Modified Honda NSR 150 SP Repsol Pro Arm 1996
Modified Honda NSR 150 SP Repsol Pro Arm
If you: love 2 strokes, the NSR, IS the only worth-while 2 stroke in Thailand with OEM parts cheaply and readily available from Honda dealers.
If you buy one for about 25,000 baht, The bike will look ok but after inspection and driving it, you will start to notice the many flaws: piston and cylinder needing replacement, RC valve clogged with carbon, improper fasteners, worthless shock, forks used up needing new internal parts and oil, radiator in poor condition, poor braking (even by it’s original design), useless IRC tires, all cables and fluids needing replacement, corroded surfaces, rusted nuts and bolts. Cracked/scratched farings, deteriorated rubber parts like coolant hoses, seat bumpers, mounting grommets to mount the coil, oil tank, RC motor, etc. Forks needing to be rebuilt. Drive chain used up. That’s simply what happens after about ten maybe fifteen years, especially with most previous owners here in Thailand not taking care of their bikes and initial build quality compromised to keep costs down. The non Pro-arm version (RR) has a different cylinder, is slower, and even older.
Imagine: You fix every issue you find buying proper Honda OEM and high quality parts, then add a host of performance upgrades. Then you have a bike like this one with about 100,000 baht total investment. When you ride the bike, you know this cannot be a stock 150. You can do roll-on wheelies, stoppies, and burnouts. However I’ve only done these things for the proof of it, I do not drive it this way daily.
The 2 stroke acceleration with the modifications is such a rush, especially comparing to any similar size/displacement bike here in Thailand, you will find yourself redlining through all six gears, slowing back down in mere seconds using the big front brakes – to first or second gear, and repeating over and over again. Just listen to video number two below. Easy clutch pull and throttle operation, sensitive, powerful, but progressive braking , and quick short throw shifting thanks to all the new parts, you become one with the bike, and no 4-stroke engine braking when you let off the throttle.
Work done /parts replaced:
Parts are Honda OEM unless specified
- Honda/Keihin NSR (MC21) 250 32mm flatslide carburetor with custom machined fuel inlet adapter and aluminum intake spacer (both pieces one-off). Carburetor is fitted with special hard to find HRC jet kit with adjustable needles, and a wide range of extra jets are included
- Tyga Performance full exhaust
- New piston with polished crown, pin, rings, bearing
- New cylinder with Tyga porting, head studs, exhaust studs, gaskets, and cylinder nuts
- New head with Tyga combustion chamber reshape, head gasket, new temperature sensor, and head nuts
- Flywheel lightened by Tyga performance, new flywheel nut
- New Real Brembo 4-piston front brake caliper and Tyga billet bracket, new front rotor (disc)
- New Michelin Pilot Sporty front 90/80-17 and rear 130/70-17 tires
- New gold DID X-ring chain
- Rear sprocket +2 teeth for better acceleration
- New radiator, coolant tank, all water hoses, fuel hoses, all hose clamps (stainless steel)
- New Tyga windscreen and high output Osram headlight bulbs, also new mirrors, new hand grips
- Forks removed/disassembled/reassembled with new internal parts and Motul Synthetic 10W oil
- New Front and rear braided stainless steel HEL brake lines
- Rearsets (for gear shift and rear brake) and extra replacement parts
- ALL new cables: clutch, throttle, Tachometer, RC valve, 2T autolube oil pump
- ALL rubber mounting grommets, seals, seat grommets
- New reed block and reeds and intake gaskets
- New rear wheel nuts, sprocket nuts, 30mm Pro-Arm lock nut
- New front brake master cylinder and adjustable front brake lever
- Polished aluminum swingarm, top triple clamp, handlebars, sprocket carrier, passenger pegs and passenger/exhaust mount brackets
- YSS special export racing rear shock (MX302-285TRCL is the part/model number-unavailable in stores). Shock is adjustable for length, preload, compression, and rebound, external shock reservoir located under the seat
- New Ignition Coil, bracket, bolts, spark plug cap
- New Rectifier
- All new Honda OEM, and stainless steel faring fastener hardware, new air intake ducts
Other stuff:
- Extra cylinder and head (used)
- Assorted Honda OEM nuts, bolts, gaskets, seals (new)
- More new rebuild parts – complete set of bearing, gaskets, seals, and springs, to rebuild the oil pump, water pump, clutch, and rear sprocket carrier
- Owners manual, Parts manual, Shop Service Manual
YouTube videos:
Contact number 085 784 5310 or email puutlen@gmail (dot) com
Images:
(click for bigger images)
