Hello all,

Does anyone by chance know of anyone who's taken a 300 out to a larger capacity? Or do any of our more technically experienced members know for sure if it can or cannot be done due to interference with the power valves for example?

The road racing rule makers here are proposing to allow production based two strokes up to 350cc to compete in F3. It just made me curious about the possibility of exploiting that allowance to the fullest.
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Hi Hermit , I am sure that you can overbore the cylinders , that rg150 , if it has the same size gudgeon pin as us then we can make a plan !

That piston is 61mm ? I wonder if they have 2mm oversize ? The powervales would need to be cut back and some porting done . I think it can be done .

I have 2 scrap barrels now that will make a good donor towards that project !
80 + HORESPOWER HERE WE COME !

Now that's a second a lap

Neal wrote:80 + HORESPOWER HERE WE COME !

You reckon you could get it out to 500cc?!

I don't see it making 80hp for long... 300's don't seem to even make 65hp for that long!
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Vampire?

I might try for 80hp out of my NSR250. Running at 75hp now I think with avgas, a bit of head work and some ignition tweeks it might see 77hp
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If I have to take the carbs off once more...

That HARC Pro ram air kit may give you a horse too!
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Andy.
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True, not running ram air yet or big carbs
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If I have to take the carbs off once more...

supercharger????

Good luck fitting big carbs into a ram airbox , i thought ram air was worth 5hp ?
What piston can we use ?

Neal wrote:Hi Hermit , I am sure that you can overbore the cylinders , that rg150 , if it has the same size gudgeon pin as us then we can make a plan !

That piston is 61mm ? I wonder if they have 2mm oversize ? The powervales would need to be cut back and some porting done . I think it can be done .

I have 2 scrap barrels now that will make a good donor towards that project !
80 + HORESPOWER HERE WE COME !

Now that's a second a lap

Hey Brother!

I'm not gonna be doing it to my engine i just wanted to see what everyone thought of the idea, these new F3 rules haven't been finalised yet anyway, its all still at the proposal stage, i'm just keeping fingers crossed that i might be able to run my 300 legitimately instead of writing '250' on the entry form... Even though most of the other riders who i've quizzed about it have just said; "yeah, nah she'll be sweet as bro, just write 250 on the side and f**king run it!", i don't want to get protested if i end up doing well on it. There's only one guy riding a 250 proddy bike who gets anywhere near the front in F3 and predictably enough, he was the only one who felt threatened and got **** about my bike's engine. He'd be straight in with a protest if i ever got past him in a race. He rides a hotted up KR1 by the way.

How the 300 compares to other proddy 250s is besides the point anyway, its the SV650 pro twins that run with F3 (and win by MILES) that i want to try to compete with... eventually.
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Maybe they should call it F2?! It's hardly F3 is it?!
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Andy.
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Got some info and it seems as though it is not a good idea , the balance is out already , the bike won't want to rev and the cranks will be under even more stress .

A proddy 250 has no chance against an SV , been there done that .
My 300 vs a BMW 800 is a good race !

The UK proddy 250 lap records are comparable to Minitwins records at most tracks.

And they're in held by Aprilia RS250's, RGV250's and the occasional KR1s....you telling me an NSR can't do better?
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Neal wrote:Got some info and it seems as though it is not a good idea , the balance is out already , the bike won't want to rev and the cranks will be under even more stress .

A proddy 250 has no chance against an SV , been there done that .
My 300 vs a BMW 800 is a good race !

Thanks man, yeah i guessed balance would be one of the biggest issues when i was thinking about it.

With regards to the regular 300's performance, i've out accelerated a fair few bigger bikes down the long straight at Taupo on mine. It flew past a standard looking, fuel injected SV650 and clawed its way past a fat dude on an SV1000 too, among other big twins. So surely it can't be far off a hotted up, race prepared SV650? Its got such a massive weight advantage afterall.

To be fair its not gonna matter how fast it is unless i sort my riding out first!
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After years of moaning about immigrants now i am one...

neal,my big carbs fit in my harc pro ramair box
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Hi Si ,
my rhs 38 touches the bottom of the airbox and does'nt fit into the boot 100% , i am doing something wrong ?