Alton starter my solution for broken woodruff key (2017)

Status
Not open for further replies.
yves norton seeley

yves norton seeley

VIP MEMBER
Joined
Feb 13, 2014
Messages
898
Country flag
Broken woodruff key is a problem with alton starters because the sprag weel is only sandwiched and the power come on the key, and the key is not made to hold the power and will brake after a while.
The solution is to make a connection between sprag weel and the triplex sproket.
Here is wat I did:
1: make two flats on the sprag weel

2: Make a new spacer with two inserts that go over the two flats from the sprag weel
The right piece is the original Alton spacer, the left one is the new one,
don't look at the two big holes, I will explain this later



3: Put the new spacer over the sprag weel



4: As you see the spacer is solidair with the sprag weel



5:You must imagine that there are no holes in the spacer, important is to make the two holes on the right place, therefore you must make two screws with a point, you screw the screws from the engine side in the sproket.
Put the triplex sproket with his woodruff key on the crank.
Put the sprag weel WITH is woodruff key on the crank.
Put a littel presure on the sprag weel to point the places where the holes will be drilled.




The following steps come in the next tread
 
Drill the holes where you have the marks
Make two screws that go in the triplex sproket




Put the triplex sproket on the crank and after the spacer over the bolts











Put the sprag weel with is woodruff key over the spacer, job done!
 
  • Like
Reactions: baz
A guess I must be just lucky having an Alton starter for over four years now and never any kind of problem with it.
Because you say your woodruff key shears is it possible your taper is not holding the sprocket in place as securely as it should?

Regardless, I like your solution, strong and well thought out. You are fortunate that you have the ability to make up such a fix yourself.
I don't and would have to pay someone to do the same for me should the day come when when my taper and key just won't hold anymore.
Is this a talked about problem I am not aware of, any one else having had the stock set up fail to the point where simply installing a new key is not enough?
 
The most important reason why my woodruff key shears is the compression on my engine: 10.5 CR
I discover the woodruff key shears when I was stripping my engine to go to 920 and bigger valves.
In fact, the sprocket only move a few degrees on the taper and squeeze
The problem is: if shear the key 2 or 3 times, you will have damage on the taper
 
Impressive!
Very well thought out and executed...your bike will be even better than before and stronger!!!
 
An elegant piece of work, Yves. There was discussion on another thread about raised compression and things that break. Even electric starters are affected.
 
BTW: I make the drawing and use my little brain to imagine the system but the machine work is made by Alain, my workshop specialist
Yves
 
The secrets is to know peopel with talents, I can use a lathe or a mill, I can weld and so on, but never so good as the specialist around me, it take me years to find the right man in every speciality, of course my pass racing career help me to find this specialists.
If one of the specialist make you a piece and the next sunday you win the race, the guy will be proud and entousiast the next time you ask him to do some job
Yves
 
As an aside, I worked in a factory making both imperial and metric part in same the workshops, the workshops were defined as being imperial or metric by the measuring equipment and the drawings. So a metric shop had all their measuring equipment as metric and their drawings were metric, imperial were visa versa. To make a imperial part in a metric shop you converted the drawing to metric and left it to the shop to make and inspect in metric.
 
Possibly hard to produce as you would have to rely on puller holes being in the same place to keyway, nice solid job though
Metric/imperial went to school got taught metric, started work & still a lot of british American and austalian , pronounced stralia, engines all imperial ,1/2 of the recon machinery was Italian so it was metric for ever converting dimension , Now I really prefer to machine in imperial as its to bloody hard to hit the metric sizes , any one who can consistently machine to 0.01mm on manual machines is very good or a bullshit artist,I can't use an imperial ruler though
 
hi Yves, very interested in your design, am having this adaption made and fitted next week to my 74 850 mk 11a. as soon as the battery weekens a bit due to age ect. there are problems. trispark ign.(supposed to prevent kickback/backfire) fitted. Can you give me any more info on the success/failure,my engineer likes and understands your process plan and your drawing, can you add any more to drawing to make dimensions clearer. regards twothumbs.
 
TwoThumbs19 said:
hi Yves, very interested in your design, am having this adaption made and fitted next week to my 74 850 mk 11a. as soon as the battery weekens a bit due to age ect. there are problems. trispark ign.(supposed to prevent kickback/backfire) fitted. Can you give me any more info on the success/failure,my engineer likes and understands your process plan and your drawing, can you add any more to drawing to make dimensions clearer. regards twothumbs.
Click to expand...
Hi
I bought the whole setup off of Yves when he broke his bike for spares
I have a belt drive on my bike so I re made Yves conversion to fit my belt drive pulley
The only difference with my version is I also use the Woodruff key as well as the threaded puller holes to drive the sprag clutch
The reason as I understand that Yves made the new drive was because he had a high compression 920
I don't think you'd have a problem with a standard engine?
Never heard of it anyway
Cheers
 
Used your excellent idea ,altered to fit my RGM belt drive made me scratch my head a bit I am no engineer . Eventually got there very pleased with the result and no more broken keys , so thank you for sharing
 
  • Like
Reactions: baz
TwoThumbs19 said:
hi Yves, very interested in your design, am having this adaption made and fitted next week to my 74 850 mk 11a. as soon as the battery weekens a bit due to age ect. there are problems. trispark ign.(supposed to prevent kickback/backfire) fitted. Can you give me any more info on the success/failure,my engineer likes and understands your process plan and your drawing, can you add any more to drawing to make dimensions clearer. regards twothumbs.
Click to expand...
Hi Two Thumbs,
My design will not help if you have a bad battery.
Its also mandatory to have the Tri Spark fitted on the recomanded degrees.
If the engine was kickback with the kickstarter, it will do the same with the E start
I don't have any more drawing
Good luck
yves
 
Hi Yves, and other responders out there, thanks for words, nice to know i'm not alone. by the way has anyone got an 850 cylinder head they don't need, mine has developed the classic 'third fin up' crack through to push rod tunnel therefore sprays oil a bit,,not bad enough to stop riding but has resisted all efforts at fixing,including 2 attempts at laser welding,new heads are crazy expensive,-must keep this bike on the road. thanks again, twothumbs.
 
  • Like
Reactions: baz
Status
Not open for further replies.
Back
Top