NSR250 Forums

Members' NSR Builds :: RE: New Member with An MC18...wait.....no...an MC16...yes MC18

Author: Hudtm60Posted: Mon May 11, 2026 4:17 am (GMT 0)Topic Replies: 370Couldn't resist pulling the carbs for a look see myself instead of sending to UK. Confirmed they are the correct ones. I got excited thinking that the slow jets look completely different, but I've been down this road before, they are supposed to be both 38's.. they ARE 38's...except the 38 for #2 (rear) is a 38S original jets back in 130 for #1 132 for #2 Checked the float height....13mm is as close as i can get it. Only other thing I discovered is that the power jets were in the wrong carbs. Website here says it should be #1 should have a 75 and #2 a 70 but it was the other way round so switched them- but is that correct? #2 usually needs more fuel as it gets hotter. Wonder it it will make that much difference- then I just remembered- need some electronics to have the power jets work....so they are non-op Phone died so no more pics for the moment...

Members' NSR Builds :: RE: New Member with An MC18...wait.....no...an MC16...yes MC18

Author: Hudtm60Posted: Sun May 10, 2026 3:54 pm (GMT 0)Topic Replies: 370All of that information is MUCH appreciated. Thank you! So I took off the tank, drained the V2 race fuel and put in some brand new NGK BR9ECM's I had a gut feeling about the RC Valves and in danger of adding to many variables to the test, took off the side fairing to check the power valves adjustment being careful to check in on exactly how to do it (thank you Andy) AND catching up on MotoGP Practice started it up with the fuel left in the bowls...let it rev to 2000k and killed it when the RC Valve Pulley moved to the HI point.....note these don't have the pointer that the original has but you can tell where it should be. they were slightly out but now are spot on... I put on the four holer airbox lid and double checked the carbs are sync'd ok. looks good. Took it out....rear cylinder acting normal- front again not happy. Felt like it was running on 1 cylinder all the way didn't reach any exciting power band. Quick u-turn home. Took off the tank and removed the airbox lid...simply because it was the easiest change to make. It was MUCH better but again didn't reach power band.....front cylinder still practically dead. OK- just to be sure may I ask: which carb takes care of which cylinder. I think it's LEFT carb for the FRONT...am I right? I think it was a mistake to adjust the power valves in all this- so going to double check those again and then I'm going to take the carbs off and I may send them to MuttsNutts to give them a good clean and going over- partly because it will give me a break from the NSR and allow me to fix some of my broken bikes of which there are TOO MANY. When I get them back I will return to standard jetting. who knows. that might be the answer. FIRST will attempt to talk to TYGA again about jetting. I've tried before but got no response. Since then however I think I have a more direct contact.

Members' NSR Builds :: RE: New Member with An MC18...wait.....no...an MC16...yes MC18

Author: AndyPosted: Sun May 10, 2026 1:24 pm (GMT 0)Topic Replies: 370The problem is we've found every setup responds differently, hence why I don't let people discuss specific settings. I do remember numerous occasions where "no lid" performed significantly worse than with a lid though, which kind of contradicts how well (a) my MC21/NSR-WORLD tune works with Ramair pod filters, (b) the F3, and (c) HRC SP runs so well with just the minimal thin plastic carb shield fitted! Our NSR-WORLD tune does include crankcase work though, but the SP tunes don't, and they work well with just the shield and open carbs! :? I'm not entirely convinced by those BR9ECMIX plugs. I hold my hand up, and say I don't know about the properties of iridium plugs, but I've often wondered if they are suitable for an ECU effectively designed 40 years ago, and if they "need" more juice than an ageing PGM can supply?! I remember Matt@TYGA telling me how, even though part of the MC28 race kit, they often even struggled with poor signal when using the R5300A plugs with the PGM-IV. We've never however, had any problems with the BR9ECMs. My little snippet would be "stock NSRs tend to run inherently rich". As standard, they need to work "out-of-the-crate" in all kinds of climates and (within reason) altitudes, on not always the best fuel! Opening the airbox up, and delimiting the ignition affects jetting much less than you may suspect. Almost as if they're pre-prepared for delimiting! ;) You may be looking at closer to stock settings than you think. It's also well worth asking TYGA (if you haven't already) if they recommend main jet sizes with their system. (When I bought my Ethos chambers and KISS delimiter from Japan, Ethos also supplied a pair of main jets -- I can't say what size, as it's irrelevant to your situation. Maybe TYGA have a preferred size too though?) Not sure if any of that waffle helps, or just confuses things even more? Basically, I'd recommend getting things closer to stock, rather than trying to make a slight mis-match work, and then restart modifications. At least you know the PGM and RC Valve is good now. :)Andy. NSR-WORLD.COM Please keep all responses to Forum posts on the Forum so that others may benefit. Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway. Check us out on Facebook! Please "like" our page!

