Ns power.

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steve d
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Ns power.

Post by steve d »

I've dyno stuff on modified 400/500.

Here's a run on the 500, earlier this year.

Steve.
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Hondaen
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Post by Hondaen »

A standard NS400R with jolly moto pipes have 62hp at the wheel.

So this means that the 500 kit only ads 8 hp at the wheel ?
Soichiro Honda - "I've never refused competitors' visits to our factory. I've welcomed them at any time. Because I am willing to jump to new innovations when they try to follow us."

wavydavy
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Post by wavydavy »

A standard NS400R with jolly moto pipes have 62hp at the wheel
I find it hard to believe that JMs add nearly 20bhp on their own.

You also need to remember that, to be in any way relevant, dyno runs on different bikes should be on the same dyno with the same correction factors applied and, preferably, the same day.

The 500 kit comes in many guises, too - we don't know what state of tune this on is in.

And finally - it *is* modded quite a lot, isn't it? YPVS on a Honda, eh? :shock: :lol:

Ah.. Just re-read the bit on the pic. Is that "+YPVS reed blocks"? That'd make more sense I suppose than my first read of "+YPVS" "+reed blocks" etc etc

Alastair
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Re: Ns power.

Post by Alastair »

steve d wrote:I've dyno stuff on modified 400/500.

Here's a run on the 500, earlier this year.

Steve.
Excellent. Many thanks for this. It seems that the 500 kit plus pipes adds 15hp over a standard bike's +/- 55hp at rear wheel. To clarify, what state of tune is the bike in? It would be interesting to compare to a standard dyno chart if anyone has one they can scan up.

wavydavy
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Post by wavydavy »

standard bike's +/- 55hp at rear wheel
standard dyno chart if anyone has one
I'd be interested to see one as the only one I ever saw was in PB, reprinted in their 'Best Sportsbike' extra in 1990, which showed the standard NS to be in the mid-40s and down on power compared to a YPVS-F2, hence me previous reply.

Dave

wavydavy
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Post by wavydavy »

Not found the graph yet, but the 1995 PB 'Powerbook' lists their dyno figure as 46bhp@8500rpm(tested Nov '86) and the F2 as 48.5@8500 (August '86)

Dave

Mat Grant
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Post by Mat Grant »

Hi all,

I've got a dyno sheet for a standard NS400, it's peak is 52bhp corrected.

I rememebr seeing in PB (it's in the attic somewhere) that they dynod an NS and go 50bhp, a Stan Stevens tuned one made about 54.

Having ridden the bike with standard tune and Shepherd pipes, I think the pipes do make a massive difference.

If you plotted a curve for a bike that peaked at 65bhp at 11,000 rpm, it's quite possible the same engine would make 50 bhp at 9,800, where the standadr pipes/atac stop the engine.

While considering options I spoke to a number of tuners, the consensus was that Shepherd pipes plus porting could get up to about 75bhp.

Terry told me to not go for tuning the standard barrels, because you may end up needing a replate, so you might as well go for the 500, then the plating that you get is stronger. This proved true when he tuned my 500 barrels, no plating problems.

To be fair Terry himself points out that the 500 gives you more midrange rather than massive extra bhp, that means you're faster out of corners and much quicker over a lap.

Mat.
Mat Grant

steve d
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Joined: Sun Feb 27, 2005 12:46 pm

ns power

Post by steve d »

ns power.
Hi, hope this next graph helps.

Small graph is stock ns v s/stephens - both stock pipes.

Larger is my 400 ( Shepherd pipes plus road tune) versus 500 with similar
tune. Intake is completely standard on both bar jet changes.

The original graph I posted (70bhp) is same spec plus ypvs reed blocks.

400 graph is really worth a few more bhp, (a later jet change felt as if it had gained 2 to 3 bhp, say 63 perhaps).

I was told not to expect alot more at the top end with a big bore, however there seems to be exactly twice as much power at 7000rpm which is quite useful :)

Steve.
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steve d
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Post by steve d »

Ignore the last bit. gain at 7k is more like 17 bhp. :oops:
(eyesight is failing)

30 bhp gain at 10k over stock on first graph though.

Steve.

Alastair
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Post by Alastair »

Once again, many thanks for this. Some of the most interesting information to come up on this forum and something I've been looking for for a long time, a man with real numbers rather than bullshit. Interesting to see the gains made by modifying the airbox quantified.

On the last graph, where you have a 400 with Shepherd pipes and road tune, does this mean that the ports were standard or were they modified to a "road tune".

Thanks

Mat Grant
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Post by Mat Grant »

I've posted real power numbers before for the Shepherd 500 barrels...

Not quite 70bhp though. :(

Mat.
Mat Grant

Alastair
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Post by Alastair »

Apologies Mat, must have missed it. That aside, what Steve has posted up is a comprehensive set of graphs enabling valuable comparisons to be made and this is the first time I've seen something this comprehensive. Can't thank him, enough for sharing.

steve d
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Joined: Sun Feb 27, 2005 12:46 pm

Post by steve d »

Hi, glad you found the graphs useful.

regarding the 400 tune, I asked Terry Shepherd for tuning with the emphasis on top end for road use not full race.

The port widths are short of the maximum and the inlet bridge is intact - this is to give support to the piston. You don't want the pistons wearing out too fast on what is primarily for road use. Compression is increased but suitable for pump fuel.

I guess 'full race' tuning may release a bit more power. It would be interesting to see some dyno sheets from people with these full race porting.

I feel, however, that the stock ignition is holding mine back from any more power increases. I've just completed a small mod in this area but due to shite weather have been unable to test out my theory.

Has anyone got a graph showing the stock advance/retard curve?

Regarding the airbox mods I'm not sure whether the engine appreciated the 3 extra holes or whether it just leaned off the mixture a bit. In any case the gains were small.

Steve

Mat Grant
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Post by Mat Grant »

Alistair - that was just a bit of black humour(!)

btw Steve D - do you still have the bridge on your inlets?

Also I think the carbs have got to be restrictive - if you look at the difference in power between NSR250s - the MC16 has 'NS400' sized carbs, makes 45bhp. The MC18 has larger carbs, plus non circular venturi for even more flow (plus different porting and pipes to be fair) and that makes 60bhp when de restricted.

If you can find two sets of NSR carbs it isn't a difficult swap - Except the carb to reed rubber need boring out - I got this done for £40 by a company in Reading.

I've got BDK 'adjustable' CDIs, they apparently work as standard up to 6000 rpm, then you can adjust the advance. I haven't tried adjusting them though so I can't tell you if it makes a difference.

Cheers, Mat.

Mat.
Mat Grant

Alastair
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Post by Alastair »

Mat Grant wrote:Alistair - that was just a bit of black humour(!)
Doh. Should have guessed as it was you that got the smashed barrels.

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