Loss of mid range torque..?

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pf85
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Bike owned: VFR400 NC24
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Loss of mid range torque..?

Post by pf85 »

My NC24 has a sports can and a large exhaust pipe which creates a brilliant noise especially at high revs but the bike is lacking a lot of mid range torque :down:

Would it need re-jetting? Or what needs to be done to regain the mid range?

The exaust is twin port so I tried blocking off one of them to see if it was back pressure related but it didnt seem to make much difference..
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porndoguk
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Re: Loss of mid range torque..?

Post by porndoguk »

id recomend doing cammo's guide to rejeting carbs, which will also show you about lifting the needle height and drilling a 0.5mm dia bigger hole (2.5mm dia) to help cure the midrange flat spot it does work as ive done it to mine.

Rick
pf85
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Re: Loss of mid range torque..?

Post by pf85 »

Yes ill take a read through it and possibly give it a go if I can do it.. :pray:

A company quoted me £100 for the rolling road dyno tests and to tune it
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CMSMJ1
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Re: Loss of mid range torque..?

Post by CMSMJ1 »

NC24 carbs are not quite the same as NC30 carbs...so be wary.

What else has been done to it?
IMPERATOR REX ANGLORUM

The V4 is the law..

NC30 - No9 - my old mate
Neosophist
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Re: Loss of mid range torque..?

Post by Neosophist »

rickyb_dj wrote:id recomend doing cammo's guide to rejeting carbs, which will also show you about lifting the needle height and drilling a 0.5mm dia bigger hole (2.5mm dia) to help cure the midrange flat spot it does work as ive done it to mine.

Rick
No don't do this to an NC24 at all!! If your bikes running propely you shouldn't need to touch the slides!

The NC24 has round bottom slides which the NC30 HRC slides are based on (may infact be the same part :P)

The NC24 slides have two small holes instead of one small hole like on NC30 slides (so they don't need drilling)

The needle profile is also different so doesn't need lifting up (it'll make it far too rich!)

...unless of course you already have problems, then you might make it better in a fashion, but your robbing peter to pay paul....

Unscrew the pilot screws half a turn each and go from there..
xivlia wrote:i dont go fast on this bike so really do not need a rear brake.. /
vic-vtrvfr wrote:Ask xivlia for help, he's tackled just about every problem u could think of...
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porndoguk
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Re: Loss of mid range torque..?

Post by porndoguk »

Neosophist wrote:
rickyb_dj wrote:id recomend doing cammo's guide to rejeting carbs, which will also show you about lifting the needle height and drilling a 0.5mm dia bigger hole (2.5mm dia) to help cure the midrange flat spot it does work as ive done it to mine.

Rick
No don't do this to an NC24 at all!! If your bikes running propely you shouldn't need to touch the slides!

The NC24 has round bottom slides which the NC30 HRC slides are based on (may infact be the same part :P)

The NC24 slides have two small holes instead of one small hole like on NC30 slides (so they don't need drilling)

The needle profile is also different so doesn't need lifting up (it'll make it far too rich!)

...unless of course you already have problems, then you might make it better in a fashion, but your robbing peter to pay paul....

Unscrew the pilot screws half a turn each and go from there..
ooops i didnt clock its was an NC24 sorry fella ignore me!
pf85
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Bike owned: VFR400 NC24
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Re: Loss of mid range torque..?

Post by pf85 »

CMSMJ1 wrote:NC24 carbs are not quite the same as NC30 carbs...so be wary.

What else has been done to it?
I'm not sure of all the work which has been done prior to me buying it but here is some:

-Single Seat tail conversion
-Sports Can and Pipe
-Modified Fuel tap (Vacuum pipe has been closed off?)
-Resprayed in White
-Smaller front sprocket (Quicker acceleration)
-Braided hoses
-New Tyres and Brakes
-New Screen
-New Suspension

I'll upload a couple of pics when I get the time
pf85
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Re: Loss of mid range torque..?

Post by pf85 »

Just on this issue.. I took the bike out for a good run yesterday and I noticed that the mid rpm has improved slightly.. ?

The only change I made to the bike was fitting a new R6 RR

Im going to try using some super unleaded (99ron) to see how it runs with that. Should NC24's need super unleaded to run properly as they are jap bikes and are probably setup to run on higher ron petrol than the standard unleaded we have here?
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CMSMJ1
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Re: Loss of mid range torque..?

Post by CMSMJ1 »

They are set for 91 RON I believe.

99 ron does nothing apart from cost more...IMO

unless you have detonation then it is a waste of moolah..
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Neosophist
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Re: Loss of mid range torque..?

Post by Neosophist »

CMSMJ1 wrote:They are set for 91 RON I believe.

99 ron does nothing apart from cost more...IMO

unless you have detonation then it is a waste of moolah..
+1 :)

91 is the necessary minimum RON.

99 RON won't give you any more power, it will detonate at a higher temp / compression (which isn't needed on this bike)

Regular '95' grade is more than enough
xivlia wrote:i dont go fast on this bike so really do not need a rear brake.. /
vic-vtrvfr wrote:Ask xivlia for help, he's tackled just about every problem u could think of...

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