Yes, as you all know i am new to all this NSR stuff (but highly interested) and i was wondering wot is the best year for the NSR? wot is better MC18, 21, 28? and if i get a model with a smart card...would i be able to get the performance card to work on the existing electronics? if not, would the "race" electronics make the road gear (headlight, indicators) obselete?
As i have said many times, im sorry for asking so many things - but...i dont know where to start
Ooops i missed the swipe card bit in the tuning section...knowing that the 28 has teh card, im pretty sure to stay away from that model because im guessing the power is resticed and using the hrc card on the stock eletronics does almost nothing (that is what i have from understandng)
So the way i see it is that the MC 21 model is the best (most rewarding) to "Tune" ie. splice, disconnect black bullet plug, port and head polish, port bore, air box and exhaust derestiction....
Also i was thinking of miling the head or using a thinner gasket? would it be worth it (i have the mill and tooling - but is the gain anygood)
Oh and here is a 2 stroke performance tip - not sure if it applies for the NSR...
between the crankcase and the reed valves there may be a spacer, if so remove it and what it should do is that it reduces the crancase volume - this then makes bottom end power lack a TINY bit but increases the top end significantly, also some bikes (not sure for the NSR) if you preload the exhaust valve spring u get better performance in teh top too...
OMG, I don't know where to start, but anyway, the MC28 is just fine to derestrict. If you like the single sided swingarm, then that's the bike for you. Thinning the gasket or milling the heads for a street bike is silly. If you want to race it, then you can think about it. All you're doing is raising the compression and that can be good or bad. It depends on the track and weather conditions that you're racing with. If you're running unleaded fuel, then compression increase can be your enemy so be careful. There are no spacers between the reed cage and case, but you can mill the cases. It's a BIG deal to do, but again, for racing it can be advantageous. The biggest gain in doing so is usually that it allows for greater rpm so you get more power and much more overrev. AGAIN, it's good for racing, bad for the street.
but what about the swipe card feature? does it restrict power? can you bypass it if it in fact does restrict? i also have a feeling that the 21 is more powerful :\
They are the same motor. All NSR250s use the same motor iirc. Anyway, you can derestrict the bike and use the same Honda card or you can get an HRC card and run different fuel for a few more ponies.
1joel1 wrote: All NSR250s use the same motor iirc.Joel
Not even close! The MC16 is different to the MC18, which is different to the MC21. The 28 is quite a bit like a 21, but uses different carbs, flywheel and different port timing.
A lot of the parts are interchangable across the whole NSR lifespan, but sometimes you need to swap several parts over at once to make things work. _________________ MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball
Hmmm, Steve's "test models" for this comment are a wire spliced (so in fact not restricted at all) but otherwise standard MC18 and an MC28 running race pipes known to cut around 6-8bhp from the mid range and no air box lid (also dyno proven to cut around 2bhp from the same area).
In fact an '18 with the same pipes (red trace here) is 2bhp down on a '28 at 8000 rpm, as is a restricted '18.
So if anyone is running a '28 on std but derestricted pipes, an HRC card, modded airbox lid and has optimised the jetting for it they're welcome to post graphs.
But back to the 'card, a '28 will never make decent power on the std card, Tom picked up 12bhp on his 300 by just swapping cards and main jets.
You can run the HRC card if you do the wire splice (bottom of page) but you lose the speedo, oil light and neutral light.
With the HRC loom you also lose all road equipment and a ton of other bits (the fuse box for instance).
Power wise with the HRC card there is no difference between a wirespliced std loom and the HRC one, the splice just removes all the signals the HRC card doesn't understand or like. The HRC loom is just a ton tidier and a bit lighter (and three points in posers).
You can't "bypass" the card, it holds too much info, the '28 isn't restricted in the manner the '21 or '18 is, there is no artifical cutting of the power at higher revs or in higher gears. The ignition curve and powervalve settings are so mild it only makes 40bhp, there was no need to further limit its top speed!
Even advancing the timing (by fitting a '21 flywheel) doesn't restore any kind of powerband.
Fact is well set up a derestricted NSR will make around 61-63bhp, any more than that will require some work inside the engine.
Derestricting an MC18 or 21 is a bit of work the some wire cutters and a soldering iron, (actually an early MC18 has a bullet connector you can just pull apart), a modded airbox lid and some jets.
Derestricting an MC28 requires a £120 smart card, a bit of work the some wire cutters and a soldering iron and either some race pipes or quite a bit of action with the dremel (so I have been told, mine have been done), a modded airbox lid and some jets.
As the '21 and '28 are exactly the same geometry normal thought is the '28 is not worth bothering with unless you want a ss swingarm and the smartcard or think being able to take your rear wheel off in 15 seconds or put your racebike (which of course has no side stand) up on a paddock stand on your own is a waste of time. _________________ Please do not PM me technical questions, if you can't find it on the Forum start a thread
Sorry Fontyyy youre wrong there. Fontyyys HRC jet kitted, race piped, HRC carded MC28 makes 32hp at 8k, a bog stock (in every way) restricted MC18 makes 32hp at 8k lol
See graph and laugh at every '28 owner Thats a fully stock '18 and a '18 with a wire cut and 4 holes in teh air box lid.
_________________ If I have to take the carbs off once more...
So in the end what bike is best to mod? im guessing that if the wire splice works in the way that it mods a standard loom to accept a hrc card (it does? doesnt it?), then id get a 28 (newer).
The only features lost (neutral light, oil light and speedo) are no big deal...lol just use a bike speedo
However, what oil light are you refering too? the transmission of the 2 stroke oil??? either way you can make a simple kit as an liquid level meter from dse...
im not worried about the dremel work, heck ill even will the heads...
Anyway thanks for clearing up most details in your reply!
Reducing crankcase volume has the benefit of increasing the pumping efficiency, so is advantageous all through the rev range. However, the biggest advantage is in the mid range, not the top end.
As the primary compression goes up, so do the pumping losses.
Once the engine has peaked (torque) you're then on a loser, as eventually the high compression in the crank case will outdo the work done by the piston so you can hit a wall.
Look at the difference between a MX engine and a road racer. The MX'er will usually have a smaller volume case as it needs to work at the lower but wider rev range.
It's very in depth, but just increasing the primary ratio isn't always the answer, unless it was too loose to start with.
looking from those graphs nsrs need the midrange lol - thers a fair drop at 8k area - just a matter of milling the case (with setup time and milling time 30mins job - then u have to assemble DOH!!!)
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i missed the swipe card bit in the tuning section...knowing that the 28 has teh card, im pretty sure to stay away from that model because im guessing the power is resticed and using the hrc card on the stock eletronics does almost nothing (that is what i have from understandng)
Thats a fully stock '18 and a '18 with a wire cut and 4 holes in teh air box lid.
