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Post by Lucass2T on Jan 21, 2019 1:13:32 GMT -5
In Holland we have the NSSC and SBO which are the dutch scootersprint organisations. They regulations state you run either 70cc or 100cc machines. From there you'll see all sorts of builds. Big carbs from 28mm up to 36mm. Cylinders and exhausts are also all over the place, malossi testa rossa, polini 94, 2f4r etc etc. Same goes for exhausts. Clutch mostly malossi delta. Tuning wise (rollers, contra, clutch) is hard to say, switches every race. But their setup/tuning is nothing special, just light rollers, red malossi contra.
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Post by ThomasTPFL on Jan 21, 2019 12:56:56 GMT -5
I notice a lot of them are using what looks like a BMX bicycle front end? to save weight. Rigid fork and all.
Are the rear shocks valved to let the bike squat and slowly come back up like on a drag car?
This all came around because I’m working on a digger inspired build and got to looking at drag racing motorcycles and went down a full rabbit hole from there and realized I’d have no clue how to start a drag race build scooter.
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Post by snaker on Jan 21, 2019 13:34:23 GMT -5
Downshift is controlled by the torque spring and the angle of the slots in the torque driver.
With a abnormal load the contra spring and the torque sensing (angled slots) team up to overpower the flyweights in the drive pulley (rollers in variator ). I like to refer to that as a backshift to differentiate from a normal downshift .
With a normal load the flyweights control both the upshifting and the downshifting.
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Post by benji on Jan 21, 2019 15:16:02 GMT -5
Downshift is controlled by the torque spring and the angle of the slots in the torque driver. Yeah, I’m still not confident on torque spring changes. I need a few more in my box, and ones to fit all my rear pulleys. I’ve seen a few driven pulleys on the market with multiple angled slots to choose from, I’ve thought about getting one of those for tinkering purposes. the big one to start with (imo) is the torque slots. Make sure you don't have a torque driver with curved slots, like the Zuma bugeye has stock. With a straight slot you can play with the torque spring rate until you get a feel for how it works. The big change comes when you replace the cvt and get a good torque driver with multiple slots to play with, like the malossi OR. Cvt tuning is key with any motor, but real important when you got that excessively narrow powerband. |
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Post by ThomasTPFL on Jan 21, 2019 15:58:49 GMT -5
Downshift is controlled by the torque spring and the angle of the slots in the torque driver.
With a abnormal load the contra spring and the torque sensing (angled slots) team up to overpower the flyweights in the drive pulley (rollers in variator ). I like to refer to that as a backshift to differentiate from a normal downshift .
With a normal load the flyweights control both the upshifting and the downshifting.
That what I want to get happening. I'd like the bike to downshift when I back off the throttle, not just when it slows down enough for the clutch to disengage. I'm |
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Post by snaker on Jan 21, 2019 16:28:24 GMT -5
Yeah see that's a different issue. In pure drag racing nobody cares how it downshifts.
Seems to me your asking about tuning the CVT for best performance, the same thing that everyone else wants.
I would think that you want to follow the advice on the forum for the most aggressive tuning.
More torque sensing will increase the backshifting (forced downshift).
I can't remember if the TS slot angle degree's are from a line parallel to the belt or the gearbox input shaft and I don't have notes around. But a angle closer to being parallel to the belt would be more TS. An angle closer to the shaft would be less TS
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MustashMike
Scoot Member
Still alive & well
Posts: 89 
Location: Indianapolis
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Post by MustashMike on Jan 21, 2019 17:08:47 GMT -5
I am so pleased to note, we are (were) not talking the same language. IS this a drag racer or a drag racer “wanna-be” ?
This light-to-light street fight that some members are talking is not drag racing. SORRY fellas. I did that on a Yamaha DUAL SPORT decades ago where even a husky guy can beat a Z28 off the line and probably to the next light.
Back to it - are you actually talking dedicated drag racing? If so, find member 2STROKED and see what he had done on a 50" wheelbase.
