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28T to 29T Front Pulley Swap

27K views 83 replies 18 participants last post by  raven 
#1 ·
Based on the owner's manual,the XR1200 uses the same pulley combination as the 883 bikes: 28 & 68T. The XL Sportster uses 29T for USA models.

I'm considering making the swap to raise my gearing.

I'd like to hear from some owners who have done the mod.

Also, are there lighter pulleys available to reduce rotating weight?

I have read the Scotty Mod thread, but I'm wondering if there may be some benefits by simply changing the front pulley, especially to a lighter one.

Best wishes,
Dave
 
#3 ·
re:

Okay, I found this quote, here goes...
The gear differences between the 883 and 1200 involves both primary and secondary gears. Changing from a 28T to a 29T only, will reduce your RPM by a factor of .9655 or 3.45%. 71 MPH at 4000 RPM will drop to 71 MPH at 3,862 RPM, for an RPM decrease of 138 RPM.*
(1200 meaning the xl sporster)
 
G
#4 ·
Okay, I found this quote, here goes...
The gear differences between the 883 and 1200 involves both primary and secondary gears. Changing from a 28T to a 29T only, will reduce your RPM by a factor of .9655 or 3.45%. 71 MPH at 4000 RPM will drop to 71 MPH at 3,862 RPM, for an RPM decrease of 138 RPM.*
(1200 meaning the xl sporster)
Thats sounds about right to me... and about a 5mph increase on the top speed at 7000rpm.
Like I said over in the Scotty Mod thread, I think a change to a 30t front pulley is a better option. Cruise rpm drops about 275rpm at about 70mph with an increase of 10mph at 7000rpm.
I have tried the 29t and honestly didn't notice much of a difference, so I put a 66t rear pulley on aswell (this is almost the same as 30t/68t combo) really like that combo, for the last few months I have been using a 30t front and the 66t rear, great for cruising, like it aswell the more I ride it, but next tyre change I'm going back to the 68t rear and keeping the 30t front on, I think I like this ratio more.
 
#5 ·
Thanks, a lot of good information.

The stock gearing around town works fine, but on the highway, it's just too short.

I checked today, the indicated mph speeds at the rev limiter in gears 1-4 are approximately 45, 65, 85, and 103. It's way too easy to accidentally bump into the rev limiter.

I like the idea of changing either the front or rear sprocket for it's simplicity and "reasonable" cost. And if an aluminum pulley can be found in the desired gearing, more the better.

Dave
 
#8 ·
This is my first HD, so I don't claim to be an expert. I did however find plenty of 66t pulleys on Ebaymotors. It seems a Dyna runs a 66t. Prices range from a couple hundred bucks for a blingey item to $20 for a used one off a Dyna. Is there any reason one couldn't bolt one on an XR?
 
#9 · (Edited)
I don't know if the Dyna pulleys are interchangeable. Could be.

I want to point out that with chain drive, one tooth on the front sprocket is roughly equal to 3 teeth on the rear sprocket. I do not know the ratio using pulleys.

Take that in consideration when deciding to swap the front or rear pulley (or both).

I am intrigued with the idea of using aluminum pulleys, especially if the current HD pulleys are steel like my '96 Sportster was. It's not the weight savings, it's that it is rotating weight. With chains it's a common performance mod to go from a 530 or 525 chain to the lighter 520, plus use an aluminum rear sprocket (I have that set-up on my SV1000) to save rotating weight. I do not know how much more aluminum pulleys cost.

Best wishes,
Dave
 
#10 ·
The nice thing about changing the rear pulley: you can buy one, set it aside, and the next time you replace your rear tire, the pulley gets replaced as well.

Question: do you adjust belt tension by sliding the axle, like a chain drive bike?

Dave
 
#11 ·
XR1200 mechanical Guru (s),

Chain drive: a smaller REAR sprocket equals a slightly longer wheelbase. A larger FRONT sprocket equals a slightly shorter wheelbase. Same with pulleys?

