1981 XJ650 Stock Project Build

Recently picked up two bikes, an 81 Midnight Maxim with a title and 10,000 miles and an 82 YICS Maxim with no title and 20,000 miles. Both are in similar states of disrepair, but there is enough all there to make one good running bike. Of course the cleaner of the two bikes is the one without a title, so I'll be swapping most of the parts from one to the other and then selling off the extra bike once I'm done.

I'll also add that I've only ever ridden a motorcycle twice before and this is the first I'll have ever owned, although I've fixed a handful over the years for friends and work. Kind of like the guy who can't drive a stick and works at a garage, but with bikes. Talk about embarrassing being able to fix a bike, but not ride it lol.

Now let's get to the good stuff. Fresh after picking up the bikes.


Both the bikes came semi-stripped down, but also came with most of the parts missing. Both engines turned over as well.

Here is the 82 with gas tank and seat on to see how the final product will come out looking. Sans carbs


I didn't take many pictures of starting to strip the bikes down, but I stripped down the handlebars, took off all the cables, gauges, ignition cylinder, removed the battery, air box, carbs. Getting ready to swap the forks over.



The wiring harness on the titled bike looked to have been chewed by rats, cut by the previous owner and reconnected by twisting the wires together, so I stripped the harness off the bike and will be replacing it with the clean harness from the other bike. Also stripped some of the rust spots and primed over them.


Previous owner stripped both screws on the signal stalk and my drill decided to quit on me so the bar grip will have to come off another day.



Left the bikes in storage and started on the carbs back home. Fortunately nothing was seized, all the slides move nice and smoothly, and all the jets came out relatively easy. Wanted to finish yesterday, but the sun went down, I don't currently have lights in the garage, and I have to wait for the gasket kits in the mail anyway, so I'll probably finish cleaning and reassembly within the week.

Upon inspection, there was rusty residue all throughout the carb, but mostly just in the fuel bowls. I blame ethanol..or something lol


That's it for now. Next up is finishing rebuilding the carbs, swapping all of the suspension, oil change, valve check, and see if she'll run! Update will come in the next two or three days

My question to you guys is this. Is the YICS 650 motor better than the non YICS 650? Contemplating swapping the YICS engine to the titled bike, but not sure if it's worth the trouble.

 

PLEASE save the airbox( you may want to actually ride your bike rather than pulling carbs changing jets ,putting cabs back on trying it ,pulling carbs repeat ...I do not have to worry about my carbs have been to church and run stock airbox ...and can ride in rain or snow ) Good luck .

 

Yeah I planned on keeping it. Accidentally broke the airbox when I pulled it out, but I have one off the second bike so I'll still be keeping it. Also throwing around the idea of welding my own air box and intake out of scratch once I get the bike roadworthy, but only after I have it running right stock

 

if you do not rebuild the midnight maxim the special parts will bring you some cash the gold trims black headlight gold wheels

 

Break the rack and replace the throttle shaft seals, along with the fuel rail o-rings. Those parts dry out and crack over time and are probably the originals.

On that stripped screw: a dab of superglue on your screwdriver might get the screw to come out.

 

I would HIGHLY recommend building the midnight back to original. THAT one is more rare. please don't cut that one.......

 

It's funny you guys say that about the Midnight. That is the one with the title, and although I'm not cutting it up, I am putting all the chrome from the 82 onto the midnight. I can't help loving black and chrome! I'm going to be pulling the motor and stripping all the black paint too since most of it is flaking off, although I may repaint it black. Not sure at this point.

If anyone wants the gold wheels, let me know!

 

The gold bits are generally difficult to find in good condition, and add a lot of value to the bike. You may consider building it into a restored Midnight Maxim, selling it, and using the profit (there will be profit) to build the other bike and title it through Vermont. You could potentially end up with a free motorcycle.

