Timing problem

[graybikemike]

Hey guys, sorry if this topic has already been discussed. Doing a ground up rebuild of a 1976 XS650 and I cannot properly set the ignition timing. The closest I can get the retard timing is where the advance setting should be. I am following the procedure in the Clymer manual. And we just installed a Mike's performance cam. Any help would be appreciated. Thanks

 

[weekendrider]

Are you using the old bobweights and springs? Are they closing all the way?

 

[graybikemike]

Using the old weights with new springs and they do appear to close all the way

 

[weekendrider]

Some think the new springs may be alittle weak and clip the hook coil off and form a new hook with the first coil. But I think they were advancing too early (1700-1800rpm) not at idle.

 

[CDNTX650]

Find a way to make the weights stay closed temporarily, and see if your idle can be set....then you know the springs are still too loose.

 

[pamcopete]

Hey guys, sorry if this topic has already been discussed. Doing a ground up rebuild of a 1976 XS650 and I cannot properly set the ignition timing. The closest I can get the retard timing is where the advance setting should be. I am following the procedure in the Clymer manual. And we just installed a Mike's performance cam. Any help would be appreciated. Thanks

Whenever I have a problem, I always look at the last thing that I did on the bike...

 

[angus67]

i used a large zip tie around the weights to keep the engine from advancing. just another idea.
also, ace hardware stores carries the advance springs.

 

[graybikemike]

Thanks for all the advice so far. I should have mentioned in my original post that the motor is out of the bike and I am trying to get the timing in the ball park so I can button it up and put it in the frame. This is a fresh rebuild of a basket case bike that was not running. Would the new cam cause this problem by any chance?

 

[gggGary]

Being off a tooth would..............

 

[jayel]

first check the cam timing mark(s) are where it's supposed to be when crank is showing TDC then set right side points main points plate

 

[graybikemike]

Ok, I've tried everything that I can think of shy of turning the cam 1 tooth. I was really trying to avoid that and was going to try that as a last resort. Before I try that tell me if this sounds correct so far. With pistons at TDC, the pin in the cam on the right side is dead nuts at 12:00 and the right cylinder valves are closed.

 

[CDNTX650]

yup, your timing is on. 12 or 6 is the pin hole if the mark on the rotor is at the "t" mark.

Is it advancing the right way? this stuff can be installed backwards.

 

[retiredgentleman]

Ok, I've tried everything that I can think of shy of turning the cam 1 tooth. I was really trying to avoid that and was going to try that as a last resort. Before I try that tell me if this sounds correct so far. With pistons at TDC, the pin in the cam on the right side is dead nuts at 12:00 and the right cylinder valves are closed.

Looking at the left side of the camshaft, there should be an index mark at the 12:00 position. Looking at the right side, there should be a punch mark on the cam gear that is exactly even with the top surface of the head.

 

[CDNTX650]

i think the head is on the bike RG, so you have to use the T mark, and the hole for the advance mechanism pin on the end of the cam shaft.

 

[retiredgentleman]

CDNTX650;

I was thinking his engine was still being assembled, but I may have misunderstood his posts...................disregard my ramblings if they don't apply.

 

[graybikemike]

Yes the head is on the motor. So if it appears that the cam is set correctly why would I not be able to set the ignition timing at the "F" mark? The closest I can get is points opening at the time they should open when advanced. And remember that I have the Mikes cam if that makes a difference. When I installed it the two sprocket bolts were exactly horizontal at 3 and 9 and the pin at 12 with the rotor at the "T" mark.

 

[CDNTX650]

I assume new cam chain correct?

As said earlier, the rod is free and lubed? The whole advancer can go in 180* out too.. Does the pin on the advancer at 12:00 match the pin on the points cam lobe side at 12:00?

 

[Downer]

Make sure to check the third pin behind the atu that's what was throwing my timing off and cause the back of the atu was cracked off throwing it off some degrees

 

[pamcopete]

This is the pin that downer is talking about:

 

[gggGary]

Is it possible to put the points plate in upside down?