c'mon guys, the possibillities could be awesome, more power and torque, possibly better balance and feel. it could be like a mini sp1/2

Polarbear wrote:c'mon guys, the possibillities could be awesome, more power and torque, possibly better balance and feel. it could be like a mini sp1/2

Sorry, but I don't see it that way. For more power/torque, then why not just buy an SV rather than try and shoe-horn the motor, electrics, throttle bodies, chain drive etc, etc into an already well researched and perfectly good NC30. The NC is 250cc down on the SV and about 12-15 bhp down as well. I'm not gonna knock anyone back that wants to try and get it all to fit, but it'll be a one-off vehicle and I can't see it ever taking off or many other NC owners wanting to copy the idea. A Hond-uki would be so wrong...

all good points, but i'd be first in da que for a test ride at least! doesnt look like its gonna hapeen for a while anyway. ricks 444 conversion still looks like da hottest fastest mod for the 30 at the mo. although, there is a guy near me that has fitted a turbo but is havin trouble with the exhaust, i keep tryin to get him to join this site but he says he's "not into all that computer stuff" shame man.......

I'd be more interested in someone who could mate 2 CBR250RR engines onto an NC30/35 block and into an NC35 chassis. :D

500cc 90bhp[1] 18000RPM[2] V8 anyone?

Druid

[1] Assuming straight addition of the power from two CBR250 engines.
[2] Best to back it down a bit to 18k for safety.

could be done, flat plane crank, custom crankcases, dry sump ..

just like the hayabusa based V8 that radical developed for the SR8*.. but smaller.. you actually get more than just doubling the power of the two "topend donors", cos there's only one bottom end sapping power.. its only a bit.. but a bit is a bit.

but what would you put it in ?

what would be more interesting would be a full bore cutting edge nc30 engine in a one off modern frame..

fuel injection, bigger bore, longer stroke, lightened/balanced/optimised everything > 90bhp @ 15,000 ? in a mini motogp bike ..

zimm wrote:could be done, flat plane crank, custom crankcases, dry sump ..

just like the hayabusa based V8 that radical developed for the SR8*.. but smaller.. you actually get more than just doubling the power of the two "topend donors", cos there's only one bottom end sapping power.. its only a bit.. but a bit is a bit.

but what would you put it in ?

NC35. :D

The CBR250 is seriously tiny, only a 50cc increase across each of the 'banks' infact, hold that thought....

<wanders into kitchen and measures engine on table>

30cm at the widest point of the head (the flange at the side used to bolt it down), 25cm for the rest of it.

What's an NC30/35 head width?

Druid

ok, so a bike ..

there goes the dry sump ..

and the torque would require a fairly hefty gearbox ..

if you're going as far as developing most of a quad cam 500cc 20,000 rpm v8, surely a bespoke frame would be a walk in the park ?

how about minimal frame, just a headstock bolted on one end and a swingarm pivot and shock mount cast into the crankcases ?

single sided swinger (of course) and gp spec ohlins up front, with a carbon monocoque seat unit/tank that clips on the top.

Well quite, you'd probably be better off starting with an VFR750, the gearbox/clutch should easily be up to it.
It would be a real pig of a job though, for a number of reasons.
1) Cam drive - CBR250 runs it off the clutch outer in between cylinders 3 and 4.
2) Power take off - also in between cylinders 3 and 4, end take off on the V4's.
3) Timing gear - on the left side of the crank.
4) Alternator - on the right side of the crank.

Now I suppose making a custom crank will cure some of those problems but then you would still run into problems with the cam drive, unless you run a reverse cylinder bank (and then you run into exhaust/carb issues) your rear bank is going to have the cam drive in the wrong place.
Only way is either to make a custom reversed head or to cut and shut the original, very tricky to do, expecially as the cams are line bored into the head, far easier when it's like the RC24/RC30 with the cams in a cam carrier.

Lots and lots and lots of work for nothing other than having a V8. :D
I'd love to try it just to have it, I could design a fantastic engine and frame combo, no way I'd be able to afford to make it though and without the experience and machine room capabilities to hand it would cost an absolute fortune, like you say though if you're going to go to that amount of grief why not go the whole hog!

Druid

didnt realise (not a honda person) that the cbr's were gear drive cams.. would be tricky, but i've seen someone put a 16v BMW bike cylinder head on a mini, and utilise gear driven cams.. they machined the end of the block flat and mounted CNC'd gears to it.. and the ancillaries, water-pump, oil pump can be mounted anywhere and leccy powered .. ignition pickup's can be tiny and unobtrusive .. so its then just the alternator needs accommodating ..

zxr250 probably a better topend-donor ..

oh to have my own machine shop ..

just imagine the possibilities..

however ... i reckon equipping a machineshop with second hand kit's gotta cost less than a desmosedici, or a posh car .. and with a business plan, you could probably get a bank to pay for half of it ...

or sell your house, move to northwest france (rundown farms for 40k) and set up there ..