1981 XJ650 Maxim small oil leak

Hello XJ community,

1981 Yamaha Midnight Maxim XJ650

Need some information on a small screw and correct installation.
I have a small oil leak on the left hand side that drips slowly on the pipes and of course starts smoking like a son of a bi...ch.

Exhaust pipes removed bike cleaned and baby powdered. Tracked it down to this small bolt that connects some wires to the bottom of the crankcase.

Can you please let me know if this is the correct bolt that should fit in there. If not what is the correct sizing for this bolt and washer. What is the order of the installation? Should the washer go against the crankcase, then the wire and finally the bolt?

Want to stop the leak for good.

Thanks in advance.

 

It looks as though this bolt is not the correct one.

From Yamaha Parts....

Bolt, Washer Based - 90105-08729-00
Washer, Plate - 90201-08087-00

What are the specs/dimensions of these? I'd like to source these locally to Oakville Ontario

 

That appears to be --- from the last image (with the flashlight) --- the neutral position switch with its lead wire, which is retained to the switch with a screw and washer as shown. []HOWEVER[/b], oil rarely leaks from that point; but will commonly leak from where the switch screws into the crankcase, and a copper crush washer is used to seal that spot. If it is leaking thru that screw, then the switch is toast (or will soon be).

It may be necessary to snug-up the switch body just a small bit, as the crush washer has lost its sealing ability, or it may be necessary to replace it, which --- depending on the model --- may require dropping the exhaust system, as almost everything down there (exhaust pipes, frame rails) gets in the way of access to the switch.

But the size of that screw is M4 x 5mm x .70 pitch.......

 

40 minute drive to my place, I have various screws, etc...... PM me for address....

Since that is a lock washer, it goes under the head of the screw, with your wire connection against the switch.

 

@chacal , you are absolutely correct. After more digging, it turns out it is the neutral switch.
Pipes already removed, they came off like butter as an entire unit since they were nicely oiled from the said leak...

Drained the oil and looking to remove the actual switch, was able to source a copper crush washer from my local motorcycle mechanic, but after reading a bunch of xjbikes posts, it looks as though I won't be able to get to it easily with a regular 14mm socket.
I will remove the engine mounts if needed to shift it slightly so I can get a socket in there.
If you have any guides on removing the engine mounts enough to shift it a bit to the right, that would be much appreciated...

@Rayzerman, thank you will PM if in need of any other fixtures.

Thank you all.

 

Posting for anyone experiencing the same leak from the neutral switch.
Order the switch and the crush washer so you have it handy. Also, get, borrow, beg a friend for a Snap-on 14mm 1/4" Drive 6-Point Metric 5 mm Flank Drive Shallow Socket - TMM14

It's impossible to get in there with a regular 14mm socket as they are thicker than the snap-on one.

Put a car jack with a piece a lumber under the oil pan and lift until snug.
Unbolt the front engine mounts (triangles) take note which bolt goes where (pictures help)
Unbolt the long bolt that goes through the front of the engine and remove it partially
Loosen the long bolt at the bottom back of the engine, do not remove it, just loosen it
Remove the carb boots from the air box side and push them back slightly into the air box.

At this point, you can jack up the engine (gently) a bit more by about an inch or so. The front wheel should be off the ground and at this point the motorcycle rests only on the centre stand.
Be careful not to tip over. Every movement/adjustments should be done carefully from this point.
I have also used a ratchet tie to hook one side of the engine to the handlebar.

This will give you enough clearance to insert the snap-on socket through that opening and remove the old switch.
Insert the new switch with the new crusher (use a JIS screwdriver to insert the switch and thread lightly, your fingers no matter how small, won't fit in there)
Connect the little blue wire terminal onto the end of the switch and reverse the process above. Check your neutral light on the console to make sure it lights up.

Re-assemble your exhaust pipes back onto the bike, oil/filter change if not done already and enjoy.

 

@Roamee does your bike still have the factory exhaust with the CROSSOVER PIPE still in place?

 

@chacal I believe so. See the pics below, this is how it came off the bike in one piece...
Just trying to get rid of as much rust as possible before I put them back on the bike.
Although, I don't mind the "vintage" looks.

Ran the bike today (without pipes, went around to all my neighbors telling them a LOUD noise will be coming from my house for a few minutes) to check for leaks.
So far so good.

 

Yep, that's as factory complete as they become. I was under always of the mind that there was absolutely no way to reach the neutral switch on the XJ650 Maxim models.....even with the special tool we had made for that purpose..........due to the absolute cluttered mess and geometry constraints that the frame tubes, the header pipe "extensions", and as the final "can't be done" obstacle, the crossover pipe (well, at least I could never get to it......but, you figured it out!). I always had to drop the "rear half" (everything from the header pipes back) of the system a bit to get the clearance.

