NSR250 rebuild - 'The ELF Special'

[Wil_K]

Getting close to a runner. Engine now mounted.

[Moooools]

Getting close to a runner. Engine now mounted.

Shouldn't you be at the shop making wheels not leak?

[Wil_K]

Shouldn't you be at the shop making wheels not leak?

Cupcake?

While I was not helping out at the workshop, I got the rest of the bike together. And I'm pleased to say, it runs!

Plenty more to do though, such as:
- Leaking carbs to sort.
- Leaking thermostat hose.
- Setting up oil pump.
- Setting up RC valves.
- Carb tuning.

Not to mention all the modifications I have planned.

[Neal]

Have you read Tuckers blog on his mc18 rebuild ? Looking good !

[Wil_K]

Have you read Tuckers blog on his mc18 rebuild ? Looking good !

Yep, I have read Tuckers blog, lots of good info on there.

[Wil_K]

New plan. So, before I get this thing set up and running sweet, I am going to swap the wiring loom to the MC18 one. I will also swap the flywheel, stator, and pickups for MC18 parts. I assume the MC16 items were left in the motor because the connections from those components to the loom are different between the 16 and 18. It will also mean I can use the PGM-II to run the RC valves and air correction circuit. At the moment I have the MC18 carbs on with the air correction circuit blocked off.

It makes a lot of sense to go this route. Currently the engine and electrics are a mix of 16 and 18 parts. I'm sure this will only complicate the tuning procedure, and also reduce performance.

[Neal]

The flywheel should have timing that is very close , there is a slight change of timing over the years . The only difference for the pickups is the connections on the loom .
The pgmii is better , even better if you can get a ignite can and plug it into the pgmii harness .
I batteled to get mine to work properly , I have since found out that there was a program error and has been sorted out .
I modified my flywheel to make it work . I don't have new dyno sheets but the improvement was better all the way up to where I had a splutter (now sorted) .

There is a mod that I have seen on the pgmii , my one had a switch installed where two wires were soldered inside it and extended outside the pgm , I flicked the switch on the dyno and saw 1.5 hp increase . I don't know how to modify it but it did work . Somewhere along the years of the bikes race life , the switch must has been flicked off by accident .

[Wil_K]

Got some aftermarket goodies. Expansion chambers and end cans, courtesy of KB member DEATH_INC., who gave them to me for free! Here's some pics of them installed. I will need to fashion new mounting brackets to attach the end of the stingers to the subframe, but otherwise they fit great. The obvious difference is they are a hell of a lot lighter than the stock pipes.




I've also installed the MC18 subframe, to make the installation of the 18 wiring loom easier.

I discovered something interesting connected to my PGM unit. Based on some research, it looks like an HRC derestrictor (has the HRC part code 'NKD'). Do you know anything about these Neal? Is this a derestrictor, and what do they actually do? The only info I could find was one topic on nsr-world showing something similar.

[Wil_K]

Electrical conversion done, and aftermarket pipes fitted. Took it for a few laps down the road. Feels damn good to finally ride it! Only took it up to 7.5k (out of 12 to 14k) revs to break in the new pistons and rings gently. Moves from low to mid range revs nice and smooth. It's quick too. No surprises there, but I was barely more than 1/4 throttle and well below the power band, but it was picking up speed nicely.

I'm still fine tuning the engine, and tidying things up. More pics and probably a video soon.

[imdying]

Don't rev it to 14.

[Neal]

Hi sorry for the delay , I am working in the bush ATM

The HRC derestrictor is a fancy wire splice . Just double check all your jetting before you blast off down the road .
What sort of sizes are you running ?
+1 on securing the silencers , they bounce around and crack the weld where the cone meets .
What is the plan with the pipes ? Black paint or clean and clear coat ?

[Wil_K]

I won't be blasting of anywhere without being sure the jetting is right. It's standard jetting at the moment. I'm on premix, but I will hook up the oil pump soon. Also, I'm thinking of putting the standard pipes on (for now). Mainly because: 1) It will make it easier to find a good baseline jetting setup, then I can make adjustments as I add modifications. 2) The aftermarket pipes could complicate the re-vinning process, as they are on the noisy side. They will definitely go back on though. 3) I would like to de-rust them. Not sure if I'll paint or clearcoat.

[al.ramsay]

Thought I should share one of my current projects. I'm doing a build thread on another forum, but hopefully I can get some local expertise, and maybe a few parts sources here.

I apologise for jumping into your thread, but just wanted to say Hi,
Ive been lurking around here for a while and following your thread as I am about to tackle a similar project over here in Perth.
Formally from Christchurch and in my late teens/early 20's had the pleasure of owning/riding many of the crazy strokers on the market - 20/25 years and about 30kgs ago!
I digress, I owned/rode/raced (all be it enthusiasm outweighed actual ability) had fun and broken bones to prove it a couple of TZR's, an NSR250 with what I was told at the time an RS motor, a bog stock NSR250R MC18 and lastly an NS400 that handled like a bag of bollocks, but went pretty well.
Ahh, Hindsight... if only I had kept 1 or 2 of them...

...Don't have the full one scanned into the computer yet, but they just upgraded the scanner/printer again from one monster to another, so it should autofeed it through in about an hour or so

+1 to an English Manual

Anyway, again sorry for the interruption, please keep up the good work, and I hope to pick your brains in the next while as soon as I get a chance to strip my '21.

[Neal]

Hi Al , keep us updated on your project and give a shout if you need help .


How's an update on the Elf special before i steal the colours for my next paint job !

[Wil_K]

I apologise for jumping into your thread, but just wanted to say Hi,
Ive been lurking around here for a while and following your thread as I am about to tackle a similar project over here in Perth.
Formally from Christchurch and in my late teens/early 20's had the pleasure of owning/riding many of the crazy strokers on the market - 20/25 years and about 30kgs ago!
I digress, I owned/rode/raced (all be it enthusiasm outweighed actual ability) had fun and broken bones to prove it a couple of TZR's, an NSR250 with what I was told at the time an RS motor, a bog stock NSR250R MC18 and lastly an NS400 that handled like a bag of bollocks, but went pretty well.
Ahh, Hindsight... if only I had kept 1 or 2 of them...



+1 to an English Manual

Anyway, again sorry for the interruption, please keep up the good work, and I hope to pick your brains in the next while as soon as I get a chance to strip my '21.

Hi, welcome to the forum. I hope you have fun with your NSR project. Feel free to ask questions, but I'm by no means an expert, this is my first NSR. There was an English service manual somewhere on this funny old site: http://www.dreamgate.ne.jp/NSR/index.html, but I can't seem to find it now. If you need one, send me a PM and I'll email you my pdf copy. The quality of the photographs are poor, but it's the only free translated copy that I know of. Or you could by an expensive one from NSR-world.