DIY primary gearing swap (step by step with pics)

[Artur]

Hello everyone!
As I'm new here the first thing I should introduce myself. I'm Artur, I'm from Poland, but live in Belgium (over 6 years now). I ride Buell XB12S. I bought it new and I've had it for 4 years now. I'm pretty happy about it. I did some optical mods to it. Please see the pics below.
I found your forum while I was searching for some technical info.
Actually I bought the XB9 primary chain and engine sprocket with the intention to replace the original primary gearing in order to gain some acceleration for the price of the top speed.
I thought I had all the parts and the tools, so I started the operation. It was going quite well until the moment when I wanted to unscrew the engine sprocket. It turned out that I don't have the right wrench/socket to unscrew the bolt holding the engine sprocket. I have a set of metric hexagonal sockets, but it doesn't cover the whole range - I have 27mm and directly 30mm. The bolt must be either 28 or 29mm, or (what would be worse) it may be even some inch scale size.
Does anyone have a clue what is the size of that bolt?
Another potential problem is that the torque that has to be applied to attach the bolt must be over 250Nm and my torque wrench covers only up to 210Nm.
I'd appreciate any views from you.
Cheers,
Artur

 

[Buellysses]

Correct me if I'm wrong, but I'm willing to bet that nut isn't metric.

 

[LeFox]

yep...probalby u.s. size....

where you at in belgium? if you want to work on your bike you will need both our metric but also u.s. sizes.

and really...i almost never use a torque wrench, i look at the material and adjust pressure accordingly...

 

[Stevenc150]

Looks like they got you covered Artur. Welcome to the Forum and congrats on the good looking bike. [up] Here's a good link to check out if you haven't already: New Forum user info ; as well as downloadable service manuals via the link at the top of this page.

 

[Artur]

yep...probalby u.s. size....

where you at in belgium? if you want to work on your bike you will need both our metric but also u.s. sizes.

and really...i almost never use a torque wrench, i look at the material and adjust pressure accordingly...

LeFox, I'm in Brussels. I know that some nuts/bolts on my Buell are metric and some are imperial. That's why I got myself already a few tool sets (both metric and imperial), but it looks I'm still short...

It would be kind of difficult to apply the right torque to attach the engine sprocket. 250Nm is twice as much torque you normally use on car wheel bolts. But having a torque wrench covering up to 210Nm, I'll just go little further after reaching 210Nm and this should do.

Anyway, I'll let you know once I figure out the size of that bolt. And I'll update you on the results of the surgery

Looks like they got you covered Artur. Welcome to the Forum and congrats on the good looking bike. Here's a good link to check out if you haven't already: New Forum user info ; as well as downloadable service manuals via the link at the top of this page.

Steven, thank you for the welcome and for the tips. I know that this swap was discussed previously on the forum, but unfortunately not in the right detail. Apparently very little guys did it themselves...
I have the service manuals: paper version for XB9/XB12 and pdf version for Firebolt.

 

[Artur]

The engine sprocket nut is 28mm metric.
And there's no f***ing way to unscrew it. It sits there really hard...
I will have to extend my wrench with some long arm.

 

[LeFox]

use some oil to loosen it up a bit. (let it sit for a few hours)

tapping it is also better then using constant pressure.

i'm about 50km out of your way

 

[Artur]

OK, here is where I stopped last time:

To be able to move on I fabricated my own Sprocket Locking Tool:

Then I unscrewed the Engine Sprocket nut:

Then I removed the Retaining Ring and Adjusting Screw Assembly:

and unscrewed the Clutch Shell with Clutch Sprocket:

Then I removed the Engine Sprocket, Clutch Shell with Sprocket and the Primary Chain.

It turned out that the Engine Sprocket is attached to the Alternator Rotor Assembly:

I unscrewed the Engine Sprocket from the Rotor Assembly:

but they stick to each other really hard and I cannot split them.

Here is what the manual says about how to remove the sprocket from the rotor:

Now I have to find some press...

 

[Stevenc150]

Awesome Play-by-play. [up] Keep it up.

 

[Artur]

Steven150, could you change the topic title to "Primary gearing swap"? It would be more helpful for the guys, who look for such info. Thanks!

I took the rotor to the garage, where they are going to swap the engine sprocket for me. Once this is done I'll continue with my work and my writeup.

 

[Stevenc150]

For some reason, we can't change a Thread Title, only Delete/Move/Lock/Make Sticky. [sad]

It's probably best if you start a new thread and then copy/paste your posts over to it.

 

[Artur]

I got my engine sprockets swapped. The XB9 one has a 11cm diameter vs. 12cm of the XB12 one:

I had everything to start assembling the engine.
First thing was to attach the sprocket to the rotor. O used new, original HD bolts (supplied with the torque kit):

Nest step: install the primary chain assembly:

First I put the rotor in:

then the clutch shell with the chain:

Then I attached the nuts:

I realized after a while, that my torque wrench works only in one direction, so I had to tighten it "manually"...

Next thing: primary cover installation:

Adjusting Screw Assembly installation:

Chain tension adjustment:

Job done (except for transmission oil and clutch cable adjustment):

I'm buying the oil tomorrow and tomorrow I plan to do the first ride after the swap.

 

[LeFox]

title changed to 'DIY: primary gearing swap (step by step with pics)'

i'll let you find it now but i'll move it to the DIY section

Aartur, [up]

 

[onelogue]

wow this helped a lot!!

Thanks [up]

 

[jeff m]

Thanks for posting this. I'm anxious to see your impression of the change in performance. If I got this right, the RPM at a given speed and in a given gear should be increased by a ratio of 12/11 based on the drive sprocket diameters. Currently I get 3000 RPM in fifth gear at about 63 mph. With this change I'd get 12/11 X 3000 = 3273 RPM at the same speed in the same gear. Seems like a reasonable change with the added benefit that the mirrors should get easier to use at highway speeds. [up]

 

[Artur]

Thanks guys! I didn't have time to buy my transmission fluid today. I will do that tomorrow. Tomorrow I also plan to have the test ride. I'll let you know about my impressions.

 

[Sidewinder]

Is the speed sensor at the crank? Would this also affect the speedometer reading? Bike tries to rip me off the seat as it is but I might wanna give this a go eventually.

PS- I can never seem to keep my bike as clean as yours is.

 

[jeff m]

Is the speed sensor at the crank?

The speed sensor has to be "downstream" of the clutch otherwize you would get an incorrect reading every time you coasted with the clutch pulled in.

Not sure exactly where it is though.

 

[phild1203]

The speed sensor is located in the tranny so doing a primary swap won't affect your speedometer since it happens before the sensor. If you changed one of your pulleys though, it would affect your speedometer since the change is after the sensor.

 

[LeFox]

move has been done!

sidewinder, this will not affect your speedo reading.