82 Seca 750 - Help

Alrighty, just dug the Seca out of the shed and wanted to fix the problems and get a good starter bike for my buddy. Heres my situation:

42k. Got the bike last year, needed starter clutch, split the cases, went through the tranny and engine, no problems. Good compression, no worn gears (too bad anyway), now the starter doesnt free spin, its lookin good! Cleaned the carbs, new plugs, sealed the tank, new gas, new tires, oil change in powertrain and dif. Fires up, took it down the road.

Heres the problems:

All the warning lights are on, no headlight, aux light, or turn signals, but tail/brake light works fine. Cant find any break in the wires, and cleaned all connections I could find, and checked all fuses.

Hesitation after warm, and revvs stay high when I flick it. Mix screws are 2.5 turns out, carbs synch'd, jets cleaned. Cant find a vac leak using the WD40 method. Ideas?

The Anti-Dive bleeder broke off inside the unit when I was trying to loosen it. Any ideas on getting that out? I was just going to bypass it for the time being so that I can get my front brakes back, but rather have it working right. Already tried an easy out, and I want to stay away from drilling so I dont touch the taper of the bleeder.

There you have it. If you need more info, I'll be happy to give.

Thanks!

 

Nobody? Did I post in the wrong section or something?

 

The only thing I can tell you for sure is that your carbs are lean at idle. Try turning the mixture screws out another half to full turn and see if that helps the hanging idle.

 

For the cluster, with that many different problems, I'd first suggest you double-check that all the plugs in the headlight bucket are connected and connected properly.

There are probably eight or nine plugs in the bucket. Six of them (three 3-pos, one 4-pos, a 6-pos, and a 9-pos) go to the cluster. The six and nine pin ones are for the warning center, and it's the 9-pos that carries headlight power, among other things.

On the other hand, though, the power for the Aux light and turn signals does not go through the clusters, and the power for the two of those is separate. If a couple of plugs got swapped, that one change might lead to all of your problems...

On an XJ, though, an original fuse box will always be suspect in electrical problems. If you still have an original fuse box, your first step should probably be to replace it with a modern ATO one.

 

Thank you sir. I will try that.

 

i recently traded a toyota 4x4 for an 82 seca. first thing i did was cut out that god awful instrument panel and put in a speedo that would actually tell me how fast this thing is. i dropped the forks thru the three tree bout an inch and a half anf put flat bars on, corners with the best of them now but my carbs have issues. gas flows all over the block if i leave the fuel cock on and it winds down in slow motion. runs like its barely gettin gas but all jets are clean and floats aren't stickin. ideas? check out the pick on facebook-troy eastridge. also looking for a belly pan

 

Thank you for the advice. I do have a couple new fuse holders in the box, but I suppose I could replace the rest. I checked all of the connections in the headlight bucket, and took off all the lights and checked them directly to the battery to see if the bulbs were good, which they were. I figured with everything not working, there must be a grounding issue or something that oversees all of them as opposed to everything breaking individually.

There was something in the headlight bucket that looked like a a relay or something that just dead ended 4 or 5 wires. It was a bit concave looking. I will check to see if the connectors were switched. I didnt even think of that before, but there has been more hands on this bike than just mine.

 

Im trying to keep it as stock as possible, and my speedo is real close until 60, then its off about 3% which seems normal. My fuel valve (or petcock) leaks too, but only when its off the bike. Otherwise the gas just goes into the bowls. You got a leak somewhere, or your bowl drains are bad. Maybe the micro screens inside the tank are clogged, or your vacuum actuator isnt pulling the valve open to let enough through.

Someone more knowledgeable about the specifics about this bike might be better suited to help you.

 

Did you re-finish the Diaphragm Bores.

A sitting bike makes an easy target for Aluma-Oxidation.
Machined surfaces get a "Dust-like" coating on them.

The Carb Bores get Oxidized and cause the Diaphragm's to: Hang-up, respond to slowly, not descend or rise, ... makes the Engine run like it has a mind of its own.

Get rid of the stock Fuse Block.

Don't make a Bad Situation, ... worse!
Leave the Dive Unit alone until you have a used one to Rebuild and REPLACE it with.
THEN, ... mess-around with the FUBAR Dive.

Consider a Non-Dive Front Assy off another Bike and swap Forks.

