Kawasaki F5 350 Bighorn F Series Clutch Improvement, Super Easy Clutch Pull!

I thought it may be of interest to those of you out there that are fond of the Kawasaki rotary disc dirt bikes of the late 60's/early 70's. This video is about an improvement I made to my vintage motocross bike based on the F5 350 Bighorn model, I raced one exactly like this one when I was a kid and also worked on them as a Kawasaki mechanic for various Kawasaki dealers. These bikes for the most part were pretty robust and actually well designed but a bit heavy, despite the weight they performed well but always had poor clutch action, by that I mean the clutch lever pull was quite heavy even when brand new, over a short time the plastic in the worm mechanism would degrade making the clutch pull incredibly hard to do. Fast forward to the present, I won quite a few races in the New England Sports Committee events back in the early 70's, I always wanted (who doesn't) to relive those days racing my Bighorn again in AHRMA "early sportsman stock", reality quickly reminded me of the lousy clutch action of the "good old days", my clutch release modification dramatically transformed the ease of riding the bike.
The modification is to use a modern all steel ball screw worm assembly instead of the terrible plastic on plastic design, the modification fits all years of F5, F8, F81M, F9 and F11. While the 125/175cc F6/F7 models shared the plastic on plastic design I have not had a chance to update those models to the modern release mechanism, I'm pretty sure those models would benefit from the updated components too with similar modifications required to complete the changeover.

[@tommcbride1526]

Hi, is Tom from San Diego? I’m just putting together an F9 three 5074. I need your clutch deal your ball screw let’s do it yeah

[@maverick3782]

Hi, My brother just did a lot of restoration on my old Bighorn. Remember the clutch was always stiff. Pulled it apart and one plastic part is cracked. Are you still doing these updates? How can I get it done?

[@Peter-V_00]

Hi Maverick, yes I'm still doing them, if you would please email me f51m at aol dot com, substitute @ for "at" and . for "dot" , subject line "clutch" and we will go from there, thank you for your interest.

[@TurbodanNM]

Are you still doing these? NOS parts are scarce and the used stuff is beat. For now my F5 is working with cleaned up stock parts but I don't think I have much life left in them.

[@Peter-V_00]

Yes, if you ride your bike these days the improvement is truly remarkable, the stock plastic on plastic was terrible from day one.

[@TurbodanNM]

@@Peter-V_00 Do you have a website? How do I buy this?

[@jenntek.101]

F7?

[@Peter-V_00]

Same design for all of the F series bikes, your F7 may use a slightly smaller version but the fix (improvement) is the same.