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- right side view
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- Tyga Performance full exhaust
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- YSS special export racing rear shock (12,000B)
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- New head with modified shape and squish band (vs. old)
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- NSR 250 MC21 32mm carb
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- New cylinder with porting and all new power (RC) valve hardware, new head and exhaust studs, all new gaskets, all new cylinder and head nuts
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- new piston with polished crown
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- NSR 250 MC21 32mm carb fuel inlet adapter custom made
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- NSR 250 MC21 32mm carb adapter custom made
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- NSR 250 MC21 32mm carb installed
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- Polished Pro-Arm and carrier, +2 sprocket, DID Gold X-ring Chain, Hel Braided steel brake line, YSS shock, rearset gear lever and footrest
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- Riders’ view showing polished triple and handlebars, new windscreen, grips, and mirrors
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- Brembo 4 piston caliper, billet adapter, Hel braided steel brake line
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- HRC service/shop manual, complete parts manual, owners manual
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- Right side view engine
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- Left side view engine
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- Right side view
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- Left side view
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- tyga carbon fiber tail
Thai Motorcycles 
March 28, rode the bike today and reached the 800km mark after the rebuild.
Reached a speed of 180km/hr on the canal road in Chiang Mai, didn’t glance at the tachometer as I had to avoid some obstacles. Remember that’s with 2 teeth up on the back sprocket, LOWERING the overall gearing (slower top speed).
In 4th and 5th, verified motor still pulling strong at 12,000 RPM. Stock redline is at 11,000. Ah, the sound…
How can I go back to a boring 4 stroke?
March 28, 2011 at 9:40 am
Did a few rides, now the bike has about 1,200km since the rebuild. Did the Samoeng Loop ride through the Chiang Mai mountains, hundreds of turns, up and down the mountain, cool air, pavement in great condition, some 4th gear turns with the throttle pinned, about 140km/hm engine screaming and happy at 11,500 RPM I’ll never go back to a 4 stroke – even a 600cc sportbike would be too much bike for these roads and a waste of money. And all the others (CBR, NINJA) just accelerate too slowly and NO top end 2-stroke rush.
April 8, 2011 at 4:12 am
Ordered every single part for a complete clutch rebuild (preventative) including bearings, thrust washers, gaskets, oil seals, springs, metal and fiber plates.
Will do this at the honda dealer at the same time as rebuilding the water pump, replacing all the 15 year old 2T oil injector hoses and new 2T oil tank.
Received the new fuel tank and ordered more bodywork.
I will have the only (partially) white NSR: upper cowl with stickers, and lower cowls with stickers.
I’ll have clearcoat over the stickers. It’s going to look awesome, especially with the one piece Tyga one piece carbon fiber tail painted white with the stickers and clearcoat.
Looks, as well as performance. These bikes were 60,000 baht new 15 years ago, mine is almost much better than new already. Soon it will be 99.9 percent new. Plus the extra 12-15 horsepower.
MORE PICTURES TO BE POSTED….SOON
April 8, 2011 at 4:17 am
Put on a new coil, coil bracket, bolts, spark plug cap, and a new rectifier.
Received rear brake pads.
Replaced the “stupid ugly” front fender bolts with Honda OEM and stainless steel ones.
Received the new front brake master cylinder.
May ride the Samoeng loop again today.
April 8, 2011 at 4:24 am
Today ordered all new bodywork!
The real color is Jerez blue, and soon the bike will be 100% new bodywork.
I’ll also have 2 complete sets. For track day riding I can use the old set!
April 15, 2011 at 12:22 pm
TIRES: Looking to get a shop to import Japanese made tires, either Dunlop TT900 GP or Bridgestone Battlax BT39SS in the proper sizes.
The Thai manufactured tires are crappy in comparison, and the NSR needs cornering grip especially when getting on the gas exiting turns with all the extra power from the engine mods. Good tires are obviously worth any price I have to pay to get them.
