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NickL #877496 04/13/22 12:17 am
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Hard luck, Nick--but I don't have to tell you--that is racing.
The old saying when I was racing back in UK in the 60s was "If you don't blow the engine every 2 or 3 meetings then you are not trying hard enough!"

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NickL #877501 04/13/22 1:58 am
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I know the feeling. Mine was caused by screws holding the outboard bearing plate behind the clutch backing out and catching the back of the clutch basket. I was at full throttle at Loring AFB, about 125 mph. The broken chain ended up inside the fairing. I was lucky to be able to salvage the broken pieces and get it welded back together again. I added an extra 6 screws to the bearing plate and lock-wired them.

[Linked Image from i.postimg.cc]

Tom

Last edited by koncretekid; 04/13/22 2:02 am.

Life's uncertain - go fast now!
Anything worth doing is worth doing well. Steve said that. Anything worth doing well is worth teaching to others. I said that.
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NickL #877512 04/13/22 4:25 am
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I guess i'm just out of practise at coping with it. LOL I should b used to it really.

We have another set of cases already machined for the bearing and crank etc so
hopefully it'll be up and running for June/July's meetings.
I'll get a good look at the damage and see if it's repairable when i get it on the bench.
He was lighting the back wheel up off the line when it let go so it was about 6500rpm.

NickL #877527 04/13/22 11:41 am
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A lot of long nights ahead of you.... Sometimes wonder why we keep putting ourselves through it all. It's a sickness I suppose.

I follow a group on [email protected] Queensland race something or other- They evidently had an event last weekend. I'm guessing that was where this happened?

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NickL #877570 04/13/22 8:56 pm
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Bad luck Nick,
I feel your pain.
My worst mistake (anong many!) was rushing a rebuild to make the next meeting, only for it to go bang again, caused by another problem related to the previous bang that I failed to check thoroughly enough for on re-assembly.

It's a real joy having to custom make go faster parts after the last ones broke!! oh the joy of racing old clunkers!
Mind you it was just the same with the TZ750 - and they were still making those at the time!!!

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NickL #877585 04/13/22 9:57 pm
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The thing that gets me more than anything is that it's not my bike.
I didn't mind so much if it was my old crate that went pop but i find
it hard to live with it when it's someone else's.

NickL #877616 04/14/22 4:37 am
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It's just mechanical Nick. It can be fixed. 6,500 off the line he's going to go through fuel riding like that. You should make a 'back off' sign with ''You are using too much fuel' to let Matt know to max it out. The other guy might hesitate, thinking about how much the Norton's guzzling. Or another one 'Stay out of his smoke it's going to let go."

My daughter knows how to do it, she was push bike Champion at Bega High, her names on the wall in gold, 'Cymmon, Cymmon wait, we'll cross together'.


mark
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NickL #877707 04/15/22 1:44 am
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As you can see here, we (the engineering team) take it very seriously

https://imgur.com/a/qtASAgG

Last edited by NickL; 04/15/22 2:17 am.
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NickL #877992 04/17/22 11:41 pm
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Exploded view of A65 primary drive area.

https://imgur.com/a/tPGamTl

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NickL #878831 04/28/22 1:08 am
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Once all apart the damage wasn't that bad, cases being welded up at the moment.
Good really as i had replaced all the bushes etc on this set and doing another set
and it's associated timing cover would be time consuming.
Sorting out a 4 spring clutch basket and machining that is next.
Debris hadn't circulated into the engine so that's good.
Splines etc are all good so is engine sprocket, getting the crank nitrided as it should
have been done originally really. Even a secret 5 speed box on it's way...........thanks
to John. Outrigger on crank will definitely go on as well, although it will not be easy
to do, space is limited. Discovered that we must fit air filters as dust and grit has scored
the bores considerably, honed out ok but it seems this bike must throw a lot of crap up
to the intake area and some circuits are a bit primitive as far as paddock arrangements go.
On stripping the carb again it seems that the float was just binding on on the side and
may be why the fuel level was going high. May have been bent slightly by transporting
with a low fuel level but sorted now and tests ok. Will fit a small regulator anyway as
the pump is delivering higher than the recommended pressure. Never had this problem
before and i used webers for years on my bike but one to note i suppose.
Frame mods have been done so the old girl should sit better now and steer properly again.
Outfits all tend to bend in the middle after years of use and the rear end mods we did
accented this.
End of 'War and Peace' for the moment eh? LOL.