 

Finally got the bike re-assembled, pipes are back on, no more leaks. Went for a quick ride around the block and realized that the green neutral light is on at ALL times regardless of the gears.
What went wrong? Anyone have any idea?

Looks as though I may have to drop the pipes again and re-check.... No fun

 

Th neutral light on the dash comes on when that circuit is grounded.....coming TO the bulb is 12V power, and the wire leaving the bulb goes to that neutral switch. It's only when that switch gets grounded that the green light on the dash gets illuminated.

So how does that switch get grounded?

Most switches, especially ones that screw into a grounded object (such as the engine case) would be grounded thru the switch housing or body. Many handlebar mounted control switches are grounded in this way (they ground themselves thru the handlebar itself). But this one doesn't work that way....

The neutral switch is located directly below the SHIFTER DRUM. On the shifter drum, there is one particular location where there is a small raised "bump".....think of a BB-sized object....that is embedded into the outer circumference of the shifter drum body and stands just a bit taller that the rest of the drum body (maybe 3-4mm "proud" of the rest of the drum body).

So when the shifter drum is rotated to that one position.....neutral....that "BB" is located directly under the spring-loaded neutral switch "plunger".....and so in that position only, the plunger tip of the neutral switch is now in contact with a grounded object (power goes thru insulated, internal spring and plunger of the switch housing, thru the BB, thru the drum, thru the engine case, and finally onto battery negative) and thus the neutral light circuit is now completed .....and the light comes on. As soon as the drum is rotated out of its neutral position, the plunger tip of the switch is no longer in contact with the BB and isn't long enough to reach the drum body itself, so.........no ground, no light.

So, why isn't it working right? Either it's the wrong switch (plunger is too long and thus remaining in grounding contact with the shifter drum at all times), or the switch was installed without its correct-thickness crush washer (the crush washer also provide a "spacer" function, moving the switch and the length of that plunger rod away from the shifter drum), or the switch is defective and the housing/body of the switch or the internal spring and plunger rod are somehow getting the power from that light blue lead wire (and thus the switch is, indeed, grounding the circuit thru the engine case thread)s, or somehow that sky blue wire is inadvertently touch the switch housing, or there is a break in that blue wire somewhere and the wire is being grounded somewhere.

If I recall correctly, that sky blue wire runs thru some metal "clip" brackets that are screwed onto the engine case, and these little brackets also route the pick-up coil wires and perhaps the oil level switch wire. Those brackets are closed tight-tight-tight around those wires, and can sometimes pinch and break the insulation around the blue wire (actually, to any of the wires), and if so, now that wire is grounded (before it even reaches the neutral switch) and thus the neutral light will be illuminated.

TEST: boy are you going to hate hearing this......remove the sky blue wire AT THE SWITCH and see if the problem persists. If it does, then somewhere/somehow that blue wire is being grounded somewhere along its path (and thus the light comes on). If disconnecting the wire does not resolve the problem (your current situation), then somehow that wire is being grounded by the switch housing (bad installation of the wire onto the switch terminal?) or the switch itself has an internal problem that is allowing current to pass into/onto the outer part of the switch body, and thus grounding itself to the engine case thru the switch threads.

 

@chacal , seriously, you are the BEST. Thank you for the explanation above. It makes total sense.
I also found this thread https://xjbikes.com/forums/threads/xj650-neutral-light-wire-routing.124190/ talking about the same situation I'm in.

I believe the switch and the washer are the correct size, ordered directly from Yamaha parts at Kelly's Cycle in Hamilton. Put them side by side and they were exactly the same.

The wiring is really tight in there and it may have gotten pinched or touching something somewhere.
I will remove the pipes and disconnect the wire to see if the light stays on. Hopefully it's just this, I will try and isolate it properly with some tape around it...

Can that clip/bracket be removed all together? It's extremely tight in there and there isn't enough slack for the wires to come lose anyway...

 

SUCCESS
The neutral wire terminal that looks like a Y was opened way to large and was sitting right against the bottom of the switch around the terminal. Jiggled it out a bit and closed the GAP leaving just enough room for the little bolt to go through. The Y terminal needs to stay put between the washer and the bottom of the terminal on the switch. (Guess I wasn't paying enough attention first time it was done).
Tightened it back up and tested the gears. Beautiful Green Light on, only when in neutral.
Thank you @chacal for your guidance with this. You were correct "(bad installation of the wire onto the switch terminal?)"

Enjoy the rest of your weekend and stay safe.

 

Hurray, a quick and inexpensive fix! Happy Motoring, and watch out for the other guy.

 

And to answer this question, yes they can, each one is held onto the engine case with an individual screw or bolt, but boy are they a beast to get to, and yes they hold the wires or bundle of wires really tightly, out of necessity, you don't want those wires flopping around down there.