 

So I was trying to swap the rear wheels and ran into a little problem. The final drive didn't want to disconnect from either wheel so I undid the 4 bolts connecting the driveshaft to the final drive and pulled the wheels with the final drives on them. When I pulled one, the whole assembly came off fine, but on the second wheel, it pulled the actual driveshaft out of the housing. Is it supposed to pull out as one assembly or no? How do I go about removing the driveshaft that stayed in the h0using? Is there a C clip that maybe wasn't installed the last time it was apart and that's why the shaft came out? Here are some pictures

 

You're correct...... Some driveshafts have a c-clip inside the u-joint....others do not. The one that you pulled out obviously does not have a c-clip.... There is no groove for one to begin with. The one that did not come out, probably has a c-clip inside the u-joint..... To find that, you will need to pull the dust boot back to be able to access the u-joint.

Now, IF the question is also how to get. The current driveshaft out of the final drive, that's an easy one---just pull it out. No clip in there.

Dave

 

Does that mean the two different driveshafts aren't compatible with the different u-joints? Could I just pull the clip off the one to pull the driveshaft out of the housing, and then slide the other driveshaft in without reinstalling the clip? Or do I have to swap the swing arms for it to go together? Swapping swing arms seems much simpler than swapping U-joints if that is the case.

Also, do the differing years of these bikes have different spline counts on the driveshafts? One is an 81 and one is an 82. Although I can probably just count them next time I go back to storage where the bikes are

 

The drive shafts are compatable. Spline counts are the same.

I'd recommend that you not swap the parts from bike to bike, but instead work on freeing the wheels from their respective final drives. You will want to put new tires (and wheel bearings) on at some point, and having a final drive on the wheel turns a simple task into an almost impossible one (tires) and makes wheel bearing replacement impossible.

 

I'll update later today, but I ran into some trouble. Got the bike all back together and I'm trying to start it for the first time, but it won't fire up. It's got fuel to all the carbs, both coils have spark, but no amount of choke and throttle will get the thing to fire up. It's about 50 degrees out so it's cold, but not so cold it shouldn't fire off. Any ideas?

Also, when I press the start button, the red oil light comes on, but it doesn't crank over. I'm assuming this is because of some safety switch wiring. anyone know the proper diagnosis of this circuit?

Edit: forgot the mention, to get the bike to turn over and check for spark, I jumped the starter solenoid with a screwdriver.

Also, gas is frsh from the local arco

 

???? those two conditions can't exist at the same time. You can't check for spart if the engine won't spin. Which happened first?

 

Jumped the starter solenoid with a screwdriver to turn it over and check for spark, forgot to mention that.

Also forgot to mention, the gas is fresh from the local arco

 

Double check that the plug wires are on the correct cylinders.

Make sure that the sidestand switch is not stuck.

 

Plug wires are as follows: Coil on left side connected to 1 and 4, coil on the right side connected to 2 and 3.

I didn't think that 81's had a sidestand switch, correct me if I am wrong?

 

Corect on both counts. I forgot about the year.

Is the neutral light on?

Will the starter turn if you pull in the clutch lever?

 

Neutral light isn't on and the clutch cable isn't hooked up, but I have the bike in neutral. I'll hook it up tomorrow and try to see if it works then. Also, it looks like a switch is missing on my clutch lever, is that likely why the starter isn't working right?

 

if the clutch safety switch is missing the bike will only start in neutral
open your headlight bucket and look for a connector about 1/8 thick 1" wide with 2 wires in it.it might be green
you will have to put a jumper wire across the leads then see if the bike turns over .
it could be that the starter button needs to be cleaned or the wire resoldered
the starter button completes the connection to ground to activate the solinoid. check the connecter that the wires coming from the control connects to .
have you painted your handle bars?

 

Harness connector wire colors: for clutch safety switch
* Blue wire with a yellow tracer stripe
* Black wire with a yellow tracer stripe.

do you hear this relay click when you turn on the key??
Starting/Ignition Cut-Off/Neutral Safety relay:
- small metal (original) or plastic (replacement) "cube" relay, inked 4H7-00, 4H7-01, or 12R-01 on the top face.