 

If you are referring to the part of the carb body that the needle-holding piston slides through, then no, I did not. The pistons slide through just fine, but it doesnt hurt to double check my work. Once I get the customer's bikes out of the shop, I'll put mine back in there.

I will get rid of the stock fuse block.

I just got shorter hollow caliper line bolts from a parts store that work and give me back my front brakes. The anti dive is capped and not being used. I'd hate to think that a broken bleeder would take out that feature. I'll put it on the bench when I can and try my luck at getting it unstuck. Maybe the torch, Free-all, and a good easy out might do the trick.

 

The Bleeder will come out.
I thought you meant the Adjuster Screw on the Bottom like on the 900.

Get a Mini-Propane Pencil Flame Torch.
Heat it.
Use an extractor.

Don't heat it with the extractor in the Bleeder.

 

Thanks for the advice. I got a good torch setup, I'll just put the smaller tip on it. Didnt know if anyone had other thoughts for getting it out, or if its a common problem and if people had the anti dive unit that I needed. I've only had to remove one other bleeder this way, but I have to extract broken/rusted/destroyed bolts all the time.

 

The relay-looking thing in the headlight bucket is the diode block. It isolates some circuits from others - for instance, providing the one-way signal from the alternator to the headlight relay to turn on the headlight when the engine starts running.

 

Brilliant! Suppose I should have checked the wiring diagram to figure that out, but figured there was something about this bike that was abnormal (like needing the fuse box replaced).

Thanks for the heads up.

 

Along with other questions about the warning lights and other electrical gremlins, I'd like to know, what the BATT warning is actually indicating. My bike is an '82 750 SECA, but has a build date of 7/81. Is the warning indicating a problem with low voltage? low electolite level? If I recall correctly it's supposed to hook into something in or on the battery somehow (?), maybe into one of the cells? My bike just had a single wire in the area of the battery, with no plug, terminal or anything, so I don't know what I SHOULD have. If I recall correctly the wire is white with a red stripe, but I could be wrong. Bike runs fine now, after a fair amount of work and checking things over, but the constant warning light flashing bugs me. When I push the button on the display twice, the warning light goes out, but returns to flashing after a couple minutes.

On a good note....after a few short shake-down rides, I took the bike out Monday for an "almost" 100 mile, relatively gentle 50-60 MPH ride. I was pleased that when I refilled on fuel it got 48+ MPG. I'm thinking that would indicate that I at least have the bike running close to how it should.

Lynn

 

Yes, the original batteries had a sensor that either replaced one of the caps or stuck in its own hole. That sensor verified both the electrolyte-level of the battery and the charge state of the battery. I'm not sure whether the original style Yuasas are still available or not. Most people defeat the electrolyte-level sensing feature with a resistor setup that you should be able to find using the Search feature up at the top of the page.

 

The Battery Indicator is supposes to monitor the level of Fluid in the Battery.

Most newer Batteries do not have a receptacle for the Sensor.
Therefore the Sensor isn't hooked-up.

Delete the Sensor if you have one.

Hook-up a wire from the Tail-light to the Sensor wire.
Add a 2K Ohm Resistor in the line.

When the Power is turned ON, the Computer will get a Signal that it needs to satisfy the computer and the light will go off.


)))>Tail light >_______>( 2K Ohm Resistor)>_______>Sensor Wire to Panel.

 

Will it hurt anything having that wire connected directly to the battery without the resistor? That's how I currently have it, seems to be working fine but i'd hate to melt anything long term.

 

Go to Radio Shack and buy a Resistor.
Short money.

Send the Integrated Circuit the resisted value that it needs, .... or you risk doing damage to the I-C.

A 2K Ohm 1/2 Watt Resistor costs about: $1.25 each.

Go get the resistor and send a HALF Watt to the Panel

 

Thanks for the solution to the glitch. It's probably a lot better than a strip of electrical tape over the flashing light! Consider Radio Shack on my next shopping list.

Lynn

 

Well, I got some good news. After trouble shooting the hell out of it, I finally figured out one of my problems. I was using the wrong wiring diagram. That would have saved me a lot of time and profanity had I clicked on the right one from the beginning.

Anyway, with the right diagram, stuff started making sense. Everything on the dash is still lit (even though the obvious ones should not be, like stand, headlights, etc.) Also the check buttons on the dash dont do a darn thing either. If the button itself is faulty, could that make all the lights stay on?

