First Cafe Racer Mod! 1983 XJ750 Maxim

how did you hookup that tach? wrap the wire or right to the coil

 

I haven’t hooked up the tach yet, it mentions wrapping it around a wire...
I’m waiting on my carbs from Dave Fox to fire it up again.
What is more reliable? Any issues with wrapping it?

 

reliable ? i guess if it works, it works.
wrapping a little wire around a plug wire just sounds hokey to me...?
i used the- side of the coil and a 1meg ohm resistor in series. seal it up good, the tach goes nuts if the resistor gets wet

 

I thought it sounded odd too!
Do you have a picture of what that looks like on the side of the coil?

 

get the wire on the coil that goes to the tci box, that's the - side. use a 1 or 1.5 meg ohm resistor
believe me, you don't want to see my wiring

 

This is an awesome write up! I'll be getting the same gauge setup for my XJ750 as I have decided to keep the stock wiring harness for now.

Keep up the good work!

 

Make sure you get the speedo cable adapter on their website! That way you won’t have to use magnets

 

Confusion with a dash of newbism...
I had my carbs professionally rebuilt by the incredible Hogfiddles so it’s time to set the fuel levels for the bowls...
I got my carbs leveled out with my unique contraption, when I first fill them up I got a reading that filled up slightly below where it should, grab some food to eat, and when I get back it’s over flowing!?...
What would cause this?
Using a ruler as well, the upside down “top” of the float is about 16mm.

newb question- the float needle has a springy rod thing for the float tang, what does the spring action do, act like a buffer???




I tried to fix the images but they keep flipping when I upload them

 

think of the needle valve/float as a controlled leak rather than a on/off valve. The more or less that tiny spring is compressed, more or less gas leaks through.
so the operating range of the float should be in the travel of that spring, theoretically while it's running the tang should never let all the pressure off the spring.
i never noticed before but if your measurement is right, the float is even with that brass tube? that might be a clue.
try to keep the measuring tube close to the bowl, less chance for eyeball error

the floats leaked a bit, was it on a vacuum petcock? did you smack the bowls a few times to vibrate the needles in, like your engine is going to?

 

That was my initial thought but when I inspect it, the needle drops down, still resting on the tang, allowing large amount of fuel to flow in quickly (empty bowl), then the tang would push the needle to the top fully engaged (full bowl), then any more fuel (overflowing bowl) would simply add additional pressure through that springy rod within the needle as it’s already been fully pressed up...
The “controlled leak” does make a lot more sense and may save my sanity with this step!

That’s a good observation about the siphon tube/ brass tube, they’re very close but it just slightly below the float by about 2 mm.

