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Post by alliekat on Sept 14, 2010 22:00:09 GMT
Hiya any one have some ideas, i have an exup rear end on my Fz with a 17inch rear wheel and 180 tyre i have a 17 tooth front sprocket and i was wondering what size rear sprocket to use. i was running a 45 tooth on it with a 17 front but it was reving to high. as i have changed the wheel tpo a smller one it is all confusing me. do i still need to put smaller rear on or a bigger. the chain kit i have got for an exup has a 47 tooth is this ok or to big.? I have had the front sprocket modified with a recess to allow me align the chain and the size of spocket is muddling my poor brain any help pleasewoudl be cool . ;D
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Post by Graham on Sept 14, 2010 22:43:20 GMT
Hiya Allison. There is a gear calculator somewhere on the internet, not sure if I put a link to it in the "Links" section but the general rule regards altering your gearing is smaller rear sprocket= less acceleration, higher top speed & bigger (more teeth)= more revs, more acceleration but lower top speed for the same amount of revs. The opposite applies for the front sprocket so bigger front has the same effect as smaller rear. If you look at the rear sprocket on your average motoX bike it is usually huge which gives them lightening acceleration out of bends etc but poor top speed. As you have had your front cog machined I am guessing you will just be playing with different sized rears so I would be tempted to buy one that is at least 2 teeth smaller & see how it feels.
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Post by Graham on Sept 14, 2010 22:50:48 GMT
I found it & have posted a link in the "links" section but here it is Ally, www.gearingcommander.com/ ;D You can alter any of the figures to suit your own settings so wheel & tyre size as well as front & rear sprocket sizes.
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Post by alliekat on Sept 15, 2010 21:59:05 GMT
Cheers graham to the rescue again , my shiney knight ... chuckle Well according to the calculator. with the 17" wheel and running a 17/47 set up it would be geared for 155.9 at 10500 rpm. 17/44 would be 166.5 at 10500rpm standard with 18" wheel 16/44 would be 144.8mph at 10500 but with a 17/44 would be 153.9 at 10500. although this depends on the tyre being 180/80/17 if it is a 180/70/17 then the the speed with the 17/47 drops to 148 so i coudl go with the 47 or as you stated graham find a smaller rear sprocket of say a 45,44,43,42 would seem to be the best, 44, 45 optimum for road and track. Wow i sound nearly intelligent ;D
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Kevin
New Member
1985 FZ 750/87 FZR1000 FR/RR suspension
Posts: 49
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Post by Kevin on Sept 15, 2010 23:36:04 GMT
Happy birthday!!! Been following your progress, looks good.
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Post by alliekat on Sept 20, 2010 12:22:37 GMT
thanks for the birthday greetings.
My tire is a 180/55/17 so with the 17/47 sprockets it will do 136 at 10500..... mmmm think need a smaller sprocket for the track.
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Post by Graham on Sept 20, 2010 13:59:32 GMT
Not necessarily Alison. All depends on the track. Mallory park for instance being 1.5 miles with only 1 small straight. Can't see you getting anywhere near flat out in 6th gear even with the 17/47 cogs.
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Post by alliekat on Sept 20, 2010 18:14:46 GMT
What about brands Gp circuit ? i did race elsies in th early nineties at brands but gearing was a bit different on the short circuit. i have raced at snetterton , mallory , cadwell, lyden, and donnington on either elsies/350k4 or passengering oufits, but the solos were a bit slower than the FZ so no idea of what to use at brands GP circuit.
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Post by fz750horse on Sept 20, 2010 19:28:11 GMT
Hi Alison, Try 16/46 or 16/47 to start with. The straights aren't very long and it's not easy to carry enough corner speed through Surtees and Clarke (highside territory ) to get silly speeds on them. 17/47 and 5 gears probably wouldn't be far off - depends how quick you are
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Post by scobri on Sept 21, 2010 20:35:00 GMT
I managed to get my FZ bouncing off the rev limiter on start finish straight at Mallory using 17 47 gearing,but was also using a 160/60 17 rear tyre,i also used 17 43 similar speeds on straights but was suffering getting good drive off the bends. Managed to upset a guy on 05 R1 by managing to stay with him quite comfortably but stoppping the FZ for the bends was a bit interesting.
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Post by booj44 on Feb 14, 2011 18:59:09 GMT
I've been reading with interest your debate on gearing woes.I've modded my FZ by fitting a fireblade front end,which is a great mod,an EXUP swingarm carrying a CBR400 17"rear wheel with an adaptor plate on the sprocket carrier carrying an R6 530 pitch conversion sprocket to align with the front cog.Now the fella who modded the rear calculated the gearing to be the same as yours,17 front and a 48 rear,now this pulls like a steam train but struggles to get to 110mph and is noticably revving far too high compared to when it was in standard trim,the rear tyre is a 170 section.I've been thinking about dropping 2 teeth on the rear but am now wondering maybe lower still,any advice would be of great help.
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Post by alliekat on Feb 14, 2011 19:40:43 GMT
hiya, well it had no problems getting to 110 at the moment it is off the road as the forks are being modified to fit four piston calipers and 17 wheel, but it did accelerate like mad... wow. it is off the road for a while now as i have to go into hospital to have an op on my leg so will be on crutches for 6 weeks oh wel th eGsxr750 slabside is almost done and now i picked up a monster for 625... did a friend a favour as he needed to sell it but shoudl make a bit on it to pay for Fz stuff ;D
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