Vintage and Classic Hondas

more speed

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cb 750 f

more speed

how can i get more speed with low refs

TOOLS1

Re: more speed

Administrator

A larger front sprocket, or a smaller rear, or a combination of both. Front would be the easiest, and cheapest.
TOOLS

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1976 CB 750-A X 2
1977 CB 750-A X 4
1977 CB 750-K
1976 CB 750 F
1981 CB 750
1966 Kawasaki SG 250
1981 KZ 750 LTD
1973 CB 350
1979 CM 185 Twinstar
1982 Honda XL 80
South of Eden (Kansas City MO)

cb 750 f

Re: more speed

the pull away will be bad but the top speed will be better if im correct
i got a 18 in front and 46 at the back im thinking of 19 in front and 38 at the back

LukeM

Re: more speed

Administrator

(Moved this posting to a more appropriate category.)

That sounds a bit extreme to me. I'm thinking your clutch may not like that after a while: pretty high revs just to get it away from a stop. I'd go with maybe a smaller sprocket out back, then if that's not enough then go with a bigger sprocket in front.

My stock bike took me to well over the legal limit here in the US, and had LOTS of revs left. How fast do you need to go?

Luke M

Used to have a 1979 CB750L, sold it as a parts bike, now riding a slightly modified 1984 VT700C. Network/Field Engineer. Central OH, USA, Earth, Sol System, Milky Way Galaxy, Universe.

cb 750 f

Re: more speed

at the moment i get 140kph(87miles)at 7000 to 7500 rpm and i want to go to about 200 kph(125miles) if its possible that why i need to bring the refs down

LukeM

Re: more speed

Administrator

Point taken. I'd recommend you find a MC junk yard, and get some different sized front and rear sprockets. Make some incremental changes, evaluate the performance, and go from there. Then when you're satisfied, go get some new stuff.

I think the CB750F (super sport) had slightly shorter gearing to give it better off the line performance, at the sacrifice of top end speed.

Sorry if this is a little incoherent, I worked at work all night and am on little sleep.
Luke M

Used to have a 1979 CB750L, sold it as a parts bike, now riding a slightly modified 1984 VT700C. Network/Field Engineer. Central OH, USA, Earth, Sol System, Milky Way Galaxy, Universe.

Rodgil

Re: more speed

My 82 CB750FZ had 18/46 sprockets, which gave me 5000rpm at 100kph (62mph) I changed the back one to 40 tooth (removed 6 chain links) which gives me 4200rpm at 100kph, that would give you 8200 at 200kph
(I havent tried for 200!) It still pulls away easily from standstill, but does need more throttle on hills.