Topic: Adjusting Breaker Plates during Dynamic Timing

[cjackel]

Do I need to wear rubber gloves while moving the breaker plates when
checking and/adjusting the timing while the engine is running?

I'm not referring to the timing chain, but the dynamic timing adjustment.

Thanks in advance.

[crazypj]

Dont need to wear gloves, you shouldnt be that close to wiring/points. You need a dwell meter though as the back plate isnt usually a very good fit in crankcase and the points gap varies when you move it. If you keep points plate pushed down (to bottom of locating recess) it shouldntt vary too much.
PJ

[cjackel]

What does a dwell meter have to do with pointing a timing light and adjusting the timing with the engine running?

I already checked and adjusted my point gap and did the static timing procedure.

I'm referring to using a strobe light with the engine running.

Please clarify what you mean.
Thanks.

[crazypj]

The points are open for a period of time and closed for another period, depending on where the rubbing block (heel) of points are on points cam. If you change the points gap the period of open/close also changes. This is the dwell and can be measured in degrees of crank rotation or as a percentage of total time (360 degrees =100%) As the points plate is a pretty sloppy fit the points gap will probably adjust itself when you move backing plate and thus change the dwell period. I think the dwell is set at 47%~52% depending on bike and year. About midway through the points gap is usually right (0.014") smaller points gap means coils have more time to 'charge up' as they open later on the cam and close sooner. This can cause a missfire and points burning though.
Bike will run and appear fine but it isn't 100% right ( OK, so maybe I want perfection but it does make a noticeable difference when its 100%)
this is why top technicians get paid so much (and ride around on 30+ yr old bikes, yea, right)
Hope thats enough information?
PJ

[cjackel]

crazypj:

Don't take this the wrong way but you misunderstood my original question.

I understand what dwell is and why points need to be adjusted. My question
pertains to the process of pointing the timing light at the timing marks with
the engine running while simultaneously rotating the breaker plate to get
the timing mark "F" to align with the reference mark.

Do I need to wear rubber gloves while using a screwdriver, rotating the breaker plate, etc?

[crazypj]

Dont need to wear gloves,


 you shouldnt be that close to wiring/points. You need a dwell meter though as the back plate isnt usually a very good fit in crankcase and the points gap varies when you move it. If you keep points plate pushed down (to bottom of locating recess) it shouldntt vary too much.
PJ

[amattel]

I don't have the steadiest hands in the world and there is a good bit of voltage running through the points plate, so I wear the disposable nitrile gloves when I fool with it for both timing and Dwell adjustments.

Adam

[TwoTired]

For every degree of dwell change, the spark timing changes by the same amount.
The points main plate movement in the engine mounts, effects the dwell and therefore spark timing.
There are three mount detents in the engine case that corral the main points plate.  Without the three hold down screws tightened, the whole points plate wanders in the corral subject to the whims of the point cam and point springs.  I use a combination of feeler gauges wedged in between the points plate and the case detents to prevent the plate from roving in the corral.  Set the dwell or point gap, then rotate the plate until correct timing is acquired, tighten the point plate screws, and then remove the feeler guage "wedges".  If you run out of adjustment range with the points plate, move your feeler gauge wedges to another corral post and repeat the process.  So far, I've found that the lower right post getting the feeler "wedge" results in a happy adjustment range for both the main plate and the 2-3 plate.  Not sure that's best for all machines, though.

There is only low voltage ( about 10) going through the points, extremely little shock potential for humans.  It's the spark plug end of the coils that have the high voltage and where all the "bite" occurs.  It's unlikely that you would even feel anything but movement by placing your finger directly onto the moving point contact while the engine is running.  Gloves, however, will help keep your hands cleaner.