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NickL #878884 04/28/22 3:06 pm
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Find neutral while it's rolling. The thing should give it a good test. Can't you box in behind the carb, or put it in an air box? I make sure back tyres cannot throw stuff into the carb area.

I should have a Norton crank nut with spigot for a crank outer bearing sometime soon, see if it fits. The spigot is alternator size and I'll make a top hat style spacer to fit to the bearing from the back, so the washer part spaces to the alternator. That way the washer is captured, It's hard keeping a loose washer in the right spot.

I use a 3 spring basket with a 4spring centre. It's just the cush centre is a bit short, but may not matter with the secret box splined hub thing, I cannot remember. The std taper one needs a little off it so the washer and nut push against the cush hub and not the end of the taper thing, or it floats.


mark
NickL #878909 04/28/22 11:39 pm
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Matt found some filters that weber do now that fit on the end of the trumpets,
so we'll try those. The area is sort of covered but a few of the pit areas are like
sand pits anyway so a set of filters is the right way really.
https://www.weberperformance.com.au/product_info.php?cPath=36_80&products_id=89

I just used to use a couple of tea strainers cut up or pop socks but that was me........

The a10 crank nut is 3/4 BSC i think norton is UNF from memory.
What i envisage is machining an old alternator carrier off and standing the bearing
plate up from that on 10mm studs, the carrier base can be fitted with 8mm c'sunk
bolts into the original holes. If it flexes then i may drill the top, bottom, front of the case
and go through with extra bolts/brackets. getting it in there and making stripping the
thing down/ re-assembling simple, is the problem.

I'd like to stick with the 4 spring clutch if i can, they hold up much better than the three
but i have both types here to mess about with, getting the centre right etc.

I'm sure it'll be fun.........

BTW Mark, i have that other head welded up and boxed with new valves etc, do you fancy
doing that up for us? (i am always on the scrounge) It'll be for the 750 offset engine.

NickL #878911 04/28/22 11:59 pm
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Send it down. Will the seats take bigger valves? Like SRM 43.5 or 44.5 Jaguar? If you use Ed's forged pistons or Omega with MAP steel rods we used 615g on each pin to dynamically balance. The first crank like that is great. The second two are done but I need parts to put together and see. One has Ed's 80mm B44 pistons. The other is for Ben's 650 racer.

This thing of Ben's promises to be brilliant. It's better in the top end than before and far better midrange. And smooth it makes you laugh. Wish you were closer and could take it for a spin.


mark
NickL #878913 04/29/22 12:30 am
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Good on you Mark, thanks, ill get it sorted.
It's a late 71-72 head so should take the bigger valves.
I actually bought a set of PM ones for it (o'size inlets) and new guides.
This will have ED's JE pistons 80mm. MAP rods etc so your numbers
are a great guide. Crank not finished yet and rods not yet ordered but
it's in hand as they say....... Matt's had a lot of expense over the last few
months so i need to 'go easy' with stuff. He was off work with covid and
the bad weather for quite a while. It's not like you win 'sheep stations'
in this game, trophy's are as good as it gets.

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NickL #879319 05/03/22 12:44 am
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MAP have black diamond B50 inlets 44.45mm if the seats are central. Not sure what the shape is. But I think it's their shape looking at pictures not BSA 500 shape so much, it's hard to tell. Just needs shortening and lash caps. I could compare them to the couple of hens teeth (Jaguar valves) I have.

What length is your inlet? From atmosphere to valve? Because long seems to be good on Ben's 90. It idles, no fuel stand off, no reversion. Hopefully it doesn't get carbon on the inlets. It would probably tow quite well.

Last edited by Mark Parker; 05/03/22 12:45 am.

mark
NickL #879412 05/03/22 11:08 pm
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I don't want to go over the top with valve sizes as piston contact and
tangling create problems. I would sooner get higher compression and
a little flexibility in valve timing. My old bike was a problem with the cam
and valve sizes it had, i'd rather not go back to that. We are not aiming
for just high rev performance and lets try and keep it progressive tuning.

Valve head to atmosphere is approx 12 inches. Possible to extend to around 13.
With the cam and exhaust fitted i wouldn't want less than 11.

In my opinion, that cam that Tom is running is not doing him any favours, just my 2c.

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Well, the secret gearbox has turned up so much enthusiasm ensues...........
It's bloody lovely!

