http://www2.snapfish.com/snapfish/slideshow/AlbumID=5671603007/PictureID=284993651007/a=59315083_59315083/share_version=version_B/

Engine # is MC16E - 1032338. I searched "engine" and "number" and found a reply from RobH indicating this number range to be within the R2J (MC18) range. I also found multiple references to the parts schematics having frame and engine numbers but could not find them there.

Top barrel is hexagon and fits the engine case perfectly indicating MC18.

Front barrel is round (MC21) but does not marry the base quite right. There is a small triangular section of engine base machined flat that looks like it should be covered by the barrel, but is not. Again indicating MC18. Is it possible to install a MC21 barrel on a MC18 case?

Yet magneto seems to be from MC21 and not MC18. Again, is it possible to install a MC21 magneto on a MC18?

This is all very confusing for me. Can anyone help?
_________________
MC21R9N track
MC18R2J track
CBR954
CR250

That looks right, MC18 2J

As you'll have seen from other postings, many parts are inter-changable, but you need to know which ones. It can get quite confusing.

The best thing is to get the parts guide. Then you can see how much of a bitsa it is.

The carbs should be TA20A as well for this model

I wouldn't try putting non MC18 cylinders or fly wheels on
_________________
Why do things simply when you can complicate them


Last edited by RobH on Thu Dec 30, 2010 3:13 pm; edited 1 time in total

How much work is involved to fit MC18 engine into MC21 frame?
_________________
MC21R9N track
MC18R2J track
CBR954
CR250

The MC18 frame is narrower. The best thing would be to offer it up and see
_________________
Why do things simply when you can complicate them

Thanks man.
_________________
MC21R9N track
MC18R2J track
CBR954
CR250

MC18 Mk1, MC18 Mk2, MC21, and MC28 will all swap into any post 1988 frame, with only a need to hook up the correct wires from the stator/regulator etc., and lengthen/shorten them as necessary.

The only motor that is not a direct fit into any other frame is the MC16 motor, as it has solid engine mounts.

All barrels and heads are interchangeable. Just use matched barrels and heads if you don't know exactly what you are doing! For example, use MC21R barrels and heads, or R2J barrels and heads, or even MC16 barrels and heads* etc... but do not mix them up. (You can even run an MC18 setup on one side and an MC21/28 on the other, on ANY cases if you wish, with little or no consequence.)

*MC16 barrels have significantly smaller exhaust ports than all the other models, so don't use them unless (a) you're restoring an MC16, or (b) you have no other alternative in the short-term.

There are plenty of posts in the forum archives over the last 10 years concerning cranks, transmissions, clutches, engine/frame, ignition, flywheel, etc. compatibility. Most of it will work with very little fiddling. It's all pretty straightforward once you have the parts in your hands! The motors, carbs, transmissions etc., were all relatively unchanged from 1988 through to 1996. Unlike some manufacturers, Honda got it right with the first design, and it's very simple to work on!

'87~'88 cranks are similar, 1989 cranks are unique, '90~'96 cranks are all the same. The cranks only fit their respective cases. As a general rule, HRC RS250 cranks ARE NOT a direct fit into the NSR cases.

The rest you can look up!
_________________
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!

Thanks Andy. Time to roll up my sleeves and start the rebuild process.
_________________
MC21R9N track
MC18R2J track
CBR954
CR250