Cheers,

[cd811]

I used tt procedure and it works great

[750goes]

TT,

I'm not sure what you mean by "using wedges". and not having done a Dwell setting yet, are you saying that the points plate isn't located centrally over the turning centre shaft, and this is where the movement can be adjusted from?

my brain is not working real clear this afternoon so please excuse me if i don't fully understand the process.

thanks

[TwoTired]

TT,

I'm not sure what you mean by "using wedges". and not having done a Dwell setting yet, are you saying that the points plate isn't located centrally over the turning centre shaft, and this is where the movement can be adjusted from?

Strictly speaking, you don't HAVE to use a dwell meter.  It's very nice for sure, but not absolutely required.  The dwell setting, sets the point gap maximum opening, which can also be done with feeler gauges and the motor not running.

The main 1-4 plate is held down with three screws.  Loosen these, and remove the points from the plate or disable the point springs so the point rubbing block on both points is making no contact with the point cam in the center attached to the crankshaft.

With the 1-4 plate loose, try to move it up and down and laterally in the engine case mount posts.  This movement is what causes the point gap and point timing to fluctuate while setting the point gap, dwell, or ignition timing.

Get out your feeler gauge pack, and insert enough of them into the space between the 1-4 plate and one of the engine posts until you can no longer move the plate laterally or up and down.  Note the thicknesses you needed to remove the plate looseness and remove them from your gauge bundle.  Leave these wedged in between the plate and the posts anytime you make point gap, dwell or timing adjustment for the 1-4 plate, engine running or not.  Tighten down all three plate mount screws in turn just until the plate will not rotate, then back off just until it does allow rotation.  Reinstall, your 1-4 points and turn the crankshaft to so the point cam is at it's highest peak for the 1-4 point rubbing block.  Set the point gap between .012 and .016 inch, and lock down the 1-4 point mount screws.  Now rotate the crankshaft so the 1.4 "F" mark is aligned with the index pointer.  With the ignition on and either a 12 v test lamp (or volt meter) attached across and bridging the point contacts, rotate the plate, leaving the feeler gauge wedged between plate and motor post, until the light or the meter changes state.  I always move the crank back & forth to verify the state change right on the mark.  Then lock down three 1-4 plate screws and remove the feeler gauges between plate and mount post.  The 2-3 points can then be installed on the now fixed 1-4 plate, gaped and timed similarly to how the 1-4 points were.  That will complete a static time of the ignition and work pretty well for street use and all but maximum output engine function.  If you wish to check dwell or do dynamic timing, just remember the combination of feeler gauges you used and insert them anytime the 3, 1-4 plate mount screws are loosened.

Is this clear enough?

Cheers,

[750goes]

TT,

thank you for the explanantion, it is now lots clearer..I've also just printed this out for when I do recheck my points, and gap etc...

[SuperVel]

Working on TwoTired's post I made a check of the web.  I found one entry that suggested "peening" the motor posts to make the fit tighter.  I cringed at the idea of beating on my engine with a hammer.  after all, I wasn't really angry or frustrated.  My solution was to use TwoTired's suggestion about the feeler gauges and make permanent shims.  I have been using the flat metal stock from a Pepsi can in the shop.  The can is .004 thick.  I clamped a trimmed shim between the plate and motor post at the 11 O'clock and the 7 O'clock position.  This took up all of the slop and when the screws were released, a gentle tap with a screwdriver at the screw slots allowed minute changes in the timing.  The dwell was easy to adjust, because when the tension on the screws was released, the parts did not radically change.  Anyway, just adding another way.

Take care.

Marty

[Steve F]

When I got my first 750F, it already had three center punch marks around the point plate recess in the engine cases.  This I have to believe was done either at the factory or by a dealer, since the previous owner wasn't mechanically inclined enough to work on his own machine (he was the original owner, I'm the second owner).  So with a center punch, you make a small enough punch mark adjacent to the screw hole to distort the casting material toward the point plate.  Just enough to keep things from wandering around. 
About the rubber gloves?  Not necessary, as there's only about 10 to 12v in the area.  However, if your condensors are bad, you may get a slight tingle due to counter EMF from the coils.