Members' NSR Builds :: RE: New Member with An MC18...wait.....no...an MC16...yes MC18

Author: Hudtm60Posted: Sat May 09, 2026 4:18 pm (GMT 0)Topic Replies: 370Much appreciate this feedback- that's fascinating about the NSR500. When I first tried the 'race' fuel I thought I felt a major difference but I think I was kidding myself. The best I can get is 93 octane and we are lucky enough to have a non-ethanol supplier nearby so I always get that. Those plugs are NGK 3520 BR8ECMIX Iridium IX Spark Plugs but I have yer normal ones too. I'll dig them out. Also I'm running without the top of the filter box but I have the unaltered OEM top AND a four holer. :)

Members' NSR Builds :: RE: New Member with An MC18...wait.....no...an MC16...yes MC18

Author: AndyPosted: Sat May 09, 2026 1:35 pm (GMT 0)Topic Replies: 370Honestly, first thing I always say is, put it back to (relatively) stock! For a start, I'd be putting BR9ECM plugs back in it. (Or are those the Denso equivalent? I've never used them.) Second, "race fuel" really might not be helping as you may be expecting. I've never used "V2", so can't comment on that specifically, but I can tell you that (a) I'd never run AVGAS in anything but a full F3, and (b) the last time we set up an NSR to run on Elf MITS-46 "race UL/fuel" (an NSR500V), it was shite! The client immediately lost 15hp, and required a completely different setup. The powerband became the proverbial light switch too! What's the best regular pump fuel you can get where you are?Andy. NSR-WORLD.COM Please keep all responses to Forum posts on the Forum so that others may benefit. Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway. Check us out on Facebook! Please "like" our page!

Members' NSR Builds :: RE: New Member with An MC18...wait.....no...an MC16...yes MC18

Author: Hudtm60Posted: Fri May 08, 2026 4:13 am (GMT 0)Topic Replies: 370Still having a hard time getting the front cylinder to fire as well as the rear. Bike really takes off when it comes to the power band but very burbly below it. Non-scientific test: stadning still and revving it Holding my gloved hand over the exhaust for the rear cylinder the heat is noticeably higher than that of the front cylinder and there's quite a punch of gas...I can't hold it there for very long before it get's too hot.....for the front cylinder it's tepid- could hold it all day and the pressure isn't that great even though both cylinders gave equal compression readings. I'm just wondering is this a sign of a weak or a rich mixture or there's no way of telling...could be anything? Running V2 race gas...front is on the right, rear is on the left.

Members' NSR Builds :: RE: R2J tail on the MC16?

Author: Spookex2Posted: Thu May 07, 2026 5:35 pm (GMT 0)Topic Replies: 51Hit the attatchment limit, this is how the fuel cap looks like now

Members' NSR Builds :: RE: R2J tail on the MC16?

