Hi Everyone,
I’ve got myself a R4J Rothmans it’s totally original it even has the Japanese labels inside all the fairings.
The thing is I was doing a top end rebuild with the engine in the frame (got all the parts from CMS – very good – all genuine Honda), but the STUPID nut on the rear cylinder (the one by the RC valve) would not undo and the nut was rounding off so I decided to drop the engine to make life easier.
Anyway the thing is I’ve also got an MC21 engine. The MC18 has 26 km and the MC21 has about 12km. Now I know the bearings & cranks on the MC18 are near on impossible to get and rebuild – so do I put (for peace of mind) the MC21 engine in instead.
I know I will have to change the flywheel and pickups on to the MC21 but because I haven’t got a flywheel puller I’ll probably send the bike and spare engine down to Andy to have the flywheels changed over and have the bike set up and any other issues dealt with before I put it on the road.
So I’m now getting myself in a stew – Do I put the MC18 engine back in & keep it all original and hope the crank & bearings last out or put the MC21 engine in.
What would you chaps do??????? All suggestions considered.
Many thanks.

We've successfully rebuilt many [what we term as] S1 cranks. (87~88 NSR/87~92 RS/NF5) The key point still however, is the centre seal must be in good condition.

A good seal can actually be reused at least twice (we have NF5s that run at the Classic IOM TT that are testament to this), so as long as you don't beat an 87~88 NSR250 to death, and refurb the crank sooner rather than later, they can more often than not be saved.

There are benefits to both types of engine, but if you can, I would strongly suggest retaining the MC18 motor in the MC18 chassis. For the simple reason now, that the more original you can keep the bike, the more it is worth. Even MC18 prices are creeping up now, and a genuine R4J SP is actually a rather rare bike. I've certainly seen far fewer R4's than I have any other SP!
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Andy.
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Gotta agree with Andy, keep it original. The Rothmans 18SP must be the rarest of all the SP's in the UK, don't think I have ever seen one in the flesh.

The 21 & 28 variants seem to be ten a penny these days. Even the Terra 18 seem to be quite common now.

paul g wrote:
The 21 & 28 variants seem to be ten a penny these days...

I would happily put my 50p on the fact that there are far more 21/28 SPs now (pro rata) than Honda ever officially/actually made!

And yeah, even the previously rather rare and desirable R6K has become pretty easy to find these days.

OEM Rothmans bikes are just lovely... all of them!
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Andy.
NSR-WORLD.COM

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Thanks Andy and Paul for your responses.

After issues with some ceased bolts I plan to run the MC21 engine through the summer months so I get some riding on the bike.
Then during the winter months when my finances are back on track and the motorcycle world is all quiet I plan to send the RJ4 engine down to Plymouth where the guys can hopefully rebuild and clean it up as it looks a very tired engine unlike the rest of the bike which looks like new.

Will add pictures when it's all back in one piece.
Hope this makes sense.
Cheers, Lamey aka Steve

It'll be nice to see it, when you have the chance to post photos. As Paul says, you probably have the rarest NSR250 in the UK!
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Andy.
NSR-WORLD.COM

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Was going to add my pictures but struggling so have added them to the NSR-WORLD.com facebook page instead.
You will see someone has added additional stickers to the lower fairings. Can't decide whether to leave them on or take them off.
I'm a little bit disappointed that the PGM sticker is missing, the one that should be by the SP sticker - I'll blame it's previous owners for that! But I suppose that as it's 27 years old I shouldn't grumble too much.
Hope you like.
Lamey aka Steve


Last edited by lamey on Mon May 18, 2015 8:48 pm; edited 1 time in total

Typical - I've now just found Andy's guide for photo's - will try & use it next time
Cheers
Lamey aka Steve

Super!




_________________
Andy.
NSR-WORLD.COM

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Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.

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