my xj issues

Hello all this is my first time posting here. I have recently gotten my dad's 1981 Yamaha XJ650 Maxim running and I have taken care of a couple of issues that Had plagued the bike.
This is my first motorcycle and I am a new rider and so far the bike has been great. I just have two major problems and I can't seem to figure them out.
Problem number one
The front brake switch whenever depressed blows the signal fuse no clue what's going on, most likely a problem with the wiring harness my dad's had it disconnected for as long as he can remember and he bought this bike second hand, anything obvious to start with.
Problem number two
Whenever I try to go full Throttle the bike will break up. Originally when I first started riding the bike wouldn't want to rev past 4000 Without breaking up.
But I've broken through what I believe to be dirt in the carburetors and the bike will rev out to 9000. This was done just by me beating on the bike on a quiet back road. But still the problem persists where I cannot go Full Throttle. The bike will just break up on me if I use the Throttle smoothly and steadily to bring the RPM's up. I can bring it up to whatever RPM I want. Is this how the carbs are designed to work or are they faulty and I'm also having a problem with gas mileage on a full tank I was only able to go about 36 miles before needing to fill up this could be because I was beating on the bike pretty hard or again the carbs are just off.

Now I do live in Massachusetts and this bike only drinks premium fuel Like I said up top the bike is an 81

XJ650 Maxim the modifications done are as the following

750 headlight and fog lamp as well as tank

Harley-Davidson Sportster Exhaust

and air box has been deleted now runs pod filters this was not done by me this was done by my father and so far I put washers in to restrict the airflow and to be honest it does run pretty well

The carburetors on the bike are the original 650 carbs for a while my father had 750 carbs on the bike in the hopes of making it go faster and as time went on he mixed up. The set and thought the 750 carbs were 650 carbs that's why the bike is now running pod filters as he thought the airbox was the problem the 650 carbs were gone through cleaned about 10 years ago all I've done to them so far is take them apart to check the needle slides and put it in a new fuel T o rings.

Any and all suggestions/help are appreciated

 

Hi mate, your first problem sounds like a wiring issue, maybe follow the cables from the blinkers to see where its wrong. Pressing the lever completes the circuit so that will be the only time that issue pops up.

The second problem sounds like you have blocked main jets or dirt somewhere. I run pods and its fine. To fix this you need to pull the carbs off and give them a thorough clean. I have a video on my channel you cna follow, mine were also from an XJ650. Find me on Youtube at "Mezzmo Engineering"

Hope this helps

 

thx man ill give it a go

 

We wont hold it against you living in Ma.
no need to run premium fuel.

 

rly because when I was first starting out attempting to get the bike to run I tried it on 81 and it didn't want to run on it so. I switched it to 93 and that got it running any suggestion on octane level or will any do?

 

Does the brake light work OK when activated from the foot brake? Both Switches should be wired in parallel. With a Brown wire supplying +12V from the Signals fuse, and a Green/Yellow wire sending the +12V to the Yellow wire of the tail lamp assembly when the switch is closed. If the rear brake pedal works fine, then the issue would be a short to chassis somewhere along that Green/Yellow wire from the brake lever, or G/Y somehow got connected to Black in the headlight bucket.

 

thx man this helped a lot did some digging in the headlight bucket and found the green/yellow wire traced it down under the tank and found it had been rubbing and shorted out on the frame like you said fix it and it works grate now

 

I run a midgrade works well .
could be the carbs were set with super and just need the mixture screws adjusted. or the fuel in tank was old and the high octane blended in made it run.

 

Most likely the carbs were jammed up I was out riding it today and it actually seemed rather fine. I just creamed my tank so old gas was not it most likely the bike was just tired from sitting for 2 years if that's a good way to describe it. But I did get curious and I found out that 91 Research Octane like the bike call's for is just 86 Pump Octane so now I know I don't have to spend five bucks a gallon anymore Now I just have to dial in the air to fuel mixture Screw as the bike runs super rich anybody got any suggestions for how many turns I should go out or is it just one of those things where I have to keep playing with it?

 

oh and quick update the brake light has been fixed as well as the carburetors have seemed to have improved I just need to work on the mixtures

 

Out is richer....

 

I'm back again and I have more carburetion problems so I did some on hammering on the bike and my secondary jets are definitely clogged anybody know of a good full rebuild kit for the carburetors? And the bike does not like to cold start with medium grade gas any thoughts on that because with premium it will start without choke and with medium I need to sit there for at least 4-6 minutes.

 

Contact Len aka Chacal he has all the parts you need, e mail him on info@xj4ever.com

 

thanks man

 

Hi mate, check out my video which shows the choke ports in the float casings, my bet is they are blocked and will be the cause of your cold start problems.

 

Hi, I don't think the XJ900 calipers will work on the XJ650. The discs are much bigger and not sure its a great idea to mix things up like that as the braking performance will change unless you use the matching master cylinder etc...

 

I see so I would need to replace the majority of the front brakes if not the front forks as well. Oh well it was just a thought anyway thanks for letting me know I was not aware of the size difference

 

main issue would be the 900 caliper mounts differently that a 650 caliper, so a front fork change would be needed.

 

that sucks does anybody know of any dual piston calipers that would fit on 650 Forks?