I have been looking for an engine for my MC18 for a while, as I totalled the last one. I have managed to find one, nut it is attached to an ex-race bike and I am curious to know what I have actually bought.

Frame number MC18/1010644
Engine number MC16E-1144365

Frame looks to be an MC21 as it has the gull arm, but this may have been put on after. Wheels are Magtek, but 18" rear rather than 17".

The engine appears a bit odd. It has a dry clutch, with hexagonal barrels stamped F and F3, with a PGM II running on premix. Carbs are TA21B. HRC expansion chambers. Could be R6J SP?

Could it be an MC21 with a retro-fitted MC18 R6J engine? Or an MC18 R6J SP with a gull arm retrofitted?

Any help gratefully received. The important questions though are, will the crank be rebuildable, and (as I have not run premix since my Gilera moped) what premix ratio should I use (is it 20:1 unleaded to castrol TTS?).

So, it's an mc18 frame with a gull arm attached.

It's got mc18 barrels, mc18 carbs.

A dry clutch can easily be fitted to any NSR engine, wheather you can externally tell mc18 from mc21/mc28 cases I dont know, though I'd guess you can.
If you take it to bits you'll soon find out anyway, if the centre crank seal is part of the centre main bearing, it's an mc18.

Offically none of the cranks are rebuildable, in reality if you can get the bearings they can all be done.
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fontyyy wrote:
If you take it to bits you'll soon find out anyway, if the centre crank seal is part of the centre main bearing, it's an mc18.

'18's have both types depending on model.
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If I have to take the carbs off once more...

According to my parts book, the frame must be a 2J or 4J 'cause 5K onwards started with MC18-11
The engine looks like a 5K onwards model

Thanks fellas, now all i've got to decide is whether to fit the R5K engine to the R4J bike or just do the new one up with bits off the old one. This NSR ownership is harder then first appears. Don't know whether the new engine runs yet through...
Still need a full fairing for either one if anyone has one?
Kieran

Thanks for the replies folks.

One further question, do any of you know if there is a difference in the main frame of the R4J and R5/6K or are they all interchangeable. It would be useful to know, as if I can fit R5/6K fairings I have a better chance of finding some.
Thanks Kieran

The frames are almost identical. The R5/6K have a hole and lug for the rear brake torque arm which the 2J doesn't. The rest is the same.
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If I have to take the carbs off once more...

Solid as in it doesn't have a torque arm from the caliper mount to the frame, yes.
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If I have to take the carbs off once more...

DifferentStrokes wrote:

StephenRC45 wrote:
The R5/6K have a hole and lug for the rear brake torque arm which the 2J doesn't. .

Is the 2J solid mounted then?

I think you are confusing torque arm and torque link.
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Andy.
NSR-WORLD.COM

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