The BSA A7-A10 Forum
Bikes, Pictures, Stories & more => Other BSAs, Other Bikes, Cars, Machinery & Tools => Topic started by: Joolstacho on 31.01. 2020 03:11
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Right, now I've got your attention *smile*... here's a challenge.
There are lots of knowledgable lads here, so...
My mate has foisted upon me, (to work on), the rarest of rare machines (or should I say 'projects).
It's an Australian 800cc sidevalve Vee twin. Who knows what it is?
But here's the thing, a nice Norton 'box is fitted, but the mag drive (off the camshaft) exits the rear of the timing case, and a 'normal' Lucas or BTH mag is too long and fouls the gearbox. (There's not enough room to mount the 'box further rearwards). So I need to find a shorter mag that can be setup for an 80deg Vee twin.
Any ideas?
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Hmm. Jools, are you sure a mag is the right route? I've never seen a single mag on an engine of more than 60°, and they're a stretch at that angle.
I can't actually think of any camring or slipring (of any make) that would make it possible to build an 80° job. If you think that a 50°-only Vincent, say, has a firing interval of 155:205°, and that in pre-ATD days the mags on HRDs could be a bit 'sensitive' with high rpm needed to get any life out of the second cylinder, imagine what 140:220° would do to the operation of a thing designed to run at 180:180° ideally. Wouldn't be very special, is for certain!
Twin mags maybe as on some wide-angle V twin engines pre-WW2 . . . but double trouble on the space front and the drive train.
The fact that space is tight for a 'normal' sized Lucas or BTH suggests 'distributor', for which a suitable cam could be ground by someone with the skill, or a modded electronic system . . . Sounds like a fun project!
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Oooh sorry , dopey of me... I mis-typed the angle, it's not 80deg it's same as a Vincent 50 degrees.
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Lucas sr2 is shorter but do they make a V twin version ? And would the angle be correct ?
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'SR2V' as it were . . . don't think so , although any cam could be made- but see comments in t'other thread 'electronic conversion'. A single mag isn't a great plan on this beast in my humble, due to large V angle.
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Sorry boys I had made a typing error with the Vee angle. It's 50 degrees as Vincent.
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I've not had any problems arising from using a lucas mag on both 50 and 60* vee twins though to be fair on the 60* I start it with the front cyl decompressed (so I can actually kick it over) and then dump the decompressor as soon as it's running on the rear. Bursts into life immediately. re there any moubting brackets etc to guide you as to what may have been there before? A horseshoe mag perhaps?
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Yeah, well it's the length of the mag which is the problem. We need a really short one.
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What sort of max length can you accommodate Jools?
Just as a rough guide to common models, from cb end cover to end of thread and taper at drive end, a K2/KV F is 7", Lucas MSL or MN magdynamos (versions were built for Vs)about 7.25", typical base-mount BTH single/twin or Lucas NC1 or NR1 (with camring and standard Lucas cb, not face cam) is about 6.25".
An MN or MS Lucas could be shortened with (quite a bit of) work, if the dynamo part weren't needed, by about an inch, and the triangular upper bit machined off. Later face cam magdynamos not really an option unless someone fancied making a twin cylinder camplate. Been done, and I have a drawing somewhere if I could find it, but not maybe the best way to go. No other rotating coil / camring mag, of any make I have got lying around, is appreciably shorter than the base-mount BTHs. Those that are a little less maybe, you wouldn't want, as they are gutless things from various European makers, and probably bloody hard / impossible to convert to V twin operation.
Of the magnetic rotor / static coil mags, SR1 is about 5 3/4" allowing a bit of room for HT cable - SR2 is similar but don't have one here to measure. Base mounted of course.
Just tried to find dimensions of the Joe Hunt V twin jobs for Vincents etc but couldn't see the info I wanted, and don't have one to hand to look at. However, 'about' like SR1 but . . . flange-fit mostly if not all of? ?The good news is they come with the right firing angle - subject to rotation of course, Vincents being clockwise drive - so something could be done if the thing would fit the space and could be bolted on and driven OK. Hunt sell cb kits for both rotations for their standard parallel twin mags, same bits for the Vs almost for sure. The on-off ramps are same profile on the points cam to allow use either way. The bad news is they cost a lot, new anyway. Well over 1000$US. If fitted with their 'competition' red-coloured HT coil, they are seriously powerful. I was very impressed by one I did for a track-days Bonneville recently. But . . . would it fit . . .? Could it be modded?? Just dunno I'm afraid.
Fascinating challenge if ever there was!
