Are MC18 head and cylinder designations similar to MC21? I am familiar with MC21 head and cylinder designations but my MC18 top end has me baffled. Head says KV3R E-1. I do not understand what the R means. I would expect it to be H (for R spec) or L (for SE/SP spec).

Cylinder is stamped "L" on base opposite exhaust and on right side where i would expect to see A, B or C. Cylinder base is also stamped F with a circle around it. This I thought would be H1, H2, H3 (for R spec) or L1, L2, L3 (for SE/SP spec)?

Thanks.
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MC21R9N track
MC18R2J track
CBR954
CR250

MC18 (both 88 and 89) cylinders are hexagonal shaped, where the MC21/28 cylinders are rounded.

88 and 89 had A, B and C marks as does the MC21/28.

Some platers will add stamps to the cylinders depending on the results of their plating. Could be that you have a replated cylinder.

Do MC18 have R and SE/SP barrels and heads?
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MC21R9N track
MC18R2J track
CBR954
CR250

There was no SE or SP for 88, so I doubt there were any differences there.

For 89 there was the R and an SP. From the parts manual, there are no differences in heads/cylinders. Can't rule out HRC/F-III parts, as there was HRC manuals for the MC18.

actually, small correction... in 88 there was an SP, but it was pretty basic difference. In 89, the differences were much more extensive. But still no part number differences listed.

thanks.
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MC21R9N track
MC18R2J track
CBR954
CR250

KV3R implies the cylinder head is for the Rear cylinder
KV3F implies the cylinder head is for the Front cylinder.

For MC18 there are actually 2 different pairs of heads.(KV3 and KV3G)
See the very bottom of this blog page for details and pics.
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