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Messages - DM

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1
British Bikes / Re: Stud Thread size
« on: October 13, 2021, 08:07:17 AM »
Yeah, if you're made of money... ::)
Hardly justifiable for the use-it-now-and-again amateur.

Coventry die heads and dies do turn up for very little money, a few years ago I was given buckets full of new and sharpened die sets from a aerospace company. They had gone over to thread milling and the die sets were headed for the scrap bin.Luckily the owner is a friend and sent them my way.

2
British Bikes / Re: Stud Thread size
« on: October 12, 2021, 07:16:04 PM »
Even better is to get yourself a coventry die head.

3
British Bikes / Re: Firing on one cylinder only
« on: June 14, 2021, 11:17:49 AM »
That means that a twin cylinder magneto - say a K2F - with one +ve spark and one -ve spark
will spark stronger on one side ??

No, I think the K2F would have been designed to provide sufficient HT voltage to fire both sides reliably.
But if the magneto deteriorates giving a lower HT voltage I'd expect the +ve spark to give problems first.

4
British Bikes / Re: Firing on one cylinder only
« on: June 13, 2021, 08:20:15 PM »
Spark plugs work better with a -Ve polarity voltage applied to the electrode, according to this write up applying a +ve polarity voltage to the plug requires up to a 45% voltage increase to fire.
 
http://www.dragonfly75.com/motorbike/plugpolarity.html

So it's not surprising that a wasted spark coil will misfire one plug when the battery voltage is too low.

5
British Bikes / Re: Spanners and sockets
« on: January 17, 2021, 08:33:02 PM »
still got some I bought when I was 16.

I still have some that my Dad bought when he was about that age.

6
Japanese Bikes / Re: Honda cb175k6, 1972 re-build
« on: October 31, 2020, 04:02:23 PM »
I think he should get something with patina like this one.



8
Identify these bikes! / Re: Alcyon Autocycle
« on: January 30, 2020, 10:01:26 PM »
Banned after tomorrow.

That's a sad end for you.

9
European and Other Bikes / Re: 1952 Berini 32cc cyclemotor
« on: January 04, 2020, 01:33:54 PM »
The Grumph is nice to ride, realy light though so last time it was MOT'd I had to push down on the rear of the bike on the brake test.



Bit of luck today though as I got given another (1957) NSU Quickly.

11
European and Other Bikes / Re: 1952 Berini 32cc cyclemotor
« on: December 24, 2019, 10:34:27 AM »
Probably most towns and cities are much the same, but surely you want to ride a little further afield where the roads are clearer? :-\

Of course, that's why I have a variety of bikes. ::)
Going further afield I'll use the A.J.S or the Grumph, and with any luck I'll be able to get the New Imperial on the road next year

12
European and Other Bikes / Re: 1952 Peugeot BIMA re-build
« on: December 23, 2019, 10:05:37 PM »
Or get the mag tested on something like this Octopus.

13
European and Other Bikes / Re: 1952 Berini 32cc cyclemotor
« on: December 23, 2019, 10:00:07 PM »
Bottom of the tank wants replacing completely, metal is a bit too thin to weld and seeing as it is a rare machine with only 4 known of this model I dont want to bodge it otherwise I'd have soldered patches over the holes.

28mph is plenty fast enough where I live in a small town by the sea, in summer traffic is heavy and you wont even get to 28mph.

14
European and Other Bikes / Re: 1952 Peugeot BIMA re-build
« on: December 22, 2019, 06:26:21 PM »
If you have wires to the coil wired backwards the spark polarity will be wrong but it should still run.

The Magneto Guys show you how to determine spark polarity with a  2 electrode spark gap and a pencil.

https://www.themagnetoguys.co.uk/spark-polarity

Years ago I made a mains powered test box to check flywheel magneto backplates off of the engine.( It will test bare armatures from normal magneto's too).
Basically I wire the ignition as per a car ignition circuit, supply DC power to the coil from the test box and use a NE555 timer pulsing a relay across the open magneto backplate points.
An adjustable spark gap on the test box makes sure I don't run the mag with too big a spark gap and damage anything.

You can get a rough measurement of the HT voltage from the size of the spark gap as it takes 3kV to jump a 1mm gap, again have to make sure the spark gap is not wide enough to cause damage to the coil.

Can leave it sparking on the bench for half an hour to see if the spark deteriorates when the mag coil heats up.

15
European and Other Bikes / Re: 1952 Peugeot BIMA re-build
« on: December 22, 2019, 04:15:48 PM »
Well you could read the instructions for checking the timing, which is set by altering the points gap.
It is done this way to ensure that the points open with the flywheel magnets in the correct position relative to the coil stator to get the best possible spark.

http://comet-restorations.uk/gallery/bima_instructions_1956.pdf

I  would have expected the engine to fire even if the timing is slightly out so would suspect you have no spark under compression.

I personaly would throw that can of easy start in the bin, before it damaged an engine.

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