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4 valve ES2

Norton Models (not Commando or P11)

Re: 4 valve ES2

Postby ballacraine » Sat Dec 10, 2016 10:35 am

S' agit t-il d' une ES4 ?

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Re: 4 valve ES2

Postby robs ss » Sat Dec 10, 2016 1:08 pm

ballacraine
Actually ES2 (I believe Model 50 head) heavily modified hence Geoff Clatworthy uses the term ES4 - it had a predecessor, ES3
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Rob
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Re: 4 valve ES2 and others

Postby ES234 » Wed Jan 11, 2017 4:16 am

Hello,
My name is Geoff Clatworthy. I have built (with the assistance of others), a number of Australian ES2 racers now known as ES1, 2,3 and 4. The photos's elsewhere on these posts are of "ES3" (long stroke) with the obviously welded/modified inlet manifold, and "ES4" short stroke, both with the cross over gearchange linkage through the 3/4" s/a pivot bolt.
No quick shift other than the quality set up of the 5 speed TT Industries boxes and Bob Newby clutches (and rider skill).
Happy to answer not too long questions should I be able to assist. I have spent 40 years developing these bikes and don't believe that there is a lot more to be gained. I standard ES2 is claimed to have produced 28bhp (rear wheel?), where my modified iron ES1 produced 46bhp, ES2 and 3 between 49 and 51bhp and ES4 considerably more. They weigh about 238lb with fairings and oil without fuel; with performance reflecting the power to weight advantage over a Manx and some excelelnt riders Chris Anderson, Mike Soderland and Ian Lovell.
I believe the 4 valve ES2 to be an exercise constructed for the amusement of a clever English enginner utilising some speedway components and not intended for racing.
Kind regards from OZ - Clappers.

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Re: 4 valve ES2

Postby Rohan » Wed Jan 11, 2017 9:52 am

Geoff, we look forward to seeing some pics of the combustion chamber and the cams in your ES4.
If that is not asking too much - ie on the secret list ?! Those are impressive numbers indeed...
Jist curious...

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Re: 4 valve ES2

Postby ES234 » Sat Jan 14, 2017 2:27 pm

I haven't sorted out yet as to how ro post photos on this site.

Anyone can extract good reliable performance from one of these motors starting with patience and a little effort. Weight:BHP advatage will see a well set up machine (sound chassis geometry/brakes/gear ratios) lap with OHC motors and twins of the same capacity. A bit more effort and time (and the same cost as other options); will see a good one at the front.

The combustion chamber on the LS motors are essentially hemispered with piston crowns to match at least for a squish portion (0.027"). Rather high comp on methanol. All twin plug heads except for the first iron motor (ES1). Around 0.425" valve lift with short duration cams. Pressed up steel crank, modified main bearing arrangement. Think the valve sizes are something like 48/44mm.

The SS has a compact bath tub design with large well disiplined squish areas providing a small compact chamber (flat dome after the last squish) - 14:1 comp. Rocker ratios 1.52/1.48:1. Roller followers although flat followers were utilised initially and possibly unneccessarily discarded. Lifts 0.610"/0.560". Cams modified to incorporate slotted gear wheels and cam carriers for fine adjustment of the timing. One piece crank on large needle roller mains. 2.1" B.E. redisigned oil pump. Ti rod. Custom pistons and valves. Dellorto SS1 carb.

Geoff

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Re: 4 valve ES2

Postby ES234 » Sat Jan 14, 2017 2:48 pm

Hi,

I had no easy choice at the time re the colour of the fittings. Now being replaced in black. Oil lines support a spin on type oil filter on the return line side). Very difficult to plumb into the pressure side. The oil filter is a must to support the plain bearing crank. 70 p.s.i. pressure relief valve.

Best wishes - Geoff

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Re: 4 valve ES2

Postby Rohan » Sat Jan 14, 2017 4:46 pm

Thanks for the engine detail Geoff, look forward to more of it sometime !

Pics need to be posted to somewhere like photobucket etc, than the links included here.
The little [img] button above makes them display.

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Re: 4 valve ES2

Postby cjandme » Wed Jan 18, 2017 9:08 pm

Rohan wrote:Thanks for the engine detail Geoff, look forward to more of it sometime !


+1
Norton Fan by Bro w/'75MKIII
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Re: 4 valve ES2

Postby acotrel » Mon Feb 13, 2017 4:48 am

Historic road racing began in Victoria in 1973. For about 8 years a class was won by a BSA 500 which was fitted with a speedway Jawa head. It was obviously cheater, but because the owner was a nice guy, nobody protested. The difference between a 2 valve and a 4 valve Jawa is about 10% in horsepower. The upper rev limit is raised because the valves are lighter.
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