NickL #879428 05/04/22 3:26 am
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The spline is brilliant. It's a little bit of stuffing around to fit. Gavin would have good posts on it. It looks like jewelry. A gear for every occasion.

All being well we can get a bit more out of the small valves. We'll find out. You are probably right on the money at 12"


mark
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NickL #879659 05/06/22 2:39 am
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Mark, please check your mail.

NickL #879802 05/07/22 6:05 am
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Re the 4 speed problem at the moment.
Found the damn gearbox issue, both boxes were spot on BUT
the daft early selector setup was returning back past centre and
just putting a little load on the camplate, just enough to push it
past the selected gear. I tried another one of the stupid stop
bracket arrangements and with a little dress with a file it now
works correctly. I also used a heavier spring so the mechanism
performs as it should. It's made the change a bit heavier but it's
now very positive and centres properly. I must have taken the box
in and out of the case 7-8 times to find it. I am going to use a late
type inner cover and setup for the 5 speed as they are just so much
better. Need to get the end feed block sorted for that though.

Very productive day all in all.

NickL #879804 05/07/22 7:05 am
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Ball ended detent plunger slick as. But doesn't fit the 5speed Gavin said.


mark
NickL #879921 05/08/22 9:13 am
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Yup, the 5 speed cam plate notches are smaller than the Std 4 speed, ball ended plunger wont fit 5 speed.Enjoy the 5 speed Nick, I had to remove a cuppla thou from the trap door body for clearance, also the lay shaft big gear on the driveside needs some casing clearance, I chewed this out with a dremel, might have been easier to make a dis.c faced with 80 grit


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NickL #880319 05/11/22 11:19 pm
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Case is welded up and looks good.
While i'm waiting for stuff i thought i'd try the box fitting just the shafts/gears
and see what needs trimming. I need an endplate as i don't have a 71/72 type
handy but it's on it's way. The layshaft 1st needs the opening for the endplate
cut out a fair bit, maybe a mill or so but all else looks good. Matt is cutting up
an old case for me at the moment,that will make it easy to see what's going on.
The new outrigger plate is loose in the case which is a pain as we have to either
weld up the case a bit or make a new plate, those plates must be a tight fit or
they come loose, you can't take the load on the fixing screws. May use a 3 spring
clutch basket with a 4 spring Hub as it will make life easier with the centres.
Nothing insurmountable. The outrigger for the crank is sketched up and after
a discussion with Viv as to whether he agrees with it, he'll machine up the bits.
The guy is worth his weight in gold, just putting up with me is a major thing but
nothing within reason is too much trouble to machine up for us.

The spring i changed on the gearchange mechanism was the return spring, we
found a 3 turn early type which are a fair bit stronger than the 2 turn ones and
are heavier gauge. It has improved the action of the return and centring, it feels
more like a late one with the opposed spring.

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NickL #880419 05/13/22 1:49 am
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If you have it breathing into the shrapnel case you can use a 16005 narrow bearing with a TC 25-47-5 oil seal on the 25mm nose of the 5speed. The crank bearing can use a 16005 with maybe a Norton spiggoted nut for the crank end, as it may thread down under the bearing. Alas, it hasn't found its way over to test yet. And a top hat spacer, if it's thick enough, with the washer side toward the alternator. Because a lose washer spacing that is a pain. I have not tested this yet for the same reason as before. But a plain spacer wears the thread with high mileage. The 4 spring center is shorter so check.


mark
NickL #880497 05/14/22 12:59 am
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Will be using an R16 open bearing for the crank outrigger, it is 1 inch id
so fits on the a10 crank. We have no alternator to mess about with.
The new 'box uses a 6005LLU as an outrigger, so as my existing plate uses
a 6204 bored out slightly, i can just press that out and the 6005 in.
The existing bearing is showing signs of wear anyway, they don't last long
in an outfit though it's been in a year or so.
The LLU types are double sealed so better than the 2RS versions.
The clutch setup requires a spacer sorting as the 4 spring flange is thicker.
I'll have to see if i can find some 3 inch diameter bronze bar. Still humming
and harring about using the 5 speed in this motor though as i just don't like
the gearchange setup. I'll see how we go time wise but unless the change is
really spot on, (which it seems to be now with the 4 speed) i won't run it.
We can wait and get it all done on the offset 750 in the late cases we have.
I would have liked to have tried the 750 barrel out but the crank's been cut
in half now so i'll have to wait until it's done.

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