Driveability Problem

[SUPERDOM 82]

Hey everbody need some help here have 1982 xj 1100 max and it runsw fine until i go 65 + mph for a little while then let off the throttle and it feels like its running on 2 cylinders the powers not there if i slow down and ride under 3500 rpm for a while power comes back until i go 65 + mph again and it does it all over again. im stumped any ideas. Thanks Superdom

[old_skool]

Inspect the plugs to try and verify the 2 cylinder possible problem. see if some are getting rich looing due to falling off, some may say carb issue, but I'm betting on sparky not delivering the necessary punch(coils) but check all electrical connections and grounds for a starting point to help eliminate the silly's before ripping your hair out.

[DGXSER]

Typically, the XJ does not show the symtoms of the dreaded pick-up coil wires which sounds alot like what your describing.

The issue tends to be caused by the fluctuating of the timing plate from the vacuum and or mechanical advance. But the XJ uses neither.

However, nothing says your wires still could not go bad.

[SUPERDOM 82]

ok ill check that issue out im with you i think its electrical the bike is 30, years old ya know even the best can break down!!!!!!!!!!!!!

[CatatonicBug]

I'm just throwing this out there as a possibility, but maybe there is a fuel delivery issue. If the vent in the tank is partially clogged, once you get to a point where the fuel consumption is too high to allow the air to flow in and compensate, it may act like it's running out of fuel for a bit, until you slow down, allowing the vent to catch up. Could also be kinked fuel lines, or even a dirty air filter.

Have you tried testing it while not moving? Just put it in neutral, and rev it at a constant 5-6k for a while and see if the problem persists.

[SUPERDOM 82]

ok ill try that but i did drive it with the cap open and it did the same thing!!!!!!!!

[XS1100_OEM4ME]

Gas cap

Open your gas cap and ride it, if it stops doing it, remove the cap and dissasemble and clean the check valve, they have a very small vent hole and the check valve gets stuck sometimes

Hey everbody need some help here have 1982 xj 1100 max and it runsw fine until i go 65 + mph for a little while then let off the throttle and it feels like its running on 2 cylinders the powers not there if i slow down and ride under 3500 rpm for a while power comes back until i go 65 + mph again and it does it all over again. im stumped any ideas. Thanks Superdom

[skids]

If you have vacuum operated fuel flow, try running on prime setting to see if it makes a difference. If so, that should help narrow down the possibilities.

[XS1100_OEM4ME]

Gravity

I have gravity fuel flow, what is the vacuum fuel flow system, is it stock on some of these bikes or are you just talking about the octy / vacuum petcocks

If you have vacuum operated fuel flow, try running on prime setting to see if it makes a difference. If so, that should help narrow down the possibilities.

[TopCatGr58]

Hey Super,

The XJ uses vacuum controlled petcocks, sounds like a fuel delivery problem also. Check the vac lines from the petcocks to the intake boots for cracks and leaks! Also, you can bypass the vac. control by putting the petcock on prime...direct flow to carbs...so you can test this by riding till it fades, then turn to PRIME and see if it returns to full power without letting off the throttle. IF it gets strong again, then you'll know it's fuel, and can trouble shoot further. The vac. valve could have a leak as well!?

from the owners manual:
In the "ON" and "RES" positions the cock works on pressure fromt he engine turning over. If the line connecting the cock tot he carb intake manifold is not connected or has a leak, the cock will not function properly.

Pri: This indicates "PRIME". WIth the fuel cock in this position, fuel flows whether the engine is running or not. If the fuel tank is completely empty, refill the tank and prime the carbs in this position and then switch to "ON" position after starting the engine.

T.C.

[SUPERDOM 82]

okay i ran it on prime and no change this bike is supposed to fly but not like this i guess it must be electrical now i have noticed that my pipes are blueing alot more now than the whole 30 years of prior!!!!!

[crazy steve]

The blueing means you're running lean or with too much timing advance...

The XJ has 'electronic' advance for both the 'mechanical' (rpm-controlled only) and vacuum (load-based) advance. I'd try disconnecting/plugging the vacuum hose to the ignition box and see if the problem goes away. The 'vacuum' advance is triggered by a vacuum switch, which if it's not switching when it should could give too much advance at the wrong time.

If the problem came on suddenly and if you're blueing all the pipes, this would do it.

[XS1100_OEM4ME]

Carbs

I would rebuild the carbs, you dont need kits, just make sure you clean EVERYTHING till completly clean and make sure the floats are set exactly correct and dont bind or touch anything, including the bowl gaskets, then set the idle mix screws 1 turn richer then recomended, you can always turn them down when you color tune the motor later