ATU springs not closing?

ipmaham

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Still troubleshooting this thing. Bike runs fine, but has loud popping out the left exhaust and hangs after some throttle. Checked everything for air leaks, sprayed carb cleaner around boots, did the whole tuneup sch'bang. But I decided to check the ATU on the right side. The springs can be pulled fully apart and will not snap back into place. I have to manually push them back. Also, they do not seem to come apart that much (basing this off of others pictures).

Correct me if I'm wrong, but they weights should basically SNAP back into place to be in proper functioning order. So I guess the springs are shot?
 

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The weights fly outwards and are stopped by the stops protruding from the plate below. That is what prevents over advancing. The springs pull them back in. They do wear and get old, so they could be a contributing factor. Also if your advance rod is dry and in need of a service, than can cause stickage too.

Here is a good thread on advance service.

http://www.xs650.com/forum/showthread.php?t=18187
 
Just take off that nut you see there, the disc it holds on will slide off the rod and out of engagement with the weights. You will see a line on the disc, it should line up with a line on the plate behind it when you reassemble it.
Once you get the rod out clean off the old grease. Now look inside the cam it will have hard dry grease in the rends.
There is a bushing and what they call a labyrinth seal in the cam. The seal has grooves that hold grease. You need to clean this old dry grease out of the grooves. Once you get all the old grease cleaned out use a Moly grease to refill the grooves and a thin coat on the rod.
Moly grease can be found most places that sell grease.
Once reassembled try the pull them open and let them snap back test. If they still act a bit stocky. take off one of the springs, mark it with a sharpie so you can identify it. Cut the loop of one end of the spring and bend one turn of the spring up for a loop put it back on and check for snap back. If still a bit balky then clip the other spring one turn.
This should make it work.
Leo
 
Sometimes the unit will be a bit sluggish after you freshly grease it. Before resorting to the spring clipping, run the bike a bit to spread the new grease around then check again. It may be OK then.
 
So I pulled out the advanced rod. It was indeed dry. Fresh rag couldn't pick up any old grease.

I greased it up pretty well with some molly-grease. but I cant figure out how to pull the bushings out in order to grease them. Any suggestions?
 
You don't pull the bushings out, you just wipe in some moly grease in the two little grooves at each end where the shaft goes. I just finished this procedure, and as 5twins said, run the motor for a wile, and then recheck the weights.

Philip
 
I also have a product called Boshield, which is a spray lubricant developed by Boeing .I use it in my woodshop for cast iron tabletops and saw blades, stuff like that. I use it on the center of the advance shaft and spray it around the springs and pivots of the advance unit. It's the best product of its type I have found.

Philip
 
greased up the bearings like you suggested. put everything back together. started it up. Big pop. bike doesn't start. i tried not to mess with the points on the left side when I was removing the rod. must have i guess... i will not try to readjust the points, i guess.
 
Did you align the rod properly when re-installing? If not then your timing is 180° off.
 
EDIT: nvm just figured it out.

So it runs and idles a lot better. basically perfect. doesn't hang with some throttle. Drops back down to 1200k/1500k. Nice and steady.
 
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