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Messages - Calum

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106
Twins / Re: Cylinder mods
« on: 02 November, 2020, 14:09:08 »
Hi,

If I remember correctly the articles that I have read relate to big competition engines were they will be looking for marginal gains in power and reliability. 

Dave.

Just read this - it helps a bit.

https://www.enginebuildermag.com/2016/08/understanding-rod-ratios/

Interesting stuff. I guess you must have to have everything else dialled in to its absolutely optimum setting before you start messing with rod ratios and seeing benefits? By that point you're probably comparing thread count of your underwear and wondering where more weight savings can be made  ;D

Certainly in the steam world rod length affects the valve events in such a way to make that the biggest consideration as far as I can tell. Not many of the effects mentioned in that article are applicable to steam engines really, so whilst the con rod length is fairly important it is for very different reasons! Also it's not so easy to change the rod length on a loco to find out ;D

Funnily enough whilst replying to this thread I am currently machining some cylinder liners, but at around 26" stroke and 18" bore they may be a cylinder mod too far!!

107
Twins / Re: Cylinder mods
« on: 02 November, 2020, 09:58:26 »
In the steam world it is more of a problem as the pistons are dual acting - it's called the obliquity of the connecting rod. The longer the rod is the lesser the effect. Basically when the crankpin is at 90 degrees the piston is not at half its travel. So on a forward stroke the piston 'lags' behind the valves a bit but on a backwards stroke the piston leads the valves slightly, affecting the valve events.

Obviously you get the same effects on the valve rods but the throw of the eccentrics is so small compared to the length of the rods the effect is very small.

On a single acting piston such as in an internal combustion engine surely the error is constant for every power stroke and the inlet and exhaust valves are adjusted accordingly to compensate?

108
The Star and Garter / Re: Help with copper tubing twirl
« on: 22 October, 2020, 18:40:38 »
Anneal the copper first, thicker wall pipe will be easier to bend without crushing. A nice even coil can be made using something as a former to bend around. At work I make pipe runs with neat bends by using a simple tool I made with two bits of 1.5" bar welded to a piece of angle that I can then mount in the bench vice. The bars are mounted upright with a gap between them just greater than the pipe diameter.

Thin walled pipe can be a pain - for bigger stuff fill it with sand and solder caps on the ends but smaller stuff you should be able to get a bending wire to slide inside. Depending on how much you work it it might be wise to anneal again and probably when you've finished too - it'll allow the copper to flex a bit more without cracking over time.

109
Singles / Re: B31 new owner - trouble starting
« on: 19 October, 2020, 19:13:31 »
I see that the plug that you using is a copper cored one. This will be a late type plug with no glazing on the porcelain. These can get soaked with petrol and short to earth. Try and find an old style plug like an L10. This might well be your problem. Worth a try changing a plug.

Well first thing after work I went straight to the workshop and dug around in my ice cream tub full of random plugs(!) and I found an old KLG F50. It actually looks as though it has never been used. Was already gapped at 0.018" so I tried it held on the timing case - nice consistent spark. Bike fired up second kick so at least it wasn't my technique, though I had obviously over-thought the situation and completely ignored the basics. Mind you the Champion plug looked okay and I didn't expect the shorting as you described - every day is a school day!
Thank you!

I started it several times and it was much easier than it has been previously. Now whether this is solely due to the plug itself or the points being adjusted who knows but I'm much happier with it already. The ignition can now be retarded quite a bit more as well to slow the idle down to a steady tick over. More tinkering and it'll only (hopefully) get better.

Thanks again.

110
The Star and Garter / Re: New member
« on: 19 October, 2020, 09:38:31 »
Sadly Bill Hignett passed away in a RTA some 3 years ago. He had a great collection of bikes and rode most of them . A well liked member of the BSA community... RIP Bill....   Griff
That echoes what I was told about him, sounded like a nice guy.

111
Singles / Re: B31 new owner - trouble starting
« on: 19 October, 2020, 07:30:35 »
If it is just to start the bike any old short reach plug will do. The values only really come in to being once up to temperature.

Yes indeed, but it's mainly long reach plugs I seem to have 'in stock'. I'll have a look after work today.

if its a magneto the first place i would look after checking points is the pick up holder for corrosion. also wipe clean the slip ring with the points plate removed.
By this I assume you mean the connections inside the plastic pickup holder? The HT lead acorn nut connection seemed fine, and the pickup brush moved freely and seemed to have plenty of life left (maybe a good 5/16" or so of length before the spring). I didn't check for continuity I must admit but all looked good (although I know these can be mutually exclusive events!). If you mean the slip ring behind the pickup holder then I tried to give it a wipe whilst slowly kicking the engine over but it didn't look too dirty to start with. A bit awkward for access with the oil tank fitted.

112
Singles / Re: B31 new owner - trouble starting
« on: 18 October, 2020, 20:31:48 »
Thank you, that's a very good shout and I'll get it swapped!
I did look for an L10S but couldn't see any in stock anywhere. I usually use the Green Spark Plug Co. but even they don't seem to have any. I'll have a rummage through my tin for something that looks vaguely suitable (and glazed porcelain around the tip) and have another go.

