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Discussion Starter #144 (Edited)
Ref the Yamaha based triple - I will have to start another thread as there's too much to write.

It is sufficient to say that in the very early 70's there wasn't much available when choosing a large capacity 2 stroke racer and certainly no "over the counter" purpose built 500cc 2-stroke racers. Of coarse there were bikes like H2R and XR11 but these were full factory bikes - you couldn't buy one. So home tuners both gifted and not so gifted set to work in secret in the darkest corners of their workshops. Now some will be thinking what about the Kawasaki H1 or Suzuki T500? Well if anyone has ever worked with one of the these engines will know that you chuck the guts and start again, true you can pootle about with modified internals but you were never going win "in period".

Enter tuners like Ted Broad, Dennis Trollope, Rudi Kurth, Barton engineering and many more built some very special home built bikes that took on and often beat the full works efforts.

Short spec on the triple engine i am putting back together;-
1. Cases are YDS7 with a bespoke extra cylinder.
2. Crank is TZ350 derived built out of phase as the crank has 13 splines (approx. 138.46 - 110.76 - 110.76 deg phase, firing order is 1,3,2).
3. Gearbox TR3
4. Primary and clutch TR3
5. Cylinders TR3 re-plated
6. Pistons are Meteor for TZ350 skirts modified.
7. Heads are TR3 standard and volume balanced.
8. Carbs are Mikuni VM34 (for TZ750)
9. Exhausts are bespoke but use TR3 dimensions.

All good for about 85hp and enough to worry the works teams in the early 70's. However things changed, the TZ750 turned up and then Yamaha made special kit reed cylinders to make the 750 engine a 500 (you could fit TZ250 cylinders but these where not reed which made this engine config hard to ride), Kawasaki's HR turned water cooled KR and in 75 the 1st Rg500's rolled out on track (1976 for customer bikes) - The triples slowly disappeared, Barton Engineering's Sparton (GT380 bottom end, dry clutch with water cooled top) continued to fight on for a few years.
 

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Discussion Starter #146 (Edited)
ABSOLUTELY needs a new thread!!!

(note THREE exclamation points)
I'll finish this Manx thread 1st, just waiting for some chrome plating to come back, oil the old girl and she's ready to start.

Then I'll do a top to toe on the triple, just a couple of posts as I should have it finished in a 3 or 4 weeks.

For interest some period press stuff, the monocoque was original fitted with a TD2 engine and later the "3".

Top-51.jpg
3 cyl scrap book-page-001.jpg
Ditch easter 73.jpg
 

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Rob Hinton has an air cooled triple and I think he still races that from time to time, but it's in a conventional steel tube frame.

Looking forward to reading the triple thread when you do it.
 

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Discussion Starter #150
Rob Hinton has an air cooled triple and I think he still races that from time to time, but it's in a conventional steel tube frame.

Looking forward to reading the triple thread when you do it.
The engine in the monocoque was originally raced in a standard YDS7 frame! Engine mounted as original but the extra cylinder hanging outboard on the drive side - this was the 1972 bike.
3 cyl engine press '72.jpg
 

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That is something special. You wouldn't need to be to mechanical to understand the time and talent required to put a machine like that together. Beautiful work, the shot of the motor from the right side gorgeous, real artwork. Made my day seeing it, thanks.
 

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That chain oiler is interesting. The oil feed to the guides makes me think it's a shame to fire them up the first time, but the sound coming out of the mega makes it worthwhile. Not that it matters, but just curious...was that carb spacer used originally or does it fall under the category of as raced?
Anyway nice work and you get extra points for breathing life back into that mag.
 

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Discussion Starter #156 (Edited)
That chain oiler is interesting. The oil feed to the guides makes me think it's a shame to fire them up the first time, but the sound coming out of the mega makes it worthwhile. Not that it matters, but just curious...was that carb spacer used originally or does it fall under the category of as raced?
Anyway nice work and you get extra points for breathing life back into that mag.
The oil feeds to the guides - The pushers on this engine are 2 thou oversize and have been hand finished and so are a perfect fit. Much off the oil one sees on the top end of a Norton result from oil passing the pusher. The oil feeds have a very small hole only in the fitting that screws into the cam box this restricts the amount of oil to the guide.

The manifold is a long type, length is the same as those fitted to "works" bikes in 54/55. I believe it a genuine works part - John was a works rider for Norton in 55 so he was a close as you could get the the works dept. I guess you could call it "as raced".

List of differences to over the counter bikes;
1. Alloy front fork shrouds
2. Alloy rear shock shrouds
3. Front brake air scoop.
4. Conical Revcounter (this was works only in 55)
5. Lucas 2MTT magneto (this was works only in 55)
6. Chain oiler (works only from 53, never fitted to over the counter bikes)
7. Works Inlet manifold which is a long type and 2" mounting centres for use with early long snout GP1.
8. Cylinder head has been works prepared (seats bored and port shape altered).
9. Works type drive side main bearing and flanged timing side main bearing (works only until 56).
10. Extended gearbox change lever.

Note the lighthouse tower bevel drive was added circa 1959 and is the only significant mod not reversed. BUT I have recently purchased bearing, bevels, drive shaft and couplings, once I find some housings I will convert back.
 

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Discussion Starter #157
Mercy sakes alive, child! That is an absolutely beautiful machine. I hope it runs as good as it looks! Will it ever be raced again?
Thanks.

The bike is too important to destroy.

So it will never be raced again but it will get paraded.

The engine has been fully rebuilt in the fullest sense - New piston complete and liner, crank has been stripped and new rollers installed, 4 out of 4 needles bearings in the bevel tower replaced, 5 out of 6 bearings replaced in the cambox. New top bevel, one new race in the drive side main, new valve springs, new exhaust valve, new valve pushers and caps..... The cam timing is near perfect and it fires 1st spin on my paddock starter. The bike hasn't been tried yet and has an imposed rev limit of 6800.
 

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I seem to be stuck in the pre pusher days. Your note about the alloy fork shrouds reminded me of these. I haven't done any research on them, but assuming they are garden gate variety Inter. I've never seen another pair on this side of the pond and guessing there aren't a bunch of extras over there.

GG fork shrouds.jpg Rockers.jpg
 

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Discussion Starter #159
Those top shrouds are standard long road holder with the headlamp ears cut off. Garden gate manx shrouds are steel - I sold my last pair of these, original, a few years ago. They also have “L” shaped brackets low at the front to fit a number board.
 

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Thanks. Good to know. There isn't any remaining evidence of having ears at one point, just two holes where it looks like a bracket was riveted on. In that case it strikes me as odd that they would use alloy. The casting is quite thick and the alloy ones without the ears are only 16 grams lighter than the steel ones with ears.... so unmolested, the alloy ones would be heavier.
 
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