Author: Spookex2Subject: Alright, part 2Posted: Thu May 07, 2026 5:34 pm (GMT 0)Topic Replies: 513. Nose cone, electronics relocation, and mirrors The nose cone is made from fiberglass and features dual round headlights. I have no idea who made it, but I got it at an auction. Currently, it is only mounted at the mirrors since it has no bottom mounts, where it would be on a stock MC16 nose cone. The bike came with no mirrors, so I'm using mirrors from a Suzuki Hayabusa. They are a bit large, but they fit the bike quite well. The original nose cone mounts get repurposed into a bracket for the fuse box and the relay. This moves them out of the path for the brake master and clutch while steering. 4. Dash I had an AIM Mychron 4 kart dash on my RS50 and decided to move it over to the NSR. Made a custom plate prototype, mounted the Mychron unit in the middle, and the light and run switches from the right controls at the top. Fits fine, but there are a few issues: The unit is not connected to the bike battery; there is a 12V cable for this, but it is quite expensive for what it is There is no temperature since I don't have a coolant sensor for it for the above reason, but I'm not sure if it would fit nicely into the NSR thermostat Another issue is with the centered mount, since it is supposed to be a street bike, I'm mounting an MC18 speedometer on it (more on this later), but the centered mychron location makes it stick out too far to the side and interferes with the steering. So I'll print another base with small changes to the dimensions and will mount the Mychron to the right, kinda like a reversed MC28 speedometer. 5. Carbs Currently, I'm running slightly modified TA21A carbs. The electronics have been removed, and I have connected the auxiliary air intakes of both carbs together. I also swapped the choke mechanism to the one from my old TA06 carbs because I thought that it was closer to what the MC16 uses. I did hack up the MC16 manifolds to make them fit, but I hope to get them replaced with the proper ones soon. Also, the previous owner removed the oil mixing barbs from the carbs for some reason, so I bought some M5 barbs and screwed them into where the calibration tools are supposed to screw in. Don't ask about setup since I haven't really gotten around to getting it to run properly, and sticking some filters on the end will need to get them adjusted again. 6. Later model speedometer adapter and cover Pretty explanatory, with the front-end modifications, there was no way to have a speedometer drive on the front wheel, so I started looking for ways to make a sprocket-driven speedometer to work. The later MC18 and onwards cover was pretty easy to fit, but the MC16 engine cases don't have one of the bolt holes to secure the back of the cover, but I think that it is fine. As for the shaft, as the previous replies to the thread mentioned, MC18 uses a different sprocket shaft, with a protrusion that interfaces with the speedometer gearbox. I was not looking forward to swapping gearbox components, so I used my 3D printer and some parts I had. I made a cap that goes on top of the sprocket and spaced the bolt retainer by 5mm with some longer bolts and washers. The retainer is still securely held in place by bolts and washers, while the metal bit acts as a holder for the plastic cap. This solution works fine, but I had to remove some of the reinforcement veins on the inside of the cover since the screws were rubbing against them. Still not sure about the accuracy of the speedometer and the size of the rear sprocket since I'm running a 17-inch rear wheel (more on that later), and the ratio is different 7. Rearsets For some reason, I thought that CBR954 rearsets would bolt right on (don't ask why), they did not, and IIRC MC16 uses different bolt spacing depending on the side. But the set that I got came with some relocation brackets meant for angle adjustment. After some flipping, cutting, drilling, and brake cylinder spacing, I got them on there. The shift pattern is a GP shift now, and I have to figure out a mount for the rear brake reservoir, but that's minor problems. 8. Rear suspension Because of the swingarm that I'm using (more on that later), I had to use a rear link from the YZF-R1. The swingarm mounts have just the two "ears" for mounting a link instead of the bushings for plates that early NSRs use; it's kinda like what the MC28 uses. But MC28 links are at ridiculous prices, so I grabbed one from a YZF-R1 1st gen. That was combined with a rear shock for the same model and a Chinese adjustable lowering rod. The link had to be flipped upside-down so that it would not interfere with the rod mount on the NSR frame, and had to be spaced with washers at both ends. The top eye of the shock was a tight fit (I had to loosen the bolt holding the frame together and had to use some eye adapters to change the hole from an M12 to M10 that the shock uses. The rear does seem to sit higher, even with the 17-inch wheel, but I'm not too concerned. As Andy mentioned in the previous page, ideally, the shock could be shorter by some mm, and there is the concern of the swingarm hitting the reservoir. Not sure about solving the length issue, but the reservoir issue could be solved by using a later model 2004 YZF-R1 shock, which should be the same 300mm length, but uses a horizontal reservoir. 9. Tail fairings Not much to mention here, but I'm using a 1-piece fiberglass tail fairing. They still make fiberglass bodywork for all of the NSR250 bikes here, in decent quality and at reasonable prices. The only issues that I have are: no access to the storage compartment since it's in one piece, and there are no clips at the front that would clip the front corners to the gas tank, but those would be pretty hard to do in fiberglass. 10. Swingarm and rear wheel Kinda the thing that got me into this whole mess lol. Anyways, from what I gathered, it's an HRC RS250 ND5 swingarm, and I got it without most of the hardware. The mounting of it into the MC16 frame was pretty easy since the swingarm is narrower than the MC16 swingarm by a solid cm and uses the same diameter axle, the rear suspension was explained previously, and I had to make some custom chain sliders as outlined on the previous page. Currently, I'm using modified chain tensioners from a VT250, but they are not the right ones. I did ask on a Facebook group about the tensioners and got a picture of a page from the ND5 parts manual. Turns out that the tensioners are shared with some of the CR dirt bikes from around the same time (but also a custom part?) found some used ones locally that looked right, but it looks like I either got a later model or the wrong part, and they don't fit, so the not-so-well-fitting VT250 tensioners are still in use. The rear axle is also unique because it is a solid 300mm long; none of the ones that I had fit the length, so I got one ordered from China. As for the rear wheel, I wanted something that matches the new front in style, but in a 17-inch size (I already had an MC17 wheel, which is a match for the MC16 style, but is 17 inches), for better tire options. So my options were either MC21 or I think that there is a 17-inch MagTek and fitting of the components from the later bikes. But I noticed that the CBR250 MC22 uses the same sprocket holder as the MC16, but, at the time, MC22 wheels were a bit scarce, so I bought a cheap MC23 Spada wheel, which is basically the same wheel, but in two-tone black and silver. After some modifications to the bearing spacers on the drive side (MC16 uses larger wheel bearings and insert spacers, while CBRs use smaller bearings with insert spacers in the sprocket carrier), I was able to fit everything with the stock brake caliper holder and outside spacers. 11? Fuel tank I still haven't given up on the rusty thing. I failed to bend back the fill neck, so I chopped it out and installed an aftermarket fuel cap. The jury is still out on whether it works, since I have to soak the thing in vinegar to remove the rust, but it does seem promising. But, at this point, it would have been easier to just spend the coin and buy a decent condition tank.

