NS125R-K de-restriction & reed mods

[dan]

Ive removed the bar & plate on the nut on the right side of the engine exuast port & put it back on as described.It allready has a micron tuned exhaust system fitted so i didnt need to drill anything.
This give a good power gain in acelleration & top speed
but it seems to struggle to rev from 7K to 8.5K then rockets away.
Ive richend the mixture a bit but still no gain, does the jets or needle need to be altered?
what size jets etc.
Is there a restricter in the reed block on the NS125R.
Im fitting BOYESEN carbon race reeds, How much power will i gain, are they worth buying & what carb mods might need doing.
Cheers.

[Keith]

Hi
I think the chamber on the exhaust should be blanked off for may power, like the ATAC on an MBX 125. Trouble is you will land up with no low down power.
The reeds will give you no extra power. They might well work better in the midrange though. I am afraid I cannot see how having carbon reeds would help (carbon fibre is only strong in tension, so on a flat piece they would not do much good as they are not tensioned).
I dont think the reed block was restricted at all on the NS. Watch out that someone hasnt modified the reed stops. This can give you slightly better power at the expense of drastically reducing reed valve life, and go too far and you will rapidly loose power
All the best
KEith

[AndyB]

Keith -
I have to say, while getting no increase in low down power, and lots in mid and upper range, I haven't actually lost any lower range power by opening up the chamber. So although its doing you no favours with the lower range its not actually slowing you down at all. if it was a case of lose some lower - gain some upper then I agree that this would have to be weighed up first. But as it appears to be stay the same at lower - gain upper, well it can only be a good thing surely! =)
Dan-
Was you carb rejetted when the exhaust was fitted? Opinion seems to be divided on whether you need to or not in this forum (I've still got the stock exhaust on my NS but derestricted). This could be why you're running with the wrong mixture. You know you can check with the colour of the ceramic on your spark plug? If its running at the right mix then it'll be a nice brown tan (digestive buscuit) colour. Too dark is to rich a mix and too light is too lean a mix...

[Peje]

The carbon is more flexible than the standard metal one's which allows the to open more and let more fuel&air into the engine, no idea bout power increase but im sure it'll make some difference! Keep 'er lit

[Keith]

Hi
For the reeds the main strength is the resin that the carbon is encased in.
Steel reeds are horrible things. Poor power, and a BIG big when they fail and drop lots of shards into the fast running engine. Even the mid 80's MBX 125 used fibre reeds
All the best
Keith