Help with timing

[vtwinjunkie]

Just trying to button things up because the bike is running like poo. I recently rebuilt the top end and I am trying to get the timing right.

Starting with the right jug and light hooked up I have the plate turned all the way to the left and I cant get the timing set right. It is too far advanced! when I turn the plate back the other way it just advances even more!!

Help!? I dont want to hole a piston.

 

[vtwinjunkie]

could this be an issue with the advance on the other side of the motor? anyone had this issue before?

 

[5twins]

How far off are you from the mark? Yes, it's possible to assemble the advance rod incorrectly. That throws the timing off 180°. I don't think the bike will even start that way though.

 

[vtwinjunkie]

It is all the way at the far end and the bike backfires all over the place.

How does one install the advance rod incorrectly?

 

[5twins]

By not aligning the locating pins for the points cam and advance disc. They must point in the same direction .....

There is also a locating pin on the cam that locks the advance unit to it in the proper position. Did you correctly install the advance unit onto that locating pin? If not then your timing could be anywhere but where it should be.

 

[retiredgentleman]

Here's some pictures to show you how the pins should line up. Since you did the re-build, you should know if you re-installed these pins correctly.

 

[vtwinjunkie]

Ok I think I figured out the timing issue.

The springs on the advance were not retracting! they were staying open at all times not allowing me to retard the timing into the proper range.

I clipped an equal length off each of them and re installed the springs (I planned on ordering new springs if it worked).

It did. WOW....what a PITA.

PS thanks for the great pics and explanation of 180 out!

 

[vtwinjunkie]

However it still pops very badly......a quick synopsis of the bike components:

Pod filters (properly cut to allow vacuum holes atop the carb inlet breath)
Open exhaust cut and baffles removed (YES ITS LOUD)
Carbs jetted with larger mains.

The timing has been set properly with a light.....but is there anything else that could be causing the popping?

I have already adjusted the valves upon reassembly of the top end.

 

[jchrisk1]

You need to go up one or two sizes on your pilot jets as well. Your mains aren't used until about 3/4 to full throttle. Your probably still lean in the pilot circuit. Possible air leaks too.

 

[5twins]

Yes, if all you changed was the mains, you probably need larger pilots as well. The pilots control the low speed and idle circuit mostly but when you close the throttle and decelerate, that's the circuit you're running off of. If it's too lean, you get that popping.

I recommend ditching the cheap pods. Besides the vacuum port at the top, there are several other air jets they can block. Carb tuning will be difficult and maybe impossible with them. Same goes for the gutted straight pipes. You may never be able to get it tuned right using those components.

 

[vtwinjunkie]

Yes I hate the pipes...trying to get different ones.


Thanks all