I know you need to get the correct primary gears between crank and clutch, and looking through the parts book, there seems to be lots of different numbers.

I'm i correct that the combination only needs to be between models, ie MC18. MC21, MC28. Or does it go further than that, MC21R is different to MC21SE/SP. Or better still, from year to year (but the same model).

Help!

Hi Tom you are correct, they differ between model type not model spec. I know the 21 & 28 have different primary gears I think ones 24t and the other 25t but the parts list shows the r, se & sp of the model type share the same part number crank primary gear.
So basically if you are fitting a dry clutch to a mc28r you need the dry clutch from a 28sp/se or the clutch and crank primary gear from a mc21.

That's as I though Paul, although a quick check through MC21 SP part numbers reveal 3 different types of small primary gear. A, B and C. The mystery deepens.....

Cant find my most up to date parts book but the one I have in front of me shows two part numbers for the primary gear but they are the same for the r and sp for the relevant years (if that makes sense) If you look at the clutch basket gear that it meshes with the part number doesnt change for the r or sp through the years so it must be basically the same gear.

Honda part numbers are made of three parts xxxxx-xxx-xxx (some have two more digits for colour code) the last 3 digits refer to the modification and sub contractor designation. So the different numbers could just mean they are manufactured by a different company or have a different treatment process.

That said the last digit of the first part number changes as well, my manual describes that as the function and component number???

Anyway time to take my anorak off!

That's kinda what I thought. And I prefer a cagoule.