Hey all, I'm wondering if there is a chart that would give me the various tooth and thus size of front and rear of final drive belt (and belt length that all this dictates.) where I could figure out how hard my engine will pull on the belt (I'm picturing a push bike chain on top of the regular gears). 

Im building a chop based on a softail swing arm style kraftech frame being dragged along by a 1340 80" Evo and 5spd '87 box that I'd like to change to final drive by belt rather than chain. Is there any one right answer or will smaller rear just take more revs to get moving (like peddling in a light gear on a pushie?) and if so where can I find what combo of X amount of teeth on front or rear teeth will equal Y result?

Might be a stupid question for all I know? I can rebuild a donk blindfolded but may as well be blindfolded when it comes to anything other than stock gearing setups. Oh yeah I'll be putting an Andrews EV35 cam in the Evo if that has anything to do with the overall factoring in of the thing. 

32 f 70 r. Early softail evo had 32 /61 which in my opinion is shit 32/ 65 better 32/70 better again but also depends what style of riding you do and if your running a low tyre profile rear and than theres primary ratio too

Cheers Perth Hog! 

I'm running an 18" rim 180 5.5 and as for style I'd say 75 open rd to 25 city however it's prob better off being a 50/50 type deal. But now I've got to figure out the inner ratio lol. Any idea what size belt I'd run on that ratio f/r pully setup? There's SO many choices it's insane, even to guesstimate and then take up the slack with tensioners. 

Front 34- Rear 70 = 2.05 to 1
Front 33- Rear 70 = 2.12 to 1
Front 32- Rear 70 = 2.18 to 1
Front 31- Rear 70 = 2.25 to 1
Front 30- Rear 70 = 2.33 to 1
Front 29- Rear 70 = 2.41 to 1

Front 34- Rear 65 = 1.91 to 1
Front 33- Rear 65 = 1.96 to 1
Front 32- Rear 65 = 2.03 to 1
Front 31- Rear 65 = 2.09 to 1
Front 30- Rear 65 = 2.16 to 1
Front 29- Rear 65 = 2.24 to 1

That's some really handy advice Perth hog, Walka thanks heaps for the table that will help me out a bunch!! What would
Any second hand pulleys or other related gear would be gladly considered (I know it's off topic - also have some wanted gear in the wanted section).
Thanks again!

Same advice as Perth Hog, don't go wider than 180 (max) on the rear tyre. Don´t know what ratios your primary and gearbox ratio's are. But on the twin cams changing the rear 66 to an older 70 tooth pulley (which also take a wider belt) drops the gearing a bit and they gain acceleration and stop lugging in top gear. The standard 32/66 is a bit too high unless your going across the Nullabor. The older pulleys are wider and that means a stronger belt. The front pulley is usually more than wide enough. Most of the belts are made by a few companies, when they are made the belt is cut to width out of a cylinder of belt material, so the wider it is the stronger it is. The belt on the wide rear tyre bikes are too narrow, they were made narrow to try and fit a wide tyre without remaking the clutch housing to sit further out to the left. The result was a narrow belt and a tyre offset to the right hand side of the bikes centreline, both points which are good for looks but not much else.
Bigger rear pulley and or smaller front pulley makes the revs higher for the same speed, just like your pushbike. Don't go too small on the front as it is a belt, not a chain and the radius it has to go around is making it bend too much, which might shorten its life. It's going around that bend a few million times. A few people have managed to strip the teeth off the belt so the more teeth there are gripping the belt the better as well, (I kept mine as a 32). The 20 mm wide belts are not really strong enough, so it shouldn't be hard to find a broken one to wrap around the pulleys and measure the gap to see how many teeth you need for your belt if your not good at maths. I personally prefer wide S&S belts (they also have a good range of sizes) if you have a bit of grunt. Sometimes there is enough adjustment to fit a bigger rear pulley without changing the belt, but the belt guards do not fit easily afterwards. Keep the belt guards on if you can as the bottom of the pulley is not far from the ground, one small sharp rock and a new belt needed next time you give it a handful. They often let go on the change into second gear.
Hope that is some help.

