I just got my plan to design my NSR250 engine,...1.HRC centure cylinder heads, 2.RS250 short type plugs, 3.wisco pistons/ring/pins, 4. rebult cranck to be stronger and strong accrection, 5.HRC Close ratio SP class gearbox set with 3th,4th,5th, 6th gear /42 sprocket in rear. 6. RS250 coils, 7.TSR.FCC carbone clutch,spring completely set 8. TSR chambers with carbone silences. 9.HRC 030 card to derestricte the speed limit. 10. Special Shift Drum center.Special Stopper Spring. 11. HRC reed stuffers, HRC reed valves 12.Jha Complete carb setting kit. 13.Daytona Turbo Filter. Actually those parts are ready to put on, but before that, just need **** direction to run for it.

What else do I need for speed?
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1996 HONDA RS250
1995 MC28 NSR250 SE red/white/green
1994 MC28 NSR250 sp W/ RS250 engine

Someones been looking at Jamies site.
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If I have to take the carbs off once more...

You can use the standard NSR plugs, they are much cheaper than the HRC shorty units and will provide no power increase. You will just need to trim the plastic if you are running stock plastic with the head conversion.

Wiseco pistons work, but the only ones I know that work are for an '85-'99 RM125 and the pin-to-piston crown distance is short by about 1mm. You will have to have your cylinder bases machined down to get them to work. Heck, while you are at it, you might as well get the 2mm oversized pistons, bore, and replate for a full 268cc NSR. The 2mm over pistons are part number 641M05600. Contact Eric Gorr www.eric-gorr.com , he does the overbore and porting required for this.

The crank has little potential. I have seen the race shops weld the crank pins, but this really does nothing in the NSR where the crank pin is not really a removable pin, but is actually part of one half of the crank itself. I have seen NO upgrades to larger bearings or stronger rods available.

I believe all the MC28 SE's and SP's use the same close ratio gears. Going with the HRC units would be an upgrade, from what Harc Pro told me, but that is mainly due to the "weak" stock 2nd gear. Most people will never have a problem with it unless they are running the piss out of a bike that pushes over 60hp on a constant basis. You can also back-cut the stock units to help the durability.

I have heard RS250 coils will help, but how much? Anyone have some data on this? I always thought the stock NSR units were the best for cost/weight/performance.

The shift drum spring is a good choice. The HRC unit is a tad stronger and helps with the 2nd gear problem.

The shift drum upgrade is actually a lighter weight MC21 piece taken straight out of the MC21 parts manual. Honda has quit production on these and superceded the part number with the MC28 unit, so if you can find the MC21 unit, snag it quickly.

The TSR carbon clutches are the thing to get. Wish I had one. But I have no problems with my stock clutch plates on the street, though I really needed the JHA stronger springs I added. My bike is nearly 70hp.

TSR chambers are actually made by Harc Pro. They are a great design, but have not been updated since about 1996. They have always been the best, but I believe the new JHA's, Ethos, and especially the Tyga's have matched if not surpassed their performance. The Tyga's are definately the best bang for the buck, and one of the best designs on the market.

Get the HRC reed stuffers. Cheap and very effective. Harc Pro sells them for around 500 yen each.

I would advise the Tyga carbon reeds, though. I tried the HRC units and was dissappointed. They helped overrev, but hurt the midrange. The Tyga units gave more overrev and hurt nothing, and you cant beat their price.

The Daytona filter will give virtually no effect on power by itself. The unit I bought was a dual-layer unit, with a restrictive layer of plastic between the foam layers. I had to peel the foam layers apart, remove the plastic layer, and sew the edges to hold them back together. That helped a tad. The best airbox upgrades, though, were to open the inlet, cut a section of the airbox divider out, and install larger diameter rubbers between the airbox and the carbs (hillbilly mod, but it works like open carbs, except that I dont have a dirt ingestion problem).

I had no luck at all with the carb setting kit. This kit is designed for race use, oil injection removed. The ONLY benefit for me was the adjustable needles. The Mains and Pilot jets were all too large for me (mains range from 180-210, pilots from 40-45). I could not get the bike to run lean enough in low RPM and get rich enough in high RPM. Seized her twice at WOT, and got rid of the jet kit. I gained alot of midrange back going back to the stock setup, lessened tailpipe spooge, and my reliabilty and fuel mileage went up. You can order the needles only from Harc Pro if you want. I have the part numbers lying around here somewhere if you need them.

