[old3]

I love the new wider ratio trans, much better than the old 250 in both spread and shift action precision. However, the gearing on the 300 is very low in first, and I was using second gear most of the time from a dead stop. Even with a passenger it was better than first which was more noise than action IMO.

On went a 2008-12 15t counter shaft sprocket, fit perfectly and suddenly I have a useable first gear! Nice mod, and I'm a guy who runs super short gears on everything I own. My Mustang has 4.56s and my KTM 950 SMR had a -2 front CS so I like my peppy gearing.

Another +, I think the speedo will be closer to actual speed now, stock it runs higher than actual speed. I'll verify that with a GPS ASAP but so far I'm convinced it is actually dong the speed it is reading.

 

[old3]

I doubt it will pull the taller gearing to redline in 6th but it might? It will lower RPMs at all road speeds and it still pulls it well with the great midrange power/torque so why not?

It took all of 25 minutes. Lets see how much I can recall to help out with the swap.


You need a 8mm socket/t-handle to remove the sprocket cover and the speedo pick up beneath it, set the speedo pick up aside on top of the engine case and bend open the thin wire strap, watch the second wire there too, just don't pull on it and watch the orientation for assembly.

Mark the shifter slot/shaft with marker so you can easily line it back up and a 10mm wrench gets that out of the way.

You need a hammer and a flat, dull screwdriver to open up the bent nut retainer on the CS sprocket.

A 12 and 14mm wrench to loosen the axle adjusters and a 1-1/16 box wrench will work for the axle nut after you pull the cotter pin. That might be a 27mm nut there but not 100% sure.

I think I used a 1-1/16 deep socket on the CS nut and I tapped it off with an impact gun, 1/2 drive pneumatic.

Once everything is loose, push the rear wheel forward and the sprocket can be extracted from the now loose chain and shaft.

Slip in the 15t, it fits but the splines can be a PITA. Add retainer washer and nut being sure the splines are engaged.

Adjust chain to proper tension, tighten wheel. I gave the CS nut a few taps with the impact gun, you don't need to murder it and I'm sure there is a torque spec but i do alot of these and the lock washer gets bent over to retain it too. A large slip lock plier makes this easy, simply engage the lip and a flat on the opposite side of the nut and squeeze it flat along the nut using a new, fresh edge of the washer so it doesn't weaken and break off.

Reassemble the speedo sensor, recrimp the wire strap and the replace the shifter/cover.

Go ride it and tell me it isn't how the bike should be delivered!

 

[old3]

There, I think I got all my typos corrected! I did the best I could from memory on the nut sizes, hope I got the 1-1/16th right for the CS nut, 100% sure on the others.

 

[old3]

JT also.

 

[old3]

Inside as I recollect. Just look at the one coming off, it was obvious.

The replacement I got had two threaded bolt holes in it that you won't use. I did a quick 15 miles on it before it got too dark, cold and "deer-y" outside, friggin rut season! Totally transforms first gear and I'm pressed to even feel it affect the other cogs. I'm very gearing sensetive so that shocked me.

 

[old3]

Sorry, don't have a pn handy. The only difference should be those threaded holes I described. Some may have them, some don't. Otherwise they should be the same if the numbers are correct.

 

[old3]

Scratch that! pn # jtf516.15, I sw the package in the bin in the garage.

 

[old3]

Top speed in each gear at the rev limiter;

1st=37 MPH
2nd=57
3rd=72
4th=88
5th=?
6th=?


I've been to 100 in both 5th & 6th, gotta find a spot to stretch it to the top of the speedo soon.


I'm still running a +1 CS which seems to have correctted the high reading speedo. (edit) GPS confirmed!!! Speedo is right on the $ every 10 MPH up to 70 MPH.

 

[old3]

So? Did ya ride it yet?

 

[old3]

Top speed in each gear at the rev limiter;

1st=37 MPH
2nd=57
3rd=72
4th=88
5th=?
6th=?

I've confirmed the reading on the speedo now matched actual speed via GPS. I don't think there is much difference in RPM vs speedo reading except the speedo is actually correct with a +1 CS. ie, you weren't really going 70 MPH when it read 70 before.

 

[old3]

which part number did u use
i ordere the jtf516.15which is what old3 listed
h ow is the acceleration and highway cruise

8k RPM = 72 actual GPS confirmed MPH, 75 = about 8300 RPMs.

 

[old3]

It does seen like I shift out of first right away but I ride in a city with lots of stop and go. Do you guys notice it's any slower at the start? Do you have to feather the clutch more now?

It just makes first gear a little longer and more useful. You shouldn't have any trouble adjusting. It feels like the right gearing now, not too tall at all.

 

[old3]

Well, are you handy at all? You need to loosen the wheel and push it forward in the adjustment range to pop the chain off the rear and then front sprockets. It doesn't need to come all the way out, you just need to loosen the axel nut.

Chain adjustment is one of the most basic things you'll need to learn or you will have alot of down time and many$ spent at the mechanics.

Do you have a friend who works on their own bikes? If not, meet some!

 

[old3]

The chain adjustment procedure is the the stock manual. You just need to get the chain to its loosest point to drop it off the rear sprocket to give you room up front.

It is easier than it sounds and just post up for help if you need it.

Another tip to make the wheel easier to move is to compress the rear caliper with your knee to loosen the brake pads. Just be sure to go slow and then pump it up when you are finished or there will be no brake when you need it!

 

[old3]

Not what I said, compress the caliper to let the wheel move freely. Pads stay in, caliper stays on the axel.

 

[old3]

It should be a tighter fit, if it rocks it will hammer the splines and can destroy the shaft. Hammering it on is an exaggeration, it needs to be tapped but it fits and is the correct size.

 

[old3]

Can a mod be done to the rear sprocket to perform the same fucntion as adding one to the front?

Adding +1 CS is roughly equal to -2/3 on the rear sprocket. I didn't look any further for alternate rears as I now find it perfect. On my KTM SE950 I ran -1 and + 5 for dualsporting and off road racing. My 950 SMR I had a -2 front CS. I like low gearing with good snap. For me to gear taller was not a normal direction but this ratio just flat out works on the 300.

The speedo correction was just a bonus too, I'd run this gearing if it made the speedo read even worse!

 

[old3]

Maybe it is a different CS than what I am used to on the pre-gen 250. On that bike the front sprocket is purposely able to wiggle laterally, not front to rear in the splines, but side to side to allow a slight amount of chain drift. Maybe I'm being paranoid but I thought I read that the 300 spline is a larger diameter than the 250, hence my concern with using one meant for the 250.

I think you are overthinking this. The chain will drift slightly across the teeth of the sprocket. If the sprocket is moving around on the shaft it will have excessive wear at that point where it is allowed to move. If the chain is moving the sprocket side to side there are other issues that need correction IMO, like alignment of the wheel or a bent rear sprocket/wheel/axle/countershaft.

I've replaced hundreds of sprockets and am comfortable stating the 250 sprocket is an exact replacement for the 300.

 

[old3]

Scratch that! pn # jtf516.15, I sw the package in the bin in the garage.

This is what I used, nearing 2k miles now. Had it on for most of that. Working great.

 

[old3]

Thats why I stop at 88!