Is the 32/66 really that tall? I would have thought that it would be OK once you have a bit more torque than stock standard.......

If it's that bad I mite have to find a 68 tooth for my 200mm conversion instead. Was it 1200 sportie's that have the 68 tooth 20mm wide?

Thanks for the heads up Captain Hook, I'm using a souped up (building it at the moment) 1340 carbed 87' Evo so even with the extra grunt that I'm hoping to achieve I don't see it ripping down the road like a 120R or other modern motors that would tear the 20mm belts to rubber dental floss. However I will def take your advice on board and go as wide as I can! What would you suggest would be the "sweet spot" setup? Keeping in mind I'm using a rebuilt 87' 5spd with the EVO that I'm hoping to get 95HP out of. Spending a farming fortune on the engine am hoping that the case will hold up with the wiz bang shit I'm piling in there. Makes sense with a belt being pulled around a small radius copping a lot of fatigue fairly quickly. I'll know how wide I can go on mockup and might post a few photos of the build on here if I can Work out how the hell to make the photo uploaded work from the iPad.

Thanks for the heads up Captain Hook, I'm using a souped up (building it at the moment) 1340 carbed 87' Evo so even with the extra grunt that I'm hoping to achieve I don't see it ripping down the road like a 120R or other modern motors that would tear the 20mm belts to rubber dental floss. However I will def take your advice on board and go as wide as I can! What would you suggest would be the "sweet spot" setup? Keeping in mind I'm using a rebuilt 87' 5spd with the EVO that I'm hoping to get 95HP out of. Spending a farming fortune on the engine am hoping that the case will hold up with the wiz bang shit I'm piling in there. Makes sense with a belt being pulled around a small radius copping a lot of fatigue fairly quickly. I'll know how wide I can go on mockup and might post a few photos of the build on here if I can Work out how the hell to make the photo uploaded work from the iPad.

 

 

 

Another pic attempt 

 

Bugger won't let me upload any other pics, just defaults to the first pic I put up. Oh well

If you have upped the capacity then the 32/66 would be fine I would have thought, but he's not running a 120 ci. My capacity has been increased too and the 70 rear is now on the border of being too lowly geared (on a Twin Cam 6 speed) only when out of town, in town its great. The difference is not a lot so I have just left it as it is as everything else fits up. Its not worth the time or effort to bother changing it. Not sure on the sportster pulley sizes. A cheaper way to go is to get the 1 1/8 or 1.5 inch wide pulleys off the older belt drive bikes. I tried 3 different ones and the most I paid was $50 for a pulley, while finding out which size was best. Why so many, because I'm a slow learner and figured out the wide rear tyre and narrow belt are a bad combination from experience. Can make a wide Harley pulley into a narrow one but not go back to being a wide pulley again. They are bolted or pressed together, so it is not much trouble to take one side off the pulley where the belt runs and machine it narrower, then put the ring back on (think I used 6 or 8 small bolts tapped in on the pressed one) if you want to keep a narrow belt. New ones are probably $500 to buy and try.

If made out of the same material, wider is stronger with the belts.

Wide tyres and wide belts don't go together easily or cheaply on a Harley. Wide tyres are rubbish for handling from my experience and I get to watch a lot of wide tyred bikes going at walking pace to get around a sharp T intersection, they are going slower than the pushbikes and holding up the traffic, the wider they are to slower they are. A lower profile tyre can help drop the gearing, but then the cornering clearance suffers and there already is not much of that on most Harleys.
I'm done, work to do.

Thanks for the words of wisdom Captain Hook. I'm running a mild 95" build. 91hp and 98tq. Similar out put to a stock 103". A bit more punchy though, , but with a 5spd. And I have a 200/55 x 17 and a 17x6 softail stand rear wheel. Hopefully the whole thing works OK when its finished. As long as it's not an absolute slug off the line in 1st I won't mind the taller gearing.

Don't forget the primary ratio is different on the EVO, but you can also play with primary ratio's too, i like the lower EVO primary ratio as helps clutch work better. also different ratio for starter motor to spin. i changed from a taller twinky primary ratio to the lower EVO ratio & saw my cranking pressure go up, no other mods.