| Author | Message | ||
     Ezblast |
Me - I'm learning from all of you - Belt is all I know - yet both of my belts - though old broke on a very hard launch - so a chain is something I think about - Also a note from Ralph -lol A 520 chain is about perfect to convert a Blast to chain drive. And FYI, my STOCK 1982 Honda FT500 Ascot came with a 530 Chain(same pitch as 520-just wider) ! Now that chain was heavy ! And most racers converted it to a 520 chain which was used on the dirt XR/XL500's which was lighter, but not as indestructable on pavement as the OEM 530 was. Also, to put this into perspective, all the High H.P. IL4's of that period(late '70-'80s) used the Huge 630 size chain ! Also note, TJ who bought my 600 engine, converted to a 520 chain, but HAD to use a spring loaded roller to take up the slack and tension the chain, just adding or subtracting links WON'T even come close ! (one link is = to about 3" of chain slack!) hmmm... GT - JBOTDS! EZ  | ||
| Gearheaderiko |
The Blast already has the same primary gearing as the XB9(1.676:1 or 57/34). The XB12 has the taller gearing (1.5:1 or 65/27). The Blast rear sprocket (pulley) gearing is 80/27. There are enough sprockets available to duplicate Blast stock gearing (not exact, but close)and with a chain tensioner or by removing links you can get the chain within an acceptable margin of adjustment (closer if you can find 'half' links). It may be possible to use another belt (there is a 1" belt available in the Blast size of 139 teeth) but I dont know if its the same pitch as the Blast (are Big Twin and Blasts the same pitch?). But if a rear wheel adapter is made, you can get whatever belt you want to fit. With a 1" belt it may be possible to to offset everything enough to allow it to fit without welding the swingarm. It seems to me the 520 is a 'standard' Buell/HD racing sprocket, so plenty of sizes should be available. (Message edited by gearheaderiko on December 21, 2006) | ||
| Gearheaderiko |
3" of chain slack per link doesnt sound right (probably less), but, nevertheless, a lot of race bikes (that I've seen) use a rubbing block on the swingarm (like on dirtbikes). | ||
| Ezblast |
then a sprocket with spring tension would be a good thing - I wonder who has one made - Hasn't Saintly developed one - also a total XB chain drive - still most useful to us would be the sprocket tensioner - a very nice looking piece from what I can tell - just do a search on XB chain drive conversion - you should find it - perhaps - we should be talking to him about a group price perhaps? GT - JBOTDS! EZ | ||
| Gearheaderiko |
I think a chain tensioner could bolt right up to the rear set plate. There are quite a few chain tensioners available besides the XB's, but all would take some 'fitting'! | ||
| Buellistic |
The tension of the CHAIN/BELT when properly adjusted is determained by the GEOMERTY of the swing arm ... Any body ever think about SWING ARM GEOMERTY ??? In BLASTing LaFayette | ||
| Jprovo |
Yeah, we did, but the rules won't allow us to change anything but the rear shock. | ||
| Jprovo |
Woody, A 530 Chain has a 5/8" pitch and is available readily down to 19 teeth. A 19 Tooth 530 Chain is 3.77" in dameter (pitch diameter) is probably closer to 4" in diameter. To keep the ratio close to stock, you would need a 56 tooth rear sprocket that would be about 11 1/2" in diameter. The stock sprockets are about the same size. James | ||
| Woody1911a1 |
thanx Jprovo  was just playing with this calculator http://www.nightrider.com/biketech/calc_gearratios.htm and looking at this  look like theyre using a rubbing block | ||
| Buellistic |
Woody1911a1: There has to be a rubbing block(or a spring tennsion sprocket) due to swing arm geometery ... In BLASTing LaFayette | ||
| Gearheaderiko |
"There has to be a rubbing block(or a spring tension sprocket) due to swing arm geometry ..." That really makes no sense what-so-ever. You're just trying to over complicate it. | ||
| Slaughter |
