Author Topic: Sprockets & Chain (Read 8373 times)

jcmjrt · « **on:** June 22, 2005, 10:11:40 PM »

I need to get new sprockets and a chain. I was pondering going for a little more low end grunt, if possible. Anyone changed their sprocket sizes? How much change was there? I'm wondering how much top I'll give up to get a little quicker take off at the low end?

b4cruz · « **Reply #1 on:** June 23, 2005, 05:51:02 AM »

everyone seems to do just two teeth
either 2 up front
or 2 down in rear

so you notice either better take-off
or lots more high speed
there seems to be
no happy medium

but if you have a limiter
you can't figure out how to disable
maybe you could go
with more pickup
and not mind the top end loss
because you can't get up there anyway

PitterB4 · « **Reply #2 on:** June 23, 2005, 06:59:10 AM »

Quote from: "b4cruz"

everyone seems to do just two teeth
either 2 up front
or 2 down in rear

Huh? First, 2 in front is equivilent to about 6 in the back, isn't it? For more low end, you want to go smaller in the front and/or larger in the back. That's why all the stunters have huge rear sprockets - to torque the front up easily.

jcmjrt · « **Reply #3 on:** June 23, 2005, 09:30:18 PM »

There's no limiter.

Pitter, I think that you're right about smaller in front and larger in back for adding grunt.

I wouldn't mind losing a little top end to make accelerating out of the twisties just a little quicker. I was hoping that someone who had already made a change would know about what the trade off was. e.g. with one tooth smaller in front and same size cog in rear would be about 110mph top end and a perceptible difference in acceleration or one smaller in front and four teeth larger in the rear would be about 100mph and would be a very noticeable difference in acceleration....or something like that....

I did do a search on the subject but I didn't find any info on the effect that the change had.

PitterB4 · « **Reply #4 on:** June 23, 2005, 10:47:01 PM »

I've thought of the same thing. The problem is that 1st is SO low already that lowering the gearing would make starts annoying, IMO.

There's no limiter? My '93 cuts out at about 13.7k (13.5k redline).

jcmjrt · « **Reply #5 on:** June 24, 2005, 02:45:01 AM »

It's definitely possible that starts could be annoying. I was just hoping that someone had already done something like that and could pass on some hard won experience. I guess that I'll have to get hold of sprocket specialist (or is there anyone else recommended?) and find out what I can get.

I can't say that I've redlined my Bandit too much..and not for a while. I don't know exactly where it stops climbing. I'm really not that concerned with top speed since one cannot go 100+ mph in serious twisties and that's what I love. I thought the guy was refering to the annoying limiters that the Brits'/Europeans have on bikes for novice riders. I wouldn't think that one would disable a redline at 13 - 14K RPM which is there to protect the power plant...at least I wouldn't.

echomadman · « **Reply #6 on:** June 24, 2005, 07:59:35 AM »

its better in general to go up 3 on the back than down 1 in front as its less stressful on the chain, it has the same effect on acceleration, but going 1 up on the back would give you a little more torque without sacrificing too much top end, and without making first gear too short..
Suzuki do this on the sv650, the naked version has 1tooth more on the rear than the faired for better acceleration.

jcmjrt · « **Reply #7 on:** June 24, 2005, 10:40:23 AM »

The change to the back vice front makes sense. Thanks. Hopefully, the one tooth change to the back is available.

PitterB4 · « **Reply #8 on:** June 24, 2005, 10:54:34 AM »

I wouldn't swear to it but I think the B4 can use the same rear sprockets as SVs. If so, there should be tons of options out there. Please verify that first, though. Maybe go look around the old board. I remember it being mentioned there.

echomadman · « **Reply #9 on:** June 24, 2005, 12:58:58 PM »

I can have a look over the weekend, measure the distance from nut to nut on the two bikes.
If it is the same then my plan of making a little stuntbike out of my 250 may come to fruition after all.

gsxr400 racer · « **Reply #10 on:** June 26, 2005, 08:37:52 PM »

i run 15 -48 but have 17's all around.

b4cruz · « **Reply #11 on:** June 26, 2005, 08:51:20 PM »

Quote from: "PitterB4"

Huh? First, 2 in front is equivilent to about 6 in the back, isn't it? For more low end, you want to go smaller in the front and/or larger in the back.

that's me reading posts wrong again, sorry

but I do remember reading more sprocket changes with 2 teeth instead of one. If the standard SV650 will fit I think that would be the best route.
I tried searching the old board but didn't come up with anything

here are the stock sets:
http://www.afamusa.com/sprocket-apps/suzuki-sprocket-apps.html

Racerruss-ducati · « **Reply #12 on:** June 26, 2005, 09:57:45 PM »

1st, the easy answer: Assuming you reach the same rpm with either sprocket set up (i.e. a rev limiter), the loss in top speed is directly porportional to the ratio change. If your stock setup is 14/46 (3.285/1 ratio) like the US spec bikes, and you go with say a 14/48 (3.428/1 ratio), your top speed will be your old top speed x 3.285 / 3.428. So, if you currently hit 120 mph, your new top speed will be 120x3.285/3.428 = 115 mph.
Your acceleration will increase by the same ratios. Since 3.285/3.428= 0.958, this means your acceleration will be 4.2% better in any gear.

Now the physics: In fact, the difference in top speed will be a less than this, since your bike will probably be able to pull a little more rpm with the new ratio. The top speed is more a function of available horse power and aero+mechanical drag, if there is no rev limiter in play, than it is of gear ratio. The trick the racers know is that you must get your bike to pull top gear all the way up to the rpm that matches the peak hp for maximum top speed.

It is fully possible that your top speed will increase due to having a lower ratio because the hp climbs with rpm on the stock B4's up to about 12.5krpm. So if you currently run out of steam at about 11.5krpm (stock gearing, 120 mph), the new ratio may allow you to pull up to 12.5krpm, with the new ratio would equal 125 mph.

BTW, Chaparral lists rear sprockets from 33 up to 66 tooth. They only list the 14 T front. Make sure the chain you order is sufficient in length to accomodate the larger rear sprocket, the Bandit has pretty limited adjustability with the rear wheel.

Good luck and let us know how it works out.

Zhi · « **Reply #13 on:** June 26, 2005, 10:05:45 PM »

I am running a SV650 Vortex rear sprocket on my 400, but I don't think the fronts are interchangeable between the two bikes though.

jcmjrt · « **Reply #14 on:** June 27, 2005, 11:31:20 AM »

Thanks guys. I appreciate all of the info. It looks like I'm going to change the rear sprocket to a larger size(TBD) and I'll check out the SV650 sprockets since that seems to work.

Zhi, did you change to a bigger sprocket or keep the stock size?