1977 xs650 wont start

[KasperTheGhost]

I could really use some help here. I cant get my kids bike to fire up. I 100% know its how the points are setup and 100% can guarantee its timing is off. I watch all these videos, but i am missing something. I get spark at the plug, but lord only knows if it is correct. Does some one have a way to just dumb down version for ol dad. All summer i been dicking with this kids bike, i mean, all summer.

 

[Jim]

 

[KasperTheGhost]

Those were what i am watching. How do i know if my points cam is installed correct?

 

[Wingedwheel]

Did you remove the cam? If it fires at the correct spot chances are it’s correct. Does the engine try to start? If it “kicks” back perhaps the plug wires are reversed?

 

[KasperTheGhost]

Did you remove the cam? If it fires at the correct spot chances are it’s correct. Does the engine try to start? If it “kicks” back perhaps the plug wires are reversed?

I did. Bike sat for a decade. It ran when parked. Everything was like locked up. I replaced the points, but they wouldnt open till i replaced that cam. I get a shudder every so often. When i try to follow those videos. My F timing mark, i cant get the points to even be close to that mark. We are almost to the point of lighting a match over here.

 

[Wingedwheel]

If you put the cam in 180 out it will fire but it will be on the opposite side. Try reversing your plug wires and see what it does.

 

[5twins]

The points cam has a locating pin to lock it in the correct position on the advance rod. There is another locating pin in the other end of the rod to lock the little advance disc in the correct position. These two pins must face in the same direction. It's possible to install them pointing opposite to one another, 180° off. This will throw the timing off 180° .....

To help with proper assembly, Yamaha scribed some alignment marks on the little disc and on the advance unit backing plate (yellow arrows) .....

 

[5twins]

Those videos are pretty good but the guy fails to mention one important thing - the feeler gauge you use for gapping the points must be totally clean. If there's any oil on it, that will contaminate the points faces and cause them to misfire or not fire at all. So, clean the feeler gauge blade with some electrical contact cleaner before using it on the points.

 

[Jan_P]

Wires from Points Mixed ??

 

[JOHNDADDY]

The points cam has a locating pin to lock it in the correct position on the advance rod. There is another locating pin in the other end of the rod to lock the little advance disc in the correct position. These two pins must face in the same direction. It's possible to install them pointing opposite to one another, 180° off. This will throw the timing off 180° .....

View attachment 248847

To help with proper assembly, Yamaha scribed some alignment marks on the little disc and on the advance unit backing plate (yellow arrows) .....

View attachment 248848

Yup Yup! I've done that twice..

 

[KasperTheGhost]

Wires from Points Mixed ??

I tried that, no luck

 

[Wingedwheel]

I guess a question I should have asked, are the plugs getting a good spark?

 

[KasperTheGhost]

I guess a question I should have asked, are the plugs getting a good spark?

Yes they are. I had some fouled out plugs, one side wasnt hitting. I had to trim back the plug wire a bit. But i see spark on both sides.

 

[Jan_P]

I did. Bike sat for a decade. It ran when parked. Everything was like locked up. I replaced the points, but they wouldnt open till i replaced that cam. I get a shudder every so often. When i try to follow those videos. My F timing mark, i cant get the points to even be close to that mark. We are almost to the point of lighting a match over here.

To sum it up you have spark but not at the right position ../ time
Does the advance unit operate as it should if you move the weights manually carefully
does it go / spring back
# 7 Mr 5 Twins

Perhaps picture of both sides advance and points
What Voltage measured across the battery everything Off and ignition ON

 

[Wingedwheel]

I just went back and you did say that in your first post. Are you trying to start it with the e-start or kick? You also need to check voltage at the coils when cranking.

 

[Jan_P]

I just went back and you did say that in your first post. Are you trying to start it with the e-start or kick? You also need to check voltage at the coils when cranking.

Yes good point .
e starter and a bike that sat for 10 years ..has little chance happen the starter uses to much power not leaving enough for spark
Adding to that perhaps a Voltag drop in wiring and weak battery ..

 

[KasperTheGhost]

We got it to fire up today. I dicked with the points and i think i got it squared away. I need to adjust the points a few more touches. Thanks for the continual support