Looking at the specs (from Buell.com)" Final Drive Kevlar® belt, 2.963:1 (80/27) ratio That works out to a 56 tooth rear sprocket (with 19 tooth countershaft) It is too cold this morning to go to the garage and look at my notes to see how many teeth the countershaft sprocket has on the XB racebike (the bike is at Bartels) - my fading memory says 19 but I've had CRS all week. That means that to drop gearing MORE, we're talking smaller countershaft (don't know if they even make an 18 tooth) - or get an even BIGGER rear sprocket. I was in Bartels race shop all day yesterday trying to fix a zillion small problems on the XB racebike and we kinda/sorta sketched out a couple concepts - but didn't have a Blast wheel there to look at. The main problem is the rules require using the stock wheel (I think - though I haven't actually READ the new rules) Still uncertain if there's a simple/easy way to do it. I still don't see the need for an idler but you DO have to put a rub strip on top of the swingarm so the chain wouldn't saw through the metal. Also, there are NO sprockets to be found for the lighter chains anyways so for a "hard core" Blast racer wanting a lighter chain, it would mean machining/adapting one from some other source. The 125GP guys all use the 415 without O-rings - say it makes between 1-2 HP difference on the dyno compared to a 520/O-ring chain. For the Blast, you'd have to weigh the pain of replacing it a couple times a year in racing. For the street, it just wouldn't make sense. Actually for the street, a chain conversion probably makes no sense at all UNLESS it could be done "cheap" without becoming a maintenance hog. Still looking, googling, calling. There's got to be somebody who did this once upon a time (Crossroads?) Since at Willow, we're probably talking the GearheadErico/Jprovo machine, Tim, Patrick - that means 3. There are probably a few more who might be interested elsewhere. The Glendale "shop" Blast is a likely one. Going to be hard to get a machine shop enthused. We'll see what the sponsor response is in the coming week (I was told to wait til after the Holiday for input) | ||
| Ezblast |
A rub block is short term - ok for racing but not for the street - so an ideler pully then needs to be sourced - the belt idea sounds interesting as well - another idea mentioned in the group - Fellow Blasters, I know his thread is about converting to chain drive to lower gearing, but there is another very easy way- which I found by accident while tire testing in the past month. And that is, to use a smaller diameter rear tire ! At present I'm running the stickiest tire I have EVER tested on the back of my blast, which is also the smallest diameter. I'm currently runny a Radial (Front) tire on the rear...it's the Dunlop Sportmax D208F size 130/70ZR-16. I mounted the tire backwards of the normal rotation arrows- mainly because of the tread grooves- which on the D208's are opposite each other from front to rear- and I just wanted to match the groove direction of a normal rear tire. The tire works fabulously and it's so sticky I've even been grinding my outside pulley guard. But some of the rear why is- because the tire is slightly smaller....which also has the effect of lowering final gearing- not alot, but some. The fully inflated(40psi) specs for the D208 vs OEM 120/80 is is as follows: OEM 120/80-16 = 23 1/2" dia D208 130/70-16 = 22 7/8" dia __________________________________________________ _______ My Original(1st) Post about this tire on my Yahoo Group: Hey Gang, I wanted to let you in on another tire experiment I'm conducting. I have already spilled the beans about this purposed test to two other group members, but now I can say the test HAS Begun and is underway. This test involves mounting a Radial tire to the rear of my Blast. But first, just a little background on available radials for the Blast, ahem....There AREN'T any in our tire sizes made ANYWHERE in the world. So what I'm doing, is adapting a size that is close, but designed for the FRONT of an older superbike (the '93-'99 Honda CBR900RR). This tire is size 130/70ZR-16 and the specific one that I'm testing is the (Premium) Dunlop D208 Sportmax. Although I'd already had mounted on my bike (for a few weeks) the Avon Viper Stryke(Scooter tire) in size 120/80P-16, I did have a spare wheel which was became free to use, when my Grey Market Michelin (scooter) tire in size 120/80-16 went bald at 2000miles :-( Sooooo.... I just couldn't wait until next year, so I mounted this "Front" radial on my rear wheel, and here are some findings: Although this is a 130mm when mounted on the proper Honda Front size rim, it was slightly squeezed onto our smaller Blast wheel, and when inflated -only measures out to 120mm wide. But here is where things are off a little. Most stock 120/80-16 tires(when mounted and fully inflated) have a diameter of 