No vacuum petcock, just an auxiliary gas tank setup that does have an on/off, bought it at Oreillys.

~~~~~~~~~~~~
I got them dialed in after 5 adjustments to 3-3.5 mm depending on the meniscus reading and the suggestion about smacking the carbs made a difference as I got a couple weird readings, tapped it with the Allen wrench and then it was good!
Highly recommend using an LED light under the tube in the work area to light up the meniscus so it’s easier to see!

 

Are these things chrome plated? (Touching with finger)
It’s badly cracked all over and looks terrible!
Sprayed with aircraft paint remover and nothing happened...

 

The outer two are chrome plated, the inner ones plated with something else (zinc I think). The inner ones are not nearly as visible with the tank mounted.

 

xj4 catalog says polished chrome and natural zinc plate

also golden chrome for midnights

 

still have some of that nickel plate stuff? try it on the zink plate ones.
chacal used to have rechromed ones that looked like they should be in a jewelry store

 

I think I'll Nickel plate them!
I did one of the inner cap, hit it wheel wire wheel, 1200 grit, then polishing wheels and White Diamond Polish like I did for the rear brake cover, I'll go back and hit it with 2000 grit, plate, then polish up again, it'll look REALLY good at that point!
I have a sanding wheel with multiple strips of sand paper on it that seems to work decently with taking it off the chrome, chemical removal seemed too harsh...

Any easy ways to clean up the carb body to make it look nicer??
It would be great if they were also painted black but I feel like that would require breaking the racks again and being a major pain..

 

https://drive.google.com/open?id=0B4j6bf_0WGweZ21LZHFZckJIVzA

 

Are the wires connected to the coils replaceable?
Don’t want to break them while inspecting it...
These spark plugs are odd, easy to pick up at local auto store?

Any recommendations on filling in the holes for the air box from the chrome covers installed by the PO? I have liquid electrical tape at the moment.

 

The chrome covers on the airbox came on the bike standard: https://www.yamahapartshouse.com/oemparts/a/yam/5004238ff8700209bc787a9c/air-cleaner
The plugs, you can get from the local auto-parts store. I'm not 100% sure, but I think the coil wires are not removable from the coil end.

 

They are not "easily" removable but a determined individual can grind out the channel with a dremel or similar tool and epoxy replacement wires in place. Other options are to splice new wires to the old near the coil or simply replace them with good/new coils. There are some threads that state the 81-82 CB750 coils PN 30500-422-013 are a direct replacement but I do not have any experience with that so do your homework.

 

Interesting, they’re just screwed into the box where it appears to be after the filter...

 

Ive seen some mentioning in here but your reply is the most specific!
I was going to change the wires as a maintenance thing but I’ll have to figure out how to test these then...

 

they sell splices for the spark plug wires the splice screws in like the caps then you tighten the compression nut
https://www.ebay.com/itm/NGK-SPARK-PLUG-Wire-Cable-Splice-Connectors-7mm-Wire-/311196846125
xj4ever sells them too

I have used these
https://www.ebay.com/itm/NGK-ALTERN...804194?hash=item1ec0b063a2:g:nuYAAOSwTglYkOxs


nylon screws would fill the holes in the air box or try to fill with abs glue for black abs plumbing pipe

how to do surgery on coils
http://www.xjcd.org/x-wires

 

There’s quite a few models that that specific coil fits, use the partzilla lookup and you can see the cross reference.

 

https://newmotorcycleparts.net/

this is where the coils come from if i remember the original ost about them , you can buy just the coils or a full setup . caps wires coils. they are a direct bolt on.


http://www.newmotorcycleparts.net/electrical/coils.html

 

When installing LED turn signals do I have to use resistors or is there a flasher/ relay??

I think I read each turn signal would need its own resistor.

anyone have experience with certain resistors if some are better than others?

 

resistors are if you want to keep oem flasher. you need to get an led flasher at the autoparts store.
one with adjustable flash rate would be good


using resistors consumes wattage defeating the energy saving leds.

 

But you’re producing your own energy so it’s not really “saving energy”

 

then saving wear and tear on the alternator, increasing gas milage with less drag on alternator or saving wattage for adding accessories with out exceeding amperage rating of main fuse or output of alternator( adding accessories would negate saving alt wear and tear and milage)

 

My main reason for using LED is for visibility and style.
I suppose I just have no idea where a pronged flasher would go, it would be the easiest!

I checked the wiring diagram so this is a guess...
Is this it?!
(4 prongs inside)

or this?

Under the coils

 

the one you have in photo under coils is the flasher

 

Do you think it would be ok to delete this White/Green wire?
I have a digital gauge from Acewell and this one is just hanging around, with engine off, power on, it's showing a little over 7 Volts.

Could I have issues getting rid of it?
