Hi all,
Just got myself a mc21 sp. Engine runnining fine at present in standard form. Am enquiring with stan stephens about a stage 2 tune. Want to put some tyga performance exhausts on, want to know what else I need to consider when doing this. Any advice will be appreciated as this is all new to me. HELP!

Martyn

What on earth do you want a stage two tune for when you haven't even de-restricted it yet?

Hold off on that tune until you've done all the goodies to unleash the proper power. You should get 62-65hp withough any need for filing stuff.

If - having ridden the full power motor - it ain't enough, then by all means think of the tune, but you'd be better getting the 300cc kit if it's a road bike you have...
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

i am with dave on this one
very quick little bikes when derestricted
if you have a look about the website you will all the info to do it
mines doing just over 60bhp at the rear wheel with no tuning at all just deresticted
wire splices
head conversion
set of pipes
modded air box
jet kit

i am in essex if you are around that area pop in say hello

If you still feel the need for port work after derestricting, you could do an awful lot worse, and I mean much, much, much, MUCH worse than going to someone like Bob Farnham or Terry Shepherd (Link here... ) - if you get the hint! ;)

Andy.
NSR-WORLD.COM

Thanks to dave,nigel and andy,
As you have probably figured from my first ever entry to this forum, I am new to nsr's. This is a project i am taking on, plan is to get this bike running sweet first, then look at the visuals. Been using tyga ref for most of the parts, so I have purchased a set of chambers and end cans from same. Having started reading all the info, changing these is not straightfoward. Can someone tell me the order of things i need to do to make this work with the bike as is. Your advice will be appreciated.

martyn

do nothing untill you have derestricted the engine. ride the bike for a bit and get used to the power, then fit your pipes and jet the carbs. the pipes will make little differance to a restricted engine. and you,ll need to know what the engine runs like, before you play with it or you never know if your making it better or worse. see the problems stephen rc45 had. do NOT fit the pipes and leave the jetting , you'll melt a piston

Hello Martyn
Martyn to get the NSR above 65+hp one thng you will need is $$$$$$$
First question is it for road or race?
1. Derestrict the engine (electrical) this is a MUST
1.a. (for race) buy a HRC wiring harness with derestriction box it also advances the timing.
1.b. If for road, buy a posh derestriction box.
1.c. if for road the cheapest way is to do a wire splice.
When you do one mod the rest must be done.
2 Get a aftermarket exhaust Tyga is the way to go.
because you have allowed more gases to ecsape you need to let more fuel in so.
3. (for race) buy a pair of pj38 carbs and jetted it properly.
you have nw allowed more fuel to get in so you also need more air to flow.
3.b. for road buy a hrc or jha jet kit.
4. mod your airbox to allow more air to rush into your carbs.
now if you still have money
5. port the exhaust ports to 1990 rs250 specs
6. buy a set of HRC or Tyga stuffers and cabon reeds.
7. lighten your flywheel for increased acceleration
8. buy a set of rs250 coils NOT CHEAP
9. do a f3 head conversion
now if you want to go further
10. machinen the heads to get higher compression and run avgas.
11. take the bike down to the drag races and pink slip your bike against any 600-750cc rember change the gearing and if all goes well you will have a few new bikes to sell.
But the best way is to just buy a 90-92 rs250 engine and pop it into the frame it's alot cheaper

That's pretty serious stuff K!

For mine, I fitted the TYGA race pipes and stuffers, HRC de-restriction unit (modded the loom to fit the standard one) and jet kit, cut a huge chunk from the rear of the airbox (about 4" square) and the web from the lid, and ran no filter. It was making 63hp at the wheel, and was fast as phuck!

The HRC unit means I didn't need to do any splicing.

All in was about £500 including shipping. And worth every damn penny!
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

Thanks guys,
Couple of points:
K you are one scary guy Sounds great though, by the way its for the road.
Jeff & Dave Thanks for the direction, I like the sound of what dave has done, budget will allow. Problem is have read the detail on jetting, not at all confident, as for a mod to the loom again not confident, is there anybody who can do this for me dont know anybody in wales.

Appreciate the help

Martyn :

Where in Wales?

The wiring mods really are easy, and the detailed steps on the site very good.

As for jetting, you can either send it to a dyno man, and pay to have it setup, or with patience you can do it yourself. The basic rule is start big and drop a size at a time until the engine runs sweet and the plugs are a good tan colour. Then, to be safe, go back up a size and you'll decrease the chances of you seizing...
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

hi dave,
Living in Swansea, South Wales

Been studying the wiring, probably be able to do that.
Jetting though, dont know.
Can you suggest someone, dont mind travelling to get it done right.

Martyn

There's a couple in Bristol, but I don't know of any In Swansea. Bristol too far?
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

Thanks dave,
Bristol is fine, be grateful for the names and numbers.

regards

martyn