The NSR uses tubeless tires: 90/80 front and 120/80 rear to fit the standard 17″ rims. The stock tires are Thai made IRC brand and supposedly too hard for performance, but last a long time.
And when they let loose (slip), it is suddenly and without warning.
April 15, 2011 at 12:50 pm
Found Bridgestone Battlax BT39SS in the proper sizes from Japan that can be ordered from a local shop, I hope. About 8,000 baht for both front and rear, for great turning ability and SAFETY! Could save my life the way I drive. Will order soon. Then I’m gonna look for a second set of wheels.
April 21, 2011 at 7:30 am
New order:
Tyga one piece carbon fiber tail section
HRC RS 250 rear brake fluid hose/reservoir
Tyga billet aluminum top triple clamp
Tyga billet aluminum key holder
Tyga billet aluminum top triple clamp nut
April 21, 2011 at 9:44 am
Hi, nice bike and vids! I want to do something with my NSR and obviously wanted to start with airways – where did you source the carby for yours? Im in Australia and not finding parts and info easily.
Cheers
May 19, 2011 at 11:46 am
Hi Dale,
I got my NSR 250 MC21 carbs from ebay in America. Price was $99 USD.
I was lucky it already had the HRC jet kit parts installed: adjustable needles, power jet blank, etc…
But it is best to start with a pipe. You’ll be amazed with the power increase, and much easier to find or put on the bike than a bigger carb.
Also you need only one carb, make sure it is the one with throttle cam to which you attach the cable. See the picture on my website.
If you buy a set of carbs, you separate them, and after taking out the floats and jets from the “other” carb, is pretty useless (for the NSR 150 SP).
Then you need a spacer and a fuel inlet adapter either custom made or bought (but I don’t know where).
Jeff
June 8, 2011 at 8:53 am
I found the carb on ebay.
June 28, 2013 at 10:06 pm
Hi,
What a great read! I myself also have a blog, specially dedicated for my nsr SP. I’m quite surprised that there’s still an NSR fan out there, who really knows what they’re riding, like you!
We can exchange a lot of information. Currently i’m using my nsr to race the Malaysian Super Series, hardly competing with those fast Kawasaki KIPS.
Oh, and the Battlax BT-39ss is easy to find here, no need to order directly from japan.
Cheers!
June 8, 2011 at 8:49 am
hi,what a wonderful…. i already bought a NSR RR but in very poor condition, already “dead” for almost 3 years..
i try to look spare parts around my neighbour hood but.. it’s too hard to find .
pls someone help..i want to convert my RR to SP…
June 9, 2011 at 3:01 pm
Hi rai,
Where do you live? If I were in your position, I would sell the bike you got, and buy a newer “SP” model.
Be patient and wait to buy one in pretty good condition. Expect to spend more money to get it looking and running good!
Jeff
June 9, 2011 at 3:39 pm
Contact A.P Honda in Samut Prakhan. 02 725 4000. Ordered body parts today at my local dealer here and i have to wait approx 2 weeks for them.
July 11, 2011 at 11:15 am
you cannot use the SP cylinder on an RR model, it will not fit, as far as I know.
June 28, 2013 at 10:07 pm
this its really great.
I stay in korat thailand,and they have here a 2 stroke club.
Some thaI they a really craizy about this bikes here.
I own a sp to,its a great bike.
Keep posting here.
June 14, 2011 at 12:01 am
hi,
where did you buy/make the custom made carb adapter? i need one of those!
Red.
June 21, 2011 at 9:32 am
I had a friend with a machine shop make that, and you need a fuel inlet adapter, and a manifold adapter too. And you need to know the correct sizes.
I didn’t know about the these parts until i tried to fit the carb, but he did because he’d made them before.
Jeff
June 24, 2011 at 1:50 am
Can a nsr sp block fit on nsr rr? Any modifications needed? And are the head of sp and rr are the same? can it be fit on rr? I interested in mod it. I can found many spare parts in Bangkok since i live in Malaysia so near to Thailand.
