15/45 Gearing

I've seen alot of posts with questions of gearing. Just wanted to say the 15/45 gearing is awesome in the acceleration department and still has controlled wheelies( It's just way easier). Looking at about 5600 RPM at 70mph that isn't bad. It'll also easily still do 150mph @12000RPM. Top gear is like in the middle of stock 6th & 5th gear.I used the speedohealer and a GPS to cal. speed. Bottom line is, bike is way more fun to ride.

 

Please..Please...due tell where you got this kit for the sprocket and chain...as well as the speedo healer...I am having issues getting the bike up...its not like my CBR.....did the speed show faster than normal or slower???

 

I got the sprockets from sprocketcenter.com 888-265-2141. My bike only had 600 mi when I did it so I used the stock chain. Going one down in the front makes it 6% smaller. Going 2 up in the rear makes it 4% bigger. So chain length is not really affected. They have kits too though if thats what you need. I got the speedo healer from sporttour.com 866-761-0936. With the 15/45 gearing without speedo healer it will read faster than you are really going. Now also stock speedo was already reading fast by 6% which is the norm for motorcycle speedos. The directions that come with it are really easy to follow to calibrate it for norm speedo error and new gear change. My speedo is dead nuts on now and verified with a GPS.

 

thank you so much...I have about 1000 miles on mine and I would like it to have a little more punch...after reading about all the modifications...this seems to be the most bang for your buck...I rarely see speeds above 120...so it wont hurt me much...probably not a bad idea to think you are going faster than you really are...thanks again..

 

No problem. I also just installed a power commander(don't worry I put it on after my original post so the wheelie thing was still easy without it) and that helped out too Vtec transition is pretty smooth. On the streets I had no problem running with a 05 cbr600rr and a 06 gsxr750 on a bike run last weekend. Now with both gearing and power commander I have great acceleration but yet silky smooth at the same time. My staintunes come in tommorow cant wait for that sound and maybe a couple ponies. If your interested I'll let you know how it all works together.

 

oh yeah after you gear it be careful. All your gonna need to do is snap the throttle a little to hard in first and your way up there. I 11 o'clocked it the other day very easily. Just get the feel for it 1st thats all. But you probably know that. If I want to take off hard without going sky high I usually lean way forward and the front end will carry about a foot off the ground and set down just in time for 2nd gear shift. Yeah its fun:biggrin:

 

Stock gearing is 16/43. I changed mine to 16/45 which has made a definite difference. I would like to go more, but with that gearing, I am at 6400 RPM (VTEC range) at 83 MPH. If traffic is flowing at that speed, then I keep up with it. I'm concerned that lowering the gearing any further and I will be in VTEC range at more normal highway speeds. If you went 15/45, you must constantly be in VTEC on the highway - true? I'm not sure if running in VTEC range for a sustained period of time is a good thing or a bad thing. Can anybody elaborate?

 

Are you sure of your speed. I verified mine with a GPS my speedo is dead on and with 15/45 gearing My VTEC engages at 84mph. Stock it engaged at 94mph. I usually cruise at 75mph which puts me at 6000 rpm, but I have run it to the edge of vtec without engaging also. I don't think being in 4 valve mode for extended periods will hurt anything mechanicly. Just your wallet for the extra fuel you burn

 

Yes. I've got a SpeedoHealer on my bike too. With 16/45 gearing, I am at 6400 rpm at 83 mph in 6th gear. I'm running an '07 like you. The only difference we have is that you're running a 15T countershaft sprocket which I believe would gear you down even more than myself. That would put you at 6400 rpm way before 83 mph. I want to either go to 16/46 or 15/43, but don't want to be in VTEC at 75 - 80 mph. In this case, I wish it didn't kick in until 7000 rpm like the ealier 6th Gens.

 

I'm not sure if there is a tach discrepancy, but using a GPS my speedo matches the reading from the GPS and my vtech doesn't kick in till 84mph in sixth gear with the 15/45 gearing. It seems on my bike the vtech kicks in at 6800 every time on my tach for some reason. It doesn't disengage untill I go back down to 6100. I checked my rpm at 84mph and its about 6800rpm. Maybe I got a lucky glitch in my ECM because it gives me more room to play with the vtech engagement. Well by my calculations on your bike at 6400rpm you will be doing 80mph when the vtech kicks in. I can give you some calculations for sixth gear going by rpm. 3000rpm=37mph 4400rpm=55mph 5200rpm=65mph 6000=75mph 6400rpm=80 7200rpm=90 8000rpm=100mph 9600rpm=120mph 12000rpm=150mph. Hope that helps

 

Yes, these calculations help very much for deciding to go with the 15/45 gearing. Like I said, I went 16/45 and the difference even with that is noticeable. The bike feels much more responsive, but I want to get even more out of it.

