F3 was a production race class for 250 two stroke 400cc four stroke road bikes in Japan that ran until the early 90's.
Like all production series, the bikes had to be homologated, but the production numbers required for F3 were very low (in the hundreds I think).
All the manufacturers took this series very seriously indeed, made entire dedicated race bikes for it with little expense spared and fielded full factory teams with top riders.
1992 Suzuka 4 hour race.
The earlier F3 bikes (mc16 /mc18) used a large number of RS parts.
But an F3 mc21 shares virtually nothing with either a road going mc21 or an RS250;
There are specific F3 frame, forks, engine cases, crank, barrels, loom, ignition (F3 PGMII), brakes, carbs and a whole host of other parts.
This is the only complete one I know of in the UK. _________________ Please do not PM me technical questions, if you can't find it on the Forum start a thread
The F3 is full-on race kit, nowhere near a halfway house.
The MC16, MC18 and MC21 in full F3 form are (or can be) 100% race bikes. A full F3 shares NO common parts with the road bike, although many of the parts can be interchanged if you mix the correct parts or modify the road parts properly.
Full F3 bikes have different frames, swingarms, engine cases, barrels, cranks, pistons, RC Valves, carbs, ignition, wheels, exhausts, the list goes on and on, even different reed cages and fairing brackets!
1992 onwards was SS/SP only, but there is no reason why a 1992 MC21 cannot be full F3 with 1991 parts. An MC28 can never be F3, as there were no F3 parts produced for it. HRC did have some "special" parts for their MC28's however, based heavily on F3 parts. They were not available to the buying public.
A full F3 NSR cost more than an RS.
If anything is a halfway house, it's the SP kit from the yellow HRC manuals. _________________ Andy.
NSR-WORLD.COM
Please keep all responses to Forum posts on the Forum so that others may benefit.
Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.
I can tell you some TZ's and RS's that would love to have the power of an F3. I kid you not. _________________ If I have to take the carbs off once more...
Yeah, racer38 has one of those RS's, and didn't you test a Dennis Trollop Racing TZ a while back that was less than inspiring? _________________ Andy.
NSR-WORLD.COM
Please keep all responses to Forum posts on the Forum so that others may benefit.
Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.
On our dyno even most normal RS250 NX5's are only around 1-3hp better off than a F3.
Racer38's NF5 RS isnt the only one to be undone by the F3. Infact I have not tested an NF5 yet that is better! Now thats saying something! _________________ If I have to take the carbs off once more...
I agree. If you put proper time into an RS it will of course make more than any F3 ever will.
However everyone always assumes that an NSR is/will always be less powerful than an RS. This is far from the case.
My F3 in full F3 stock trim made 67hp. Very good really but not that impressive. It's taken almost 2 years of near constant development to find the extra 8hp.
Thsts included a 1 off F3 crank, crank case work, barrel work and more types of pistons and head combos than you can imagine. Thats before you get to exhaust work.
I love the F3 for the fact that people find it so hard to believe that an NSR can be so good. Only when they ride it does it show its colours. _________________ If I have to take the carbs off once more...
Yamaha had the RC-Sugo kit for their TZR, Suzonkey had their RGV 'Kit'parts, even Kawasaki had a KR1 kit, I have heard, although only for factory teams...
They also made Kit parts for the 400cc inline 4's _________________ The Chopster
Honda made F3 kits for their CBR400's and for the VFR 400 range though both are quite rare. A NC30 F3 is very good. I've set a couple up that came from Honda America and they were very good. _________________ If I have to take the carbs off once more...
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