23-1/2" But this 130/70 tire, when mounted and fully inflated (to 40psi, max states 42psi) only measures out to 22-7/8" diameter, so that makes the tire 5/8" smaller in diameter :-( But (LOL) no clearance issues to worry about with this baby :-þ I'd also like to point out another significant difference between front and rear tires, normally rear tires have Deeper tread grooves(sipes) than do the same(matching) front tire, and this was also the case with this Dunlop D208. And another thing that isn't the same for some Radials vs Bias Ply tires, is that although the tread grooves match (directionally) on most Bias Ply tires, this isn't always the case with Radials, and they often have a Reversed pattern on the front tire compared to their matching rear, again this was the case with this Dunlop. ANYWAY... I mounted this radial(front) backwards on my Rear Blast rim, so the directional arrow is pointed opposite it's intended rotation- BUT it's tread pattern now is equivelant to what a rear Dunlop D208 is running, and also it looks pretty similar to the Tread pattern used on (both front & rear)of the Avon Viper Strykes. Btw- I mentioned this Dunlop IS a Premium tire, and when aligning the yellow balance dot(circle actually) with the valve stem, and then mounted on my static tire balancer- it needed ZERO weights to balance- it was perfect already (yes, I triple checked this- and it's balanced perfectly). So today it was a sunny day, albeit only with a high of 44º F ! But I layered up under my leathers. And with the newly swapped wheel installed (taking off the Avon Viper), I headed out (very cautiously) to do the first tire testing of this Radical Radial Experiment :-) Well I made it back in one piece, but I'm darn COLD ! The tire NOW has 65miles on it, and has also been taken upto a top speed of 105mph (you can ask my neighbors for verification-LOL). The results so far are fantastic ! It sticks extremely well under hard acceleration and moderate lean angles, but I have NOT tested it under maximun lean; as the tire needs at least 100miles of scrub-in before I'll even attempt that phase of the test. The tire rides Extremely smoothly, probably more-so than ANY of the 10 different rear tires of tested. The tire is also more comfortable than a bias ply, as it absorbs the bumps and road irregularities better. Anyway, it's just the beginning of testing, and as weather permits I'll be putting more miles on it. BTW- in case any of you were wondering, No...there are no radial front tires small enough to use on the front of the Blast, as matter of fact the smallest front radial tire made, is a 120/80-16(front) made by Avon, and no other maker makes a radial in that size either. ~Ralph I don't know if I would play with the tires like that, and I hate dragging parts - lol - still - it is a thought - Actually - what front and rear gearing are we looking at, and what gears - more importantly - fit and bolt up - though the rear would be drill and bolt, and the idler would bolt up to the case like the ones on the XBs? GT - JBOTDS! EZ | ||
| Woody1911a1 |
hey whether anything comes from this , i'm finding it a pleasant mental excercize . the biggest problem i see in all this is the cost . a given is the cost of the chain and sprockets of say $200 and i think the original cost est of $1-200 for having an adapter made that would allow bolting an already available sprocket to the mounting points on a stock blast rim is WAY low . i mean we're talking about a major hunk of aluminum and alot of machining considering the @11" diameter by @1 1/2" offset getting from point a to point b . the crossroads bike above did it by using a different rim with the sprocket mounting closer to the hub/axle but again $. ok enough naysaying and sorry if i'm rambling , but this does have to be cost effective . ok idea , make an adapter of a smaller diameter to match a readily available sprocket mount and just machine flats on the spokes of the oem blast rim ? this might seem daunting to some but it would be alot less work than trying to make an adapter "11 ins in diam . the adapter would be WAY simpler and cheaper and even if you cant do it yourself any good machine shop could do it in less than 1/2 an hr . tensioner/rub block hmmm $5 nylon cutting board at wallyworld = lifetime supply , but topic of another discussion . actually EZ i'm expecting/hoping you take this to the extreme . i still can't understand why buell/hd made the gearing on the blast so high . | ||