- on all XJ650 Maxim/Midnight Maxim/RJ Seca models: under the gas tank, in-between the frame tubes, on a welded bracket just behind the flasher self-canceller relay.


if your neutral light is not coming on the bulb may be burnt out or your neutral switch is not working or connected.
check your bulb. and check the switch to make sure it is grounding when in neutral

do you have the diode block? I do not see it in the picture of your headlight bucket

 

1 ignition fuse feeds 12 volts to run switch. R/W wire
2 run switch feeds 12 volts to coils and tci and starter relay. R/W wire do you have 12 volts at coils and tci with key on?
3 R/W wire goes into starter safety relay which requires a ground to close ground 1 is neutral switch ground 2 is clutch safety switch
4 when relay closes the 12 volts is delivered to the solinoid via R/W wire out going from S.S. relay, then runs the L/W to the starter button
5 pressing starter button closes to ground activating solinoid starter spins also oil light comes on.

so with key on you should hear the SS relay click.

check for 12 volts at
the TCI R/W wire and R/W wire on the solinoid
and check for a little less that 12 volts at the L/W wire on the solinoid. no voltage at the L/W +=wire bad solinoid

no volts at TCI check run switch and fuse

volts at TCI but not solinoid check starter safety relay for 12 volt input at R/W wire and out put at R/w wire

got no click at relay
got input but no out put on R/W wire

check the grounds for neutral switch and the clutch safety switch (for you is jumpered across connector)

when you press starter button does oil light come on?
if not check starter button and ground
disconnect solinoid connector and ohm the l/w wire to ground when pressing starter button.

then ohm out the connector on the solinoid

also may want to ohm out your pickup and ignition coils
bad pick ups = no spark

 

Starter button worked on the parts bike so I know it's not bad. Also, when I press the starter button, the oil light DOES come on so that indicates it does work.

Neutral Safety Relay 4H7-01 : Not clicking, but all the wires are getting power. I'll replace and see if that fixes the starter button problem.

TCI R/W wire – 12 volts

Coils: 12 volts at both

Starter Solenoid R/W wire: 12 volts

Also I checked the neutral safety ground and it looks nice and clean and is tight.

Bike still doesn't want to start just jumping the solenoid to turn it over. Tried semi choking the carbs with a 2x4 and it didnt help, and also tried hooking up the air boots and still nothing. I DO have spark, I DO have fuel, and the timing on these I'm pretty sure is set by the TCI (right?), so it has to be an air/fuel ratio issue, correct? Or maybe this wiring issue is messing up the TCI (but there is spark, so I would think not). Maybe the bad relay could be a cause for a no start, although I would think jumping the solenoid would make that issue void.

My other thought would be a vacuum leak big enough to stop it from starting, but choking it with a 2x4 didn't help.

If you guys have any more ideas, I would love to hear them because I am completely lost at this point.

Edit: And to the guy who asked if I have the diode block, yes it is connected in the headlight housing.

 

I'm thinking it's a carburetor issue on why it won't run now. So as of now, the carbs are getting fuel to the float bowls, but the bike doesn't act like it's getting any gas (not even stumbling when I'm cranking). If I spray starting fluid directly into the carb mouths, it'll start to catch and sometimes backfire, but won't actually start/stay running.

Is it possible that the float bowls are filling, but the gas isn't being fed into the engine? I'm not even sure if this is possible, but it's my only guess so far.

Also, does turning the idle speed screw clockwise increase the idle or decrease it?

 

If the neutral light isn't on, the safety relay isn't seeing the bike as being in neutral. The thing that is keeping the starter from spinning is the safety relay not seeing the bike in neutral, which keeps the starter from being able to spin.

The no start may be a different issue, but let's fix the starter problem first so we're not dealing with trying to solve multiple problems at once. You can do a temporary bypass by gounding the blue wire from the neutral switch to the frame.

 

you can also test the neutral switch by ohming the tab the wire goes on to ground


you can also put a jumper across the clutch safety switch connector the green one in your head light bucket then the bike will start in gear or neutral just make sure it is not in gear

the relay should click and close.

 

did you take the wiring harness off of the 82 maxim and put it on the 81 midnight ?
we are talking aboutstarting the midnight maxim correct?

