Thanks mich for the informed reply.The 1970 Bighorn was identified as "F5" and the 1971 was "F5A".
These were the only two years that Kawasaki produced the F5 but it appears the frames were all stamped with F5F.
If you can get access to the back page cover of the factory service manual it will list all the frame and engine numbers and the year of production.
I’m looking at one now that is F5F-20459, it’s listed by the seller as a 72 F5 bighorn. Is this correct?Back in the stone age, before everything could be looked up on your 'device', we had to use microfiche cards to look up parts. We still have all our old stuff.
1970 F5 350 Bighorn frame # range F5-00001-07182 eng.# range F5E00001-07268 dark tan color
1971 F5 350 frame# F5-07183-13633 eng F5E07269-13665 lime green color
1972 F9 350 frame# F5-30402-42370 eng# F5E13666-24484 lime green color
73-75 frames had an F9 number, but the engines continued to use F5E
These would of course be for U.S. models, Other countries most likely had a different range.
I'm unable to explain why your frame number falls outside the range of 71, maybe Canadian or imported?