Ns power.

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ian wright
Posts: 155
Joined: Sun Oct 02, 2005 8:16 pm
Location: huddersfield

NS Power

Post by ian wright »

Hi all,
Last year i built a NS to race & after many nights in the garage & a few hours on a dyno, ended up with 72BHP / 47ftlb torque at the back wheel.
I competed in 6 meetings, the bike never missed a beat until the last meeting where i discovered the crank oil seals were shot!

Full Engine Spec
61mm Wiseco Pistons = 444cc ( No barrel Spacers required )
Transfer ports opened up & lowered to match base of barrel
Heads machined & O-Ringed
NSR250MC21 Carbs / Homemade High/low speed air corrector kit
Standard Airbox. No filter / No air trumpets 130Mains
Modded Carb rubbers
Shepherd kit pipes
50:1 Castrol 747 Premix

Mat Grant
Posts: 357
Joined: Mon Sep 09, 2002 1:01 am
Location: Sandhurst

Post by Mat Grant »

Hi Ian,

Interesting! btw did you try the bike on the dyno with no airbox? I've got mine running with individual ramair filters and 195 mains... With the RGV frame the airbox had to be cut down to smaller than standard.

And did you get a back to back with standard carbs versus NSR carbs?

I hope the guys who are saying the NS crank is rubbish because after 20 years and 44,000 kms the crank is shot aren't reading this!!!

Cheers, Mat.
Mat Grant

ian wright
Posts: 155
Joined: Sun Oct 02, 2005 8:16 pm
Location: huddersfield

NS Power

Post by ian wright »

Hi Mat,
Only dynoed bike with NSR carbs & standard airbox. I started off with a filter, rubber air horns & all the air corrector tubes blocked off =45BHP!
Remove Filter change jets= 55BHP
Remove air horns change jets =62BHP
Join all high & low air correctors together with T pieces=69BHP
Change jets = 72BHP

I did all this last year & have since discovered some aftermarket reed blocks that are worth another 5BHP! Modified YZ85.

Mat Grant
Posts: 357
Joined: Mon Sep 09, 2002 1:01 am
Location: Sandhurst

Post by Mat Grant »

Hi Ian,

Fascinating, really good stuff! - supports the idea that the airbox/filter is restrictive...

Btw I'd be interested to hear about these YZ reeds, and how they are modified....

And I bet everyone else will be interested in what the replacement pistons are from... :lol:

Cheers, Mat.
Mat Grant

Lynton
Posts: 47
Joined: Fri Mar 25, 2005 6:57 pm
Location: Bathurst, NSW

NS power

Post by Lynton »

Ian

What were your various jet changes as you progressed through your modifications ?

Lynton

ian wright
Posts: 155
Joined: Sun Oct 02, 2005 8:16 pm
Location: huddersfield

NS Power

Post by ian wright »

Hi Mat / Lynton,
Jets - Started with 140s & dropped down a couple of sizes on each run till we got the mixture right.
PISTONS! - Wiseco 61mm. These are the ones that are used in the RGV / RS 250 / 300cc Big bore kit & as I discovered work just fine in the NS. Even the cut out in the back lines up perfect with the inlet ports etc.
I paid £90 each, but theyve gone up to £110! now. Stan Stephens stocks them & maybe Vic Eastwood.
Reeds & Blocks are V - Force. You have slot the holes & attack the out of line inlet tract with a Stanley Knife & a grinding wheel! to line everything up. Sounds crude but it works. Try your local crosser shop for these, about £90each a go! Ar well development work / horses are never cheap to come by!

Mat Grant
Posts: 357
Joined: Mon Sep 09, 2002 1:01 am
Location: Sandhurst

Post by Mat Grant »

Thanks Ian,

That's great news that there's a piston that can be used without a spacer - just from the point of view of keeping the bikes running, it means if someone has a siezure, they can get out of trouble, you'd need a replate anyway, you'd just be adding the cost of a bore to the job...

Do you have a part no / model/ year etc for the reed? I think I'll look at geting those reeds... Have you got round to fitting them yet?

