back in.

Anyway, this turned out good, except I still have no neutral lite, and now, no oil pressure light. So, when weather breaks, I'll address that problem. I have plenty of oil pressure. I put a new mechanical guage on the oil pressure, and it came up to 80psi cold, and then held steady at 40-50 psi. I had changed to fresh oil and filter.

I hope to have the light stuff going really soon. I have the owner's manual, Clymer's and Haynes. These are the newer manuals, and both the Clymer and Haynes told me where the fuses are located, but they are not where these guys said they were. I have searched everywhere, except in the headlight area. Now, how in the devil do you get in there without disassembling the bike (Fairing)? A man would be in a heap of trouble if a headlight goes out on a trip. I do know books says 2 8amp fuses, and I see them in the wiring diagrahm, but they are not found on this bike so far. I am thinking they must be in the instrument panel or have to be behind the headlight.

Thanks for all the great help.

Casper_zip

[brickrider]

The fuses are in there, all the way to the back of the headlight shell, behind all the wires, hidden from sight and attached to a board. They are (usually) made of a white porcelain material with the metal fuse strip exposed to the air. They are a cylinder about an inch or so long, diameter of an ordinary wooden pencil. They are not covered with glass or plastic they way we think of a fuse on this side of the Pond. Ends are kind of pointed to keep them in place with pressure against the metal tangs.

Located right where they are easy to get at if you needed to change one alongside a busy highway.:banghead

How many people (raise your hands) would prefer that all engineers be forced to actually use the stuff they design before it is released to the market?

Ride Safely,
BrickRider

[lostboy]

Your problem may be at the two-pin connector just "upstream" of the neutral switch, which makes the connection to the main harness. In the case of your bike, this connector is behind the let battery cover. These are often unplugged inadvertently.

[casper_zip]

Hey everybody:

SUCCESS AT LAST !!!!!!

I read and reread all the info on this forum on this problem. This morning, I pulled the tank, and the left cover. I finally found the 2 wire plug that Lost Boy told me to check. I could hardly believe it, it was UNPLUGGED !!!!

I raced to find the keys, inserted them, and bingo, all lights that should come on did. I now have a neutral green light, a red oil pressure light, a red alternator light, etc. Hallulluyah, the all work just fine now. It's amazing how sometimes, you can't see the trees for the forest.

Again, thanks again to all of you, and especially to LOSTBOY, who gave me the last hope before doing something major.

Thank you, thank you, all of you.

Casper_zip

[sumran]

Glad your working again. As an added advantage you now have a neutral switch for your spare parts stash.:)

[brickrider]

I always pay special attention to any comment made by Lostboy.

He's one of these guys that doesn't say much, but the gears are always turning in his head. He is perceptive and sharp as a tack, and his advice is dead on accurate based upon experience.

Here's to ya', Lostboy!:beer

Ride Safely,
BrickRider

[mitchell0481]

The neutral switch on my 1981 R100S went out a while ago. Never bothered changing it, I just feel for neutral. I don't have any problems starting my bike. One day I will get to it.:dunno

[sumran]

The neutral switch on my 1981 R100S went out a while ago. Never bothered changing it, I just feel for neutral. I don't have any problems starting my bike. One day I will get to it.:dunno

I felt the same way. The day I got to it was the day my clutch switch also went bad.:banghead Push starting in a tie and gear is so much fun. Now both have been replaced.

[osbornk]

The neutral switch on my 1981 R100S went out a while ago. Never bothered changing it, I just feel for neutral. I don't have any problems starting my bike. One day I will get to it.:dunno

I might get to mine someday. My R80RT switch was shorted out by me about a year ago. Not a big deal to go without it.