January 2, 2012 at 6:23 am
By block you mean cylinder, yes I think so, I’d buy a new head also as they are only USD $30. The Cylinder new is about USD $150. In Thailand anyway. You need to connect the powervalve cables but I don’t think you need modifications. I haven’t done this personally as I stay away from the older model.
NEW – I think I am mistaken and the cylinders are not interchangeable.
February 6, 2012 at 10:44 pm
Very sorry, I have promised not to release this information.
February 6, 2012 at 10:36 pm
I had a friend who knew exactly the size needed, make it using a CNC machine, as a really huge favor fro me. If you get the spacer wrong (it’s not really an adapter, the bolt holes are the same) I doubt it would run. Another friend had this exact problem trying to convert his bike (Honda CBR 150, 4-stroke, in Thailand) to a Flat slide carburetor with a shorter carburetor intake length … tried every jet combination, had to give up..
June 28, 2013 at 10:13 pm
how much did it cost, and most importantly can he make 1 for me?
June 27, 2011 at 8:31 am
he cannot. it was a personal favor. Sorry.
February 6, 2012 at 10:40 pm
What a lovely bike. Just bought an old 150 RR,,,, condition not good. But bought for the reason to build it up and keep myself busy after work and weekends. Yes, the Sp i agree is a faster and more sought after bike. I live out Khampaengsaen way(Nakhon Pathom), Nice to hear and see other farang here enjoy 2 strokes…lol
July 9, 2011 at 11:12 am
Thanks philip.
June 28, 2013 at 10:16 pm
Hey iv also got a very clean repsol !
Wanting to mod her..
Loving this read 🙂
July 18, 2011 at 11:13 pm
Thanks.
February 6, 2012 at 10:39 pm
Thanks Jason!
June 28, 2013 at 10:18 pm
Hi Can i ask what jetting you used in the nsr250 carby and are you still running the powerjets? i have just installed the same carb but cannot get it to rev over 7000rpm. i am using standard jetting thanks.
February 6, 2012 at 12:16 am
sorry I can’t remember, it was much leaner than standard. I also had to play with the needle clip and slow jet, and make SURE the float height is correct. I removed the powerjet and blocked it off with a ‘blank’, you can also fill in a regular one with “JB Weld”. It sounds like you’re way too rich, but I don’t know what it revved to before. You need a big fat spacer between the carb and manifold or it will not run correctly.
February 6, 2012 at 10:34 pm
Hi there, love to see all the works done to your bike. That’s really a beast. I’m riding Phantom 150 which use the same engine, but slightly different gearbox. Enjoy the bike vey much, but the stock pipe is choking its power.
Is Tyga cylinder and cylinder head available in Thailand? How much are they?
February 13, 2012 at 4:32 pm
Sorry but the phantom is nothing like the NSR. Nothing is similar about the 2 bikes at all, for example, your bike is a heavy, 4-stroke cruiser, and the NSR is a 2-stroke, lightweight, performance bike. I’m sorry someone gave you this incorrect information.
Cheers,
Jeff
February 14, 2012 at 1:26 am
Hi Jeff,
There are 2 version of Phantom in Thailand and Singapore, 4 and 2 stroke. Almost identical body parts & frame between the two. Mine is 2 stroke engine, exactly the same cylinder with SP150. Using the same cylinder block, head, RC valve, reed valves & reed blocks, radiator, 2T pump, but different carburetor, pipe, piston, gearbox, possibly ignition.
So do you have information about getting Tyga cylinder and head in Thailand? The price seems much better than the USA supplier, I checked their website.
The phantom is definitely heavy, at the moment top end max out at 140 km/hr. with Vapor digital speedometer. Well, it’s a 10 years bike bone stock. I’m in Singapore, and it’s very hard to modify or use racing expansion chamber because it’s illegal. S$500 fine. What I did was only gutting out the chamber which helps the low end pretty good. But I need more boost. Thinking of modifying the silencer because stock ones is very restricted as well. That one I can do.
I’d like to try the cylinder though. Will appreciate any help. Thanks!
February 14, 2012 at 2:39 am
I bought my cylinder and head from my Honda Dealer, not from Tyga. But you can Google for the Tyga website if interested. I don’t know anything about Singapore bikes, sorry!
