77 kz650 fork question

Hello guys and gals. So I have 2 bikes now. An 81 csr650 with no title, damaged carbs and no seat that my father had laying around. Got her really nice and was planning a cafe build. After a lot of reading and thinking I decided to just get an actual kz650 frame with title here in florida to just swap everything over. I came across a 77 bike...complete...for $300 with a clean title and jumped on it. It has the kick start engine too and it turns over. The issue I have is with the front forks. They have some pitting an them. No leaks...just rusty and pitted some in a coulpe of areas right below where the head light is located. So I got to thinking and the inner fork tubes on the 81 csr650 are in great condition. Can the inner tubes be swapped to the bottom of the 77? I can't keep the csr bottoms because they have a leading axle and I would just like to know if the inner forks could be swapped over with no issues? I haven't found anything in those regards and really would love to be able to just swap them out with no problems. I will be putting new seals and also read somewhere that the springs can be swapped for something from another kz to give it better performance or something from racetech I think I was reading. Anyone know anything in regards of this I would love to hear from you. Thanks guys!!!!!

I don't know, but they're both 36mm. The CSR fork tubes are probably longer, but just guessing.
I would disassemble them & swap parts to see if it will work.
Here are some pics of 1981 KZ650-CSR forks. measurements >> forks extended to max length.






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Thanks for the reply Martin...that info will surely help me out...I have a feeling they will.work but want to make sure...I have to take them appart anyway so this helps so much...

Disassembly. For the bottom allen bolts, use an 8mm brake caliper socket or hardened socket. A cheap allen tool can get twisted if the bolts are stuck. The head of the inner cylinder on the 70s 650s is smooth, but the CSR is the same as a 12-pt 19mm socket. I used a left-hand-threaded bolt w nuts along with a socket, ratchet & extensions. 19mm = 3/4" approx.



A pic from KZR. someone used a long bolt w a nut welded to the other end for removing the inner cylinder.

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If the top of the fork cylinder on your bike is like the one on my 1977 KZ650-C1 it will just have a round hole rather than shape that a hex bolt can engage (see image below). If that is the case you can either make a tool to hold it as shown in the image below or you can buy one like the one shown in the middle of the top row at www.racetech.com/page/id/70 . Ed