I've got a bit of a problem on my hands in that I want to get an oil pump back on the MC21 engine for road use (dry clutch, in an MC18 frame) but I can't figure out if I've bought the right oil pump. As clarification, I already had two MC18 oil pumps for the extra engines I have, but I was hoping to get this Dry clutch engine working first. Anyway, I bought a MC21 oil pump (from eBay) and it looks identical to the MC18 oil pumps I already have. I know the MC21 is supposed to have an oil feed down to the RH bearing and the "MC21" oil pump I purchased doesn't fit over the hole. And looking at the parts diagrams, it's all one unit too. So I'm suspecting I've bought another MC18 oil pump due to the seller incorrectly listing it or sending me the wrong item.

Just to confirm: The MC21 and MC18 oil pumps are completely different? Does anyone have a picture of an MC21oil pump picture up close? I have assumed they're different from the differing part numbers, but I know sometimes Honda has different part numbers for the same things.

Also, perhaps I've just assumed at the engines for all MC21s use the same crank cases/oil pumps. Do the oil pumps differ between the wet and dry clutch engines too for the MC21? Any help is appreciated.

Later MC21 and all MC28 cases have an extra feed to the bearing, earlier ones don't.

watfordhorn wrote:Later MC21 and all MC28 cases have an extra feed to the bearing, earlier ones don't.

Hmm, this might make finding the correct oil pump more tricky than I expected. Even finding parts on Yahoo Auctions is tedious. Thanks for that though.

Have you checked your cases have the extra inlet for the bearing oil? Most NSRs I have seen don't have the later oil pump design.

There are a couple of potentially helpful pictures at the bottom of this webpage:
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Thanks for the help, and yes, I did come across that page too. I took some pictures of the problem at hand which explains it. Well the other 4 engines I have don't have that inlet, but I guess this dry clutch motor must have been out of a late model MC21 or MC28.

Images: http://imgur.com/a/fqza1

Also, I've just assumed that it's an MC21 engine. I don't recall the guy who sold me the stuff actually saying anything about it so I guess it could be an MC28 engine too. I'll hopefully get a chance to check engine numbers tomorrow. There is an MC28 oil pump for sale on eBay (coincidentally from the same guy who sold me the other one!) so I may buy that one too since it looks like the right one. And forgive me on the dirty engines, I'll hopefully be soda blasting them in a few weeks.

Can you do a dry clutch conversion on a R (early mc21) motor?
Or do you need this oil pump with the extra feed to the RH bearing? Which would also mean that you also need the 21 SE/SP cases?

The clutch is independent of the oil system. The injector pump bolts to the crank case.

The dry clutch can be retrofitted to any wet clutch model. Slight modification is required for the MC16, and maybe the R2/4J (can't remember, to be honest).
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Thanks for clarifying that Andy.
I've read the dry clutch conversion threads on here and none of them mentioned this.
I thought I missed something.

Well thanks for the information. Would anyone be able to direct me to an auction site which has the oil pump with the extra feed? Obviously I don't want to buy another oil pump which I don't need. The oil pump I'm after has the extra oil line: http://i.imgur.com/EaY8eD7h.jpg It appears that TuckerBag's mate was in a similar situation as me with a missing oil pump. I guess I'll run premix as a temporary solution.

Well, this seller uploaded some detailed images of an MC28 oil pump. Would this pump (http://i.imgur.com/YyqVHqA.jpg) fit the engine I posted above? It appears different to the MC18 pumps, and there seems to be only two types. As always, any comments are appreciated. Learning about the NSRs is like motorcycle archaeology!

Well, that looks correct to me.
I can't say I'm 100% sure. (but that applies to a lot of things)
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