 

Yeah I did, the harness on the midnight was in disrepair from rats and a previous owners poor attempt at fixing it. The harness from the '82 is on the 81 now.

 

that makes it a whole different thing to find the problem.
did you install the sidestand safety relay if so unplug it. that will shut down the tci if you don,t have the side stand switch installed
also check to see if the tci has the same part number for both years

you now have to look at 82 maxim wiring diagrams

 

The two harnesses are NOT identical.

 

you have to put the 82 tci into the 81 bike and the 82 pick up coils into the 81.
you can just unscrew the pickup coils instead of removing the whole base plate assembly

81 pickups to the tci are wired differently than the 82 pickups to Tci

81 pickup coils both black wires go to tci seperatly different locations

the 82 pickup coil black both go to same location with a seperate black/white wire going from the other location to the side stand relay

you also need the diode block from the 82 to make the neutral light work

 

As it stands, 82 coils are on the bike, and same with the 82 diode block. Also did not install the side stand switch. Currently using the 81 TCI as I read it should be paired with the engine, I take it this is wrong? And I thought the only differences between the TCI from 81 to 82 was the timing curve advance at idle and the extra plug for the sidestand switch, but if I used the 81 TCI without the 5th plug, it would be fine.

Also, what is the number for the side stand relay and where is it located?

Feel free to correct me if I am wrong on anything

 

Does the 81 have a YICS engine, or a non-YICS engine?

If it's non-YICS you can't use the YICS TCI with it. It'll idle, but it won't advance correctly, and will run like a huge pile of poo.

 

81 is non-YICS, 82 is a YICS engine.
Can the YICS port really make that much of a difference?It seems like a very non-vital aspect to timing profile.

 

1980-81 Sidestand (kickstand) relay (blue): did not use.
1982-84 Sidestand (kickstand) relay (blue): frame bracket outbound of LH frame tube, just behind the left ignition coil.

the side stand safety relay grounds out the tci to disable it
just unplug the relay to disable relay / that will overide the function of the relay and missing sidestand switch

compare the tci connector in the harness to the 82 harness

81 both black connect th tci one above the other
on 82 oppsite sides of the connector

 

time to go minimum wiring

 

put the 81 pickups back in the bike use the 81 tci.

and remove the sidestand safety switch.

bike should start

also put a jumper wire accross the green clutch safety switch connector , ground out the neutral safety switch

bike should start

 

if you want the tach light to work you willl have to change the connector 81 is a mechanical tach 82 harness has a 4 position connector 81 is a 2 position connector for the meter light

also make sure that the tci connector from both harnesses match up wire wise colors match in the correct positions

check your in box for a link to haynes 650/750 manual

 

Thanks a ton man, I'll try to see if I can get the switch working and the bike running tomorrow and post back with my results. As much as I'd prefer the minimal wiring, right now I just want to get the thing running before dismantling it again.

Are you saying to use the 82 pickups and CDI instead or just telling me how to do it both ways?

And one more question, it seems the speedo light only comes on once the thing starts sputtering to a start, is that normal? So far the light has only come on when I got the thing to run off starting fluid (still doesn't want to run from the gas in the carbs, my only thought on why the plugs aren't getting wet from turning it over is maybe the floats are set too low? Although I set them dry to 17mm if I recall correctly)

Also thanks for the manual as well. Time to run to the library to print it off!

 

use pickups and TCI from the 81.
just make sure the connector thet goes to the ignition coils on the harness matches the 81 harness

 

head light and meter lights come on when motor starts or spins fast enough there is a relay for that

 

So I went at it today and I'll list what I did and what happened

-Got the start button to work. All I needed to do was ground out the clutch safety wires from the harness. Relay now clicks and starter button works.

-Installed new spark plugs, gapped to .028"
-tried priming the carbs by covering them with my hand one at a time while I was cranking. When I covered 2 or 3 of them, the motor would start to catch and eventually fire up for anywhere from 1-5 seconds at an rpm of no lower than 4 or 5000rpm. If I let off the throttle it would die. I never got it to idle, and even once running, it would eventually die after at most 5 seconds.