February 14, 2012 at 4:23 am
Reading frm the ‘works done list’ I thought you got the cylinder with Tyga porting, and head with Tyga expansion chamber.
You mean you bought them already modified off the shelf from Honda dealer , or bought stock then DIY porting etc to match Tyga spec?
February 14, 2012 at 4:47 am
Nope. As I said – I bought my cylinder and head from my Honda Dealer, not from Tyga. I did not port them myself. Doing so is a sure way to reduce performance and reliability, unless you know exactly what to modify, and hopefully have this knowledge from experience porting (many) NSR cylinders.
June 28, 2013 at 10:22 pm
hi jeff..
what the tyga website??
March 23, 2012 at 12:35 pm
Please figure this out yourself…thanks.
June 28, 2013 at 10:22 pm
Hi guys, I have just got my hands on a NSR RC bought for 24,000bt. It runs, but after reading this article I am going to try for a lot of rebuild and new bits, the Thai mechanic who helps just wants to put a load of second hand parts on it, I am not for that. These Tyga parts you talk about are they readily available in BKK if so a trip is in order. If I need help as I am sure I will would any body be good enough to help, thanks Ian. Phone no. 0883132283
June 18, 2012 at 9:58 am
You must pursue this yourself, sorry. I am not Tyga and I don’t know what they have available now. Start by finding out their website?
My stuff was done as a favor…so it’s hard to comment on how far you can go with them.
June 28, 2013 at 10:25 pm
Hi everyone.
So glad to read your comments in this blog.
I am from Indonesia, and here many people still using this bike, NSR R, NSR RR, NSR New RR and NSR SP.
I am looking for new and original spare part for my SP.
Could you please anyone help me to share the information for the place to buy complete spare part?
I’ve seen on http://www.2strokeclub.com there is a seller for the parts, but it is not complete at all.
We have no access tothe original part here in Indonesia.
Please inform me for the place in Thailand.
Thank you.
September 15, 2012 at 7:41 pm
Parts can be ordered at most any Honda Dealer.
June 28, 2013 at 10:26 pm
Hi Jeff, great work on the bike! About to go over to a bigger bike myself but still have my beloved NSR150SP and would really like to upgrade some parts. I have already replaced the exhaust for a TYGA performance system and looking at the carby next. Are you able to send any more details or photos to me about it?
September 25, 2012 at 4:08 am
Nicely done man , i’m currently restoring a SP in Indonesia < kinda rare with parts here …
January 5, 2013 at 8:02 pm
Great to read up on your mods. I have an older, but in good shape RR here in Samut Prakan. Currently goiing thru it and fixing a few small things and cleaning it up. If you had to list the first three performance mods, what would they be? I also understand that the SP cylinder has different porting than the RR. Is this correct and if so are they direct bol-on replacments. Maybe the Tyga versions.
January 16, 2013 at 6:52 pm
Yes there’s a big difference in the 2 cylinders. I don’t know (think NO) if they can be interchanged.
Pipe, new piston, new cylinder (can check the old one), lower gearing, better tires, shock.
An old bike would desperately need front fork rebuild.
The carb is the biggest benefit, and the hardest to get parts and install.
June 28, 2013 at 10:30 pm
wow……GREAT JOB, I’m still restoring my NSR R 1997
February 1, 2013 at 4:34 am
Cool.
June 28, 2013 at 10:31 pm
You’re spot on with the front fork needing rebuild. I had a nearby honda shop do mine with new parts. As for the cylinders the SP will indeed fit on an RR model. Howeve since the RR models have the water intake line as a seperate bolt on flangem it is integraal to the SP headd, What has to be done is that 2 of the studs need to be replaced with shorter ones. That is if you use the SP head. I think if you stuck with the RR hea don the SP cylinder not much has to change. There are also some small differences with the pipe mount and gasket. You’d have to sort that out also. There really are not many substantial differences between the SP and RR models. The transmissions are identical, but primary reduction gear is lower on SP. Most NSRs being raced are actually the RR model as it is lighter and shorter. The Pro-Arm was mostly a marketing thing and gives no real advantage to the bike. Unless you need to change tires quickly! It is heavier than the conventional swingarm. It does allow a slightl;y wider tire though.
June 29, 2013 at 1:30 pm