Just wonderin whether anyone has converted their late model rear pulley from a 66 tooth to a 70 tooth? (mines a 2010 Fatbob)

If so, what brand/ model pulley?

Did you get original belt over it?......... or have to buy a longer belt? (no doubt  could depend on age (stretch) of existing belt)

Have researched on this and US sites and have got conflicting results. (who'd figure from forum sites!!)

I know I can achieve similar/same results by changing Trans pulley and/or belt, but was hoping it may be possible to get the required ratio the quick and easy way. (yeah right!!!!!!................gotta ask though, eh?)

Burto.

Figured it was alway easier to change the front sprocket/pulley as it usually worked out that one on the front was worth 4 on the rear.

 From Andrews website.............

"Rear axle position adjustment for each one tooth change on transmission sprocket = + / - .125 inches (3.2mm)."

Burto.

I have a 2009 fxdc with some engine work ie : cams  + 103 + heads  +  D&D fat cats i fitted a 30 tooth front pulley and a 68 tooth rear got the rear pulley made to order by colorado wheels in the States this combination puts the wheel smack bang in the middle of the adjustment range using the original belt. 

This mod really brought things alive you wont regret doing it. 

 

 

Bruto do it. If you can even buy a pulley that does the job. I've been thinking of the same thing myself for some time..been interesting to here about the sporty pulley fitting

 Just picked up a 2nd hand 68 tooth Sportster pulley off Ebay Motors. $27  + $40 shipping.

Will give it a try and see how it goes!

Burto.

Burto what model sporty do you have to use? does it matter or are they all the same?

 Thanks Skulz,

Will check em out and keep them in mind when I snap my first belt (hopefully not anytime soon!)

How do you find the 2.2/1 ratio?..........that is what I was after, but will try 2.13/1 first , when I fit the 68T pulley. 

Burto.

I know its an old post, this advice may help someone else with the newer, about 20mm wide belt.

Just get a 70 tooth pulley off an older bike that runs the wide belt, take it to a machinist, remove the inner ring that keeps the belt on which is held on about 8 bolts or pressed on, if pressed on drill about 8 holes and tap them for a 1/4 bolt, Machine the teeth on the inside down to the width of the narrow pulley, put the ring back on. I've done it twice without any problems and the spacing is right as the outside edge of the pulley is in the same place for the wide and narrow belts on the pulleys I used, this will give you the same offset as before. If your not sure put them side by side on something nice and flat resting on the surface that bolts against the wheel. Only problem is if you use the old belt the wheel moves forward by the distance of two teeth if you had a 66 tooth before. You need enough adjustment at the axle for this and the belt guards may not fit back on as the wheel is now forward a bit. Make sure you keep the wheel square as belts do not like the wheel running crooked, so wind the adjustment bolts by exactly the same amount each side to keep it square. Read the manual for how to do the belt tension. Old pulleys cost me $50 each and machining about the same. Whole job only cost $100 each time if you do the labour yourself, when I did it new replacement pulleys were about $500. Quick and cheap and better gearing, but it still feels like it wants a bit more reduction, so will change the front one for a smaller one next time the motor is out, but will not go too small as then, there are less teeth to hold the power and the radius is getting tighter which belts don't like, so will only go down to a 30 front tooth and definately no more. At a guess there is about a 10% reduction in engagement on the front pulley going from a 32 to a 30.

Felt it was worth doing as the reduction helped and it was not much move effort than taking the rear wheel out and putting it back in. Hardest part of the job is getting the rear brake caliper back on when doing it by yourself. Speedo will be out by about 6%, just check it against the GPS, have the speedo adjusted next time your on the dyno. There was talk about the pulley bolts snapping or working loose, from what I could find out this was only on some bikes about 2006 or 2007 (guessing from memory) and the holes for the pulley bolts were a tiny bit too short or the bolts were too long, so the bolts were torquing up to specs and the pulley was firm, but not tight enough against the pulley. Easy fixed by grinding 2mm off the end of the bolts or a thicker washer if your bike has this problem, thread a bolt in and make sure it can go in far enough to be sure. Most wheels do not have this problem or the threads go through into the centre space anyway on a some of them.