Is there a way to bench test the starter motor? 1975 XS650

Ok, so here is my issue...

when I built this bike I decided I would be macho and have it kick only, well, with the rephase and the bore and new rings and everything I can barely start this bike with the kick starter (when it bucks back it throws me off the bike, there is a huge bruise on the bottom of my foot)

I was wondering if there was a way to bench test the starter motor, I am confused as to how there is one ground wire going to the starter and that is it, It is very confusing to me, so I was wondering if I could just hook up the starter to a battery (or other 12v power supply) and get this motor to spin?

If this is possible, how would I do this?

thank,
Jordan

Yes, you can test it off the bike with a battery. The one wire on it is power, not ground. The ground is through the case. Bolt a wire to one of the mount holes and attach to the battery negative. JUST touch a wire from the battery positive to the wire connection on the starter. If the starter is good, it will spin like crazy.

I had simular situation. I was replacing the battery and cables Because the stock set up didn't want to crank my 750 kitted 75 as well as I liked. When it's cold out like 35-40 degrees I couldn't hardly kick it or crank it well with the starter, To start it then, I would stand on the kicker and as I started to kick it I would punch the start button too. This got the engine spinning enough to start. The new battery 275 cca's instead of the stock 180 -200 cca's, and the 4 ga cables helped a lot. Running a ground cable from one of the starter mount bolts straight up to the battery bypasses any weak connections from starter to engine to frame through the mounts, frame to battery ground.
To get the cable off the starter you have to remove it from the bike.
Anyway once I had it out I was wondering which of the starters I have would be the strongest. I did as 5twins said but held the starter on the negitive of a battery and touched the cable to the positive. I did this with all the starters. I used the one that bucked in my hand as it started to spin. I figured the one that bucks hardest was the most powerful.
Just had a thought, car parts stores often have a machine that tests car starters and alternartors. I don't know if they can test bike starters. Might be worth a shot.
Leo

If you really want to get the most out of your starter motor, then clean up the commutator. That is the #1 cause of sluggish motors. I did this on a couple of my bikes and a friends as well and the difference is unbelievable.
Before and after



I did these on a lathe, but you can do it by hand or use a drill press.

I concur totally with Pamcopete. When I was doing a top end re-build several years ago, I decided to take a peek at the starter motor. I found the brushes were in good condition and exceptable length. The commutator looked similar to Pete's first picture. I just used some emery paper and cleaned it up by hand. Very worthwhile to do.

I've never had a starter apart so I have a few questions. What are all the scrape marks from on the larger part? The brushes ride on the smaller part, right?

I took my power supply and hooked the positive up to the cable coming out of the starter motor, and then touched the negative to the case on the starter (where the bolts go) and it just sparked, no motor spin at all, not even a try.

since it sparked I thought that maybe something was messed up inside the starter and it was just shorted out, so I hooked up my ohm meter from the cable to where the bolts go through and I read 13 ohms, I believe it should be OL, correct? otherwise it is a continuous loop and it is just like shorting the battery

JNizza92 said:

I took my power supply and hooked the positive up to the cable coming out of the starter motor, and then touched the negative to the case on the starter (where the bolts go) and it just sparked, no motor spin at all, not even a try.

since it sparked I thought that maybe something was messed up inside the starter and it was just shorted out, so I hooked up my ohm meter from the cable to where the bolts go through and I read 13 ohms, I believe it should be OL, correct? otherwise it is a continuous loop and it is just like shorting the battery

Click to expand...

You can't connect a starter motor to a "power supply", unless you have a 100 amp power supply. What kind of power supply are you talking about?

You would have to use a battery that is capable of supplying 100 amps, such as a 14 amp/hr battery.

As for resistance, 13 ohms is much too high. It should read around 0.01 ohms.

Re-test the starter motor using a proper sized, fully charged battery. Since you measured 13 ohms, it almost certainly will not spin. If it fails to turn rapidly, then its defective inside the starter motor.

Your question about ohms through the starter got me curious, so I went out and ohmed the four starters I have. Three measured at .1 ohms, the fourth 1.2 ohms.
They all work well.
I don't know if there is a spec for that.
As RG said a plug in the wall power supply needs to be at least 100 amp. Is yours that or is it one of those jump start boxes? A too small power supply will spark on even a new starter but not have enough current flow to spin it. The spec on the starter is a 35 amp draw with no load, And cranking the engine at 300 rpms a 75 amp draw with the decompessor lever pulled. The only Specs I could find on the starter are the 72-73 years. Without the decompressor as in the later years probably 100 amp draw.
Leo

Haynes manual has the following:
Armature coil = 0.0067 ohms
Field coil = 0.004 ohms

If wired in series that would be 0.01 ohms

Leo, your measurements at around 0.1 ohms sounds more correct. I think Haynes manual has errors. I suspect Haynes should have printed 0.067 and 0.04 which would add up to 0.1 ohms, that you found.

