Winton Historic Racing, May 2021 Luis Gallur

medat727

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Greg, BTW, didn’t mean to creep the thread, what you guys are doing is fantastic, Cam is quite the talent, the way he rides that Comet looks like he’s hanging off a Moto GP bike wringing its neck.
 

greg brillus

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Hi there Dave, No problem........sorting out ways to lighten these bikes is a challenge.........always a risk to shave things until they break...... I'm still waiting for the bike and parts to come up to me, and time is ticking, plus my normal workload is not getting any smaller so time will be against us if the owner takes too long. There is lots to do, and I am unfamiliar with these engines.........They are far higher spec than a normal racing Vincent engine, and able to handle much higher rev's up to 8500 no problem.......It will be interesting, but again i can't do much without the bike here. I have a race myself in early July on the Norvin single, next week i am hoping to put it on the dyno for some runs for the first time, just to play around with the timing and fueling to see where we are at.
 

vibrac

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Here is the b great hole in my Grey Flash Rep RFM -No I did not do it! I guess it was done when it was raced back in the days when an RFM was worth sweet FA
It just shows you how much redundancy is in the standard unit (the big tube in the LH side of the picture is my 500cc regulation catch bottle those of you who may have been shocked seeing me in a hiking/ramblers store will be pleased to know I found some decent use for a aluminium water container :cool:
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greg brillus

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I think there is a lot more strength value in a Vincent rear frame than meets the eye.......Not only is the triangulation of all the tubing a major factor, but also the large forward lower section........Yes it is heavy, but it creates a very strong foundation for the tubing that branch out from it.........I've seen footage looking at the back of Honda 750/4 unlimited race bikes racing at Phillip Island, and you can clearly see the terrible wobble in the back wheel almost certainly from the main tubes of the swing arm flexing under heavy cornering and acceleration out of these corners..........I don't think the swing arm on my Featherbed would behave any different, except I don't have 100 plus HP going through it, like these other bikes do, and they are many years younger.
 

medat727

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Lots to be saved on the other end as well, wish the Godet alloy version was available before tackling this, same weight as the alloy but arguably stronger. It also takes taper roller bearings which allow the fitment of the wonderful David Dunfey steering stem.
 

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Cyborg

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If they can run fuel injection, any idea why they chose mechanical fuel injectio?

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greg brillus

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Problem is most early mechanical injections suit engines designed to put out power on full throttle only, anything in between is a real compromise. A proper timed injection like the one shown above is fine, but a lot of work obviously........The Horner's are trying injection because of continued aeration of the fuel in the fuel bowls on their race bikes........My thoughts are, they need to run some kind of pressurized system like pressure carb's on earlier aircraft engines. I think many people have made up alloy head stocks over the years........It will save weight but perhaps not as much as you like to think........the main bearing areas need to be beefed up, so this will counteract the effort to some extent........Perhaps a fabricated item might be better......who knows. There is very little weight saving in simply drilling holes in things, these days machining slots on a CNC mill is much better........It's all time and money.........but it does work well.
 

Cyborg

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Do the rules specify that you can only use mechanical injection? Electronic injection means providing power to run the pump, ECU etc, as in added weight, along with all the sensors, but would think that one is less likely to go insane getting it to run right.
Interesting way of going about it. It would also be interesting to know why they can’t sort out the aeration.
 

greg brillus

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I think the injection has to be period correct, so unable to use electronic injection. A lot of their issues are the fact that the engines put out so much power that the fuel demand is very high.........apparently the problem is obvious even running the engines on the dyno let alone out on the race track.
 
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