Members' NSR Builds :: RE: NSR250 MC18 R5K Engine Rebuild

Author: philup_7@hotmail.comPosted: Thu May 07, 2026 4:22 pm (GMT 0)Topic Replies: 45PGM II Problems The PGM Unit on Chris's bike had been playing up with the usual problem of the RC Valves not actuating when the RPM increases. Please refer to the following link to how this was resolved: http://www.nsr250.net/forums/viewtopic.php?t=15789

NSR250R Discussion :: MC18 PGM II Problems

Author: philup_7@hotmail.comSubject: MC18 PGM II ProblemsPosted: Thu May 07, 2026 4:14 pm (GMT 0)Topic Replies: 0Hi all Probably most of you reading this already know of the sterling work that Nick from 2t-racelab.com in GREECE does in repairing & refurbishing these PGM Units, but thought I would post it just in case. The PGM Unit on Chris's NSR250 MC18 R5K had been playing up with the usual problem of not actuating the RC Valves when RPM increases. Therefore Chris & I sent the PGM Unit away for Nick to work his magic on. Most impressive was the level of service and the information provided on the PGM�s progress & also a video of it on a test bench after all the work had been completed. Nick also supplied a few precautions that can be taken in order to prevent similar issues occurring in the future. Well impressed. Nick can be found on Facebook 2t-racelab.com & also eBay. Philip & Chris

