|
|
Post by richard on Sept 5, 2021 20:24:57 GMT
hello,
how much top end speed is lost replacing the standard 250n front sprocket with the 400n front sprocket, so 15 tooth to 16 tooth....do they share the same chain size..?
thanks richard
|
|
|
|
Post by johnjones on Sept 5, 2021 20:40:04 GMT
Try standing in a bucket and lift your self up...☹️
|
|
|
|
Post by comstar on Sept 5, 2021 21:02:28 GMT
hello,
how much top end speed is lost replacing the standard 250n front sprocket with the 400n front sprocket, so 15 tooth to 16 tooth....do they share the same chain size..?
thanks richard
Chain on 400 is 100 link, 250 is 102. |
|
|
|
Post by johnfcbn44dx on Sept 5, 2021 21:51:25 GMT
hello,
how much top end speed is lost replacing the standard 250n front sprocket with the 400n front sprocket, so 15 tooth to 16 tooth....do they share the same chain size..?
thanks richard
Year for year perhaps CB250N 15:41/ CB400N 16:36, 1978 / 79 & 80 5/8"pitch 3/8" width 530 (or50 in some lists for sprockets) with a standard chain. CB250N 15:41/ CB400N 16:36, UK models 1981 onwards 5/8"pitch 2/8" width 520 with an O ring chain. The 520 is much better in my opinion. sprocket at the teeth is approx 6mm width, but the center thickness of the rear sprocket is the same as a 530, on a bike with comstars. ( at least until you get to some mainly non uk 1984 models) When I received NHK (CB250NA) it was running 17:38, the same as a CB400F, not good.. Going to a 16T front, speed ?? whatever you currently get in 5th + a couple of mph, 6th may become an overdrive, tailwinds, flat motorways and slight downhill gradients. 6th may also then not be a mechanically sympathetic option otherwise?? If there were a 15T / 40T rear....  |
|
|
|
Post by richard on Sept 5, 2021 22:07:14 GMT
Try standing in a bucket and lift your self up...☹️ hello
i think you lost me with the bucket reference...from my limited understanding the standard gearing on any bike is a compromise, set by the manufacturer, i have a lazy riding style and have no need to scream about on motorways etc, so was passing the time [ as you do ] thinking about various things [ aside from actually getting the bike to run properly ] and the question about gearing popped into my head, i am sure that folk have raised and lowered gearing from stock, so was curious really..
thanks richard
|
|
|
|
Post by richard on Sept 5, 2021 22:30:25 GMT
hello,
how much top end speed is lost replacing the standard 250n front sprocket with the 400n front sprocket, so 15 tooth to 16 tooth....do they share the same chain size..?
thanks richard
Year for year perhaps CB250N 15:41/ CB400N 16:36, 1978 / 79 & 80 5/8"pitch 3/8" width 530 (or50 in some lists for sprockets) with a standard chain. CB250N 15:41/ CB400N 16:36, UK models 1981 onwards 5/8"pitch 2/8" width 520 with an O ring chain. The 520 is much better in my opinion. sprocket at the teeth is approx 6mm width, but the center thickness of the rear sprocket is the same as a 530, on a bike with comstars. ( at least until you get to some mainly non uk 1984 models) When I received NHK (CB250NA) it was running 17:38, the same as a CB400F, not good.. Going to a 17T front, speed ?? whatever you currently get in 5th + a couple of mph, 6th may become an overdrive, tailwinds, flat motorways and slight downhill gradients. 6th may also then not be a mechanically sympathetic option otherwise?? If there were a 15T / 40T rear.... hello
that's a very comprehensive post..thanks
so all things being equal my 1979 250n would have a 15 front and 41 rear [ never checked as it all appears standard ]
you mentioned that a 250n you have was using 17:38 and wasn't any good, was it geared to much ?
would a 1 tooth increase on the front [ leaving the rear standard ] be beneficial for general pottering about, i.e cruising a - b roads rather than racing
not withstanding the engine problems i am having, riding about seems quite " hurried "
thanks richard
|
|
|
|
Post by terryc on Sept 6, 2021 10:15:56 GMT
Try standing in a bucket and lift your self up...☹️ hello
i think you lost me with the bucket reference...from my limited understanding the standard gearing on any bike is a compromise, set by the manufacturer, i have a lazy riding style and have no need to scream about on motorways etc, so was passing the time [ as you do ] thinking about various things [ aside from actually getting the bike to run properly ] and the question about gearing popped into my head, i am sure that folk have raised and lowered gearing from stock, so was curious really..
thanks richard
I've got a 16 tooth sprocket fitted on my CM difference in speed is so small you won't notice, if (as you say ) you have a lazy riding style you'll like it as there are fewer gear changes needed it pulls for longer in each gear .I put a 16 tooth on my old deluxe too as I found the standard gearing on the 250 SD was far too busy riding is supposed to be fun not hard work so the extra tooth made a noticeable difference and increased my riding pleasure . |
|
|
|
Post by johnfcbn44dx on Sept 6, 2021 11:12:48 GMT
Year for year perhaps CB250N 15:41/ CB400N 16:36, 1978 / 79 & 80 5/8"pitch 3/8" width 530 (or50 in some lists for sprockets) with a standard chain. CB250N 15:41/ CB400N 16:36, UK models 1981 onwards 5/8"pitch 2/8" width 520 with an O ring chain. The 520 is much better in my opinion. sprocket at the teeth is approx 6mm width, but the center thickness of the rear sprocket is the same as a 530, on a bike with comstars. ( at least until you get to some mainly non uk 1984 models) When I received NHK (CB250NA) it was running 17:38, the same as a CB400F, not good.. Going to a 17T front, speed ?? whatever you currently get in 5th + a couple of mph, 6th may become an overdrive, tailwinds, flat motorways and slight downhill gradients. 6th may also then not be a mechanically sympathetic option otherwise?? If there were a 15T / 40T rear.... hello
that's a very comprehensive post..thanks
so all things being equal my 1979 250n would have a 15 front and 41 rear [ never checked as it all appears standard ]
you mentioned that a 250n you have was using 17:38 and wasn't any good, was it geared to much ?
would a 1 tooth increase on the front [ leaving the rear standard ] be beneficial for general pottering about, i.e cruising a - b roads rather than racing
not withstanding the engine problems i am having, riding about seems quite " hurried "
thanks richard
"you mentioned that a 250n you have was using 17:38 and wasn't any good, was it geared to much ?" CB400N 1978-1985 1 :2.235 16T/36T CB400F2 1977-1979 1 :2.25 17T/38T CB250N 1978-1985 1:2.73 15T/41T 1:2.56 16T/41T The CB400F2 gearing far to steep for the CB250NA! I think with the 16/41 I would want to make sure I was always above say 3000 rpm on acceleration, otherwise I would feel I was being cruel to the engine.....Other than that, as terry said it would stretch out each gears range. So 16/41 Ok, but with a floor to the rpm in the chosen usable rev range. No black and white, only shades of grey with gearing... |
|
|
|
Post by richard on Sept 6, 2021 18:30:37 GMT
hello
ok, i have a better understanding of real world tests now, so thanks for the reply's...all i need to do now is figure out why she runs poorly..
thanks
richard
|
|
.jpg?width=1920&height=1080&fit=bounds)
