I read that running the ns on a track should run a little rich to avoid seizure. What would be a safe jetting size for its mains. The bike is an mc18 and it's stock. Thanks.
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ride it like a horse

If it's running great now, and the plugs are a good safe colour, then you might like to go up one size on both main jets, but to be honest tracks are generally better for a two stroke as you never cling on to flat out in any gear for any length of time - what normally kills a two stroke.

Keep an eye on your plugs after each session, and keep notes on any changes you make with relation to the temperature/humidity/elevation. After a while you'll have built up a decent log of how it runs at any given air condition and can jet far more easily.
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

Estrol there is no safe jetting whats good one one bike at one track at so and such temp etc will seize another bike you can go over the top but then you lose a bit of power last season was a big learning curve for me the cost 2 cylinders but i have now bone 8 races without a prob er till the crank went.
Start rich and see what happens ifb you are rich get a couple of egt sensors.AIM do a nice set up.

Thanks for the advices . This is my first shot on a track and will do it step by step following your advices. FC I read your seizure on the end straight...nasty. The ns250 is a very interesting bike. It actually shocked me when she popped an almost 45 degree wheelie on first (omg!) Backed off the throttle and smacked the fam jewels. Thanks again it's great to be here.
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ride it like a horse

I think it depends on the track very much. I ran a whole day damn hard with one setting at a medium-sized track and then blew the engine riding home calmly on the expressway.
If the track doesn't have monster straights, and you're not hitting top gear for long then you probably have less to worry about than you think.
If you're geared long and have big straights with time spent in top gear then it is really important to get the (main jet) jetting right. If you're not using premix then you can just add a capful or two of oil into the petrol tank.
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MC28 SE -sold-
MC21 with RS250 engine -for sale-
MC21 race bike -soon for sale-

Careful invigiator, what you do by doing that is weaken the mixture (as oil is now in place of some of the petrol) which can tip you over the edge into siezure if you are already close to the limit.
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

A tank has let's say 15 litres at least (pessimistic), and a capful is about 15 ml (pessimistic) so that would change the mixture by less than 0.1%, but probably closer to 0.05% (above estimates pessimistic). Is this significant??
I was given this advice by veteran NSR racers here (after failing to persuade me to remove the oil injector completely).
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MC28 SE -sold-
MC21 with RS250 engine -for sale-
MC21 race bike -soon for sale-

Is that amount of oil going to make a difference then?
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

It's going to give you a lower ceiling (is that a floor?) I would guess. Ther e is a ridiculous amount of NSR wisdom floating about here amongst Japanese racers; I am yet to meet anyone that has been in the game more than 6-7 years that hasn't raced NSRs. Of course that doesn't mean it's correct but they all tell me to do that.

Of course they're all riding CBR600RRs now, or the '05 GSXR1000 or some even the Kawasaki '05 ZX6R but no doubt 10-15 years ago the NSR was THE bike to race. It's almost a joke ... every time I go to the track they praise me to the heavens. When I ask them what I need to do to improve .. they say "get a 600". I don't know if it is specific to my riding style or just the current trend, but I literally can't even think about racing without everybody getting on my case to move on to a good modern 600.

I've been racing a CBR600RR via a team and I have to say it handles almost as well and has MORE lean angle than the NSR and is waaay easier to ride fast. My times are consistently 5% faster with less practise on the bike.
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MC28 SE -sold-
MC21 with RS250 engine -for sale-
MC21 race bike -soon for sale-

Yeah, that's why I switched to a 400 for racing. They're just so much easier 90% of the time.

Still, it's so much fun on the 250 when it all comes together huh?
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

Hello estrol, I have logged in na. Hello guys been reading and have learned a lot.


Query, the race track here in the Philippines is almost similar with the Valencia race track the motogp guys are racing. Our track is roughly 3.5kms in distance and now has been increased with additional 300 meters in the fast lane. We do a 200 kph before late braking and attacking the first corner for a 400cc stock cbr400rr tri-arm with a gearing of 14/40 and roughly a 290 kph approach on a 2002 stock r6 with a gearing of 14/48.


What would be a nice set-up for an nsr250cc (15/42 on a 17 inch rear) like Estrol's? Speciffically on the oil-premix and gear ratio. any suggestions that could help us.



Hope our NSR masters could shed us some light.

I would go with a 16 tooth sprocket in the front and start with the stock 40 at the rear if you're using a stock wheel size. When you are consistently hitting all your shift points in the right places then change to a 39 in the rear and try to hit the same shift points, once you can do that take another tooth out of the rear and so on as you get faster.

To get proper info you'll need to know what your laptimes are at the circuit and see what the locals are running at the same laptimes. Don't try copying the fast guys' sprocket ratios because they won't work for you if you are slower.
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MC28 SE -sold-
MC21 with RS250 engine -for sale-
MC21 race bike -soon for sale-

I just got me an NC 30 and I now have 2 bikes siting in my garage.As I m about to go on my very first track days , let me tell you , the vfr will be the racer , hands down.No seizure fear and less maintenance hassle make the choice obvious for me.As far as rideability goes , I personaly don't care at all , because my main concern is fun and not being competitive. (.Now if I could get my hands on a second MC21 )

invigiator, cool. the top guys here uses the gearing set-up at 14/44. strong take off but comes short on the fastlane... while im using 14/40 for the tir-arm...i lost the championship by a point from my teamate, was leading the series but my suspension gave in at the fast and last corner or the track...damn!


but this time i'm using a stroker, my first time to try it in the track. will feed info's if i pushed thru...will be using the 15/42 on a 17inch tire. will try using a smaller rear sprocket soon.


what is the topseed of the nsr?
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Team Roadmasters

bigfeather wrote:
what is the topseed of the nsr?

I don't have time to go looking for it now, but that was covered in a thread only recently. Look back through the Forum or do a search.

Matt Patterson claims the highest top speed so far, on his SS spec/ram-air Castrol Thailand MC28 at Pretchuap Kiri Khan air field... that's 151mph to anyone in the real world!
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Andy.
NSR-WORLD.COM

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