Hi everybody,

I finally got back from my travels and took the NSR300 to a race mechanic to get it dyno tuned, as the last mechanic jetted it with 125 sized jets, which I wasn't happy with as I felt it was still too lean.

It's now running 145 mains with two spacers under the needles and the dyno chart reads out a maximum of 65bhp. After taking it for a ride on the road I still feel there should be more power, as 65bhp isn't much more than a lot of 250's are getting.

So far I have a set of two up the one side TYGA pipes, TYGA silencers, and four 2cm diameter holes in the airbox with the standard filter and jetted to suit. What should be next on the list?
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MC21 Honda NSR250. TYGA 300 conversion.

Thats about right.

Most I've ever had out of a road 300 is 67hp.
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If I have to take the carbs off once more...

Yes mine made the 67hp and on the road it was very good. To get this the cases were all matched and the barrels had some porting work done to them along with machining the heads to get a different squish band shape. I also had some reed cages made which made nearly 1.5hp so 65hp from a bolt on kit is pretty good.

However after a track day it has now died so i may go back to a 250 providing i can find a decent top end!
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MC21 300
Aprilia RS250 track bike

250 is the way to go.
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If I have to take the carbs off once more...

May I ask why it died? I hear of a lot of 300cc related two stroke deaths and want to avoid this...

250 is perhaps a way to go, not necessarily The Way to go.
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MC21 Honda NSR250. TYGA 300 conversion.

When i have stripped it down i will let you know.
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MC21 300
Aprilia RS250 track bike

Why Stephen? You have a lot more experience than me so I'm curious to hear your opinions. Had considered a 300 kit for a track bike (want to wheelie out of corners to impress the girls you know) but now you've scared me.

Thanks,
Craig

A 300 is fine for 90% for people.

But as has been found they do not produce much more power than a good condition 250 overall.
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If I have to take the carbs off once more...

Rats........Then how am I supposed to stand it on the back wheel like Luca Cadalora coming out of the turns so all the girls go "ooooooooooooh!"?

Lots of detailed work.

A well prep'ed 250 can make very good mojo.

Or

Buy a bigger bike.
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If I have to take the carbs off once more...

StephenRC45 wrote:

Or

Buy a bigger bike.

I tried that and slowed down. Ask SLF-951.... the bike ol bike had me skeeeeered! lol

Craig

I am having my kit ported at the moment and will let you know how it turns out . I don't have a before dyno reading but sure will get a after dyno reading next week !

As T3racing said, his was ported as well as having the heads remechined.

Most I've personaly seen from a fully tuned and reworded 300 is 72hp. Which is still a fair way behind what can be produced by the NSR in 250 trim.
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If I have to take the carbs off once more...

So is the magical 80 + bhp out of reach ?

Well, 72 was produced by a motor with Wiseco pistons, VHM heads, ported barrels, ported an flowed crank cases, rebulit crank, PWK 39 carbs, HRC air box etc etc and built by the best.

You can take it from there.

Of course you could get 80hp if you got a crank figure of some degree.
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If I have to take the carbs off once more...