I've got a 2007 flhtc with a 107 build and stage 2 heads. I just recently went to change out rear tire for the new season and noticed the teeth on my belt are barley on the belt. They are all cracked at the base and now what I thought was going to be an easy get on the rode project has turned into much much more. I am now going to do the clutch and spring since I've got almost 70k on her and I'm running quite a bit more hp and tq than stock. I'll save that for another thread. I'm going to change out the rear 66t pully to a 68t to give a little more in the pants. I know it's a real tight fit with the 137t belt. I'm wondering if Harley makes a 139t x 1inch belt. I found one from Goodyear but have not heard good things about their belts. I might be able to make the 137t work but figured a 139t would be ideal since I don't plan on going back to the old pully. Anyone know if harley or gates makes a 139t x1inch?

 

http://www.bdl-sales.com/Gates-Poly-Chain-Belts_c_774.html

This site has a 139x1" Gates Poly- chain. Handles my 100 / 100 no problem. IF you're gonna go to a 68 and have a 6 speed I would do the 70 tooth. They have them also. I believe the ratio to increase belt length is 1 tooth belt to 2 on the rear pulley.

 

I have the 68t rear pulley on my '08, yeah it fits, barely but it fits with the stock belt. Tension is correct. Another idea is to go 31 or 30 on the trans pulley to keep the stock belt along with the 68 pulley if a higher ratio than a 68 pulley will give you by itself. If you tour a lot I think it would end up being mighty inconvenient to have fitted a non stock belt and have a failure out on the road somewhere and be waiting on some special order belt. The 31 gets you 2.96 and the 30 gets you 3.06 with the 68 pulley. 68 pulley with the 32 gets you 2.87, stock 66t with the 32 was 2.79. A 32x70 would be 2.95.

I know the 31x68 will keep the stock belt fitted, and I am pretty darn sure the 30x68 will too.

 

I'm running a 68t pulley on my street bob with the stock belt, but it made it to where I had to pull the rear axle forward a bit more than expected and not much adjustment slack left, but it still fits fine. In your case the 139t belt would ceartainly be a welcomed upgrade and practically free to do because you're already replacing it. Honestly though I'd do a 70t pulley or a 68t rear pulley and 30t transmission side drive pulley and stick with a 137t belt. The 68t pulley over a 66t the noticeable differences were pretty miniscule, SLIGHTLY more noticeable grunt in the low gears, and I wanted to turn more RPM in 6th (I do a lot of 65-75mph riding) and 6th wasn't happy before at 70mph but now it's OK. But the biggest difference is I can now pull the front wheel up 3-4in when going into 2nd gear if traction holds on a stage 1 103ci, which some of I'd attribute to my shifting skills getting better as I became more accustom to the bike. Sometimes I use the clutch to shift when it comes up and sometimes I don't clutch to shift when I'm looking to go fast. Wish I had got a 70t or maybe pick up a smaller front pulley later on when I'm looking for something to do.

 

Yeah now you got me Thinking about doing the 30t front pully. If I do that with the 68t rear the stock 137t belt should work just fine, right?

 

Just checked your final ratio. It definitely would be the way to go with the most noticeable improvement. A 3.15:1 is a nice ratio.... a little more work to remove primary and backing plate but well worth it. Probably the cheapest way out too....

 

Yeah gotta replace drive belt anyway so I'm gonna be right there