| Author | Message | ||
     Gentleman_jon |
Olinxb12r has asked if I might share some information on chain conversions. There seem to be two different approaches. One is the modified swing arm version by Hals. I believe one of our sponsors, Revolution Performance may make a similiar unit. These have the advantages of being able to adjust the chain length, and in the case of Hals at least, also lengthens the wheelbase by 2-3 inches, which I think is a good idea for stability. Hals uses a rubber wheel on a non adjustable chain tensioner made from the stock Buell belt tensioner. This is the system that I use. These systems require a special swing arm, cost about $1.500 to $2,400 and can not be converted back to belt as the swing arm brace is welded shut. The other system uses the stock Buell swing arm, and and adjustable chain adjuster in place of the stock Buell item. These are offered by American Sport Bike and Trojan. Cost is about $900. One of our talented brothers, Saintly, among others, put together his own conversion for less than $150. When it comes to selecting appropriate sprockets, you might find this analysis that I made for myself, to be useful. Lil’ Blackie Gear Analysis XB12S Stock gearing Primary: 57/37 = 1.5 Secondary: 2.407 = 65/27 total 1.5*2.4= 3.6 gear box ratio in fifth is 1:1 Lil Blackie Final selection primary  ratios from XB nine) 1.676 ( 57/ 34) Secondary chain 46/20 = 2.3 total 1.676*2.3 = 3.85 Rear tire cicumference Dunlop Qualifier 1991 mm =.00123715 miles = (6.53215 feet x 60 min) = .074226 =k Question: How many teeth are required on the rear secondary sprocket so that the final gearing equals the stock XB12S or some other selected ratio. There fore : in the stock set up, each 1000 rpm in fifth equals 1000 engine rmp/1.5 =666.7 rpm /2.4 = 277.8 rpm To get 277 final rpm from 1.67 primary you need a secondary of 2.15 : 1000/1.67 = 599rpm/ 2.15 = 278.5 Leaving the primary unchanged, and using one of the existing rear sprockest we could get the 2.15 final ration with a 50/ 23 combo using the existing 50 tooth rear sprocket or a 43/ 20 using the existing 20 front sprocket. However, we are going to reduce top speed by ten miles an hour, and increase acceleration, using a 46 tooth rear and 20 front sprocket because: a) the rider is larger than average, b) S model is less streamlined than R c) rider prefers acceleration to top speed d) the 20 tooth front sprocket is already installed and Hals said that is the size they normally furnish. Estimate top speed with the selected 46/20 combo total reduction = 1.67*2.3 = 3.841 6800 rpm /1.67 = 4072 rpm/2.30 = 1750 rpm x .00123715 mi. x 60 minutes = 130 mph 4000 rpm/1.67 = 2395 rpm/2.3 =1041 rpmx .00123715 mi. x 60 minutes = 77 mph 3500 rpm/1.67 = 2095rpm/2.3 = 911 rpm x k = 67 mph Estimate stock 6800 rpm/ 1.5 = 4533 rpm /2.407 = 1885 rpm x .00123715 mi. x 60minutes = 139 mph This is mostly like overgearing for 235# rider on S model. . Stock Nine for comparison 7500 rpm/1.67 = 4491 rpm/2.5 = 1796rpm x .00123715 mi. x 60 minutes = 133 mph Lil’ Blackie as Delivered ( It had "Nine" primary with a 57/20 secondary!) 6800rpm/1.67 =4072/.2.85 = 1428 rpm x .00123715 mi. x 60 min. = 106 mph. I think it was set up as a supermotard. (Quick Calculation: Speed = rpm/total reduction *k ex: 6800/3.85*.074226 =131mph) 1000/3.85x.074226=19.2 mph = minimum speed | ||
| Eurotwins |
Huh????? | ||
| Olinxb12r |
So in a 20 tooth front sprocket with a 43 tooth rear will give about the same gear ratios as the factory 12 set up. That is awesome! Where do you find just an adjustable tensioner? I'm interested in how the costs were kept so low. | ||
| Olinxb12r |
Thanks for the info Jon! | ||
| Gentleman_jon |
Good Point John. Bottom line: Going to chain, allows you to easily change gearing. Many people find that for a variety of reasons, stock bikes are somewhat overgeared for normal use. One way of gearing down if one owns a Twelve is to use Nine primary gears. This low cost mod reduces theoretical top speed by about 10 mph, and increases acceleration. In my case, the previous owner had put nine primary gears on, and had selected a radically low chain sprockets that reduced the top speed to 106 mph: not good for normal riding. What this analysis did was allow me to select a front and rear sprockets suitable for my size and use. Since I am an oversized senior streetfighter who rarely goes over 100 mph, I opted for slightly lower gearing. The result was a twenty tooth front sprocket and a 46 rear which gives a top speed of 130 mph at 6800 rpm. There. Does that make a bit more sense?  | ||
