classic motorcycle forum

Mag-Platform bracket mk2:

In progress:


In place:



To be honest....  I'm not convinced.  I bent that bit of steel cold, with just a hammer and then twisted it with mole grips.  I think it's just a bit of mild and may not provide the support that I would get with the thicker stuff.

But - it'll do initially and I can have another go if I decide I want to.  At least now I have a "pattern" piece for reference when making another one.

I made this one by doing the bend first: after figuring out roughly where it should be with the bracket bolted to the cases; then I put the twist in to bring the upper hole (the mag-platform end) into alignment with the underside of the mag platform.  However - that meant that the twisted part of the bracket works against getting the bracket flat against the mag-platform.

If I try again, I'll probably start at the other end - the mag-platform end, and work out what the bend needs to be from that end.  I thinkt it could be done with a single bend, but at a funny angle across the bracket, it's not quite 45 degrees - maybe about 30 or so.

Remembered I had some loom tape yesterday, so completed the job:





I also took some remediating action concerning the battery flopping about on it's single screw....


Will help for now - but a better solution will be engineered eventually.

Did some more tinkering on Friday night:

This is the dural bar I mentionted previously:


The intention is to use these two holes - yes, yes one of the bolts is the upper shock mount, but it'll be fine....


Just a shot of the general arrangement of what's under the saddle unit:


Current shock mounting bolt on bottom... hmmmm
Two found 3/8" bolts above - much better shanks!


"Found" bolts is pretty much the right length (2"), but not completely convinced that the shank is long enough.


Ideally the shank of the bolt should interface with the inner part of the shock mounting plates as well as the full width of the shock eyelet.  This is to reduce shear forces on the bolt - thread forms are a weak point when dealing with shear forces.

The Allen-head bolts looks trick.... so if I end up searching for custom bolts I "may" go back to Allen heads - but the hex-head is a loer profile which bh, I think I prefer.




I was cleaning up the botls and looking for possible bits and pieces to convert into spacers, but I had a bit of a blocker happen when I used one of the new Cycle thread Dies to clean up the thread on one of the bolts.  They were a bit manky (but good), so I cleaned them in the usual style with a bras brush, but then decided to spin the Die down them as well.  Loaded the die in the stock for the first one, and started running it down the thread. 

Hm - this is a bit stiffer than I expected... but maybe the gunk in the bottom of the threads is harder than I though.... carry on...

Got most of the way down the thread and took a much closer look - and realised in shock that the thread had been destroyed!  The top half of the thread form had been scraped off uniformly all the way down!  I ran a cycle nut down the thread and it IS a cycle thread, checked the other found bolt against the TPI guage, yup - 26TPI, and the mutated thread on the bolt also checked out as 26tpi.  Checked other known 26tpi bolts and nuts....


the friggin Die is damaged, or badly made.  :angry-cussingblack:  :angry-cussingblack:  :angry-cussingblack:  :angry-cussingblack:

Checked the other dies from the same purchase, and where I had a known good bolt - the dies ran fine (1/4" and 5/16" seems to be all I have in known good bits and bobs).

So - going to have to ring the supplier today and see what can be done.  Thankfully I've only wrecked one bolt... but it's a tad frustrating.  :roll:


I've also been thinking about these bolts and where to get bolts with a proper long shank, and I think I'm probably just going to have to get the longest 3/8" bolts I can find, with the longest shanks and turn down the thread to match what I need.  Buying custom made bolts will most likely be ruinously expensive, I don't really need 1000+ of the bloody things.

I'd been dong some general tinkering the last couple of evenings, it's frigging cold out there so anything that requires proper thought is being put to one side.

I was going to reassemble the head, and made a start: I'm only going to put a couple of mica washers on each spring assembly because the spring weights are good:


But then I discovered that the valve-stem circlip I put on looked very tired, so I thought, bugger it - should replace them, and tidied the head away again for later.

I've been looking at the engine cases trying to figure out the best way to get the upper-surface as flat as possible (ie where the cylinder sits), and realised that the two small engine case bolts that are the first two that get used, and which hold the cases together while the engine is mounted etc really should be proper shoulder bolts, and I've got 2 set-screws.  So I'be been trawling the net for a 1/4" BSC bolt with a long shank (7/8").  See my other thread  for details : https://revtothelimit.co.uk/viewtopic.php?t=11380 .

So - while I was in the workshop last night I had a good furtle through my collection of Imperial bolts from random sources..... and lookee here!

"Bolt" ( aka "Partially-threaded-Bolt") on left, "Set-Screw" on right.

No idea where this came from... but I have a feeling it may actually be the exact bolt that Speedway Service sell!


Knowing my Dad, he probably didn't fit this because it's actually too long, and would look odd.  It's longer, to allow the Magneto Platform Support Bracket to sit on it!

Win!

So - I spent the rest of the evening cleaning up the engine studs:


And then, because the Mag-Platform bracket was on my mind and something was feeling off.... I bolted up the cases (empty) and fitted them into the bike to check a few things :

This is how I was initially envisaging the Mag-Bracket sitting :




But... there's an issue:
The engine stud isn't long enough.


I'm going to have to rethink that Mag-platform bracket.  Even though it will be a pain making sure it clears the engine plates - I think I'm going to have to use the smaller bolt as per the usual practise, so I need to remake the bracket.  With any luck I can use the existing piece of metal, but if not, I do have more of that stuff, which is quite handy.