Cheers, Mat
Mat Grant

ian wright
Posts: 155
Joined: Sun Oct 02, 2005 8:16 pm
Location: huddersfield

NS Power

Post by ian wright »

Hi Mat,
Dont have a model number, but you need the latest model YZ85 V - force II. Reed & Block come complete as a kit and are well trick snap-together plastic items.
After quite a lot of messing about to get them to fit, I fitted them to the bike right at the end of the season, after id realised my crank oil seals were knackered. Before i put them in the bike, the bike made 62BHP with knackered seals, put the V - Force reed blocks in 67BHP! A rise of 5BHP! & 3ft lbs of torque! Which says to me if the motor had new crank oil seals it would make at least 77BHP & 50ft lb torque! Not bad for an old stink wheel!
Building a full 500 as we speak for this season & using the 444cc as spare / wetbike. If it dont make 80BHP forced air induction here we come. Will hopefully be ready end of May, if i get me finger out!

steve d
Posts: 66
Joined: Sun Feb 27, 2005 12:46 pm

Post by steve d »

Hi,
Good to see others getting stuck into tuning the ns.

Also, it's encouraging to see alternative parts are available.

Mat, I've not been able to visit the site lately but to answer your earlier questions re the Shepherd pipe kit for the middle cylinder, this didn't make much difference, perhaps only shifting the power slightly up the range.

The only changes made before my latest dyno runs were main jets down to 120 and a new air filter plus power jets cleaned.

I may try it again with the yvps reed blocks.

Steve.

Mat Grant
Posts: 357
Joined: Mon Sep 09, 2002 1:01 am
Location: Sandhurst

Post by Mat Grant »

Hi,

I was just doing a search, because I want to get some of those V force YZ85 reeds to add to the changes for my crazy engine build, and found this thread....

It struck me that no one has mentioned clutch slip when tuning the bikes? My NS/RGV (which just has Shepherd pipes, NSR carbs with bigger jets, and ramair filters) slips loads when going from one gear to another, whereas when it was in the stadard NS frame with standard pipes it didn't slip at all.

My NS engine must be less powerfull than some of the 500s that are about, so have people had clutch slip problems? Have people modded the clutch with stronger springs or different plates etc?

Cheers, Mat.
Mat Grant

steve d
Posts: 66
Joined: Sun Feb 27, 2005 12:46 pm

Post by steve d »

Hi,
Yes Mat, mine slipped as soon as it was given extra capacity - even though it was in good nick.

The cure was a h/duty clutch kit ( ebc i think )

Only downside is a heavier action at the handlebar lever ( due to the stronger springs supplied).

Steve.

wavydavy
Posts: 374
Joined: Thu Dec 30, 2004 5:41 pm

Post by wavydavy »

I have had no problems whatsoever from the clutch. Engage gear, give it a big handful, massive forward motion, no slip.

Then again, that's the only part of the bike I've *not* had problems from... :shock:

Yet :roll:

Dave

ian wright
Posts: 155
Joined: Sun Oct 02, 2005 8:16 pm
Location: huddersfield

Ns Power

Post by ian wright »

Funny that the subject CLUTCH SLIP has come up. I did a trackday the other week on the rebuilt 444 & it slipped all bloody day! So just fitted new friction & steel plates [ standard Honda ] + fitted washers under each spring to stiffen it up a bit. Ive got the same again for the 500 ive just finished. Going to Dyno them both back to back in the next couple of weeks, can't wait to see the result, just hope the clutches hold out!

steve d
Posts: 66
Joined: Sun Feb 27, 2005 12:46 pm

ns power

Post by steve d »

Hi,
Here's a recent dyno run showing a small improvement - the previous
run is included for comparison.

Not much change some may say, but it was 20 f hotter than the previous runs - so it may be worth a bit more.

I ran my tzr 3ma at the same time and it was 2 bhp down. The latter ran
65-70 deg. c - slightly hotter than usual.
The ns however, was soon close to red on the gauge.

I should be happy though, finally i have more than Hondas laughable
72 :shock: bhp claim for the stock bike.

Steve.
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ian wright
Posts: 155
Joined: Sun Oct 02, 2005 8:16 pm
Location: huddersfield

Post by ian wright »

Hi Steve,
Dynoed both NS444 & NS500 last week same set up on each. 444 made 72BHP/ 47ftlb, 500 70BHP/45ftlb. Given the extra 50cc capacity of the 500 it would appear a little more tuning work is required! The 444 has an arched cut out to the bottom rear of the piston, I also made the transfers larger, but everything else seems pretty much the same porting wise. Going to try the V- Force reedblocks in the 500 in the next couple of weeks & long term make a set of my own pipes as I still think there is more to come in this area.

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