'87 Honda NSR250 'ELF Special'

[Moa]

We have power...electrical power. Petrol power coming soon, pistons and gaskets will be ordered before the end of next week.

 

[Moa]

Getting there. Shiny new top end parts arrived, plus new crank outer seals as I discovered the old ones were actually the wrong size.

 

[Moa]

Bottom end re-assembled:

 

[andycafe]

Nice Mate coming together then.

 

[620dark]

Very nice! I love the "Honda Racing" on the motor cover

 

[crazypj]

Is that a genuine HRC magnesium cover?

 

[Moa]

Is that a genuine HRC magnesium cover?

No just the OEM aluminium cover. Don't think they did magnesium covers? The next best thing would be swapping to a dry clutch.

 

[Moa]

And the top end:

Cylinders have been professionally honed. The top one looks almost brand new inside. The bottom one good, with some minor scoring. Power valves and exhaust ports have been de-carbonised.

 

[Moa]

Getting close to a runner. Engine now mounted.

 

[Moa]

It runs! Will try get a video up shortly. Right now I need to sort out one or two small issues, such as leaking coolant.

 

[stroker crazy]

Damn good job Moa! Looks great as is!

Crazy

 

[Moa]

Thanks Crazy, I'm very please to get it going, it's been a big effort.

Plenty more to do yet though:
- 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 8)

 

[tegboi]

Love everything about the NSR bikes. Everything from the 50 to the 250. Awesome build!

 

[Moa]

Thanks tegboi.

Got a new plan. It's a slight backwards step, but will be better in the long run. The bike is currently running MC16 electrics, including the flywheel generator and ignition pickups. This is less than ideal for my MC18 motor, which I assume has slightly different ignition timing and RC valve timing, since Honda changed virtually everything between models. The biggest difference is the lack of a PGM controller on the 16. The PGM unit controls the RC valves, ignition maps, and air correction solenoids. I'm currently running the MC18 carbs with the air correction circuit blocked off.

I will be swapping the entire wiring loom and flywheel components for MC18 parts from the spare bike. This seems like the smart thing to do. I'm sure the bike will be easier to set up and certainly perform better if everything was MC18.

 

[stroker crazy]

Good move Moa - it will probably save a heap of time (and aggravation!) in the long run.

Crazy

 

[620dark]

Sweet! Good luck with your wiring loom swap - I've been fighting with getting the stock loom back in place on my 360, as it was in a box when I bought the bike, so I feel your eventual pain ;D

 

[Moa]

I hate electrics.

But never mind that, check this out. I'm running a duplicate build thread over on the kiwibiker forums. A guy on offered me some aftermarket NSR expansion chambers for free! Just picked them up today. Despite the surface rust they are in pretty good nick. Don't think they have been used much as there is very little carbon build up inside. One thing that's very noticeable is they are much lighter than the stock exhaust, probably a lot louder too.

 

[stroker crazy]

Great score!

Crazy

 

[Moa]

Electrical conversion done, and aftermarket pipes fitted. Took it for a few laps down the road. ;D Feels damn good to finally ride it. Only took it up to 7.5k (out of 12k) 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.

 

[Moa]

I've been riding the NSR around the neighborhood a bit. It's starting to run very rich, fouling plugs and just lacking power and crispness. Thought I'd better strip the carbs and give them a proper clean. They were pretty clean inside but I pulled all the jets out anyway and sprayed carb cleaner through all the passageways. I also gave the outside a good clean with carb cleaner and brake cleaner.



They have unusual two piece bodies.


As clean as I can get them.




After all that, the engine runs exactly the same, very rich. I'll keep fiddling with things until I get the motor to crisp up. I know this isn't the place to get technical advice for this bike, but if anyone has any suggestions for solutions please let me know.