| Buellistic |
"i" have a extra set of Tube Frame rims to put on my BLAST if "i" ever get to it ??? BUT is more fun to ride it than work on it !!! In BLASTing LaFayette | ||
| Woody1911a1 |
yea but buellistic ,up here in new england we've been lucky so far , but know winter snow ice slush and cold is knocking at our door and we'll need something to get us through til spring . cheers and happy holidays | ||
| Swampy |
I saw some ilder wheels made out of skate board wheels o0n something recently, the chain wears a pattern into the rubber wheel but it spins and lasts for a while. Use the ones with the heavy duty sealed bearings. | ||
| Ezblast |
What front sprockets will fit - pt numbers and tooth count - also what rear sprockets any sportster - pt number and tooth count, the rear sprocket would be mounted on a plate - how thick? - that would bolt to the stock mounting place for the belt sprocket with the chain sprocket - properly spaced by spacers - bolted to the inside exterior of the plate which would have the center part cut out after that bolt pattern - a sprocket tensioner bolted to the engine ala XB chain kits - contact a maker -  This very bad Paint shop illustration should at least show what I basically have in mind for the rear sprocket - the rest should be straight forward - sorry for the very bad pic, but it should bring forth the idea - lol GT - JBOTDS! EZ | ||
| Swampy |
If sprockets and adapter can be had I have a friend that can fab up a chain tensioner, this guy really knows how to think outside the box, I have seen him do some incredible things. His spacial orientation is incredible. | ||
| Gearheaderiko |
Chain tensioners are readily available and I think its a non issue at this point (I run one on my '77 FLH and it works very well). If large enough sprockets cant be found then changing the engine sprocket could put the gear ratios in a manageable range (I did a quick search and found sprockets available from 26-38 teeth, stock being 34, but they were for 91-up XL/Buells, but I'd have to imagine there are XB sprockets available). I cant verify it but I think the Jawa speedway sprockets are 520 and go up to 74 teeth. | ||
| Gearheaderiko |
And (before the obvious is stated) If I went to a sprocket big enough, which seems necessary, I'd just re drill the sprocket and bolt it directly to the wheel. | ||
| Slaughter |
Erik, How much offset would be needed to line up the rear with the front? (guesstimate) This is just an intellectual exercise for me anyways until next week when I get back close enough to Tim's Blast to have a look and maybe take some measurements. I'll also expect I'm going to be hearing back from a couple of our sponsors by then too. | ||
| Woody1911a1 |
slaughter , 1 3/4 from the bosses on the rim to the inside edge of the belt so guessing a lil more to sprocket and 5 1/2 " from the center of axle to mount bolt so @ "11 diam bolt pattern. | ||
| Ezblast |
For a race bike a non-issue, for a street bike it is an issue - ok - list for me parts and numbers that will bolt to our Blast. GT - JBOTDS! EZ | ||
| Woody1911a1 |
Gearheaderiko said "And (before the obvious is stated) If I went to a sprocket big enough, which seems necessary, I'd just re drill the sprocket and bolt it directly to the wheel." explain how youd just bolt it on please ? it's got to be spaced out almost 2 inches | ||
| Slaughter |
We might be lucky and only have to have the offset mounts machined. You then buy your own sprocket (Attack, Vortex, ??) and countershaft sprocket. May have to fabricate your own gizmo to protect the top of the swingarm pivot. (just thinking out loud) I have too much time on my hands today between banana nut bread in the oven and fixing the sink (trying to put that off til next week) | ||
| Gearheaderiko |
"For a race bike a non-issue, for a street bike it is an issue - ok - list for me parts and numbers that will bolt to our Blast." Sorry, EZ I dont know which post you're referencing to as far as part #'s. | ||
| Gearheaderiko |
Woody, I'd just start out with 1 3/4" spacers and go from there, possibly using a spacer ring, but I really wouldnt know until I go about bolting one up (which may be never as I dont care for chains!). | ||
| Slaughter |
It'd be so much simpler if there were a smaller front or larger rear pulley. | ||
| Ezblast |
Wouldn't larger drag? GT - JBOTDS! EZ |