Also, I compression tested with a harbor freight compression tester that my friend had on hand and got roughly 75 psi at all 4 cylinders. It seems odd that they would ALL have the same shitty compression numbers so I'm going to try tomorrow again with a compression tester NOT from harbor freight. I'll post back with the numbers I get with the good tester tomorrow.

As far as getting the tach light to work, the 82 harness has a 4 prong plug and the 81 has 2. What do each of the wires do? Can I just use the two leading to the light and forget about the other two? Or is the 82 tach better/more accurate and I can fit that into the gauge cluster and run it instead?

On the bright side, it finally sputtered to life for the first time since 2009. Except I'm not sure how to tune the carbs to get it to run properly. Any ideas?

 

first you should not use the throttle when starting bike, it will flood out .
are you using the choke lever to start the bike?

75# sucks but is even across the cylinders did you put oil in cylinders to see if it improved?
your rings could just be stuck and need some treatment


the 2 extra wires run an electronic tach. orange and brown are tach leads , black and blue wires are for meter light

where did you set the mixture screws when you cleaned the carbs? you might have the course mixture screws which would be less that 2-1/2 turns from soft bottom

also stop covering up the carbs to start it these carbs work on airflow the butterfly on the throttle shaft is all ready closed

 

Compression testing, I did not put any extra oil in the cylinders. Doesn't it seem odd though that if it were rings being stuck it is every cylinder, not just one or two?

I set the mixture screws to 2.5 turns initially and bench synced the carbs as per http://xj650.blogspot.com/2009/04/how-to-bench-synch-your-carbs.html
When trying to start the bike, the choke doesn't seem to help much, but I made sure to clean the passages out when cleaning

Clearly something is off because the only way I can get the motor to start trying to run is by covering the carbs momentarily. Only external adjustments on these carbs for idle is all 4 idle mixture screws and the idle speed screw, correct? I'm, not sure if the idle mixture screws are course threaded, but if they are, what should they be set at?

I'll post back in the next couple hours after fiddling with the bike some more.

 

I know the Haynes manual has couple jets wrong in the instructions. Its the two under the diaphragm under that zinc coated plate. this threw me for a loop all weekend once.

 

it shows they are all the same which could be good if you use a good tester. oil will tell if your comp is low due to rings or valves

give your idle adjustment knob another 1/4 turn

course would be around 1-1/2 turns
are you sure you are getting spark at all 4 cylinders?

 

have you wet set the fuel level or did you just set the float height when you rebuilt the carbs

 

If it made no difference Yamaha would have saved themselves money and not used a different TCI.

That's my snarky-short answer. XJ550H beat me to the long, helpful answer

 

Well today I rented a compression tester and it was a total piece of junk. The lines on the tester didn't have a proper seal so it leaked pressure faster than I could crank the engine... using tape on the lines I got up to 120 psi on cylinder 1, but gave up on trying to get the shitty compression tester to work for the rest of the cylinders after fiddling with it for close to an hour.

Double checked and I am positive I am getting spark to all four cylinders.

Tried adjusting the carb mixture screws from 2.5 where I originally had them set up to 5 turns out, as well as turning the idle air adjustment screw in all the way to out nearly all the way. With everything on the very rich side, I got the bike to run for maybe 6 seconds at around 4000 rpm, but that was the best I could do. To get this to happen I still had to prime the carbs by covering them with my hand. Still no idle or anything.

Float levels were set dry to 17mm when I rebuilt the carbs.
At this point, I'm going to take the carbs off and see if I messed something up because something is very obviously wrong. Every car I've ever worked on after rebuilding the carbs, the thing would at least fire up and idle (poorly or not) and I could dial them in from that point, but the amount of work I'm having to do just to get these carbs to try and start is clearly wrong.

On the bright side, I rebuilt my brake master cylinder today, going to rebuild the caliper tomorrow and then the bike will have functional brakes.

One question, I put the clutch cable on the bike and not only is it way too hard to pull the clutch in, but it isn't fully disengaging the clutch either. Is this probably an issue of routing and lack of lubrication in the cable or do these bikes just have a really heavy clutch?

 

just to get it here correct pic