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Power delivery question


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ricey3

 
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Power delivery question

Thu Nov 20, 2008 12:56 pm » Post: #1 » Download Post

Hi, i'm in a question asking mood today.

I'm a recent convert from many years spend riding rs250's and rgv so have a quick question on the NSR, aquired a 21sp, m-max box fitted, std pipes.

Quick comparrison against the rgv is that a lot more midrange is present but does not fly through top end revs as I would expect, just wondered if this was an nsr'ism? power a bit more spread rather than all top end

The rgv's very easily rev out, i'm doing a full strip soon was will check the exhaust valve set up etc, does feel a little strangled and wondered if the standard pipes were a bit restrictive?

Cheers
Brendan
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racer38
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Thu Nov 20, 2008 1:11 pm » Post: #2 » Download Post

Not quite sure how an RGV makes it's power, but the NSR is legendary for it's midrange. I suspect the top end power is similar between the two, it’s just the RGV has **** all low down.

As for pipes, the std MC21 pipes are as good as any aftermarket set. It’s just they weigh about 2.35 tonnes. A nice set of Tyga or Jha’s are soooooooo much lighter. Nikon’s are pretty good too.
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silikesguiness
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Thu Nov 20, 2008 3:08 pm » Post: #3 » Download Post

i had them both at the same time and their diferent in power delivery so as said that could be it as the sp was spot on as i remember mate
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Andy
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Thu Nov 20, 2008 3:33 pm » Post: #4 » Download Post

A delimited, good condition well set up MC18 or MC21 compared to a similarly set VJ21 or VJ22, generally makes a couple more peak HP, but as Racer38 says, the spread of power is a lot wider. The narrow powerband of the RGV is what makes them feel deceptively fast, and consequently, the NSR deceptively slower.

The following were all run on the same dyno. The numbers are unimportant (so it doesn't matter if the dyno is accurate, read high, or read low, as the graphs are all relative!); it's the shape of the graph that matters.

Two well set up, but otherwise untuned NSR's:





Very well cared for RGV250K VJ21 Pepsi edition, comparable to an MC18:



My MC21SE with nothing more than optimised ports (standard shape/sizes), barrels matched to cases, race pipes, and HRC head/jet kit, compared to a ported (barrels and crank cases) and well developed VJ22 race bike with DC valves, Sugaya ignition and Sugaya pipes:





And the two graphs combined:



The 3XV is a far more comparable motor. Like the NSR's design, it is a lot more efficient than the RGV, and very similar in design to the Yamaha GP motors of the same era.
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ricey3

 
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Thu Nov 20, 2008 4:18 pm » Post: #5 » Download Post

thanks guys, comprehensive reply that andy, cheers
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