Honda-SOHC
SOHC.co.uk Forums => CB750 => Topic started by: alexjb666 on February 03, 2012, 06:39:10 PM
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Hello people.
As will become clear very quickly I'm not all that experienced mechanically but willing to.give things a try with a little advice.
I am doing up my 78 750 F2 Super Sport to a modern blended cafe racer. After riding the bike for a little while I have decided I would really appreciate the ability to stop in a timely manner.
I'm looking to replace wheels, discs and calipers.
Wheels: I was wondering if anyone knew what the widest wheels (front and back) can be put on the SS without too much modification (and maybe some advice where modification will be needed).
Calipers: I have seen that the brakes from a CB900 fit the 750 but was wondering if they make much difference compared to stock?
Discs: I definitely feel the discs need to be modernised. Has anyone tried any specific discs that they found worked well?
Sorry for all the questions but who better to ask than the enthusiasts?
Thanks,
Alex
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you could make a fair bit of difference keeping the original set up but change the brake lines to braided hose, drill your disks and use more aggresive sintered brake pads,
pete
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Hi Alex,if you ride a modern bike and a classic bike the brakes are miles apart , but as Pete says braided hoses etc make a lot of difference, you should have a half decent set up as standard on the f2 with twin discs etc, good luck and keep us posted with your progress ;), cheers Mick.
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I have an 77 F2 and but also owned a CB900 sometime ago. I stand to be corrected but think the brakes are exactly the same on the early models (with the similar comstar wheels as the F2). The FD 900 had 4 pot calipers from memory and may be worth a look?
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Thanks for all the replies its all good to know.
Love the F2 restore and cafe build in your sig.
Alex
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What people don't usually take into account is that these bikes can be someting like 70Kgs heavier than modern stuff which has a big influence on stopping.
In short they just can't be stopped as quick as a lighter bike whatever brakes you put on them, the std F2 with some mods as Pete says are not a bad setup. You should make sure that the fluid is in good condition as part of any planned improvement.
With the all up weight and fairly skinny fork legs you reach a practical limit.
Unless you go down in rim diameter (will also change geometry and handling) you may find a limited range of tyre widths for the front end.
Modern tyres seem to have more grip during breaking than original types anyway so should have brought an improvement anyway.
A change in mastercylinder to a different size would influence the feel to you more.
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Thanks for all the replies guys. I am thinking a wider rim (if possible) may ease my uneasiness and provide that little bit more traction i am looking for when stopping as some times the wheels have stopped before I have. I know this is also due to me not yet being used to the pressure required on the pedal so it isnt all the bike.
Alex
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You've got something of the feeling in the last post in that the feel is very different from modern lighter bikes in that with say a good new 600 when you hit the brakes hard you get quite a bit of dive at the front but the forks support it well and still give reasonable feel to you of what the tyre is doing.
Practical limit coming as the back comes off the floor and the bike still turns well.
With a longer/heavier older bike, the forks don't support such a hard hit and end up very close to fully compressed and lose more feel of what the tyre is doing. Also they tend to just push the front along when locked rather than you getting more warning of what's happening.
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Thanks for all the replies guys. I am thinking a wider rim (if possible) may ease my uneasiness and provide that little bit more traction i am looking for when stopping as some times the wheels have stopped before I have. I know this is also due to me not yet being used to the pressure required on the pedal so it isnt all the bike.
Alex
If you are new to the world of these beasts, worry not they do stop with enough effort.
I raced and did many track days on my tuned CB900 on similar if not the same brakes / wheels to the F2. Never locked a front wheel (rear yes) with some serious braking efforts.
If you are used to more modern stuff, this will seem so slow and lethargic with no doubt. However you will find you develop have a different attitude, enjoying the bike for other reasons. I'm building (eventually) a cafe racer from my F2 for the enjoyment and just to look at it. Any riding will be chilled.
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Dont ride modern sport bikes to he honest. Up until i got the 750 i rode purely cruisers. I just feel the rear loses traction rather quickly under braking so was looking for any improvements. Looking forward to her being done for afternoon cruises round town or trips to work i actually look forward to!
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Put Kyoto organic pads in the rear, they are f--ing useless in the front but i have found them suited to the rear as they dont bite as much
pete
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Thanks for the tip. Ill also learn not to be so heavy footef
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I like your explanation Pete, that made me laugh.
I guess I hadn't considered it from the point of using a lot more back brake as you tend to on a cruiser at a different pace generally alex.
These 70's bikes had some of the earliest rear discs and they did seem to make them far too big for the intended use so the rear is easy to lock on most of this era.
To elaborate more about the front for you, this F2 is also at the start of the fitment of "not bad at all" twin discs and properley working should cause you no real probs, they are reasonably progressive too so are fairly quick to feel more comfortable with.
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Loving all the help you all provide and cant thank you enough.
Pictures of the 750 etc. are in my introduction thread.
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You have all been a great help so far but I was wondering if anyone had any input on another point, the wheels. The comstars are very iconic but I am wondering if anyone has any other recommendations and also any experience with what the widest wheel/tire is that will fit a super sport with little modification. I am guessing the caliper brace would need moving/changing and I would probably need offset sprockets.
I blame riding cruisers, I feel safer with more rubber.
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I don't know if there are many 18" tyre options available unlike 17" so you could be looking at a overall size change.
Measure the width between the swingarm at the widest point of your tyre to give you some idea of the max you can get into there.
A reasonable start point maybe (if you want spoked wheels) would be to go with an F1 rear wheel and have a wider rim laced to it or even a K7 17inch rim if suitable.
Unless you have a reasonable skill for this sort of mod you may not get too far without some fairly involved changes.
Saw in a recent USA retro bike mag a CB650 with a modified rear comstar to make it much wider, think he had the rim machined off to leave just the centre, then a bespoke wider rim welded to the remainder.