5twins, that scoring on the starter motor laminations is certainly not normal. That motor must have had some dirt/debris of some type inside it??? My starter motor did not have those marks.

I think the field coil they are referencing is in the starter relay. The armature coil reading they spec is probably from one contact on the armature to another. The extra resistance found can be in the brushes where they contact the armature. As well as the resistance in the connection to the cable and the cable.
Like when you test the rotor on the alternator the readings spec are from slip ring to slip ring. If you test from the brush wires it adds some ohms. I checked once and as I remember it was around 7 ohms.
Leo

Bringing up this old thread to see if I can get some guidance.

('79 Special II, stock wiring)

Recently, my starter has been VERY sluggish when I hit the start button. Kind of growls a little...and then it will start to turn slowly, then a little more, and more, and then it finally will start the bike up. (Note: The next time hitting the button may do the same thing, or it will start up without any sluggishness). However, today it simply clicks at the Swtich/relay. My initial thoughts were low battery...and/or poor connection, loose wire somewhere.

(Kicks/runs great...so no issues starting otherwise).

So here's what I've done so far:

1) Cleaned all connections (from starter switch- back and from battery forward)

2) fully charged battery: 12.6 at rest

3) functional charging system...14.2-.5 at 3000rpms

4) Starter switch/relay clicks when starter button is pressed. Thus positive wire from battery going to the starter switch/relay is almost no resistance and registers 12.5v, when starter button is pressed the switch/relay sends 12.5v to the starter motor wire.

5) Grounds check out...almost no resistance at the frame bolts for the starter, starter button, or anywhere on the bike.

So, at this point is there something else I may have missed? Or is the starter motor what I need to check next?

If so, I'd like to test it without removing from the bike first...so thoughts on doing that? I have a spare battery, but when I ground it, and touch the starter motor's connection, nothing...so probably not enough amps going to it...or another sign that the motor is dead I suppose.

Is there any other tests for the starter motor that I can do before pulling it?

To pull it, do I drain oil, and take off the 4 bolts, or something else I have to remove?

Thanks for the help in advance.

12.6 on the battery is not fully charged. that's almost dead. After I take a battery of the charger reads closer to 13.5 to 13.8.
Do you have jumper cables? If so hook them to your car battery. No need to start the car. Hook the black clamp to a good frame ground. I use a front foot peg mount nut. Put a large screwdriver in the red clamp, Peal back the rubber on the cables at the starter relay, Find the one that goes down to the starter, touch the tip of the screwdriver to this cable. Your car battery has plenty of amps and should spin the starter very well. If not your starter has problems.
If it cranks well your battery may have issues. I might fully charge it then try again. Or fully charge it and take it to a place that sells batteries and get a load test.
This will let you know if the battery is ok.
Leo

That's a good idea, thanks XSLeo...I guess I assumed 12.6 was charged as that's what it's been at since I got it new (10 months ago).

Old trick to bench test. Ground it, hit the hot post with the juice. If it's good it will hit hard and spin with real authority. If it's a bit sluggish and lacks snap it's going to be a weak one. I hold the starter in my hand (yes), and if it's good it will almost try to leave your grasp. No problem if you have a good grip on it. From garden tractors to small block Chevies.

OK, so last night I fully charged my battery...and it read 12.8. Still low I suppose, but that's what I got...and it still just "clicks". So then I tested the starter with my Tundra battery...jumper wires to a solid ground and straight to the post on the starter and nothing.

Wanting to ride, I kicked it over, runs great...rode about 30 miles (Enjoyed the ride), and came back home. Just for kicks, I hit the starter button one last time, and it worked! WTF?

Turned it off...and tried it again...and it just "clicks".

Tried the jumpers again, and still nothing.

So I think I've ruled out the battery issue. I think I'll need to pull the starter.

Any tricks to get it out, or is it pretty straight forward (Drain oil and pull the bolts)?

Pretty much. You might need a home made wrench to get to some of the bolts. It needs the right bend to fit between the frame/engine and around the starter.
Leo

Both removal and install will be easier if you remove the little gear train cover below the countershaft sprocket. The large gear that ties the starter shaft into the engine will just slip right out. That way you won't have to fight with meshing into it during the install. Don't lose the little wave shim washer on that middle gear shaft .....