I think that this may be a good time to jump in.
The 300 in it's 'normal' state is not for all, as it loses that 250 kick in the pants when it comes on the pipes. It's not that it makes less power, just that the transition from mid to high is not violent like a sorted 250. The rev ceiling is also kept lower due to the heavier pistons/ design etc.
However....
Tuning is of course possible. Andy rode my bike in both it's sort of normal, and stage one guises. Everything worked, but Andy is very hard to please as far as strokers are concerned and the 300 just has big wads of mid range that will stay pretty much where it is unless I make some new pipes.
My latest spec (stage III 1/2) is using a stock (trued) crank, but just about everything else is non-normal. In the top we've got Wiseco slugs in radically altered cylinders with VHM heads running avgas. Still using the normal TYGA pipes, which work great and allow revs up to 13,000rpm, but still give that juicy mid range for the lazy among us.
From the crank back we've got RS250 NF5 straight cut primaries with NF5 clutch and NF5 transmission. Countershaft is NSR so that I can run NSR sprockets, but NF5 could be fitted if necessary. Clutch case cover is NF5 with a plate fitted to fill in the kick-starter bit. Have to push start this puppy.
The water pump is removed and a Bosch electric pump control the flow.
Ignition is taken car of by an NF5 system that uses a NF5/Dash 125 hybrid flywheel. This can obviously be advanced and retarded in the same was as the NF or F3 ignitions.
Carbs are 38mm HRC jobbies, with '92 NF5 big reed valves. Needed a day of chopping the cases to fit these bad boys!
The brain is F3 PGMII with changeable ignition map chip.
Does it work?..........Oh yeah
Was at Bira Circuit this morning cutting a few laps for fun. Came up behind an '03 GSXR750 down the chute and blinking flip I had to pull out the slip stream and pass the big fat fourstroking lump. Yep, I was pretty chuffed with that. Carbs were a jet size rich, but I wasn't gonna mess with that. Could've also done with filing half a tooth off the rear sprocket, but this is a street bike so I couldn't be bothered.
Could be faster of course, if I knocked up some specific pipes for the tune.
Probably '91 RS250 NF5 pipes would be a reasonable choice. I used these as a base for some pipes we made for tuned NSR a couple of years ago and they worked really well, but in true RS fashion it was the mid range that jumped ship and ran to hide up in the 12k band
Basically, the TYGA NSR pipes are designed for peak around the 11500 mark, with good mid range and good over rev, but my 300 cylinders are cut to work in the 12k+ arena, so I've a good mind to shorten the pipes a tad to shift the tuned length up the scale to match the cylinders closely. Mid will suffer but I don't think that will matter too much. This motor was pulling clean as a whistle from 4k up to gear change at 12,500.
So can it go further?
I think it's possible.
The first issue is of course the pipes for a modified cylinder, but this also rings true too for a modified NSR250 cylinder. One other 'problem' is the stock NSR crank. It's ok, but it ain't an NF/F3 crank by a long shot. The problem with those (NF) cranks is the rods, or more specifically the small end size, but there are no rules, so it's possible to fit the NSR rods onto the F3 crank and go from there. Another good point here is that I've just found a bloke forging rods. His samples looked pretty good, so I'll give him an NSR rod and see what he can do.
Ignition is quite a simple task of throwing away the stock electrics and fitting a fully adjustable unit. However, getting one to work with the stock harness as a plug 'n' play is proving a bit of a pain.
What else can we do? FI? HRC tried and abandoned it. Fast but fiddly. Bimota got it all at 6's and 7's. Megasquirt claim that their system can be set up perfectly with patience and experience, but I doubt it's ever gonna be that much better than a well set up carb. TPS etc mapping would be handy though.
Oh well, I guess I'll have to think up something else to please Andy.
Got my eye on a 50cc two stroke mini Motard. I reckon with a bit of whizzing that could be making some serious power up around the 14,000rpm mark. Oh what fun that would be