I just took a scotch lock and connected (I think) the red/black and the blue/black wires coming out of the right side handlebar controls. Then the headlight and aux lamp worked, including the relays and on/off or hi/low switch. Took all the stuff out of the equation for the turn signals and everything checked out OK. Put it all back together and now the turn signals work. Put a new fuse block in too, and replaced the inline one inside the bucket.

My lean condition and hanging revs are probably not being helped by the fact that the bike has no mufflers. Its just straight pipes because the old ones rusted off. Im gonna go to the junkyard and get some off of a similar bike to get that thing quieter and get a decent tune on it.

Thanks for the help so far. By connecting those two wires and the headlights working, would that be indicative of a bad diode block? Checked all the relays, flashers, and even the cancelling unit. Everythings good so far.

 

If all the LCD alerts are staying lit, the computer isn't running. A bad check button wouldn't lead to that, but a bad signal from the alternator/diode block might, as I don't think the test starts until the engine is started. I'll double-check when I get home and let you know.

Please remind me: is your headlight off when the ignition is turned on, but coming on when the engine is started?

 

I suspected diode block, but dont have anything to test it with. The headlight now comes on as soon as you turn the key on. Kicks off for starting. The LCD panel still doesnt go off even when I go down the road.

 

RickCoMatic....Thanks VERY much for the simple fix for my BATT warning staying on. My small town Radio Shack only had 2.2K resistors, not 2K, and didn't know how critical the resisitance was, so I bought a package of five 1K resisitors, and put two in series (same result as a 2K). I wired them in line from the taillight to the battery sensor, white w/red stripe, wire coming out of the wiring harness. Shrink wrapped all the exposed, bare parts, took the bike for a short ride and everything is great.

Thanks again!

Lynn

By the way....the package of 5 resistors was only $1.28, including sales tax. I did ruin two resistors by getting a little overzealous twisting the tails of the resistors and wires together to solder them, but was a bit more gentle the second time and the solder joints held everything together nicely. I zip-tied the whole works to the rest of the taillight and turn signal harness so it can't flop around.

 

OK. Just checked mine. When the key is first turned on, the headlight is off, and the warning center has all LCD's displayed (STAND, FUEL, OIL, etc) and the red lamp on solid. The only active display is the four bar fuel gauge.

When I start the engine, the headlight comes on and a second or two later, the red lamp starts flashing and the LCD cycles through its test - normally turning off everything except STAND (if the side stand is down).

Your headlight coming on when the switch is turned on is not normal. This may be another symptom of the same root problem, or it may be a coincidence. What's the history on these problems? Have they always been like this since you got the bike? Can you ask the PO about anything he/she might have done regarding headlight relays and such?

BTW, the same alternator wire that triggers the headlight relay looks to trigger the warning center, but the warning center is on the other side of the diode block from the headlight relay. You might try unplugging the diode block and see whether that changes anything for the warning center.

 

Wow, thank you sir. Seems like you are going over and beyond what most people on the internet would do for someone else on the internet.

Anyway, I jumpered the wires to make the lights work, so that probably explains why my headlight comes on early. The only thing that works is indeed the fuel gauge. No luck on talking to the PO. Got the bike on a mechanics lien for 250 because of the starter clutch.

I didnt think about simply unplugging the diode block. Figured I would have to jumper some wires, and didnt think of which ones I needed to jumper. Maybe thats the problem then. The warning center is not getting the signal to cycle through stuff. Anyone know of a place to get (or make) a working diode block as a replacement?

 

First question is how you jumpered the headlight.

Second question is whether unplugging the diode block makes a difference.

Then, if needed, we can worry about replacements.

 

I just put a scotch lock on two wires coming out of the right side hand control unit (aux/kill switch). I believe that it was the red/black and blue/black wires that I connected, which made the headlamps work. Didn't cut anything, just connected them.

Ill get that diode block outta there and see if that changes anything. Figured that I would have to send power to the outputs of the block or else it would just dead end there, unless I don't understand how a diode works.

 

Red/Black to Blue/Black wouldn't do anything but make your Aux lamp stay on all the time, once the headlight relay was engaged.