This is the rider's view when in the usual riding position :

The cylinder axis is directly in-line with your head!

Incidentally: You can see the longer 1/4" engine bolt in that photo.

While I was looking at less-fundamental things I also tinkered with the "saddle-bag" fitting that I have never been really happy with: it's a cruiser-style "yoke-bag" that uses two thick leather straps and I had it hanging by the side of the saddle, banging against the shock:


I was never really happy with that arrangements, so spent some time trying to figure out a way to improve it, and found a length of Dural in the box of metal bits that Dad had drilled a large number of holes in: no idea what it was for - maybe an early attempt at a brake-tension-arm or something, but it's absolutely ideal for mounting this bag onto the bike. I'll do more photos when I do more on it, but I spent some happy moments on the grinder tidying it up somewhat for use.

So - as part of that I looked into where it would be mounted, and discovered something that made me both laugh and curse.

The bike has always been "bangy" at the rear end when riding.  It crashes about and is noisy, not just from the engine.  I now know why....





The shock uppers have at least 1/2" of movement side-to-side!!  :wtf:

I need to look into what a regular Featherbed frame setup uses here - but at the very least I need a couple of 1/4" spacers to hold the shocks in place properly!  I also think that the bolts should again have longer shanks, so we'll see what can be found, or bought to bring these shock support mounts up to scratch.

$%^&&in ell....

Made up the new Timing chest gasket last night.

Started out with locating the bolt holes




Punched them using a 6mm punch (closest thing to 1/4")


I hammered the edges round for about 20 minutes, and got the inner shape punched out, then tidied up the outside with scissors.
This is why kids get taught to make crafts....


Perfect fit.


The active components installed


All perfect!  The camshaft rotates freely and there's a little bit of play on the cam-followers, but not enough to worry about.


I'm still pondering on getting some cap-head bolts to use instead of the studs and nuts.  Dad did have that on one of the earlier incarnations of the bike, but I've no idea why it's back to studs and nuts.


So - here's another mystery.  I dissassembled the timing chest again because there's still a lot to do before final assembly, and while I was doing that, a washer dropped out of nowhere into the chest.

w.t.a.f. ??

Where did that come from?

Cue about 20 minutes of utter bafflement and poking and prodding.  The workbench was utterly clear before I started, and this washer definitely "fell" into the timing chest - I saw it and heard it happen!

It's NOT one of the washers from the outer casing - there's 4 of them and besides the fact that I count them all on, and count them all off again each time I assemble and dissassembly the thing: it's not the same diameter.  It's 1/4" alright, but it has a slightly smaller outer diameter.

EVENTUALLY I worked out that it had come from the socket cast into the outer casing which the cam-follower-shaft pushes into.

In fact... there's 2 of them in there.


I can only surmise that they were "stuck" in the by a little bit of oil that was still in there, but still baffled as to "WHY" they are there.  The cam-follower-shaft is pressed into the main cases, it's going nowhere fast (or at all!).  I reassembled the chest with the washers removed to see if they were having any effect on the gapping: none whatsoever, then reassembled it again with them in place: no difference that I could see to anything at all.

I am confuzzled.

Given that they were there to begin with: I'll likely replace them on final assembly... maybe they stop vibration or something??

So.  I stopped thinking about that, it was giving me a headache....

And I looked at my stock of old bits of metal, and decided to make up a mag-platform bracket.

I found a length of steel that looked about right - I think it was originally part of a foot pump...

Faced it up to the cases a few times and realised it just need a straighten and a twist.


5 minutes of heat (gas-can-torch) and some judicious heaving and belting with a hammer....


Checking the fit with a stand-in bit of engine plate


Of course I've made it so that it's bolting to the WRONG engine bolt.... the one I was shown by the Guru actually bolts to the smaller lug you can see on the photos. D'oh!  BUT - it should do the job, and may even be a little easier to fit and means I won't need to compromise the engine plates (any further).

Obviously it'll be tidied up and (probably) polished once it's been proven.

Next, I turned to finding a plug for the valve-lifter-cable-hole.  I'm not going to bother with the valve-lifter, at least to start with.
It may become necessary later, so I'm not throwing it away, I'd need to get the exhaust cam-follower modified again by someone with a proper machine shop.
However - all last year I managed to turn the bike over without the valve-lifter working (I always thought was as innefective as hell) so, despite a dodgy right knee, I'm hoping I'll be ok.

Rummaging through all the stuff I've got, I eventually found something that matched the threads in the casing:


No idea what this stud was from originally, but it was in the "odds and sods" box and the only person who might know isn't with us ( ).

it's 7/16" x 26tpi.... which makes it a British Standard Cycle thread. (anybody got Bingo yet?)

It's tempting to look for a bolt in that spec... but tbh, I'm going to just cut the stud down, saw a slot in one end to make it a flat-head-screwed grub screw and be done with it by using a lot of loctite.   TBH, the threads at the bottom of the hole are knackered, so the stud only goes in about 3/4 of the depth, so it does "go tight" by itself.  The loctite will be to guarantee permanance. (obviously I'll be using blue.)

I'm also going to redo the plug in the top of the main cases that is over the cam-follower shaft: the plug that's in there is loose and is only being held in place by silicon sealant.....