20 Most Recent 1982 Yamaha XJ 650 - Page 8 Questions & Answers

There are several wiring diagrams available on this thread:

http://xjbikes.com/Forums/viewtopic/t=22706/view=next.html

There are actually a few sub-models of the XJ750, so be sure you look carefully, but it looks like the oil indicator wire is "B/r" on all of them. That most likely means black with a red line.

XJbikes.com is a great source of information for the maxims and secas from the 80's, but it is not a substitute for a good shop manual. If you are planning to do some work on your own bike, a shop manual will be a worthwhile investment. the Haynes manuals are great, and you can usually find a new one on ebay for around $25. The best part about those shop manuals is that they cover a few years and models of similar bikes, so you may even be able to reuse it for future projects.

Good Luck,
-Josh

Hi,

These engines tend to resonate right around 4.5k-5k rpm. Originally they came equipped with rubber bushings between the engine cooling fins to absorb the vibration, but at this age, they are probably long gone.

It sounds like you have a normal XJ. Beyond that midrange buzz, it should pull like crazy right up to redline.

Hi,

Hope this doesn't reach you too late. These bikes take some time to fully warm up.

You can adjust the idle down by turning the knob between the #2 and #3 carburetors counterclockwise until you reach 1050rpm. Wear a glove or you will burn your hand!

Ride the bike some more, and see if the idle stabilizes. If not, you may have a vacuum leak somewhere.

A quick way to diagnose this is to take a propane torch (NOT LIT!) and run it around the carb boots and vacuum caps. If there is a change in rpm, then inspect the boots and caps for tightness and cracks.

Hi,

They all do that :)

Hi,

First make sure the fuse is intact and seated. You can also open and clean the blinker switch contacts. Sometimes the relay can go bad, you may need to replace it. The relay is located under the frame near the middle of the tank.

There were a couple of different carbs fitted to this era of bike. One of them has a diaphramme that works a 'fuel pump' system and floods the carb as the throttle is opened. They will split and cause problems.

under the seat where the fuse box is. Take the tool pouch out & 3 philps screws lid pulls up

I would recommend adjusting the idle screw on the carb. If it is not the idle adjustment, then check the choke as it may be sticking and that will cause the engine to idle at that rate.

hi sounds like the main spindle shaft that operates the carbs has seized spray penetrating oil wd40 or similar all over the outside of the carbs giving them a good soaking leave for a good few hours
and gently try and wriggle the throttle cable till it starts to move then spray it some more if this doesnt work remove the carbs and clean them out putting penetrating oil inside the throttle bores
you will probably need to take off the lower fuel bowls and clean them out too if its been standing a long time the fuel avaporates away and your left with a lot of corrosion inside that must be cleaned
out as it will block fuel flow through the carbs

J&P cycles.com

Hello,

It sounds like you have bad gas in your fuel system. If your bike sat for a while, you will need to drain, and clean, the carb bowl(s) (turn off the fuel valve before doing so), check the fuel filter for any blockage (replace if necessary), and then add Sta-bil to your fuel tank. This will stabilize the remaining fuel in your tank. With today's fuel having Ethanol added to it, the fuel gunk's up quicker.

Turn the fuel valve back on and start your bike - run a full tank through the fuel system. After a full tank is used, get a bottle of SeaFoam and add the recommended amount to your fuel tank when filling up. The SeaFoam will clean your fuel system and your bike will run better. Use Sta-bil when your bike is not going to be used for a while and use SeaFoam every other full tank - if you are not going to use a Premium fuel with no Ethanol added.

Hope this helps.

If you find this information useful, please vote on this post. Thank you.

Regards,

Oz

These bikes need the carbs ajdusted rather frequently, once they get out of adjustment the they juste don'e idle good. Also as old as this one is I can guess that you may have some air leaking around your some of the gaskets and this is why after it warms up it runs better, the gaskets get heated and the swell a little and then start sealing better. It would do you good this winter if you replaced all your intake and carb gaskets and get the carbs adjusted by a trained technicianan you will be ready to roll when summer comes around.

retighten engine on frame affter getting torque values from a shop manual--the fork area shud be looked at also

There are kits available in Europe that install a lower triple clamp with a different rake angle from the stock forks. I have seen them on cycles before but do not know the name of the company. If there is one that is designed to bolt on to your bike , that would be the easiest way to stretch your frame with out structural weakness being a factor. Start with the article at roadstar clinic :http://roadstarclinic.com/content/view/10/97/

Everyone has a problem with the bolt. You need to use a 6 point socket or you strip the head. The problem is the previous oil changer overtightened it. It only needs to snugged up enough not to leak.You can buy an aftermarket replacement bolt for around ten dollars. The problem is it comes with a seventeen millimeter head , with a bigger head comes a bigger wrench and the problem amplified. Once when I was really desperate, I carefully cut the head of the bolt in half down to the oil cup and squeezed the two halves of the head together, releaving enough tension on the cup to turn out the old filter bolt.

The ignition switch may be bad. With a bad electrical connection in the switch it will cause you to have these symptoms.

I'm assuming the bulb is good. If the fused link is not blown and the relay is good, then you should be getting voltage to the hot side of the circuit to the light? No? If not, then you should be getting voltage to the hot side at the switch?

Hi and welcome to the site,

Would the whole wiring diagram be better? Please click here.

Good luck and thank you for asking.

try running a wire from the frame to the side of the h/light bulb as might be a bad earth also check fuses and bulbs is the rear light still working as usually if no h/light rear light goes as a final measure check all wiring connectors within h/light for corrosion etc and that a wire asnt simply vibrated out of its joint

Start off by checking your fuses, they are generally the culprit. There is not a freebie manual for your model at this site, but fossick around, you may find one that will be a good guide. It is always better with a manual, it definitely helps when you have a bucket of bits and dont know where they go. :D