The BSA A7-A10 Forum
Bikes, Pictures, Stories & more => Chat, Offtopic & Everything Else => Topic started by: chaterlea25 on 25.12. 2020 21:53
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Hi All,
Knowing how I was struggling with my f**ked knee starting my SR during the year and that I the replacement knee joint op was imminent I ordered an electric starter kit from Steve McFarlane , It arrived in time to place it under the Christmas tree!! LOL
I have to say I am impressed with the quality and engineering of the kit, it comes with everything needed to do the conversion, I mean everything!!
Although the kit has been on the market for five or six years I was a bit surprised that my kit is numbered 164
indicating only that many have been made ?
It will be some while yet before I will be fit enough to get the bike on the bench to start work on it
I will be overhauling the gearbox as it has started to jump out of third when pushed hard . I am also hoping to finish the Suzuki clutch conversion that has been sitting there for longer than I care to remember
A couple of photos borrowed from "startyourbsa,co,uk"
Looking forward to getting back on the road
John
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G'day John.
You've got a long winter to do it. Take your time. Many more miles smiles to come.
*yeah*
Cheers
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Here's the big takeaway from this (and Steve McFarland could market on it), a great engineer recognizes this kit as great engineering.
Richard L.
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Hi John,
Good on ya.! I also am looking into Stephens electric start. Becoming inevitable as we get older.
I have heard only good things about it.
Does any A10 owner have a longer experience on the ups & downs of this?
My main concern is that Stephen wants my cush parts for machining on his jig.
Postage from Oz to UK and back ?? - Risky. :-\
It is on my January to-do list.!
Col
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Hi Col,
I had a spare sprocket and cush drive parts so I was able to send those instead of the ones on the bike
Just saved having another bike in bits
Maybe you could source a set in UK and send them those rather than your own?
John
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I note the two bigger bearings in the kit are one-way (sprag) bearings. I believe most kits put these on the crank, but when I started designing an electric start conversion I found a problem: the small ones (eg ID of 20mm or less) were not only physically too small, but wouldn't take the torque (max 68Nm) whilst larger ones are limited to max revs below useful engine revs - eg ones with 35mm I.D. are limited to 3,600rpm. Couldn't find a way around this, so am presently building a centrifugal ratchet instead. Proving to be a bit of a challenge to get the strength required into the space available.
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Excellent, congrats++
That many parts in the kit *eek* and with the development time + testing etc, looks like it's surely worth whatever it costs.
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Hi John,
It would be best if I can obtain another cush set. I'll see how I go.
RDFella, bears thinking about.!
Col
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Hi RD,
I saw on another forum where Andy Higham made jis own electric starter for a replica gold star, after sprag bearing failures he got one from a modern Enfield and successfully adapted that to fit his set up
John
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I've fitted the Pearson starter kit to the goldie and it uses a bendix throwing a ratchet into mesh. Works really well and only leaves a chain and one bearing turning when engine is running. Can be used with manual advance as there's not the same risk with a kickback as there is with a sprag. Mr Pearson doesn't say it can be used with a swingarm A10 but isn't the primary case the same except for the little drop edge on top of the inner?
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G'day fellas.
On the subject of sprag starter clutches. My rHonda used to eat them, a very weak design with only 3 rollers. Got a kit where a Yummahaha R6 sprag clutch with about 20 little hourglass shaped rollers is married to the Honda. Just have to look at the start button and the beast comes to life.
Cheers
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Trouble around aftermarket fitments is that bikes made with electric starters were designed that way, with their sprag clutches in the crankcase oil. It's when you isolate them in self-contained units that the rev limits seem to apply.
I've looked at this from so many directions - a bendix coming onto a crank-mounted gear (but by then it'd be rev-reduced, so the bendix would be unlikely to 'throw' and it'd also need a reverse helix compared with readily-available Lucas ones). In my case too, primary is belt drive meaning a) sprocket is wide, leaving only 1" of exposed shaft for nut and b) because the primary runs dry, the idea of running a layshaft at 3 x engine speed in there is not an option.
Add:
Forgot to make clear - the problems I'm having trying to engineer an electric starter is on my project, not my A10.
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You're right RDfella. I had to revert to chain primary drive in order to use the Pearson starter.
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Hi Reg,
I have looked at the web photos of the Pearson setup, The reduction to the crank via a chain looks to be in the region of 3 or 4 to 1, so the small sprocket is spinning that many times faster than the crank, ? that seems a lot for a chain and sprocket?
The McFarlane gear on the sprag bearings is a little smaller than the crank gear (I haven't counted the teeth numbers yet) so there is not a huge increase in the speed there
It would need the alloy plate that bolts to the crankcase changing to the single cylinder bolt pattern to get the McFarlane starter to fit the singles
John
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that's a nice Christmas present John.
wouldn't take the torque (max 68Nm)...
RD - are you saying the torque required in 68Nm or the sprag gears were rated at that?
i've read elsewhere a rule of thumb is a 1000cc twin requires a starter with 12.5Nm and a reduction of 10:1 -> 125Nm... so (guessing) an A10 2/3 of that...? your thoughts?
...btw a pic attached of a local guy who made an electric leg for his goldie - with a NEB belt. due to the the gear to the sprag being on the inside at the crank end, the clutch basket had to be spaced out a bit. starter underneath like the srm one. quite an achievement.
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Mike - that's what the sprag (one-way bearing) is rated at. Currently to start the project I use a mains-powered roller starter (guaranteed to start any race bike). 50% of the time it blows a 13A fuse when easing the bike's clutch out (in 3rd gear). 13A X 230v is around 3bhp, so I've figured from that a figure similar to yours. Given the initial shock load on a starter, I'd be happier with 200Nm. Either way, it's just not possible (unfortunately) to include a one-way bearing for my purpose. At least, not with the various options I've considered.
Pity, it would have made life a hell of a lot easier. Well on the way with the ratchet design, but it's throwing up several challenges.
Re belt issue - mine is 40mm wide, so doesn't leave much room for anything else.
forgot to add - very neat and professional conversion shown by John in that pic of his. Unfortunately I can't go that route because I have an idler tensioning the belt in that area and my gearbox (plunger type) is bolted to rear of engine thereby precluding mounting anything behind the primary case in that area.
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Hi RD
I was searching the web for starter ideas and saw that a Honda gold wing has a chain drive from the starter to a sprag sprocket that looks to be a decent size
The other starter I saw was for AMC singles where they fitted a large gear to the clutch basket and a starter mounted on a new modified primary case.
A friend did something similar on a vintage Ariel , at first with a scrap yard Honda starter, these do not have a nose bearing
A after some time it was struggling so he went and bought a new pattern starter
This one has an internal gear reduction
It now spins the engine over easily even against compression
John
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Thanks to John and others for helpful suggestions. I discounted driving the clutch - first of all there's hardly enough space to achieve the usual reduction of around 15:1 by running a starter bendix onto the clutch - made even worse by the fact the clutch would drive the engine faster. I played for a while with the idea of getting a bendix to engage with a gear mounted on the crankshaft but eventually discounted that because it was becoming impractical for several reasons. Seems the only viable solution is a variation on what most others have done for A series, Gold Stars etc. I'm currently trying to complete a ratchet to sit outside of the engine sprocket which will in turn be driven by chain from a layshaft above the primary case, the other end of the shaft being driven by a Honda starter motor via a spur and set of bevel gears. Pic of ratchet progress attached - currently struggling trying to find the best way to spring-load the pawls (there'll be three when complete, currently using the alloy master for development). Not much room in there!
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Hi RD
That looks like a good strong device, I hope you can get the rest of the bits together and working
John