NSR250R Discussion :: Mc 18 r2j rebuild project

Author: Fason88Subject: Mc 18 r2j rebuild projectPosted: Thu May 07, 2026 10:35 am (GMT 0)Topic Replies: 0Hello to everyone! I 'm George and I 'm very happy because after too many years whithout my mc18 r2j I manage to buy one in a very bad condition and I started to rebuild it! (Sorry for any mistakes but enlish is not my native language) So I will need your help and I will enjoy the conversation with guys with the same passion! I m starting with these: where can I rebuild the crankshaft ? Where you suggest to replate the barrels? I was thinking of replace the barrels with mc21 ones for better cooling but I m confused about H and L barrels and heads of mc21 as in the engine tuning section of nsrworldcom there is a confusion about this aspect. It is written "The diagram illustrates the difference between SE/SP (H) cylinders/heads and R (L) cylinders/heads" but the table given by HRC, for dry clutch models ( ie SP and SE models) gives L barrels and heads... (?)

Members' NSR Builds :: RE: NSR250 MC18 R5K Engine Rebuild

Author: philup_7@hotmail.comPosted: Thu May 07, 2026 8:42 am (GMT 0)Topic Replies: 45Tarting up/Sympathetic Renovation (Cont�d) Front Forks The Front Forks were looking a bit tatty, so with Wheel and Calipers removed and some Scotch Pad and Wet & Dry to hand, the paint was rubbed down, cleaned and masked up ready for respraying. Body Pro P965A etching Primer was used first off followed by several light coats of Pro Touch Grey Primer rubbing down between coats. The difficult part was finding a suitable shade of Silver top coat that wasn�t too bright or too dull. After using different sprays including Hammerite Smooth Silver, Honda Silver etc.. we settled on Halfords M0-380 rattle can (couldn�t find what colour it was equivalent to though) and re-sprayed the Forks. Front Axle Shaft Last job, cleaning out thread on the Front Axle Shaft.

Members' NSR Builds :: RE: R2J tail on the MC16?

