Restoring my XZ550... troubleshooting... need some help...

[lonerider]

Hello guys,
I guess I solved the carburetors, changed the needle seats o-rings. Fuel level constant ant okay. I rebuilt the second TCI that I had and it works, bought the two transistors, replace them, resoldered all joints. Until now, I thought that the aftermarket TCI was not the right thing. Now I think the whole problem is carburetion. The original TCI and the aftermarket TCI behave identically in the current operation of the engine. The carbs are set like the book said (repair manual). Only things that I have questions are the pieces between carbs and cylinders, manifolds. Tomorow, the day for manifolds...
I had a VX800 before, bike stalled for years (3 or more) before I bought, carbs blocked, paint burned, chassis rusted, etc..., but I never encountred so so many problems like I met with this bike. I miss my VX... Meanwhile, I listen some music to my own builded tube amp...

[Rick G]

The Vision will out run the VX , especially on a twisty road. The VX is a better long distance bike, after you do something about the horrible seat ! 
YMMV

[lonerider]

Rebuilt the tacho, today. Four hours of work. Maybe you think I'm mad, but I like to REBUILD instead buy other. Maybe I am a poor man, but I have patience (and some knowledge). I will try to explain the operation, if you want, but I need time to try to translate...
Manifolds, There are big questions about these... The idle speed could not be set, it is oscillatory, I have big questins...

[Rikugun]

Maybe you think I'm mad, but I like to REBUILD instead buy other. 

We applaud that thinking here on the ROV. Well, I do anyway!  :P  :D

[sunburnedaz]

Rebuild the tack? I would be interested.

[fiatracer]

I run Royal Purple full synthetic in both mine. Everyone says syn oil is bad for the older bikes but both mine love it and i actually get better performance and lower temp. I also toggled both my fans as the switch has a tendancy to fail. Jon

[lonerider]

Need help, again... How could I remove the needle bearing, to change the oil seal (used) in the rear arm? Thanks.

[lonerider]

Hello again. Anyone know the dimensions for oil seal, beside the needle bearing, in the rear arm? Thanks.

[The Prophet of Doom]

The bearings you can get out with a drift/screwdriver & hammer from the opposite side. Get them in with a home made bearing press made of long threaded rod and a some washers either side.  Tighten the rod to pull the bearing inwards.


The seal (which is not much of a seal) - I never measured, but it's the same size and shape as the bearing cap, and about 3mm thick.

[lonerider]

I'm talking about that. I think I didn' said it well, in my poor English.

[lonerider]

"The Highwaymen" music calm me (http://www.youtube.com/watch?v=2DKfZsLjpCQ), after a carbs troubles day. I dont' know how to solve the problem. I can't explain the cause. Engine is running good, mixture is okay, the idle speed is oscillatory (but doesn't matter). I cleaned the carbs, once, twice, third, i think I do those more like new... That is not all..., some times I run my bike and stop the engine for a while (half hour, one hour, two or more hours) and start it again to continue the trip... after more engine revs, the gas begin to flow to drain nozzle (especially from front carb, sometime from back carb) . I inspected the needle seats o-rings (changed last autumn) and okay,  Fuel level constant and okay. Fuel pump seems to be okay... I have suspicion about bypass and regulator diaphragm (visually seems to be ok), but i don't know how to check this. In this case, when  the gas begin to flow to drain nozzle, this happen in any condition of petcock (full, res or pri). So, I don't know, where to start and what check, again... Any idea welcome.

[QBS]

Do you have an inline fuel filter installed?

[Rikugun]

"The Highwaymen" music calm me (http://www.youtube.com/watch?v=2DKfZsLjpCQ), after a carbs troubles day. I dont' know how to solve the problem. I can't explain the cause. Engine is running good, mixture is okay, the idle speed is oscillatory (but doesn't matter). I cleaned the carbs, once, twice, third, i think I do those more like new... That is not all..., some times I run my bike and stop the engine for a while (half hour, one hour, two or more hours) and start it again to continue the trip... after more engine revs, the gas begin to flow to drain nozzle (especially from front carb, sometime from back carb) . I inspected the needle seats o-rings (changed last autumn) and okay,  Fuel level constant and okay. Fuel pump seems to be okay... I have suspicion about bypass and regulator diaphragm (visually seems to be ok), but i don't know how to check this. In this case, when  the gas begin to flow to drain nozzle, this happen in any condition of petcock (full, res or pri). So, I don't know, where to start and what check, again... Any idea welcome.

the idle speed is oscillatory (but doesn't matter).

It just may matter. If the idle isn't steady, it's telling you something is wrong. The overflowing carb(s) reinforces this idea. I tend to doubt it's the fuel pump regulator or bypass feature. Even without this feature, I'm not sure that pump can develop sufficient pressure to overpower a properly sealing needle/seat assembly, but anything is possible.  :) Just out of curiousity, did the leak develop after having the pump apart or did you take the pump apart after the leak started?

You can eliminate the pump to make sure it is not the cause but it would take some reconfiguration of the lines. You'd have to connect a line from the petcock directly to the T fitting that feeds the carbs. Fill the tank and run the petcock on "PRI". If the intermittent leaks persist, it's not the pump. If you plan on running like this for any length of time you may want to disconnect the vacuum line that powers the pump and cap the port to stop any vacuum leaks.

I'd suggest re-checking the float height and fuel level also.

[QBS]

To dependably flow fuel without a pump you'll need at least 1.5 gals. in the tank.  Full would be better.  As suggested by Rik, bypass the pump, go for a ride, and see what happens.

[lonerider]

My bike is 11U model (European), 1985? year. I never found this year of fabrication for this motorcycle, except this http://en.wikipedia.org/wiki/Yamaha_XZ_550#Specifications. Otherside, i never saw more then two tipes of carburetor sets: one here http://www.cmsnl.com/yamaha-xz550rj-1982_model8893/partslist/B-10.html#results, and one here http://www.cmsnl.com/yamaha-xz550rk-1983_model8947/partslist/B-10.html#results.
I have first tipe with bypass regulator. What happen if I suppress the bypass regulator. Normally, need to work without it.
The gas do not flow over today. Like nothing happened.

[QBS]

Again, do you have an in line fuel filter installed?

[lonerider]

Again, do you have an in line fuel filter installed?

No, I haven't, except the strainer of petcock, inside tank.

[QBS]

Install an in line fuel filter and see if your world doesn't get a little brighter.