Since I'm now thinking about this, when I was out yesterday on the highway, at steady throttle, the VTEC did NOT kick in at 6400 rpm. I took it up to 6500 rpm and it still did not kick in. I couldn't go any further due to traffic, so now I'm wondering if the 6400 rpm mark for VTEC is only under heavy load and whether it is higher if running at a steady pace. I'll have to experiment with it some more.

 

Thats what I think about the vtec too. I think it comes on earlier under load. If I inch it up to 6800 thats when it engages. If I'm on It hard it seems to come on a little earlier.

I have an update though. I just put on Staintunes and PC3 dialed in. Didn't expect much(I was just looking for sound mainly),but very noticeable power increase. Front end coming up all over the place and was a little hard to RIDE wheelies because it came up way to easy and fast!!!. Even shifting to second gear alone under acceleration popped the wheel up. So I am at a 16/45 now and its perfect for it with my present mods. I still say though for a stock bike the 15/45 is the cheap easy way for fun.

 

15/45 Group Buy?

Any Chance That One Of You Can Set Up A Group Buy For The 15/45 Sproket Kit? I'll Send Some E-mails And Make Some Phone Calls To See How Many Would Have To Be Ordered Before A Price Break. If One Or More Of You Are Interested And Do The Same We Should Be Able To Come Up With A Damn Good Group Rate Over The Next Couple Weeks.
Please... If You Are Interested Go Ahead Drop A Line Or Two On This Thread So We Can Get A Feel For The Number Of Kits. The More We Buy The Cheaper They Will Get!
Personally I Just Want A 45 On The Back But If I Can Save Some Money On The 15/45 I Think It Would Be Fun To Play Around A Bit.

 

I would be interested in this group buy too!

As far as your Vtec questions go, it hits at 6800 on the way up and then stops when coming back down at 6200, which is a change from the 2002-2005 bikes, which hit and stopped at 6400. I think it just seems to kick in earlier under hard acceleration since the needle is climbing as fast as it can but your RPMs are already at 6.8K.

This winter I am putting in a K&N air filter, PCIII, CF Leo Vince, and am now considering this gearing change too....

Thanks very much for the data on your changes, it is great food for thought!

 

I'm acutally thinking of switching from my current 16/45 to 16/46. At a quick check, I think it is equivalent to 15/45. I just don't want to go smaller on the countershaft due to chain wear.

 

16:46 is not equal to 15:45
stock gearing is 16:43
16:45 gave you a noticeable improvement on low end torq
16:46 is alot more torq than the stock gearing but barely a noticeable improvement over your current 16:45
I agree with you as far as not doing any long term changes on the front sprocket. However, rule of thumb is (senior members correct me if I'm wrong) 1 tooth on the front,(+ or -) is equal to 3 teeth on the back.

- a wise man learns from another man's mistakes, a fool must make the mistake for himself

 

I understand how going -1 up front would wear the chain out faster, but by how much? I'm thinking about going -1 up front and -1 in the back, too.

stock gearing: 43/16 = 2.6875 final drive

option 1: 42/15 = 2.8000 final drive (104.19% of stock)

The reason I'd like to go with my first option is because the slightly lower gearing will give me a little more oomph on the bottom end and will sacrifice very little on top. I also want the rear sprocket to be smaller because I think the stock rear sprocket looks hideous (i.e. it's too big.) A size 42 rear is the smallest I can go because of the bolt pattern. There's a chance I may not even do this because the diameter of a 42 is only .19" shorter than the stock 43's diameter.

Have you guys seen the rear hub assembly on the Ducati 1098? That's got a 38t sprocket out back and looks way cool.

 

Yes, you're right. I did my math way too quick. I'm still thinking about going to 16/46 which should be equal to 15/43. I believe the -1 Front being equal to +3 Rear is accurate. I hope I can do this without having to lengthen the chain. I put the 45 rear sprocket on when the bike was new (before the chain stretched) and it barely fit.

 

Ride Red:
Yes in, theroy the chain will wear faster but we're still talking about thousands of miles down the road. Chain wear is the least of my concern. Load on the trany is what I worry about but this comes from problems that I've had with my dirt bike (Honda CR500) when I've gone bigger on the front sproket; it has never been an issue when going smaller. Regardless, if I can acheive what I'm looking for by changing the back that's where I do it.

stewartj239:
Oh and by the way, you will not have a problem with your chain being too short with a 15:43 set-up but 16:46 might be a problem without adding a link or two.