Hi just thought I would introduce myself my name is Alex, I am born and raised in Italy but I now live in Japan. I am currently just begining a build of a MC21 NSR from scratch Ive started with just a bare frame, yahoo japan auctions is great cost me 2000 yen! I am a auto mechanic in italy with alot of experience but I have never tried to build a bike from scratch so should be interesting no? haha Anyways I am sure I will have a few questions for some of you eventually!
Hi Alex, welcome to the site. No doubt you'll have lots of questions and no doubt they'll all getanswered here!
What are you planning to build, a stock road bike or a tuned track weapon? _________________ MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball
I wanted a RS250 that can be driven to and from Tsukuba circuit which is only about 40 mins away! As owning 2 vehicles in japan is very exspensive and I dont want a van to go along with my car (1999 mazda rx-7) _________________
Ah ok, so it'll littered with as much RS stuff as you can find eh? Or an F3 with lights on!
Have a look at the F3 Stephen has for sale, it'll give you an idea of how mad you can go! _________________ MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball
yes I saw that I had been looking around for the last couple days! I think fairing wise I will most likely use those Tyga RSW fairing with the lights it looks great!
Also living in Japan rs250 tz250 etc and in general 250cc 2 stoke is very popular so there is lots to be found quite easily so it makes building much easier with more option _________________
On this forum? You're brave! _________________ MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball
Haha well my FD has nothing to crazy just basics for fun it also sees lots of track/street time just has the good stuff covered coilovers, sway bars, LSD, air intake/exhuast, bucket seat, etc etc
I do have one engine question tho I have a mc21 frame do all model of engine bolt up like 18, 21, 28 etc and I come across alot of RS125/250 parts do things like there heads work on nsr crank case sorry if these are dumb questions but I am new to nsr!
oh another thing which swing arm provides the best stiffness/feel I dont care what looks cooler haha I know the single side 28 weighs more is it as strong/stiff as the 21? _________________
mc21 and mc28 engines are the same as far as fitting and working goes, top ends, bottom ends, heads etc. can be swapped freely.
mc18 I am unsure if a whole engine is a straight swap, mc18 barrels do fit mc21 or 28 cases without issue and vise versa.
standard mc16 bits are best avoided
Early RS (nf5) top ends can be made to work on NSR cases but it's not a straight swap, for starters the power valves are not cabled up in the same fashion, RS pistons are a different pin size, NSR pistons will be the wrong height etc. Potentially some big power there if you get it all working though.
That era RS also didn't run on unleaded fuel.
The later nx5 RS250 stuff (the single sided swingarm RS) is totally different.
The mc28 swingarm is actually lighter than the mc21 one if you put them both on the scales.
The extra 5kg (mc21 to mc28 dry weight difference) is not in the swingarm.
The bad thing about the mc28 one is the rear wheels are damn expensive, the good thing is a wheel change is a one minute job. _________________ Please do not PM me technical questions, if you can't find it on the Forum start a thread
fontyyy wrote:
mc18 I am unsure if a whole engine is a straight swap, mc18 barrels do fit mc21 or 28 cases without issue and vise versa....
Early RS (nf5) top ends can be made to work on NSR cases but it's not a straight swap, for starters the power valves are not cabled up in the same fashion, RS pistons are a different pin size, NSR pistons will be the wrong height etc. Potentially some big power there if you get it all working though.
That era RS also didn't run on unleaded fuel....
MC18 complete motor is a straight swap.
NF5 can happily run unleaded if set up correctly, but I wouldn't advise going that route unless you're hard core and really know what you are getting yourself into. _________________ 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.
Finding 5kg in little differences isn't that easy though. The cans are heavy, but they aren't that much heavier than MC21 cans... certainly not 2.5kg each!
The steering lock mechanism doesn't really weigh a lot, but maybe there is more weight in the exhaust system. Whatever... it's all crap! Stick with the MC21 stuff!
Fitting a Pro-Arm to a '21 isn't as straigtforward as it would outwardly seem anyway. _________________ 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.
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Tell me more about your RX-7! 
maybe I misunderstood english is not my first language