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Seems to me if the SR2 doesn't fit (the horseshoe type I suggested earlier) then no mag will fit. Did it ever have one? Was it ever a runner? Either way, it'll be either a different gearbox that gives enough room or move the gearbox (presumably, judging from opening comments, that'll mean surgery). A photo may help.
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Right, now I've got your attention *smile*... here's a challenge.
There are lots of knowledgable lads here, so...
My mate has foisted upon me, (to work on), the rarest of rare machines (or should I say 'projects).
It's an Australian 800cc sidevalve Vee twin. Who knows what it is?
But here's the thing, a nice Norton 'box is fitted, but the mag drive (off the camshaft) exits the rear of the timing case, and a 'normal' Lucas or BTH mag is too long and fouls the gearbox. (There's not enough room to mount the 'box further rearwards). So I need to find a shorter mag that can be setup for an 80deg Vee twin.
Any ideas?
A picture of the engine might help
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Orright... tease ends here.
This is it, the venerable Aussie Howard. Complete with straw from the barn! (But note I have put a BSA tank on it.)
I've included a pic of the mag that the bike came with, which as you'll see is far too long. But I found this pic of another Howard (yes there are more than one!) with the sort of mag we'd need, note how much shorter it is (though I dunno how you'd access the points apart from dropping the gearbox way back). It's a platform mount.
Morris Magneto do one which looks possible. The FMZ.
adm edit: please remember the no1 rule of the forum, see https://www.a7a10.net/forum/index.php?topic=2545.0
(https://imagizer.imageshack.com/v2/xq90/923/A22yLr.jpg) (https://imageshack.com/i/pnA22yLrj)
(https://imagizer.imageshack.com/v2/xq90/922/uvUArF.jpg) (https://imageshack.com/i/pmuvUArFj)
(https://imagizer.imageshack.com/v2/xq90/921/rlLnTy.jpg) (https://imageshack.com/i/plrlLnTyj)
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Right, now I've got your attention *smile*... here's a challenge.
There are lots of knowledgable lads here, so...
My mate has foisted upon me, (to work on), the rarest of rare machines (or should I say 'projects).
It's an Australian 800cc sidevalve Vee twin. Who knows what it is?
But here's the thing, a nice Norton 'box is fitted, but the mag drive (off the camshaft) exits the rear of the timing case, and a 'normal' Lucas or BTH mag is too long and fouls the gearbox. (There's not enough room to mount the 'box further rearwards). So I need to find a shorter mag that can be setup for an 80deg Vee twin.
Any ideas?
This has some info. After a quick google. Did howard make bikes or just engines and ag equipment?
https://www.accessnorton.com/NortonCommando/howard.15143/
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It seems Howard made Rotary hoes and the like. But with development, it could make a very handy motorbike... IF you are into heavy-duty Harley style stuff.
The real attraction is that it's Australian, and there are precious few Australian made bikes. It's actually quite nicely engineered... the camshaft is a work of art!
This magneto fitment is the biggest barrier, almost all the other major hurdles have been jumped.
We'd need to find a suitable front disc calliper, a number of smaller issues (you can imagine). The owner will probably spend on it what it needs, for example I don't think we'd come out much less than 2 grand just for the maggy.
What do we think? (Yes I should just advise Simon to find a decent Golden Flash... but that's not the point, for him).
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G'day Jools.
I remember (yes right) using a Howard Hoe back in the 80's. I wonder if it's still there (fire permitting). Will look in a week or so.
Cheers
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Looking at the pic, it appears the box has adjustment to go back at least an inch. Failing that, and assuming a usable mag is either not available or hugely expensive, I'd either alter the engine plates to tilt / raise the engine slightly or alter the box mountings to give sufficient clearance.
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Hi Jools,
What about a short chain and sprockets to a mag on a platform mounted outside the timing case? Mag fore and aft
I have seen some photos of other Howard's but I believe the engine is a low rpm unit so don't expect to break any speed records *smile*
BTY, i have a Howard with a 600cc sv J.A.P
John
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Wico/Wipac made some short magnetos.
Here’s one on a Wolseley engine.
(https://www.bing.com/th?id=OIP.6A8OqvvpyZsoUMYB9Gbl5QAAAA&pid=Api&dpr=2)
Or, perhaps you could mount the magneto behind the gearbox, driven by a shaft passing over the top of the box.
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TT - got one of those mags on my Ransomes pump (sv 600cc japanese engine). The impulse starter device really helps starting, but not aware if they made twin cyl versions.
I see the spellchecker has done it again. despite writing Joseph Arthur Prestwich it got converted to 'japanese'.
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They did.
(https://i.imgur.com/ze112EL_d.jpg?maxwidth=640&shape=thumb&fidelity=medium)