Julian's Scrambler build "Post 1"

[JulianM]

Exactly the reason for this little baby


 
Had the same problem but mine went in my own yard!
Probably due to the idiot who assembled it and partly due to being crap anyway. 

Stripped the box on Saturday and am so happy I did.  If anyone tells you "i'm and engineer" built it all myself, and lives in Barrow in Furness  RUN FAST  cos he has three left hands     All the good bits but my god was he a crap builder!!

Regards,
Julian

[Topdad]

Hi Julian, been following this post with admiration for a few weeks .Have you costed the barrells ,crankshaft etc or would that be to frightening , really is wonderful what you're putting together best wishes BobH

[JulianM]

Hi Bob,

Barrels not costed but will try to do a costing.  However probably a bit pricey.
Crank was about 1000 euros all in. Steel billet, 2 x heat treatment and then grinding, plus imaginative price of machining etc.
Just do it as and when you can afford the parts and forget the total cost    that's what I do 

Julian

[muskrat]

 Yep, it can be frightening if you add it all up. I WAS keeping a log of the '57SS when racing, put it away once I got over $25000AU then add another $5000AU to transform it into the cafe on the road. That was just parts so in all with my labour it owes me about $50000 
Cheers

[chaterlea25]

Hi Julian,
The engine bits are looking great  ???? ????
Looking forward to seeing it come together
Going back a little to the clutch conversion it looks as if you have (or are going to) weld the splined Yam shaft to the BSA shaft adaptor??
If this is the case how will you keep it true while welding? It also leaves in place the weak link in the transmission, (in my opinion) the taper and key onto the mainshaft!!!

Even on standard bikes these can cause problems, mostly due to the tapers not being perfect or the nut not being tightened enough 
I normally lap the taper and then use loctite retaining grade ( the one that is supposed to eliminate splines press fits and keyways ) and then tighten the nut with the air rattle gun
It can be a right Bast**d to get them off afterwards though 

Regards
John

[JulianM]

Hi John,

A good question and thanks for mentioning it.
The answer is thus.  The splined Yam shaft is big enough diameter for the taper and key and will be bored and taper cut to fit the crank.  Lapped as you do but I then heat the fitting with a hot air gun to "spit" hot  (till it is hot enough to fry spit) and then do as you do with an air hammer (with caution)  do the same with our hubs and halshafts and cured an age old problem with this easy fix.  Like you say though. Not easy to remove without heat  ;o)

The collar was bored out "line perfect" to 0.002" under, Heated and then dropped over the shaft to the correct depth in a little Jig.  Onced cooled it was tigged into place on the back.  The collar is only to hold the clutch bearing and does nothing else so no real load other than a little axial thrust to hold the bearing seated.  There was no warpage during welding, though I did check with the clock.

Regards,
Julian

PS.
I may just use this adaptor as a sample and make in one piece, depends on how happy I am when finished and how well it all lines up. I don't have much room in the primary cover as the clutch is quite thick.

[JulianM]

Little Q for all you experts!   

Just rebuilding my SC gearbox and after scratching my head and banging it on the floor a few times to find out why the selector won't work properly, I find that it's been fitted with a reverse pattern sellector plate,  Why would you need this in an SC box?   I thought it was only fitted and "Needed" on the RR boxes due to the reversal caused by the rear sets?

Any thoughts?    Not that it worries me as it matters not where the gears are as long as I have them all 

Julian

[JulianM]

Block is now finished and ready for final bore and Nicasill

Steel ring in top is just a bore indicator to show where a 76mm bore will sit.  (outside of steel ring)









julian

[chaterlea25]

Hi Julian,
I WANT ONE 

On the reverse camplate issue, with the reverse plate the indexing plunger needs to be fitted to the top tapped hole in the gearbox ( not drilled on STD boxes)
I am in the market for a reverse one and have standard to px if needed

Regards
John

[bonny]

Hello Julian

Just seen your thread , very interesting on what you are doing with your project. A quick point, have you considered using a rephased crankshaft ? it drastically reduces vibration (50-60%) if you use a 76 degree or 90 degree rephased crank. While one piston is stopped at tdc or bdc the other piston is at mid travel in the bore and at maximum speed , offsetting a lot of the vibration. just a thought , srm engineering in wales are now doing the cams to match so no difficulty on that front, its just the ignition thats a bit tricky to get correct but its possible with a bit of work.

regards.     

[JulianM]

Hi Bonny

Thanks for the input.
Yes, I did consider, but in my thinking it would stop it being a BSA if it were not a 360.  Some of the fun is the vibes and the sound etc.  I am also pretty sure that with the redesign of the crank and the lighter pistons etc it will keep the vibes within reasonable bounds.
I am also building two Laverda 750SFs at the same time, one absolutely stock and the other converted to 1034cc with bore and stroke at 87mm.
That one due to its pressed crank layout will be built up first as a "90? i.e.  270/450 and then changed back to a 360 as an experiment "like for like"  as most 90 conversions have been incorporated with many other changes so hard to tell what gains come from what exactly.  I will leave the Laverda as a 360 in the end also for the same reason as the BSA.   It has to sound like a Laverda and not a Ducati!   


John,
Thanks for the offer but sorted now,
Flicked the selector fork to not line up with the dots but be in a similar place on the other side of the fork and hey presto.
Strange though but hey!  that's the fun of these old things I suppose!  (although that was not what I thought at 12.30am on Tuesday morning )

Julian

[Motoanimal]

Now that's what I call 'thick flange barrels'!!! 

Looks great, well done, can't wait to see it completed, keep the pics coming....

Phil

[JulianM]

Thanks Phil,

Nice bike in your Avatar by the way!

Regards,
Julian

[JulianM]

Barrels as of yesterday,

Just got to do the final fin finishing and Nicasil coatings then ready to fit!





Julian

[JulianM]

Another little update,
As I don't like constantly leaking pushed in exhausts, i decided to make some proper fixings.

So first step was to bore out the exhaust port to 40mm dia.


Then make up my stainless stubs and flanges


Heat shrink and press together. (Hard work at 0.012" interference)


Then fit my Yam FZR exhaust retainers,  These will be a little modified before final fit.


Still need to make a small register on the flanges to locate the exhaust stub as I forgot when making them
Port is now 35mm ID ready for my exhaust to be made in 38mm OD  1.5mm wall  Stainless.

Regards,
Julian