After my race at the weekend, I realised how underpowered I am.
My pathetic 56.5hp just doesn't cut it at all. In the race most bikes pulled away from me, and some bikes, e.g. the JHA bike walked away like I was standing still.

Even the bikes qualifying behind me were astonished at my wimpy 56.5hp, nobody really admitting to anything below 60hp, and most, significantly above that.

I'm going to post a 10 minute highlights video later, but here's a 2:18 lap mid-race where the JHA rider whomps me in the power department at the end of the lap (I pass him back at the start of the next lap but make a mistake and he's gone in a puff of smoke).

http://invigiator.com/crap/hot_lap_battle_jha.wmv

I'm getting some cylinders ported by a most respectable authority, which should help, but the only other modifications I can think of are:
1) removing the oil injector and going to premix
2) fitting a jet kit (block off power jet, change needle or whatever)
3) airbox is chopped with high-flow filter, but I could remove the lid altogether, or just remove the entire box.
4) carbon reeds
5) remove kickstarter
6) lightened flywheel
7) new/clean chambers and endcans

After that I've done every mod. I know of! I was thinking of doing just (3) and re-jetting. Which of these are going to push me above the magic 60hp mark? I'm not asking for much above 60, and I'd like to avoid creating something that is going to be oversensitive to climate and elevation changes.
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MC28 SE -sold-
MC21 with RS250 engine -for sale-
MC21 race bike -soon for sale-

For Gods sake don't remove the kickstart - you're gonna save a few ounces and have to bump start every time. It really isn't worth it.

You can go to premix for safety sake, but I doubt it'll gain you any power, and suspect it hardly uses any either.

The wire splice or HRC box, decent exhausts, HRC kit and rejet to suit, together with a modified airbox should see you in the mid sixties. Loosing the filter is worth a few HP too - 3 on mine.

Have you hacked off all the un-neccessary bits? Rear subframe, junked the rear brake master cylinder, lightweight racing chain, coolant expansion tank, rear footrests, silencer support brackets, speedo, excess wiring no longer used (lights, horn etc)?

As you only weigh 60kg, I won't suggest you diet!
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

I dont have a kick start in my 21 race/track bike and its pretty easy to start.... as long as i dont flood it. If you remove the kick start lever and all the internals you save quite abit of weight.

Then again I weight about 109kg so I could do with a diet, but I like food to much so the weight has to come off the bike!
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If I have to take the carbs off once more...

StephenRC45 wrote:

Then again I weight about 109kg so I could do with a diet, but I like food to much so the weight has to come off the bike!

dude you know its not the food.....its the beer
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MC21SP - Roth-tax
CBR400 - track
MC21R - sold
MC21SP - sold

Dave Ett wrote:For Gods sake don't remove the kickstart - you're gonna save a few ounces and have to bump start every time. It really isn't worth it.

It's not much weight, but it is rotating mass which counts for a little.

Dave Ett wrote:You can go to premix for safety sake, but I doubt it'll gain you any power, and suspect it hardly uses any either.

OK, won't bother with that.

Dave Ett wrote:The wire splice or HRC box

got the HRC box

Dave Ett wrote: decent exhausts,

Not sure if they're decent. They're old and rusty but I tried to clean the inside, no visible markings, could be JHA or HRC from what the bloke told me.

Dave Ett wrote:HRC kit and rejet to suit,

No jet kit fitted, but I have of course re-jetted, 165 mains I think.

Dave Ett wrote:together with a modified airbox

back is chopped off it and the separator on the inside has been removed

Dave Ett wrote:should see you in the mid sixties.

Hmmm! So why am I down at 56.5?

Dave Ett wrote:Loosing the filter is worth a few HP too - 3 on mine.

It's a dry Daytona high-flow filter.
... sounds like the airbox has to go basically

Dave Ett wrote:Have you hacked off all the un-neccessary bits? .

Some of them.

Dave Ett wrote:Rear subframe,

Nope it's still holding up the rear cowl, which I sit on.

Dave Ett wrote:junked the rear brake master cylinder, lightweight racing chain,

Yep! Light sprockets as well. Magtek wheels ... all rotating mass

Dave Ett wrote:coolant expansion tank,

Nope that's still there

Dave Ett wrote:rear footrests, silencer support brackets, speedo,

All gone, that saved a heap of weight.

Dave Ett wrote:excess wiring no longer used (lights, horn etc)?

wiring is still there, but lights, horn etc. themselves removed, and of course FRP bodywork

Dave Ett wrote:As you only weigh 60kg, I won't suggest you diet!

Thank-you for that consideration.

I've also got tyga high-flow reed stuffers, I blocked off the air bottles under the carb.s, cleaned and adjusted the power valves, top end rebuild, HRC front cylinder head conversion, removed the sidestand of course, clutch and stator covers, even have a small front brake reservoir, RS250 front forks are lighter (i.e. shorter!), lightweight clip-ons, I'm more worried about lack of power than weight at this point.

So if I remove the airbox altogether and fit my newly ported cylinders, then I should get over 60HP? Does the jet kit reallly give you more power? And at what cost to reliability and sensitivity to conditions?
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MC28 SE -sold-
MC21 with RS250 engine -for sale-
MC21 race bike -soon for sale-

The jet kit just gives you more adjustability.

Those mod's should see you over 60hp at least. At the last Dyno Day mine was making 60hp and was running WAY rich just after my rebuild! Don't ask me to go into jet settings though... I just won't do it!

I'm running a wire splice, Ethos chambers (10 year old design now!), Jha jet kit c/w PJ blanks and big mains, foam pod filters, HRC head c/w RS plug, and will be hoping to see low to mid 60's with it still on the safe side at Saturday's dyno test.