Of course, this is just my personal opinion. I spent alot of time and money trying all kinds of things on this bike while I was in Japan. This bike was my daily driver and weekend warrior for 3 years while I was over there, so I racked a ton of miles trying all kinds of stuff. I you want a reliable streetbike with a great compromise of durablity and power, just follow Tyga's simple upgrades. You cant go wrong. And put a .6mm base gasket on the lower cylinder if you do the head swap.

Hope this helps!
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Paul Herr
'88 FZR4/GSXR/YZF Frankenbike
MY BIKE PICS

hi,paul
Thanks a lot, those infomation are really helpful to me. appreciate..
About the Wisco pistons,I sent my stock NSR piston to Lio in Wisco, they helped me to match it. when I got back my Wisco pictons, they are forged and beautiful also exacetly same!! perfectly matched and I don't need to mod them. But when the engine started, the RPM has little bit higher, Is that normal I have pic that I took to compare with stock piston, they use Kawasaki 125 cc to match, if some one need pic info, page me a message, i think it will wake up your NSR.

I used to contact with Jamie in Japan, I got some NSR knowledges from him, he is a very nice person and knowledged, hope Jamie is on this forum to share with us.
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1996 HONDA RS250
1995 MC28 NSR250 SE red/white/green
1994 MC28 NSR250 sp W/ RS250 engine

Hung do you have a part or order number for those pistons please?.Also did you weigh these pistons are they lighter?.Are they single ring?.

Yes, they are single ring and lighter, part number- Kawasaki KX125 2001-02 GP 2126CS-54mm. This is what I have....
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1996 HONDA RS250
1995 MC28 NSR250 SE red/white/green
1994 MC28 NSR250 sp W/ RS250 engine

The Kawa piston you are using has (I think) the ring stopper pin bang in the centre of the piston. Correct me if I'm wrong. this means that the ring ends will be in the centre of the boost port at the rear of the cylinder.

Although this is not a problem because of the boost port's angle it requires extra maintenence to stop the nikasil plating taking a hammering.

This is the same on the A kit RS125/250 pistons and I found we had to regularly dress up the nikasil on the port top edge with fine (1200) paper as the ring ends start to wear a groove and this can cause the plating to lift up.

Just thought that was worth mentioning.

Hi,Matt
You are right, after I have it compared, the stopper pin is in the centure of piston, also something what I found the differently are Wisco piston has flat top of piston(the top end is like mirror), and single ring that I described at first.
I gotta MC21/MC28 stock trany compared, they are different, MC21 has close ratio and now i have stock MC28 tranny on my MC28, but I will try on MC21 to HRC set, becasue I think MC28 trany will not be very interesting for me, I mean not even rev fast, but smoothly goes, correct me if i'm wrong....
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1996 HONDA RS250
1995 MC28 NSR250 SE red/white/green
1994 MC28 NSR250 sp W/ RS250 engine

Thanks for that Hung.Thanks Matt guess thats not the way to go then bah!.

Quick note on transmissions.

MC21 all models, all years, same transmission

MC28 all models, all years, same transmission.

MC28 has longer 4th, 5th and 6th gears compared to MC21. 1st, 2nd & 3rd are the same ratios.

MC28 gear selector cog heavier and different design to MC21. Smoother change, but MC21 unit more positive.

Both transmissions can be swapped back and forth without problem.

Thanks for Matt, those are very expensive experience ...
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1996 HONDA RS250
1995 MC28 NSR250 SE red/white/green
1994 MC28 NSR250 sp W/ RS250 engine

Wrench, you have PM....
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1996 HONDA RS250
1995 MC28 NSR250 SE red/white/green
1994 MC28 NSR250 sp W/ RS250 engine

Hi Matt
So...we can use 1993~RS125 pistons to fit on NSR250? do they need to mod?
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1996 HONDA RS250
1995 MC28 NSR250 SE red/white/green
1994 MC28 NSR250 sp W/ RS250 engine