Topic: Static timing question for a CB500

[stevenmgrr]

I am having some running problems with my bike.  It seems to run okay, but it just doesn't have any power or zip.  Anyway, I am doing a full tune up.

I am at the point of addressing the points and I am doing the static timing procedure using a multimeter.  I have the positive lead attached to the blue wire/lead of the 1-4 point.  Negative attached to the frame ground.  When I rotate the crank, the highest reading I get is about 0.29 volts.  Shouldn't I be getting 12 volts?  Is this an indication that the points need to be replaced or do I need to check out some other things (coils)?

Steven M

[mjstone]

You are not checking for voltage here.  What you want to do is check continuity.  Set you meter to ohms. When the points contact you will get close to zero ohms and when they open you will read much higher.  If you disconnect the wire and condenser it would read infinity for open and zero for closed.

MJ

[TwoTired]

I am having some running problems with my bike.  It seems to run okay, but it just doesn't have any power or zip.  Anyway, I am doing a full tune up.

I am at the point of addressing the points and I am doing the static timing procedure using a multimeter.  I have the positive lead attached to the blue wire/lead of the 1-4 point.  Negative attached to the frame ground.  When I rotate the crank, the highest reading I get is about 0.29 volts.  Shouldn't I be getting 12 volts?  Is this an indication that the points need to be replaced or do I need to check out some other things (coils)?

Steven M

You have to have the key switch and run switch in the on position (and a good main battery).  Voltage will probably be more like 10V, as some power is lost through the coil windings, etc.  The voltage will rise when the points open.  You must set the gap first while the points are riding the high point of the cam.  Then set the 0 to 12 V transition to occur at the F point by rotating the whole plate.

[scw1984]

I am also trying to set the timing on my bike using the static method outlined in the clymer's book but with the audible continuity setting on my meter. I have the neg cable hooked to the battery's ground, but when I touch or attach the positive to the points with the ignition on it beeps constantly. I have adjusted the points and have a timing light however the bike won't start at this time to use the light unfortunately. I am going to try and disconnect the positive wire and see if I can read it using ohms. Was I doing something wrong before?

I fairly new to motorcycle mechanics so bear with me please

[TwoTired]

You have to be aware of where the power is coming from, the meter or the bike.

If it is coming from the meter, you need the power on the bike off and you need to insulate the "other" set of point contacts during the timing test.  (Both circuits are joined at the power input to the coils.)

If you are using the bike's power source, then the meter must look for voltage on open points and no voltage when the points are closed (Key switch and run switch on, of course).

Cheers,

[scw1984]

Ok I will try to test it with the bikes ignition off and then if that doesnt work I will try with the blue wire disconnected off the 1-4 point. If I'm understanding this right one of those ways should work. The meter I'm using is a basic GreenLee one from Lowe's just fyi if you are familiar with it.

Shawn

[Spanner 1]

Wait... don't disconnect anything...way too not needed!!
Just put your meter on DC volts ( lowest setting above 12v ) and turn the ign. 'on'..... When the voltage display on the meter suddenly jumps up to 12v ( or there abouts ) from 0 volts then your points have opened = spark = needs to happen at 'F' mark, so turn the points plate accordingly.

I would strongly recommend you take a minute and unplug the headlight so it's not on and running the battery down while doing this... ( will deplete a good battery FAST ).

[scw1984]

Check check, I'll work on it tonight or tomorrow morning and hopefully have some good news. I did set the points according to the book but could that change the timing enough for the bike not to start or is more likely a possibility that the D7EA (found out just recently that they are the wrong type for summer time) would be fouling out?

[Spanner 1]

The point gap needs to be set at the highest 'lift' of the cam. If you examine the cam you can see an obvious 'hump' to it and need to set the gap ( 12-16 thou. ) while the 'heel' of the point is riding 1/2 way across this hump. Repeat for the other one, then start into the timing as above.. good luck.
If gap not done correctly then the points may not be actually opening = no spark.......... also take the plugs out and lay them on the head ( still connected in the caps ) and see if they spark as you turn the crank after setting the timing.... or quick test, just 'flick' the points open with your finger, spark should happen with ign. 'on' .... one last thing  ; the point faces are shiny clean, right ?

[scw1984]

lol yeah I lightly sanded the tips down to flat surface even though it looked clean beforehand, I mean with 3200 miles on it and garage kept I haven't seen anything terribly wrong with the bike. Only thing I've noticed is after I adjusted the valves with feeler gauges to spec then double checked the seem to tick louder than before I adjusted them which a couple were too tight to begin with. I checked for TDC before I adjusted each set and made sure the in/ex valves were slightly loose on each one beforehand as well.

[TwoTired]

Sanding was a mistake.  Sand is an insulator and it leaves behind tiny particles embedded into the soft point contacts.  You can expect to need replacing them early, as they will now burn up faster.

[mjstone]

Sanding was a mistake.  Sand is an insulator and it leaves behind tiny particles embedded into the soft point contacts.  You can expect to need replacing them early, as they will now burn up faster.

Listen to TT, he's right!  Use a points file to dress your points not sandpaper.

MJ

[scw1984]

It was a very light sanding, could I possibly use emery cloth to clean it up with some alcohol?

[TwoTired]

Alcohol does not dissolve sand.

Unless the emery you have chosen is itself conductive, it's isn't going to help.  A points file has better chance.  But, I'm not sure how to determine if ALL the embedded particles are removed.  It would be better than doing nothing, I would think.

It is the basic nature of abrasives to trade some of the material from one surface to the other, not necessarily in equal proportions.  In the case of points and current flow, any embedded particles are best to be conductive in their own right.

Hmm... Is light sanding like being a little pregnant?   
Or, was that the inner lawyer coming forth?

 
Cheers,

[scw1984]

Haha funny little pregnant, my wife is actually 7 weeks pregnant. Yeah I say light sanding because with less force there is less sand actually coming away from the adhesive on the paper. Ive just read to clean the points somewhere to make sure and use dabs of alcohol to dry the surface but that makes more sense if someone used a liquid cleaner of sorts I suppose.

I went ahead and switched the plugs to D8EAs and it started right up, so the other plugs must have fouled out. I started using the time light and adjust the 1-4 plate as much as it would go but it appears that it still needs to moved another 1/4-5/16 of inch over with no more room for moving. I did take the rpms up to 2.5k and it was close to with the 2 tick marks on the plate probably 1/16 off if that makes any difference. Number 3 cyclinder didnt appear to be firing and wasn't sure if this was do to the timing change or perhaps another issue, all the other cyclinders were firing and 3 was also before the timing adjustment.

Thanks again for the help lol just happy that she starts up again right now Originally I thought perhaps a coil was bad because of some odd ended voltage testing on them but after using the search function found that most likely wasnt. So started at square one with plugs.