Honda-SOHC
SOHC.co.uk Forums => The Black Bomber Board => Topic started by: royhall on September 22, 2024, 03:49:26 PM
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Hi. Got a weird problem that I haven't encountered before. Using the starter on the Bomber, the engine turns slowly and you get just 3 to 4 presses on the button before the battery goes dead. The engine does not start. This problem came on suddenly rather than getting progressively worse. The battery is pulled down immediately to about 5 volts. I guessed the battery was done so I replaced it with a standard lead acid type but it does exactly the same. I have taken the starter motor off and tried it on the bench but it seems to spin okay. I have a rebuild kit for the motor so I will rebuild it before it goes back on. Other than checking all the earths I am at a loss, any ideas out there. Thanks.
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Hi Roy. Never worked on a Bomber before but I guess starter circuit can’t be much different to a 400/4. Battery connection to starter solenoid, solenoid connection to starter motor. So, if all the connections are ok and you have good earth to me that only leaves the starter solenoid. You could disconnect the battery and starter leads from the solenoid and use a meter on ohms setting to check the solenoid contacts. Will be open circuit until you press the starter button then should go to 0 (short circuit). If there is a high resistance, then that could be your issue.
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Thanks Deano. To be honest most of the components in the starter circuit are 57 years old so I am thinking of rebuilding the starter motor, replacing the solenoid, checking all the leads and cleaning the contacts so everything is new. Don't know why I didn't do that at the rebuild as I replaced virtually everything else.
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In my experience albeit mainly automotive of almost 60 years the order of decline has been as follows.
1. Poor earths.
2. Solenoids.
3. Main leads.
4. Starter motors.
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Whatever it is it's serious. It pulls a new fully charged battery down to 5 volts in about 4 goes. That's a huge drain comparable to a full short circuit, maybe a chafed lead earthing on the engine. It must be between the solenoid and and (or) the motor as the battery stays fully charged until the button is pressed. And as I say it started suddenly, one day fine next day doing this.
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Could it be the main earth cable Roy.
I had very similar symptoms on Kittie when Graham 1st built her, he used the original earth cable but this is what we found that was causing the problem.
https://www.sohc.co.uk/index.php/topic,15937.msg133703.html#msg133703
[attachimg=1]
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Looks like I may be replacing the cables as well. Do we know a place that can make up new cables.
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Looks like I may be replacing the cables as well. Do we know a place that can make up new cables.
Graham mades his own by unsoldering the attachments on the knackered ones and re soldering them on a new length of cable.
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Sounds like a plan will check it out. But thinking about it I may have replaced the earth cable when I built it, or that could have been another bike. I defo got a cable from Vehicle Electrical Supplies at some point. Cheers.
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Have found this site for custom cables. Not too expensive so I may strip out all the cables and replace it all.
Build your Battery Cable : Speeding AB (speedingparts.co.uk) (https://www.speedingparts.co.uk/c/engine-management/battery-accessories/battery-cable-8822/build-your-battery-cable/)
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If you've an "amp clamp" try a measurement of feed pre and post solenoid to at least see what you've got there.
Also try it off the engine (the starter motor) to see if there's significant drop as you'd expect.
Would give good comparison too, if you rebuild it.
A double check though .... pull plugs and turn engine over to see if there's significant resistance there that may be causing it. Unlikely, but not completely out of the question. Was helping someone recently with a starter motor "problem" which had been replaced, only then to let all the smoke out of the new one ;D ultimately he'd got a significant problem with crankshaft much to our consternation.
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At the risk of looking stupid, what's an amp clamp?
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One of those multi meters that have something of a "lobster claw" sticking out the front, that to open and then close around the lead .... then it measures load going through that cable while you operate the circuit.
Essentially reading resistance load on that circuit while it's fully cranked up.
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I think I have that attachment on my meter, never used it. Will have a look.
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I hadn't previously used in automotive diagnostic.
Recently someone showed me on a suspect failed fuel pump (located inside diesel tank) by jumping across the pump relay loom contacts, so the pump line was permanently on, then checking with clamp on that jumper wire to see load through that supply point. It should have been drawing 4.7 ohm but was at 12.7 ohm and had in fact partially siezed to such extent it wasn't pumping much at all. Certainly a good illustration.
Relevant info clip but on ac volts in this case https://youtu.be/z-KfZvbjyBY?si=vyNvatTYpJx9RwZ3 which may be of use.
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Just checked the resistance on the starter between the live terminal and the case and it's zero on all meter ohms settings. A dead short circuit somewhere, or am I getting it wrong again.
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I'd have expected open circuit for that Roy so something not right.
Is that with the motor on the bench or is it still on the bike and connected to the wiring?
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On the bench.
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I didn't think there should be any contact from pos to case, if that were so that should be a problem.
What have you got if you go from brush to brush, through the winding in other words.
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There has to be a reading or the starter wont work, electrons have to get in AND out but it should show resistance NOT zero
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I did notice that the gaps in the commutator were totally filled with carbon from the brushes. Is that likely to be the problem? Will test the resistance on the windings tomorrow.
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It could well be mate, we used to clean out the segments with a ground hacksaw blade but not too deep
If you take your multimeter probes set to ohms and check between adjacent segments all the readings should be the same, idealy you should test with a growler but that needs an old school rebuild shop.field coils will seem black and smelly if gone normally
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Also check the soldering of the armature wires to the copper segments of the armature. Sometimes the soldering looks OK but you will see a thin black burn mark line around the outside of the copper wire, which eventually creates an open-circuit
Normal multimeters will be useless other than checking continuity, as the resistance of the armature coils will probably be in the milli-OHm region. Say for example, the armature current is 100 Amps that would make the resistance of the coil typically 120 milli-Ohms. The best thing to do is pass a known current through each winding and compare the millivolt drop across that windings (which should be almost all the same value for each individual winding) . As Bryan said the old school method of testing by an auto-electrical shop. would be to test with a 'growler' . Another way is to pass the same current through each winding and get a gauge of the electromagnetism created on the steel laminations associated with that coil by holding a small screwdriver near to it. A headlamp bulb in series with the winding would give a decent current. After cleaning out the segments with a ground down piece of hacksaw blade, as Bryan suggests, I would wash it in something like isopropanol to remove any debris using an old toothbrush.
So what's this 'Growler' thingy/gizmo that Bryan is talking about? .....well I am not going to explain the facts of life to you ;D ;D but in the electrical world it's this :
https://en.wikipedia.org/wiki/Growler_(electrical_device)#:~:text=A%20growler%20is%20an%20electrical,a%20source%20of%20alternating%20current.
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Well, you learn something every day. 😁
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I certainly learn something every day, usually things I knew a while ago and forgot. Thanks for all the info guys, I will rebuild the starter motor at weekend using the stupidly expensive kit from Wemoto. £118 What!!! Will keep you posted. Bye the way, resistance reading across the brush terminals shows zero ohms.
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Any ideas on what's the best grease for a reduction gearbox on the front of a starter motor?
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I'm using CV joint type black grease on application like this.
Very high anti size, also virtually impervious to moisture, with possibly the best mix of attributes in something loaded as a small gear train is.
If it was constantly running and higher rpm, then plain lithium spec like wheel bearings use, would be ideal.
It's that load protection ftom molybdenum disulphide that's really beneficial I feel.
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Thanks for that. Confirms what I was thinking, and handy that I already have a tub.