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Old 11-21-2012, 09:57 AM   #31
disston
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Originally Posted by chasbmw View Post
if the starter only gives problems when it is under load, then ther problem is often due to wear in the bushings, this allows the armature to cock sideways under load and everything starts to go really slow.

I dont know if the bushs are available for these old 8 tooth Boschs, but given that you can buy either Valeo or Nippon Denso 8 tooth starter motors nowadays I would go for replacement.
The bushings are available several places. Motorad Electrik comes to mind.

The only part that I think I see reports about not being able to buy is the early 8 tooth pinion. These reports are rather universal however I'm not really sure that there isn't some obscure source, it's a Bosch part after all, or there isn't some way to make do, adapt, another 8 tooth pinion to the Bosch starter Armature.

If you need the 8 tooth pinion it doesn't look hopeful.
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Old 11-21-2012, 11:13 AM   #32
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The guy at motor works in the UK that rebuild Bosch starters said that the solenoids were NLA.

If the bike was mine I would replace with valeo, they work well
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Old 11-21-2012, 11:08 PM   #33
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What do I have to do to use one of the 9 tooth valeo starters with my 8 tooth setup?

(although the question may be moot as its working properly now)
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Old 11-21-2012, 11:29 PM   #34
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What do I have to do to use one of the 9 tooth valeo starters with my 8 tooth setup?

(although the question may be moot as its working properly now)
Change the flywheel to one that uses a 9 tooth starter. Since they also changed to the 11 mm flywheel bolts change the crank shaft.

It's a big job and you would need help and extra money. Much easier to buy another engine.
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Old 11-21-2012, 11:39 PM   #35
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Change the flywheel to one that uses a 9 tooth starter. Since they also changed to the 11 mm flywheel bolts change the crank shaft.

It's a big job and you would need help and extra money. Much easier to buy another engine.
Or pick up a new 8 tooth starter
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Old 11-22-2012, 01:45 AM   #36
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Don't make the mistake of trying to use a 9 tooth starter on an 8 tooth flywheel as you will ruin the teeth on the flywheel

I have heard of people fitting the later 9 tooth flywheel to the earlier bikes, they use sleeves on the flywheel bolt holes, so that they can use the original sized flywheel bolts. By the account I heard this worked well.

It's really good that we can get new starters for 42 year old bikes!
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Old 11-22-2012, 12:47 PM   #37
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Must say, even after rereading this thread. I never saw anywhere where either batteries old or new were properly load tested to verify good rebound.

I just think spending any time at all doing other than that is unwise. Go back and verify resting volts, volt drop when hitting the starter, then rebound volts after a few minutes rest. Those numbers tell where to go for faults and key to finding culprits.

I have indeed seen NEW batteries that do not meet specs. Though rare, a load test can prove the right in every case.

Once that's done, then you can confirm what the charging systems is doing. Get that spec.

THEN check the starter relay and starter.

Sometimes on an poorly serviced airhead you can find weakenesses as you go everywhere through the machine. It's a synergy of weaknesses adding up to poor and non function.

But if you assume a new battery is good then go on about troubleshooting for days and weeks, best get back to PROOF of VOLTS/AMPS in the battery. Has not yet been as far as I could find. A multimeter and 5 minutes is all that is needed to rule out the battery as a contributor in the equation.
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Old 11-22-2012, 04:47 PM   #38
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Ok, lets start over here. Cliff note style

starter was clicking (off and on, not consistent), did some testing, took it apart and bench tested, etc

put it back together, same thing.

Alternator rotor failed.

Alternator rotor replaced.

Now not clicking unless I have been messing around and battery is low.

Currently I can test whatever with the starter and the battery....but its acting normal as if the problem has solved itself.

So again, most recent question. Any ideas on why a new rotor would effect the starter circuit?
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Old 11-22-2012, 06:52 PM   #39
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You still haven't proved the battery via a standard load test. Tell us current static volts at rest, volts when start button held for 5 seconds, then rebound static volts after some 5 miutes rest. Rule this out with a very quick and simple test, rather than speculations on other evidence that depends upon volts/amps available. Nothing downline can do it's job if the power supply is weak, so rule that out with just a simple, standard load test.
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Old 11-24-2012, 08:08 AM   #40
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When the battery is weak, it doesn't have enough power to turn the starter motor, PLUS operate the starter relay or starter solenoid.

So then the starter solenoid opens up - CLICK!

Once it opens, and the starter motor is out of the circuit, there's again enough battery power to power the solenoid and relay. CLICK!

Once the starter starts turning, battery power to the solenoid drops and CLICK! it opens and the cycle repeats.

When diagnosing these things you have the question: is it the solenoid? starter? battery?

The starter can draw way too much current (when needing a rebuild) and pull so much from the battery it can cause this phenomenon.

A bad relay that won't handle much current can do this.

Or, a bad battery with low capacity, or just not sufficiently charged can cause the same scenario.

In your case, it's now working after replacing the rotor, so obviously the battery wasn't getting sufficiently charged previously. I see no other explanation for what's happened. I have no answer why a volt reading would have told you it was fine, yet wouldn't crank the engine. But it seems obvious to me the battery wasn't filled previously to capacity.
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Old 11-25-2012, 03:46 PM   #41
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Did your rotor fail by having low resistence? If so, it could pull too many amps and drop your battery voltage when you need the most amps: when starting the bike. I'd also check your resting voltage, with the bike on and off, the voltage under a load, and check the resistance of your batter cables as well as the resistance between the neg battery post and the mounting bolts on the starter. Then you'd have some numbers as to what's happening with your electrical system.
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