MIKE
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Post by 90GTVert on Jan 21, 2019 18:52:06 GMT -5
I see these stripped down "50"cc bikes that are smoking the back tire and launching super hard and got interested in what kind of clutch and other components they run with. I mean, I wouldn't run the same setup on my road Mustang as I would on my quarter mile Mustang... Hell, I also wanna know how road race twist n gos get their transmissions to "downshift" harder. I hate to be a broken record, but I'm gonna say it again anyway... Over Range. I spent a long time playing with CVT setups in my Minarelli clones. Learned to mod this or that to improve stock and aftermarket parts. That pays off in the long run because you get to know what actually works a little better. Tried rear pulleys from other scooters to try to make my own over range setup. Then I bought my first OR kit (all of my OR stuff has been Malossi). I messed around with more standard stuff some for a bit, but now I really have no desire to screw around with it unless it has an OR kit on it. I have built and rode a lot of mild 100ccs. They can make quite a lot of low end power compared to any of the other stuff I've messed with. The OR kit, and specifically the variator, works so well at making RPM snap up under WOT that I have tried really heavy weights to see if I could stop that. Even with a stock clutch and stock springs the RPM would flash up to peak and I couldn't get that low end grunt that is kinda fun to play with at times. I went back to more standard parts and I could get that grunt back. There was an issue though, it didn't launch as hard. If you want to launch as hard as possible then basically you need to get into peak power as quickly as you can and not muck about anywhere else. Same goes for any racing. You want to be in the power whenever you hit the gas. Nothing has done that for me like the OR kit, be it leaving a red light or coming out of a corner. I have never really messed with aftermarket clutches, at least nothing nice. I've gone with the "if it ain't broke don't fix it" mentality on that one. When you start dealing with really high power (some of those scoots that you're seeing smoking the tire and having a hard job keeping the front on the ground and such are 20HP and beyond) then I would imagine the clutch starts to play a larger role. I honestly don't differentiate real drag racing from trying to whoop a stock 4T off the line at the beach. Regardless, all I really care about is that it takes off as quickly as it can. I have gone so far as to do timed runs many times to make sure my butt dyno and real world results are telling me the same thing. The main thing I've seen at the track is that you may be amazed what a large amount of traction does to your launch. I've never taken a scoot on a track, but I used to spend an awful lot of days at test and tunes or track rentals with a friend and his 8-10 second Mustang and I started going to the track at least twice a month before I could drive so I do know at least a tiny bit about it. You can even see these differences on different surfaces if you're used to your setup a little. Sometimes I'll notice that a different patch of asphalt or concrete will make the scoot perform better or worse just on regular roads. Sometimes tires or the belt slip, even though they aren't really discernible to us at the moment. We'd put white marks on the rear tires of the Mustang and then watch video of the launch to try to figure out how much the tire slipped. Now there are better ways to figure out wheel speed and such. Regardless, track or street you'll need to find out how to deal with various surfaces and maybe you want the clutch or belt or tire to slip a little so it doesn't make the engine bog or maybe they slip too much. The big difference I see is that at the track you must tune for the surface you're on for best results. On the street, you're all over the place. You just tune for what works best on whatever surface you're on the most. I'm not gonna set up my CVT to launch on concrete when 99.9% of the time I'm on asphalt for example. There are definitely things that can be compromised for best launch, but most of the time it doesn't even matter that much for me. Example, the 0.5mm spacer may take 2MPH off of my top end... but I can deal with 62MPH instead of 64MPH if it puts that poor dude on the rental scooter an extra foot behind me on green. Stuff like gearing is not as effective as one would think with the CVT from what I've seen. Traditionally in cars you'd put some hellacious deep gear in if all it did was 1/8-1/4 mile track duty because nobody cares about cruise RPM. Really doesn't seem to work that way so much with the CVT from what I've messed around. You can get good results with deep gears, but the gains just don't seem to be the same and you can really knock down your top speed. Considering our little scoots were never made to go very fast, you can knock speed off that even affects your drag races if you go too deep. A hard launch isn't so great when you then get stuck at 45MPH and that Zuma with just a pipe blows by shortly after you top out. I guess the other thing about the drag racing is you don't care how hard it is on parts. I'll change a belt after a day at the beach sometimes though, and I'd think if you're too much harder on it than that then something is probably wrong. You could do more swaps between rounds to keep it closer to ideal. If you start talking about the engine, then the compromise really starts, but I guess I thought the thread was geared more toward CVT and such. There's a reason you don't see me building 25HP high end engines... because I want to ride 200 miles a day without breaking the bank. |
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Post by gsx600racer on Jan 21, 2019 19:17:17 GMT -5
This is all you need.
