Running problem.

bassgoat1979

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My bike will start up after a few kick only if I have the timing full advanced, the carbs choked and full throttle. It will only idle at full throttle though for a litttle while and die. If you let off the throttle it dies. The plugs are wet with gas after that too. The carbs are rebuilt and the fuel level is exact. I did the VF500 magneto swap with the accel capacitor. The spark is nice and fat though. I have a new condensor too.

The bike is a 80 that I added all the points parts to. Could it be possible that the advance is working? It is tight and you can only move it with a wrench. I got brand new bushings and laberinth seals for the cam, but it seems too tight. The point gap is exact. The valves are adjusted good too.

The carbs are original. The diaframs are nice and the slides move freely. It just seem like it's running retarded or the carbs are feeding too much fuel. I just don't under stand how the cabs could be off. I even tried putting the original size jets in and it didn't change at all.

When it does run for 15 seconds it sounds good (no backfires) I'm stumped, anybody?
 
The bike is a 80 that I added all the points parts to. Could it be possible that the advance is working? It is tight and you can only move it with a wrench. I got brand new bushings and laberinth seals for the cam, but it seems too tight. The point gap is exact. The valves are adjusted good too.


- what does this mean?...
- the points, advance shaft should rotate cleanly without resistance, your bushes may need reaming, a reason i prefer to use needle bearings here
 
You are probably right. I watched a video and you can move the advance ears easy with a finger. No way to do that! I'll have to ream them, I am kicking myself for not spending the extra $4 for rollers now! So that with mess it up even at an idle? It alway try to start, so there is no issue there, it's keeping it running!
 
- moving the 'ears' by finger is a test of the ability of them to function centrifugally and the tension required on the springs so that they return to rest position...they should 'fly' outwards without restriction, except for spring resistance, and snap back to rest when released...see here and this finger operated function should have little to do with the bushes
- the shaft that lays through the bushes should fit neatly but rotate freely
 
hm. If your advance mechanism is "stuck", then you should be able to "lock" them closest in, and still be able to idle the bike.

You mentioned that you put the points stuff in - are you running dual points? Is it possible you've got the points cam 180 degrees out or have the leads from your points backwards? Having either of those things wrong might cause the behaviour you're describing.
 
Well if I try switching the timeing (swap the points plugs at the coils) It doesn't even try to start. I have the R wire to right coil and L wire to left coil. I'm sure it's this timing advance I worked at it a little bit and got if to move by finger, but it doesn't return on it own. I little more rheaming and it should work. It make sence, the only way I got it to run at all was to advance the timing on the points plate. I don't know if you are familiar with Yamaha 2 strokes with TORS, but the they retard the timing when they fail, and it acts just like this. I'm used to CDI's mainly, any points I have worked on never had a issue with timing. I'm going to try that then go to the carb.

So that advance must open a little even at startup?
 
- at rest it should open and close as per the video
- take it apart and carefully clean it, check the springs too
 
I know it's clean and lubed, I had to put it all teghether. I had it off one and rheamed the bushing a little and it works better, but you stull have to push the ears back down with you finger. . At least no wrench is needed! getting close.
 
- are the bushes and the new seals properly seated, is the large nut under the advance arms done up properly, as you do it up the advance plate should slide into place, if the seal isnt seated properly the flange behind the advance plate wont go back far enough

P1260014.jpg
 
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