The GT Performance dyno is pretty bloody accurate too. Nigel Moss expected 64hp from his MC21 since that was what he got on a previous run after his tuner had sorted it, and guess what, GT showed 64hp presactly!

Something on yours sounds like it's not quite doing it's job correctly I'm afraid!
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Andy.
NSR-WORLD.COM

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I agree, on mine, I had

Tyga pipes,
Tyga stuffers, reed block, reeds.
No air filter,
Huge hole in the back of the airbox (5 inches square?)
HRC jet kit,
HRC ignition box,

And it made 62 when running a bit rich.

Something on yours is not right. When was it last rebuilt? Have you done a compression check?
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

Julian,
I suspect it is your pipes. They are probably the older JHA design, which really makes the bike fall flat on its face at 11k rpm. Peak on those is in the mid-50's, provided the rest of the bike is in top shape.

Or your jetting may be a tad rich, killing the top-end.

Your port job will not net much at peak. The exhaust port timing was not advanced (raising of the port), but the blow-down timing was increased. You should notice the most increase in the 7-8k rpm range, and a tad more everywhere else. Basically, the same powerband you had previously, but beefed up everywhere and more noticable in the low-end of the "hit".

Also, I noticed something about the Daytona filters. They are dual-layer with a paper-thin layer of somewhat restrictive adhesive plastic in between (looked like a sheet of plastic with alot of holes). I was able to successfully peel the layers of mine apart and peel off the plastic layer. I then took some standard sewing thread and sewed the outer edges of the two layers back together. I can remove my entire airbox and notice no difference in power at all, just alot more noise.

Best way to clean the exhausts is to cook them. Red-hot with a torch, or run them through the "cleaning" cycle of an old oven that is no longer used to cook food.
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Paul Herr
'88 FZR4/GSXR/YZF Frankenbike
MY BIKE PICS

Sorry made a mistake with the pipes. The pipes were HARC-PRO pipes when I did the dyno. I forgot that I'd cracked one of the chambers and swapped them. I'm pretty sure that was after the dyno run. So I may have more (or less) power now, but nothing I can notice ... I'll get to the dyno again after next round of minor mod.s.

The jetting I think is OK because I dynoed it with 160 and 165 main jets and the power was about the same, slightly more with 165 mains (running 170 or 175 is noticable too rich just by riding it). Did a plug chop at the weekend on the circuit and it looked good. I've done plug chops a few times at the circuit and showed my plugs to resident 2-stroke experts and they always say they look good.

Top end rebuild was recent. I looked for that layer on the Daytona filter and couldn't see it. I'll look again.

I'll have to reconsider after the next dyno run, but thanks for all your advice.
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MC28 SE -sold-
MC21 with RS250 engine -for sale-
MC21 race bike -soon for sale-

Jha have been building NSR's for a long time, so they know what's going on.

Harc-Pro are (or at least were) big fans of strokers and can also build a quick NSR.

I used to work for Harc, so I'll have to recommend them if you want any tuning work done.

Most of the missing power on the NSR is in the exhaust port. It's too small to make any real power, but just cleaning up all the nasty over hanging nikasil plating can make for a better engine, more power and more rpm.

I gather you have a set of cut cylinders now so it'll be interesting to see how they go.

Unless there's been any changes, Harc pipes should be good for peak power around the 11000 mark, with over rev up to 12500, which in my opinion makes for a better ride around faster tracks than older Jha designs which peaked lower, but gave better mid range.

If you want to compete on equal terms then you'll really have to start looking at a full SP Race set-up. Talk to the guys with the faster bikes and see what they're doing.

Removing kickstart, 2T oil pump etc all give tiny power increases, as well as losing weight. Some say don't take 'em off, but it's a race bike, get rid of them!!

How about going total loss ignition? If regs state that you don't have to have a charging ignition then you can remove the stator so no magnetic frictional losses. Then heat up the flywheel until the glue holding the magnets in melts and flick them out. Instant super light flywheel. Just make sure you've got a good condition, freshly charged battery at the start of every session. Should be goof for at least half an hour.

I'd throw the airbox too, but fit an HRC type air box, or make something similar.

Oh well, let's see how you get on with the new barrels first.

Thanks MAtt.

THe HARC-PRO pipes are history, I'm running the mystery (maybe HRC) pipes right now. I'm not hoping ot compete on a level (bike-wise anyway) with the likes of JHA, but I could definitely do better than I am. There were some total loss bikes there, with quick-change mini-lighteight batteries. I am just not that extreme ... I'll buy a 600 when the NSR gets to be so much work I need a full-time mechanic in the pits.

My bike totally dies at 12,000 rpm, so overrev to 12,500 would be a godsend, especially on one or two fast corners.

I'll post the dyno results in a few weeks.

J
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MC28 SE -sold-
MC21 with RS250 engine -for sale-
MC21 race bike -soon for sale-

Maybe Matt wont do it but I will:

Julian, you need a set of Tyga pipes!! (plug for Tyga there...) The Tyga GP chambers I put on were a very dramatic step in the right direction over my old set of JHA chambers. And they look so great, even after being on there for a few years! When it comes to 2-strokes, there is nothing like having a great set of chambers.
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Paul Herr
'88 FZR4/GSXR/YZF Frankenbike
MY BIKE PICS

Yeah! It's been on the shopping list for some time.

The thing is my NSR racing future is uncertain right now. I may be leaving the country at the end of the year, and I've been coming under pressure from all quarters to move to the ST600 class.

If I do continue then the TYga GP system is definitely going to get ordered. I've been thinking about it for some time.
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MC28 SE -sold-
MC21 with RS250 engine -for sale-
MC21 race bike -soon for sale-

Cool fast ride! I enjoyed watching it.
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Team Roadmasters