Tuning.....Where the hek to start!

[Paul75]

So I'm onto the timing now. The manual shows the dynamic method using a timing gun but can this also be done the static way ie with a bulb? Can you do it either or?

I must say I find the service manual isn't very detailed, I have found some good videos on Youtube which are more informative.

Learning so much on this bike.....no wonder my dad always had stacks of oily old Harley and Indian manuals piled up....I guess back then there was no forum or internet to refer to.....just old manuals!

 

[grizld1]

Yes, the ignition can be static timed. In fact that's usually where one would start. But the XS650 ignition rod is driven by the camshaft, and because the camshaft of a 4-stroke motor must turn at 1/2 crankshaft speed, any error at the cam is doubled at the crank. No doubt some guys have better technique, but I don't trust myself to get static timing closer than +/- 4 degrees, and always finish with the strobe.

Be sure to inspect timing at both full retard and full advance. Wear at the tips of the weights can alter the advance curve enough to cause trouble.

 

[Paul75]

That's good.....I have a strobe coming so will check both ways.

 

[5twins]

Yes, static time it initially. That will get it close enough to start. Then check it with the timing light to get it exact. Also, you must check it at full advance to insure it's not over-advancing. You may need to retard your idle timing setting a little to prevent that.

Over-advancing is a common problem on the mechanical advance equipped models. If you run the timing too advanced, eventually you can hole a piston. The advance unit is designed to advance the timing a set amount, 25° when new. As the advance unit loosens up and wears, the amount it advances begins to grow. Yamaha provided a way to compensate for that, at least for a while, by giving the idle timing spec as a range, not just one mark .....

It is acceptable to set the idle timing anywhere in that range. I set mine over near the right slash mark, at the more retarded end of the range. This puts my full advance just under the full advance mark, about like so .....

I think the bike runs better like this. I think it performs a bit better at high RPMs and speeds.

 

[TimeMachine]

Super good advice and info 5twins

 

[grizld1]

Bob weight wear is sometimes bad enough that when advance timing is set anywhere out of the piston holing range, the spark occurs so late in retard mode that carbs pop out of the boots at startup. Several fixes for this have been posted (seek and ye shall find), but the one thing you do not want to try is to bend or tap the tabs on the rotor to limit travel of the weights. No matter how careful you are or how good things look when you're done, you'll have started a small fracture, and vibration will do the rest. Result: motor will fail in an inconvenient place, and you'll find a tab lying loose in the advance governor housing. (Been there, done that, used the damn ugly T-shirt for a shop rag.)

 

[MaxPete]

Result: motor will fail in an inconvenient place, and you'll find a tab lying loose in the advance governor housing. (Been there, done that, used the damn ugly T-shirt for a shop rag.)

.....in the middle of nowhere, in the rain, at night, with a girl on the back......

....don’t ask.

 

[Paul75]

Bob weight wear is sometimes bad enough that when advance timing is set anywhere out of the piston holing range, the spark occurs so late in retard mode that carbs pop out of the boots at startup. Several fixes for this have been posted (seek and ye shall find), but the one thing you do not want to try is to bend or tap the tabs on the rotor to limit travel of the weights. No matter how careful you are or how good things look when you're done, you'll have started a small fracture, and vibration will do the rest. Result: motor will fail in an inconvenient place, and you'll find a tab lying loose in the advance governor housing. (Been there, done that, used the damn ugly T-shirt for a shop rag.)

Great advice I'm going to look into this in more detail as at the moment I don't understand bob weight wear. One thing I do know is that when I had the bike running there were massive 'blows' hitting the backs of the air filters which sound like what you describe!

 

[TwoManyXS1Bs]

... at the moment I don't understand bob weight wear...

Paul, have a look at this *extreme* example:

http://www.xs650.com/threads/no-pow...ouble-xs2-1972-xs650.50599/page-4#post-526280

 

[littlebill31]

My addition to the valves.
After you get one set (intake or exhaust) rotate the engine one time and recheck. It'll be off. Readjust them.
I found this to get them dead on.
It takes some patience and time, but they will be dead on.

 

[Paul Sutton]

I also do exactly as Littlebill31 stated above. Takes a little longer but the result is excellent.

 

[TimeMachine]

After checking cam chain tension, valve clearances, point gap clearances, and static timing.
I can't even imagine anyone not being curious enough to manually turn the engine over watching it all happen and rechecking as it rotates.
This is easily done on the center stand, spark plugs out, transmission up in 2nd or 3rd using the rear tire.

 

[Paul75]

Ok I'm attempting static timing, this is something simple but I cannot get the light to light up at any point within the range. Ive checked the bulb and all good. Ignition is on. It has a good ground......

Any ideas!

 

[grizld1]

Spark occurs when points open. Look for the point at which the light goes off.

 

[Paul75]

Hi Grizld1, yes I know that but the light is not lighting at all...bulb is good and ignition is on.....this is when I wished I was good with electrics!

 

[Paul Sutton]

Years since I used a bulb (late 70s) but I think it needs to be low wattage i.e. like the bulbs that light up the speedo. I may be wrong but too much current drain by the bulb causes too much voltage drop over the coil.

Just a thought - Has anyone used a logic probe for static timing. Should be very sensitive.

 

[Paul75]

Paul this bulb is 12v and 21w.

 

[TimeMachine]

Aside from the static bulb checker functioning or not, I am strongly recommending a timing light be used with the engine running for the last word on timing. You probably have one ? And am heading that direction.
When my old " buzz box" would no longer function a few years back , I simply learned to watch closely with a magnifying glass as to when the points open and close while manually rotating the engine.
Even just watching will get the timing close enough to run. Then use the timing light for the adjustments on both cylinders. Compromising on the "seen error" with the timing light to balance out the right and left cylinders.
You are getting close to that timing adjusting process ! Almost there -RT

 

[5twins]

Maybe Paul Sutton is right and the bulb you're using is too big? I've always used a little instrument cluster bulb. I think they're 3.4 watts. Also, my bulb comes on when the points open, goes out when they are closed. So, as I slowly approach the "F" mark, the bulb is out. If the timing is correct, when I get to the "F" and the points begin to open, the bulb comes on.

 

[MaxPete]

Hmmmm.....I find it hard to imagine that the wattage rating of the bulb (as long as it is a 12v bulb) reallly matters.

PAUL - the bulb definitely should go out exactly when the points open. If the light definitely is good, but doesn’t light-up when connected to the points, I can think of two things to check:

1) is the kill switch in the “run” position? If the switch is in one of the two “OFF” positions, there will be no power in the ignition circuit (that is how the engine is shut-off in fact).

2) are you certain that at some point in the rotation of the points cam, the points are closed?

In you photo above, the lower set of points is clearly open, but the upper set may be juuuust open as well. When you mounted the points on the plate - did you set the gap? Perhaps the points are mounted such that they are always open....

I may be wrong, but as I recall it, you must first set the points gap (how much the little contacts open when the cam pushes on them) and THEN you must rotate the points mounting plates to set the timing (which is WHEN the points open).

BTW - another good way to set the static timing is with a multimeter that has an audible diode check setting (essentially a built-in buzzer that sounds when a circuit is closed and contact is made). That way, when rotating the crankshaft, you can watch the timing mark and simply listen to the buzzer. When it stops buzzing - the points have juuuuussstt opened.

A meter with this feature will cost a little more than a real cheapo, but not much more.

Stick at it - you’ll get there.

Pete