Hmmm...this is one of those situations where my book would "walk you through" the issues with the clutch.
First: somewhere around 2004 Honda "purged" their online parts diagrams, which in English means they removed the 5 variants of the clutch and show only 2 different ones, now. That's most likely why yours is being hard to match up.
The K1 clutch (your bike is gorgeous, BTW!) came in 3 variants. The first was the K0 version, which has a thin stamped-steel plate on the top of the stack. Some of these are held in place with a wire circle that clips into the top plate. This sheet metal piece sometimes warped, causing clutch plate drag on the top 2 plates. It can usually be removed with little more than just a slight clutch readjustment of the lifter when you put the cover back on.
The next version was similar to the K0, but without the sheet metal plate, and the first plate in the back of the clutch is a steel one that has the tiny oil dimples on just one side: the other side of it is not machined, so it is obvious which way it goes in. Apparently this was not obvious enough for some Honda mechanics of the day, as there were some bulletins (they were called "Shop Bulletins", not "Service Bulletins") about how to put these in the correct direction. These clutches (and the K0 above) had 6 cork plates.
The last version, when the K1 was made in the New Factory, is a clutch that uses the top aluminum pressure plate as the last steel plate, and the top steel plate is gone. This version has 7 cork plates. The hub is slightly longer than the earlier versions. This version remained until the F0 bikes,
All of these clutches had too few oil holes in them by today's standards, because today's oils have almost no zinc in them. Also, the tried-and-true mineral oils of the past are long gone today, which was part & parcel of the clutch design. So, to work around this, additional holes need to be added, or at least the existing holes altered (per my book's pictures, otherwise hard to explain) to capture more oil.
Today we have some confusion, too: the superbikes out there have more plates in them, and they happen to be the same size as ours, but thinner. The stock plates are 0.143" thick when new, and at 0.131" are considered worn. At 0.128" they typically slip pretty badly. The superbike plates, which fit in perfectly, are 0.131" thick when brand new(!), so they often don't work well in our bikes. In addition, Honda screwed up their part numbers in 2008-2009, so many shops have cork plates from the post-1976 bikes mixed into the supply for these bikes: these plates are thicker yet, with slant-cut cork blocks on their plates - this was the CB500/550 clutch late, revisited. These will slip in the 750 clutch.
That's just some of the history: now, to the problem.
If the clutch drags, the #1 thing to check is: your oil. Is you have a high-detergent oil, or a too-light-weight oil, or a low-zinc oil, yes, the clutch will drag. Reason: the cork will not let go of the steel when you pull the lever. This is easy to test: get the right oil, change it and try again after 50+ miles. The right oil is: a made-for-motorcycles oil (NOT the "V-Twin" oils out there, long story...
) that has zinc. The characteristics are:
#1 - low detergent: if it says on the label "prevents sludge", don't buy it. Your bike won't sludge, anyway (no engine actually does...).
#2 - must have zinc. The EPA, in a VERY crooked 'business deal' with BMW, passed a regulation outlawing zinc in all oils so their platinum catalytic converter could be imported to the USA, in the early 2000s. That's all I'm gonna say about it now, or I'll get mad....the result is: all flat-tappet engines and all wet-clutch systems immediately suffered damage and poor performance from this issue. It wasn't until 2010 that manufacturers found a way around this regulation, and are now beginning to offer us good oils again. To find zinc now, you can either add it to the oil as an additive, or maybe try the new motorcycles oils from Vavoline, or look for diesel oils, which have less suds and more zinc (and were exempted from this ridiculous law).
#3 - the 750 MUST use 20w50 oils, unless you're riding in winter. Another long story I won't put here, but a mistake by Honda in 1973 led to the confusion where owner's manuals and labels on the bikes came noted 10w40 oils. DON'T use 10w40 oil in your K1.
If all these things fail, you may have a warped cork plate, steel plate, or top plate (aka "pressure plate"). If it comes to that, you'll have to replace a part or two. At 30k miles, my clutch was finally smoothing out so it DIDN'T grab anymore, and it lasted to over 90k miles with hard use and 20w50 oils. So, don't rush to change it, just yet?
