Hi. There are several possible reasons for an erratic output. Check for. Loose connection. Dirty or worn commutator. Dirty or worn carbon brushes. There are others, but these are the easy ones to fix. Note, the carbon brushes must slide easily in their holders.
Misc: Charging Systems Battery Charging Help!
- Thread starter pmcmanners
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Did you use a digital voltmeter ? These types can be irritated by voltage spikes when no other loads are connected. The old analogue voltmeters can be better for diagnose. Better hook a very weak bulb of say 5 W to the lot and only then do a power test with voltmeter connected. Did you do the motor test with a battery connected to the dynamo ? It should spin like a motor.
Vic
Vic
THANK YOU ALL VERY MUCH !!!
Many thanks to all those that read the original post and a BIG thank you to those who took the time to answer - much appreciated.
After many hours carrying out tests, writing this post and reading replies we final fixed the issue.
After all the tests, we decided to flash the dynamo. So we took the end cap off to see the "F" (field) and "D" (armature) wires and make a note of their colours. As we were figuring the "F" and "D" wires out, at the last moment we found a very fraile looking loose wire that looked as though it should be connected to a Brush - the only way to get a good look at this was to remove the whole dynamo from the engine. The removal went smoothly, especially after we found out the sprocket turning the dynamo was running on top of the chain. After removing the dynamo it was clear that the small copper wire built into one of the brushes has snapped! After repairing this with a small piece of multicore wire and a soldering iron we reattached the wire. Also, as the dynamo was off the bike we gave it a good clean with thinners and a small screwdriver (segments). We attached the dynamo back onto the engine, connected the regulator and started the bike - YES, the amp meter on the headlight moved up to 6 amps with a small rev of the engine and you could see the lights get slightly brighter/dimmer with each rev.
The medium/long term plan is to fit an Alton 12v system for reliability and better lighting on the bike.
But as usual with old engines it's 2 steps forward and 1 step back. After finally fixing the dynamo issue we notices a decent petrol leak (constant drip every 4 seconds) from the right hand side carb. which was not there previously. It looks like it is coming from the bottom of the carb. itself (large cylinder) and not the pipe and fibre washes below. Just wondering if the base of the carb. is screwed on?
Thank you for being a great little community and helping out a new Vincent Black Shadow Owner
Many thanks to all those that read the original post and a BIG thank you to those who took the time to answer - much appreciated.
After many hours carrying out tests, writing this post and reading replies we final fixed the issue.
After all the tests, we decided to flash the dynamo. So we took the end cap off to see the "F" (field) and "D" (armature) wires and make a note of their colours. As we were figuring the "F" and "D" wires out, at the last moment we found a very fraile looking loose wire that looked as though it should be connected to a Brush - the only way to get a good look at this was to remove the whole dynamo from the engine. The removal went smoothly, especially after we found out the sprocket turning the dynamo was running on top of the chain. After removing the dynamo it was clear that the small copper wire built into one of the brushes has snapped! After repairing this with a small piece of multicore wire and a soldering iron we reattached the wire. Also, as the dynamo was off the bike we gave it a good clean with thinners and a small screwdriver (segments). We attached the dynamo back onto the engine, connected the regulator and started the bike - YES, the amp meter on the headlight moved up to 6 amps with a small rev of the engine and you could see the lights get slightly brighter/dimmer with each rev.
The medium/long term plan is to fit an Alton 12v system for reliability and better lighting on the bike.
But as usual with old engines it's 2 steps forward and 1 step back. After finally fixing the dynamo issue we notices a decent petrol leak (constant drip every 4 seconds) from the right hand side carb. which was not there previously. It looks like it is coming from the bottom of the carb. itself (large cylinder) and not the pipe and fibre washes below. Just wondering if the base of the carb. is screwed on?
Thank you for being a great little community and helping out a new Vincent Black Shadow Owner
That is what this club is all about. Passing on help and encouragement.
Yes, but it is tricky to hold the body while doing that. I suggest a new thread.
Yes, will defo. start a new thread if we have issues. Hoping it's an easy fix.
Congrats on your first repair. The carburettor leak is probably because the fuel level in the float chamber is too high. This is probably caused by leakage passed the fuel inlet valve. This may be simply a bit of dirt. Try taking the bike for a run on a bumpy road before you consider disassembly.
Tell the new owner not to take out the old dynamo unless he reads on how to re-install it, set it into the chain, etc. See if you can drum up a copy of Know Thy Beast because you're going to need some knowledge of the machine overall, or it can hurt you. If he has stock brakes this old-timer's suggestion is not to ride it at all.Cheers timetraveller.
It definitely is the original Miller setup with the old fashioned voltage regulator.
If we can not get any output from the dynamo then we may need to go for the Alton 12v system.
Neither of us are used to working on a Vincent, but the owner of the bike is now a retired mechanic who had his own business for 40 years and can turn his hand to anything - one of the reasons he bought the bike was to mess around with it
Any trick on how to test the dynamo - think we have ran out !
I swapped the original Miller dynamo and JG 12v converter to an Alton on my C Rapide.
Well worth doing and quite a straight forward job. It comes with a regulator that sits on top and is suitable for positive and negative earth bikes.
Good idea to use the original steel sprocket from the Miller rather than the plastic one provided. It wears out in a few hundred miles. I paid £524 and bought it from BTH Components LTD.
I have a post on here ‘Series C Rapide battery not charging’ if that helps.
Well worth doing and quite a straight forward job. It comes with a regulator that sits on top and is suitable for positive and negative earth bikes.
Good idea to use the original steel sprocket from the Miller rather than the plastic one provided. It wears out in a few hundred miles. I paid £524 and bought it from BTH Components LTD.
I have a post on here ‘Series C Rapide battery not charging’ if that helps.
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