Red/White to Blue/Black would power the headlight as soon as the ignition was turned on, but would also be placing extra load on your ignition circuit and fuse... load that that fuse and wiring were not designed for.

 

Red/White must have been what I did then. Hasnt blown anything yet, and I just needed it to ride it home since it was night time.

Took the diode block out, and no change. Doesnt do anything different. All the lights come on, and dont go off or cycle through, even after started and riding.

Ideas? Id rather have this working correctly since Im thinking about selling it soon. I dont need 5 bikes, since I only ride two of them regularly, and another one is no longer a bike persay.

 

Sorry to say, but it sounds like the computer itself is bad.

The Yamaha price on that part is stupid expensive, even if any were available, which I don't think there are; but enough people have removed their stock clusters that I would think someone on here would have a working unit they could part with for reasonable money.

For the headlight, I'd be a bit more concerned with melting the R/W wire's insulation somewhere from the extra load it's carrying. Headlight adds about 5 Amps... Aux lamp would throw another 2 or 3 on there. Another more subtle side-effect you might see is reduced spark intensity because the supply voltage to the coils will be reduced due to the extra voltage drop on their supply wiring.

 

Well, heres more data. I undid the wiring I had for the headlight, so its back to stock. Took the diode block out, and put 12V to the white wire going to the computerized monitor. It started cycling through the tests! The only thing on was the BATT because I dont have the "correct" battery, but thats easily fixed.

So I guess I'll order a new diode block and see what happens. Or do you know of a replacement?

 

It's not the diode block. At least not for the computer piece. It's the white wire, the regulator/rectifier connector, or the alternator winding itself. Check the connector under the left side cover that carries the white wires. You should have continuity from one of the white wires there back to the white wire are the computer.

You may find that the contacts in that plug are burned or melted. Cleaning them up and treating the connector with electrical grease (bulb socket grease from an auto parts store) may help, or you may need to replace the connector and socket.

By the way, that white wire is also the source of the signal to engage the headlight relay, so that's probably why your headlight wasn't coming on as well.

This sounds like good news.

 

I checked real fast before I had to get to work. I have continuity between the white wire at the diode block connector, and all three wires under the seat. Also checked at the R&R connector, and good there too. Cleaned up the connectors, and getting good signal through them. Took off the alternator winding cover and all three white wires go to the winding, no problems.

I will check the wire directly to the monitor, and the wires going into the R&R once I get some free time (finals this week).

I did notice that the innermost magnetic stanchion sticking up in the cover was broken off. Could this effect anything?

 

Any idea on the magnet being broken off inside the Winding cover?

If I take a switched 12V power and just have that go into the monitor as a signal rather than having the alternator give it the signal, would that cause maliciousness?

 

That would not provide the correct behavior. The point of getting the signal from the alternator is to trigger the headlamp relay and computer test cycle once the engine is started.

Assuming all the connections are really good, then it sounds like your alternator is not producing output on the phase that is connected to the computer and diode block. You could try switching that white wire with one of the other two white wires at the connector from the alternator to the regulator/rectifier. If that fixes things, it's a solid indication that your alternator needs to be repaired.

 

Hey Nightviper19 and SQLguy,
Did you ever resolve your dash lighting activity issue?
I have an 82 XJ750 that i'm now having some problems with not starting.
History:
When i drive bike it will suddenly stall (electrical type dead). Most of the time it would start right back up. Thought it was the Kick stand safety, so I bypassed that wire, along with the dash indicator wire for the same and tied all of them together (3 wires)..

Worked fine after that....but yesterday drove down the street again died...
This time it wouldn't start.
All Dash indicator lights are on, but no starter action. Can't get the dash to do its checking or respond to hiting any of the buttons.
Its almost like i need to reset the computer like we do with other electronics.
Bob

 

Have you rebuilt or replaced the original fusebox yet?

If not, there's the place to start.

 

I rewired the main fuse, when i bought the bike as those cheap little spring metal holder fingers break so easy.
I'll check the other fuses, but they looked okay.

 

Those cheap little metal holder fingers crystallize over time and can be cracked and you wouldn't even know it. My very first "XJ rude surprise" was one that broke all by itself without being touched.

The fusebox can be rebuilt with new real metal clips from Radio Shack, replaced with a new original style, or (recommended) replaced with a modern, blade-type fuse box.