No glasses, no helmet, no foot protection, no front brake, no fan, no engine shrouds, no seat cushion, no wiring, no lights, no plastics.
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Post by ThomasTPFL on Jan 21, 2019 20:26:48 GMT -5
Yeah see that's a different issue. In pure drag racing nobody cares how it downshifts. Seems to me your asking about tuning the CVT for best performance, the same thing that everyone else wants. I would think that you want to follow the advice on the forum for the most aggressive tuning. More torque sensing will increase the backshifting (forced downshift). I can't remember if the TS slot angle degree's are from a line parallel to the belt or the gearbox input shaft and I don't have notes around. But a angle closer to being parallel to the belt would be more TS. An angle closer to the shaft would be less TS Yeah, sorry. I derailed my own thread. no, I am interested in real strip builds. The comments before about the rear pulley with no angle on the slots, things like that that would suck on the street. i guess you can tune much more brutally too since you’ve only gotta run a quarter mile at a time. Push timing and air mixes to the extreme? Kind of areas that’d burn things up on the street. |
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Post by snaker on Jan 21, 2019 21:00:11 GMT -5
 The more hard-core racer you go, the less streetable it becomes. I found some Utube's from I believe a Dutch event with wheelie bars, Hoosier tires (possible car tires) and expansion chambers all over the place really cool Also little to no bodywork. Finless engine jugs I assume to be watercooled but no radiator which usually means they have to shutdown pronto or burn up. I think these CVT's are good transmissions but they are designs of compromise. You can improve upshifting performance to a point and any more may be detrimental to downshifting performance-and vicey/vercey. If you set a perfect tune for your target rpm's on upshifting you may get different rpm's on downshifting. Torque Sensing is not a part of the basic CVT, it's a add-on feature to improve normal riding. The diagram I included shows a old Ski-Doo snowmobile driven pulley which came prior to TS. Notice no angles, the moveable sheave slides laterally on the fixed sheave pins. It would have been a fairly crappy ride but then it didn't have the power robbing and heat generating characteristics of the modern TS equipped pulley. |
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Post by 90GTVert on Jan 21, 2019 22:42:37 GMT -5
i guess you can tune much more brutally too since you’ve only gotta run a quarter mile at a time. Push timing and air mixes to the extreme? Kind of areas that’d burn things up on the street. Those kinds of things can add up. All the kinda obvious stuff like not having lights, horn, or anything else that is not necessary to go up the track can be eliminated. Robert (2strokd) used no cooling fan on his air cooled Mina clone for example; something that you aren't going to get away with long on the street. Frees up power, shaves off a few oz. Even if it can't be removed, maybe it can be minimized. Do you really need that cool huge aftermarket brake rotor and caliper to stop you once every round? How big do your tires actually need to be? Do you have to sit on a padded seat with a cover? The perfect tune for a drag race is definitely more lean than the perfect tune for a street vehicle. You're at a known elevation the entire event and you get out your weather tools and calculators and change fuel delivery as needed. The sprinter chassis is a trick of drag racing I suppose. Don't think they'd appreciate those on the street. Even tricks like having handlebars flipped around so they make you lean forward and low is something that wouldn't work great on the street. You can also play with very track specific things like rollout. Doesn't make a bit of difference when you're pulling up to a red light, but it does when there are staging and guard beams. Learning the tree is another. Some people will sit around with practice trees for hours. |
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Post by ThomasTPFL on Jan 21, 2019 23:50:45 GMT -5
Pure sprint chastises look cool but I wouldn’t want to ride one more than a quarter mile.
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Post by ThaiGyro on Jan 22, 2019 4:00:57 GMT -5
I am no expert on drag racing scooter, having done zero since I was 18 or 19...now 62.(That was cars) But for my money, I would stuff a wild ass Honda CR500 into any goofy frame and add some OMG wheely bars and just rip it! Chain drive or CVT? Who cares? It would scare your shit right through your worthless fake jeans.  |
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Post by ThomasTPFL on Jan 22, 2019 9:52:18 GMT -5
I am no expert on drag racing scooter, having done zero since I was 18 or 19...now 62.(That was cars) But for my money, I would stuff a wild ass Honda CR500 into any goofy frame and add some OMG wheely bars and just rip it! Chain drive or CVT? Who cares? It would scare your shit right through your worthless fake jeans.  Maybe a long case Mina paper clipped into one of these?  |
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