Author: Spookex2Subject: What exactly is this thing?Posted: Thu May 07, 2026 6:58 am (GMT 0)Topic Replies: 51Kinda forgot what I mentioned and didn't, so I'll just write the stuff that I have done to the bike and what was needed to do it. Added the pictures I have now, and I'll try to update this when I take some more. If you are interested in any part up close or in more detail, let me know. The bike started as a run-down NSR250 MC16, which was quite nice at some point (had a nice custom paint job on wheels and front mud guard), but probably sat for some years before I got it as a non-runner. Later, I realized that the bike also had the chambers from the R2J MC18 with some Daytona aftermarket silencers because they didn't go up to the stock mounting points and rub against the rearsets, hence the first mod. 1. Lowering the exhausts slightly As mentioned previously, the exhausts were hitting the rearsets and the new swingarm (more on this later). Pretty simple, just some steel brackets, one bolt in the old frame mount, and one bolt in the exhaust. Now the pipes don't hit the swingarm or the rearsets. 2. Front end The front-end parts are as follows: Forks, axle, and calipers: Suzuki GSX-R1000 K1 with 6-pot calipers Mud guard: carbon mud guard for GSX-R1000 K3 Wheel: CBR250 MC22 Brake discs: dual 320mm Yamaha rotors, found as singles on various bikes from late 80s to early 90s. Bridges and ignition key: Yamaha YZF-R1 2002 (bottom) and 2008 (top and key) Clip-ons, brake lines, and brake master: Chinese NICECNC clip-ons, FireYou braided lines in a racing setup, and Adelin 17.5mm radial master cylinder Clutch perch and lever: Matching Adelin PX1 cable clutch Throttle: Knock-off of a Domino throttle with adjustable rings For the how: Forks, axle, and calipers naturally work together since they are from the same bike. Carbon fiber mud guard is also a bolt-on. To fit the wheel, you need some non-standard bearings and seals (easily available from China) since the GSX-R1000 axle is way thicker, which also requires a custom inner bearing spacer (I just bought a pipe with the right ID and had a shop machine the OD on a lathe). The axle also requires some outer spacers, where I did the same thing and had the shop machine the OD down to the OD of the GSX-R1000 axle spacers. For the brake rotors, I designed a simple part and contacted Mark from Tokyo Offroad, who is based here in Japan, and I have used to get custom parts made before. He got back to me with a nice CAD drawing, and I had them made. The inner counter-sunk screws mount to the MC22 wheel with the stock pattern, and the outer threaded holes mount to the Yamaha brake discs that go over the counter-sunk bolts. I forgot the offset, but my eyeballing was slightly wrong by a few mm anyway, so I shimmed the brake calipers by adding some washers under the bolts. The bridges and key: the YZF-R1 bridges work with the GSX-R1000 forks since the fork diameters on both bikes are the same, but one of them has a slightly wider spacing between the forks; however, this poses no issue. One thing that has to be done to mount the bottom bridge is to cut off the steering stops, since they are in a different spot on the YZF-R1. I also had to machine the bottom of the stem to use 30mm ID tapered roller bearings instead of the stock ball bearings. This meant that I could get some non-standard bearings to fit the bridges to the frame. The only other modification was machining the bottom stem nut from the MC16 (the one that covers the top of the frame from the elements) into a spacer by boring out the inside. Otherwise, mounted in place with the YZF-R1 hardware, no cutting needed. For the key, I cut off the wires for both cylinders and used an additional connector to splice the MC16 harness connector to the YZF-R1 lock. It functions perfectly with the parking light and everything, but the steering lock only kinda works by allowing steering only left, but not right. One thing to note is that the fork offset is now 25mm instead of 35mm. This could be fixed by using the bridges from the 1st gen YZF-R1, which have the same 35mm offset and the same fork size as the later models. Not much to mention regarding the steering setup, besides the right-hand light controls interfering with the clip-ons and not fitting anymore, and along with the blinker relay and fuse box being relocated (more on this later) The throttle doesn't work with the return wire on the NSR, so I'm just running the pull wire; there seem to be no issues. Continued in part 2 soon

NSR250R Discussion :: HRC Close ratio Transmission

Author: Marky ParkySubject: HRC Close ratio TransmissionPosted: Wed May 06, 2026 8:02 pm (GMT 0)Topic Replies: 0Evening All, So I've got around to install the NF5 transmission into my MC21, unfortunately it hasn't gone quite to plan!! Installed with no issues, however when it came to trying to put the bike into gear it was was not happening :cry: Adjusted the clutch and moved the gear linkage on the spindle and still no joy! so I made the decision to take out and see if there were any obvious issues. With the transmission out again, I noticed the left shift fork was an NF5 one 24213-NF5-710, however the centre and right shift forks are KV3. looking at the HRC 90-93 set up manual the centre shift fork should be 24213-NF5-710. from my very limited knowledge would or should the transmission work with the KV3 centre fork shift selector?? (just answered my own question!! having a look at the parts list for an 87 NF5 the right & centre shift forks are KV3) any suggestions as I'm at a lose atm!! cheers

Members' NSR Builds :: RE: NSR250 MC18 R5K Engine Rebuild

Author: philup_7@hotmail.comPosted: Wed May 06, 2026 8:46 am (GMT 0)Topic Replies: 45Tarting up/Sympathetic Renovation (Cont�d) Exhaust Brackets Hangers One of the Exhaust Brackets Hangers had a couple of cracks and required welding. Both Exhaust Brackets Hangers were then cleaned and sprayed with some Hammerite Smooth Silver to finish off. Front/Rear Pegs Front/Rear Pegs were removed stripped, cleaned and sprayed with some Hammerite Smooth Silver.