Use it for something else, possibly small fan for oil cooler??? (Arizona heat)
colored LED lights to illuminate the bike for night time safety?

 

many of us have taken out the canceling unit with out issue if you cut that wire your self canceling unit will not function as it will not get its signal from speedo.
if you did the atari delete with the acewell installed the wire does nothing for you. unless the acewell has a reed switch .

 

What does it cancel?
The turn signal???

I don’t think it has a reed switch as this is the new setup.


Sadly this brand new speedometer cable is way too long, hopefully it’s not too expensive to have a custom one made

 

blinkers

 

Then wouldn’t I want to keep it?

perhaps I don’t know how it’s meant to function...

does it self cancel after a certain time or speed?

without it would I just have the move the blinker switch back to middle or press it?

I just played with my turn switch, it may be different than my other bikes, I think I push it “down” to cancel the signal... I didn’t get to ride it much before tearing it apart.


PS: Thank you for helping!

 

A combo of both time and distance travelled.....the reed switch "counts" tire revolutions and this provides the "distance travelled" input to the self canceller.

Yes, and BTW, you should ALWAYS press the signal switch "in" (or down, on some switches, such as yours) after signalling is done (self-cancelled or not) as that is the way the system is designed to be used, says so right in the operator's manual!

 

Wow, did not think that would exist on a bike of this age, some newer bikes don’t do that!
ive always presses the button even on my newer bike that self cancels, I don’t look down enough to care if it’s on or not.

so it’s safe to remove the Self Cancelling box and all the wires connected to it?!

 

Yes, the system is designed so that if the self-canceller fails, the signals will still operate. Just un-plug it from the harness.

 

awesome, then it’s going on the trash unless someone wants it!

 

Now I can’t figure out the Peach and Brown wires for the tachometer...

The only other Peachis attached to the horns, simply to connect them so that’s useless...

black is definitely Ground.

what’s the function of Peach and Brown, how do I get them to read tach?

completely confused by this one!

 

We'll take it!

 

don't care to look it up, don't think you do.
that wire that says (plug, ign coil) yellow, goes to the - side of the coils, thinking it's a gray wire.
-side of the coils should go to the tci.
or wrap that yellow wire around a spark plug wire a few times, and don't connect it anywhere.
if you go with the gray wire you might need a resistor in the wire, about 1 MEG ohm if i remember right.
if you see rpm's all over the place, crazy numbers, you need the resistor

 

Quick-draw Len beat me to that one——-

 

Thanks! The wiring step had me scared to jump in for awhile but after going through it at least 100 times, I'm getting slightly more comfortable especially with the help of the community!
I have a terminal wire removal tool coming in on Wednesday that will allow me to use the same plastic clips so I can trim the wires back at least a foot, while untangling the mess they created by wrapping wires around and through each other...

 

After doing a test run I’m gonna have to install the upgraded fuse block I have waiting, to avoid future issues here.

Everything seems to run fine... HOWEVER

When looking at its current status:
~2 solid Reds- tied together NO FUSE! (Main, should be 30A)
~2 Brown- currently on 20A (Signal, should be 10A)
~ 2 Red/Yellow- currently on 20A (Head, should be 10A)
suppose to be 1 Brown?
~ 2 Red/White- currently on 20A (Ignition, should be 10A)
is this also suppose to have a Brown?


Is this guide correct and my wiring is screwed up but functioning or is there an error with the guide?
I obviously have the wrong fuses installed but the wiring guide has me concerned

 

Yes, but you don't have to "remove any wires", just un-plug the connector shell from the main harness that leads to the self-canceller. Don't cut anything or your risk becoming the "dreaded P.O."..........

 

The main fuse for 750 seca and the 82 750 Maxim a 30 amp because of the Atari package. The way the fuse system works is the battery feeds the main fuse, the main fuse feeds the ignition switch, and the brown wire coming back from the ignition switch feeds the other fuses. So yes the drawing is correct all the fuses except the main fuse are fed by the same
Wire. The brown wire comes down from the key and then they crimp Subwires to that main brown wire and feed the remaining fuses.

 

right now is the time to think about headlight relays to run the light with some #14 wire and get a brighter light

 

That was on my mind as I saw that somewhere in the forums, I'm having issues releasing the terminal spades from the terminal boxes using a tool I bought from Amazon so I'm going to just cut back the wires and install them into new waterproof terminal boxes that will function much better!

Once the wires are looking good, I'll do another test run, then install the new fuse box!

Next I want to do as you suggest with the headlight wire as it works Okay but needs to be much brighter!
I saw this idea a long time ago somewhere in the forums...

This is GREAT to know!