113
Singles / B31 new owner - trouble starting
« on: 18 October, 2020, 19:14:40 »
Now I know what you're all thinking... another newbie who doesn't know how to start his bike, but please hear me out!

I've recently acquired a 1953 B31, which is complete and running and I have seen it so. I have also started it myself a few times, but it was pretty difficult and now cannot seem to get a spark at all.

Bike has been sat for a few months under a cover outside before I bought it, petrol in the tank was a bit stale but still fired up okay on viewing (took him a few goes mind, to be expected I suppose) and I have ran it a few times since then too. I have since filled the tank up with fresh petrol (though admittedly did not drain out the old stuff that was still in there, around a third of a tank perhaps).

I struggled to start it the other day, but once it was running and warm enough I could start it again no problem.

Ignition timing might be a bit out - move the advance/retard lever towards retard and it cuts out at idle (taught wire advance). There was a lot of slack in this at first so I've eliminated the backlash in the cable. Currently waiting on delivery of a timing disc and TDC tool to double check the timing (in the meantime I'll also buy or make a mag sprocket puller as I'm bound to need one eventually).

So after failing to start it today I checked through everything I could think of. Plenty of fuel getting in. Removed the plug, cleaned it up and gapped it to the book figure of 0.018" (gap was much larger). Plug looks very recent, Champion N83C I think it was (L10S equivalent is an N86C I think?) Checked the magneto points which were a bit close. Cleaned them with a bit of emery and opened them up to 0.012" (as per the service sheets).

I then tried kicking it over with the plug held against the engine. I probably got a spark once every 10 kicks or so... but not consistently either - sometimes 3 or 4 in a row and then nothing at all. I removed and checked the brushes on the pickup and on the earth brush too. Seems to be plenty of life in them both so I cleaned with electrical cleaner and refitted.

The carb is new and probably wants fine tuning (which I am fine about), the fuel might be a bit stale and the timing might be out but of course none of these would have an effect on the fact I cannot seem to get a decent spark kicking it over.

All I can think is it must be the mag (MO1), is it worth just taking the plunge and having it reconditioned? If so, recommendations for a firm to do a decent job most welcome. I'm not adverse to having it overhauled as I don't want to have problems with it in future and would like complete faith in it to be honest.

Any tips gratefully received!

114
The Star and Garter / Re: New member
« on: 15 October, 2020, 10:32:19 »
Hi Pete yes I agree. Some bikes are due a restoration but for those still showing original paintwork etc in good nick it's nice to see them preserved - they're only original once!

Unfortunately mine left the factory as a maroon bike but has been repainted and gained an earlier tank (silver over chrome with the small winged B badges). I like the earlier colour schemes so the tank is staying (it seems to be in original paint and has gained a nice mellowed look) and the rest will get a refresh in places (mudguards and headlight currently bright red... not for long!). The mechanics seems relatively unmolested, many date stamps on Lucas items all tally with the age of the bike for example.

Most of it will get a once over before I start using it, for peace of mind. I want to be able to jump on it and go wherever I want without worrying about any unknowns!

115
The Star and Garter / New member
« on: 14 October, 2020, 10:58:56 »
Hi all

Following my recent wanted ad, I am now the proud owner of a 1953 B31 plunger. I hope to get my club application sent off this week. Complete newbie to bikes, but thankfully no stranger to old British metals - I run a small range of British classic cars (no modern vehicle owned!) and my day job as a machinist/fitter restoring steam locos.

Taken me far too long to take the plunge (excuse the pun) and get one, but here I am. I'll get some pics up of the bike shortly, some of you may have seen it before - it was owned by, I think, a member of the Cheshire branch, Bill Hignett. Plenty on it to keep me busy!

116
Singles / Re: More About B33 Advance/Retard?
« on: 14 October, 2020, 10:25:42 »
Depending on where the break was, if it was to actually snap, you could surely pull the inner taught and tie it to retain the position in order to ride home (be it the advance cable or the choke). Obviously if it breaks at the engine end you don't have much choice.

Whilst I don't think it likely the cable would snap my thought as to why you'd prefer slack wire advance is a positive return to the same advanced ignition setting every time, and one that isn't affected by wire stretch or bad adjustment.

117
Singles / Re: b31 crankshaft bearings
« on: 15 September, 2020, 16:16:53 »
get in touch with Darren Wrudd. He runs a bearing company and has been very helpful in supplying quality bearings to me and many others.



John Fenwick Rossendale Ltd
Unit 3 Vine Grove Works Carrs Industrial Estate,
Commerce Street
Haslingden
Rossendale Lancashire BB4 5JT


john-fenwick@btconnect.com

And a 'Wrudd'y good firm they are too... local to me. Have dealt with them many times for various projects at home and at work and they've always been very helpful indeed.

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