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1975 cb750f

2112 Views 12 Replies 3 Participants Last post by  Geeto67
about a month or so ago i picked up a 75 750f from my physical therapist for a couple of hundred bucks. i'm wondering, what are the main differences motor wise? i've been told a few different things, big valves, bigger cam, more compression? it's all there and all original, not sure whether to restore it, chop it or cafe this one too. i havent really given it a good once over yet

some people are like slinkies, basically useless but they still make me smile when i push them down the stairs

Edited by - fuzzybutt on Apr 17 2007 8:34:30 PM
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75 motor has a different cam and a little more compression, but it is not the big valve head that the 77-78 bikes had (sorry to dissapoint). Personally the F bikes (despite being one of my favorites) are pigs and the more you can do to lighten them up the better (leaning toward cafe here). just out of curosity, what color is it? some colors are rarer than others and should be saved. If it is flake sunrise (orange), sulfur yellow, or Blue you should try to save the paint. Candy Anteries red was pretty common on 76 models so if you scrap the paint no big loss. The biggest thing I like about the F's over my K bike is the disc brake rear, although it needs to be drilled to be a true all weather bike.
I always forget where to find the differences between the model years, here is the actual differences for the 75-76 F1 supersports:

new camshaft, carbs w/additional idle air. New pistons, compression ratio 9.2/1. New case w/o primary chain oiler. Final drive gear ratio 43/50 i/o 48/50. 4th gear on main shaft 31 i/o 30, 5th gear on countershaft 31 i/o 32.

Candy sapphire blue is a rare color for F's, Mostly because candy finishes don't seem to hold up well over time. If it is shot then you have nothing holding you back - cafe that bitch.

You can't use the 836 kits out there now because of the pistons and increased compression, but right away you are ahead of a stock k-bike. Some of the guys at SOHC have expiremented with the 77-78 carbs and found that they work better than the earlier carbs(they are just a pain in the ass to rebuild) because of the redesigned accelerator pump. K&N makes a filter that fits in the stock airbox.

Anything you can do to shed weight on these pigs is the best thing for it. That taillight/grabrail assembly is just a nightmare of heavy metal. The seats (as pretty as they are) are not light either. a bumstop fibreglass seat (like those from 1hotwing on ebay) and light weight taillight and signals frees up like 10-15 lbs. Don;t buy fibergalss seats made to work with cb750 seat hinges, the F models have a different seat hinge that actually unbolts and can be used with any seat. The F has the tank modeled after endurance racers of the era so it is a great starting point.

Clubmans are espically a pain in the ass on this bike because of the gauges and the master cylinder (the M/c hit the gauges) so go clipons right away and save the aggrivation. Raask and tarozzi both make specific rearsets for this bike, but you can use the passenger peg holes and make your own as well.

The exhaust is a heavy contraption on these bikes and really isn't worth the hassle of keeping if you are cutting it up. A Kerker is the best right now for the bike, lighter and more power but hella expensive. Macs are just lighter and you need to repaint them before you use them to keep them from rusting.

keep us posted on what you do.
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why not just keep the 74 cafe and chop the F?
I still don't get why you are undoing one bike just to do it all over again on another. Seems like a lot of work to me where as you can just use the F stuff in the chopper.
a very good point.
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