The reason I ask is that I'm leaning toward a larger front pulley (from 28 to 29) because a shorter wheelbase will slightly increase steering response.

Dave
 
G
#12 ·
lol this is a big decision for you isn't it....

Yes a rear pulley from a big vtwin will fit, but you need to machine it down. However, you cannot use a 66t rear with the stock 28t front, unless you buy a shorter drive belt.
 
G
#14 ·
40409-04 < part number for the 29t, sorry I don't sell anything related to my bike,plus postage from Australia wouldn't be cheap...but your local dealer should carry it, I believe the 29t is stock on the XL's in the USA, I payed $50 for mine here.
Don't forget the big nut is lefthand thread, goodluck :)
 
#16 ·
I've ordered a 29T front pulley from Surdykes HD: $51.50+$7.00 shipping.

It's a compromise solution, but the moderate cost and ease of installation decided me. It will go on when the rear tire is changed. I also ordered my next rear tire: Pirelli Angel GT dual compound.

An added benefit of the larger front pulley is that it will shorten the wheelbase slightly which will quicken steering response.

And, if the Sportster speedo reads high like most bikes, the larger pulley may make it accurate. In any event, the speedo won't be off by much.

I will report back when the change is made.

Thanks to all who contributed to this thread.

Best wishes,
Dave
2010 XR1200: Night Rod Special bars, HD long stem mirrors, V&H Fuel Pak, V&H Black Widow, E-A-Rgripper 31db ear plugs!
 
#18 ·
Now that's funny as hell!

Harley finally got something right!

Just try to find a Japanese bike forum where there is not a thread about speedometer error.

HDMOCO never ceases to amaze........

Dave

The speed limit: When your engine hits the rev limiter in top gear!
 
#23 ·
"The speed limit: When your engine hits the rev limiter in top gear!"

"10-4, That is correctamundo..................some on here have verified that as well."

__________________________________________________________________

Quote: "If your motorcycle can't exceed the speed limit by 50mph, you need more horsepower."

I just made that quote up,.............so the XR1200 drivers were included.

That's cutting it close!

Be careful out there,
Dave
 
#33 ·
113 underwater is pretty d@mn impressive. :whistling:

On the highways we have 3 limits. 100, 120 and on some stretches of road 130 KM/h. I'm not sure how accurate 'dead on' is but mine is 5 KM/h off. No biggie, about the same as various KTMs I had before the XR.
I meant laws about the speedometers themselves. Like I said early, in Japan they have very specific laws about how the speedometer can read. And I can't read slow, so they err on the side of reading fast.
 
G
#28 ·
I think Dave is right about the speedo being slightly out, I have mentioned this before, the VSS (vehicle speed sensor) has a calibration range from 2140 to 2355.



The XR VSS setting from the factory is 2354, but when you use the VSS calculator supplied with TTS it comes up with 2417. Which is out of range.



Changing to a 29t front pulley is taking the calibration to the other side 2354 to 2333, which is closer to the OEM setting 2354

 
#37 ·
Guru of Gearing,

NOW you tell me.

There's a "world model" pulley cover?

So, HDMoCo (in their infinite wisdom) may make several different pulley covers, each clearanced for a specific model and/or market for 28, 29, and 30T pulleys? Dare we try to compute the number of variations possible?

Mind boggling.

Dave
 
G
#38 ·
I told you this before... in the other thread.

Don't know about world model... all the XR's are 28t/68t aren't they?

Its not hard to do. Bolt up the cover evenly untill it feels firm. Spin the back wheel, the pulley will mark the inside of the cover, remove cover, get your grinder out and attack it, gently, where its marked by the pulley, keep going untill it fits.
 
#41 ·
I got my 29T from Surdykes yesterday: $51.50 + $7.00 shipping.

The pulley weighs a hefty 3.8 pounds according to the bathroom scales.

I know Harley-Davidson traditionally uses STEEL and disdains using aluminum, but the XR is their performance model. Throw us a bone.

Dave
 
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