| Gentleman_jon |
I believe one of our sponsors, Trojan, sells an adjustable chain tensioner. Might want check with Al at American Sport bike. | ||
| Diablobrian |
freespirits makes the adjustable tensioner. Anyone that carries their products can get it for you. Vortex makes the sprockets used by most people that do the conversion. | ||
| Pcmodeler |
Problem is, most of the companies won't sell you the components separately. You have to buy the whole kit. I've got the Freespirits setup with a steel rear sprocket. | ||
| Ronlv |
its not that we dont want to sell it to you in seperate parts, its that we have to buy it in kits. its a catch 22 thing i would love to sell parts seperate, but then i would have extra sprockets or chain guides or what ever part is sold less in order to get a new tensioner for you i would have to buy another whole kit we cant afford to stock whole kits to sell you one part hope this makes sense for you | ||
| Fullpower |
please note that 20 tooth front and 43 tooth rear sprockets will yield usable final drive RATIOS, but will leave the chain in very close proximity to the swing arm. you will suffer cosmetic damage with these sprocket sizes. I am having good service from the easily obtainable 21 tooth (1991 sportster OEM) and 50 tooth rear sourced from vortex. 11,000 miles on this pair, with negligable wear as yet. | ||
| Fullpower |
check the KNOWLEDGE VAULT for more details. chain drive conversions have been done, are inexpensive, durable, and dont require intensive engineering. "this aint rocket science" | ||
| Xb12rdude |
Yep, knowledge vault has a good description. If you have good mechanical knowledge, with a little work it seems the do-it-yourself conversion is under $200. The full kits are nicer looking and less work for around $600-$900 that I've seen. I believe I'm going to go with a black rear vortex sprocket, gold o-ring change and the sportser front sprocket, which needs minor shimming. Of coarse I have the black & gold XB12R. I need to mill a slot in the lower bolt hold of the idler for adjustment and purchase the standard idler pulley from Autozone as mentioned in the "Knowledge Vault". Wish me luck. Sainty has had good luck with his so far. | ||
| Ronlv |
fullpower, where is the picture of your idler with a additional bracket on it to keep it from slipping? i think it was yours. i know i have seen it on this forum somewhere | ||
| Xb9ser |
Freespirits has an adjustable idler for sale on there website just add your sprocket.I dont know how to convert there price to dollars.  | ||
| Ronlv |
thats not the adjustable idler, thats the spring loaded one for the belt | ||
| Hammer71 |
Ronlv has done right by me so far... have nothing but good things to say. If you need any parts dont hesitate to contact him. And by the way that spring loaded idler will not work with a chain conversion as of yet. | ||
| Gentleman_jon |
Hammer - Why won't that spring loaded idler work with a chain conversion? I do believe the XBRR has some kind of spring loaded chain tensioner, but I don't know exactly what it is. | ||
| Trojan |
The sprung belt tensioner wouldn't work on a chain kit because it is set at the same 'angle' as the stock tensioner, but has the spring to act as a shock absorber more than anything. The spring does not push the tensioner arm upwards, which is what you would need for a chain setup. We have these Free Spirits belt tensioners in stock at GBP75.75 (approx US$136) | ||
| Hammer71 |
What he said | ||
| Sokota |
Trojan can you elaborate a little more on the free spirit and its effectiveness with belt drive. I am interested in getting one ...seems like it might be worth a couple HP and less strain on components. Not trying to hi-jack the thread , thanx. | ||
| Ronlv |
here is the pic is was talking about from fullpowers bike i believe, isnt that bracket to keep it from slipping?  like is said before i have been there done that, trojan has been there done that thats why we sell a quality kit and not modified stock tensioners | ||
| Djkaplan |
"this aint rocket science" Probably not rocket science, but a bit more involved than just making sure the chain will have enough clearance. Raising the chain higher above the swingarm pivot decreases the resistance to squat the rear suspension has. It's a subtle tuning parameter, but it does have an effect. |
