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Jubilee racer

Submitted by dan_field on Tue, 30/04/2019
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Light Twins

I see the “racer” is for sale again in this months Classic Motorcycle! 

Racer

Submitted by david_flaxington on Fri, 14/02/2020

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I was told this week that Willie Wilshire used to roll out a Jubilee occasionally that revved to 9500 rpm. Maybe this is it?

Submitted by nicholas_clarke on Fri, 14/02/2020

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……..I'm just imagining what a stripped and lightened Navigator classic racer might be able to achieve Dan, given it's Roadholder forks, excellent brakes and modern racing tyres.   With 12v total loss electrics to get rid of the alternator, electronic ignition, twin carbs, a blueprinted engine, some sensible gas flowing and less restrictive tuned exhaust , higher compression ratio, modern valve springs to reduce valve bounce, statically and dynamically balanced lightened bottom end, belt primary drive...….reliable 100 mph+ top end must be achievable!    A bespoke alloy tank, lightweight period faring and bob tail seat it would look cracking too!   It was always a teenage dream of mine......Nick        

Submitted by george_farenden on Fri, 14/02/2020

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...Do like Patrick M and Uli H have shown pictures of - fit a Honda CB350 or Yamaha XS400 engine in and have a reliable, leak free faster bike!

Says he who has a Morini sport (which has been superbly reliable, leak free and surprisingly quick over the last 98000 miles)

Submitted by nicholas_clarke on Sat, 15/02/2020

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A well built Norda or Yamton racer is a worthy project George if you have a spare Lightweight frame and no engine but a Naviracer is 100% Norton so unapproachable...….and with a little TLC reliable and leak free.....making it faster than it's contemporaries is the great challenge that classic racing is all about.   Luckily CB350s and XS400s aren't contemporaries!   Love the Morini sport but never owned one sadly.      

Submitted by dan_field on Sat, 15/02/2020

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A while ago I spoke to Les Emery about their efforts to create a jubilee racer, I can’t remember all the details but it involved head work (they even tried reversing the head to enable twin carbs to be fitted- but am not sure that was successful) it had vertex pistons and Kawasaki valve springs to stop the bounce, I think it revved to 12000, was clocked well over the ton, but still wasn’t fast enough to be competitive.

I thought about  putting a Navigator on the Scrambles track as with lower gearing it might perform better, but it would be up against 350 triumphs and in some clubs bigger bikes. The engines aren’t that well known and I might be able to pass it off as a jubilee and race it in the upto 250 class ...... or would that be cheating ?!! 

Hi Dan,

Interesting notes you put about your conversation with Les Emery. I think the Racer concerned was called Mark Capewell - and they made the little Jubilee go much faster!

As I heard the story, it was that they tried the heads the other way round to fit twin carbs, but that did not work as well as intended. What they noticed is that the motor produces more power as it spins faster, the limiting factor being valve bounce.

By the simple expedient of beefing up the springs (by adding an extra hear washer underneath), they found it would rev higher, and thus go faster.

I think they finished at 24bhp @ 9,000 revs, against a claimed 16 bhp @ 7,500 revs - quite credible as I bet a few of those 16 horses were missing to begin with.

Submitted by david_flaxington on Thu, 12/03/2020

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My Electra parts list has an entry for fibre washers to go under the heads of the gearbox cover. Are these available? Will I have to use some sealant instead?

 



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