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Post by 90GTVert on Oct 22, 2024 19:29:20 GMT -5
I played with the ignition curve a little today. Started out with what I've had in it for a while for a baseline against 3 other slight alterations that I made in advance. I only altered 2 spots on the curve. 13,500RPM is noted because that's roughly peak power AFAICT. These are best runs with each. 60ft | 0-30 | 0-40 | 0-50 | 330ft | 0-60 | 660ft | Baseline = 16* @ 13,300RPM and 13.2 @ 14,000RPM (15* @ 13,500RPM) | 2.12 | 2.17 | 3.21 | 4.74 | 6.04 @ 55.75 | 7.04 | 9.61 @ 66.72 | 001 = 17* @ 13,300RPM and 13.2 @ 14,000RPM (15.5* @ 13,500RPM) | 2.1 | 2.08 | 3.1 | 4.56 | 5.98 @ 56.37 | 6.8 | 9.53 @ 66.49 | 002 = 17* @ 13,300RPM and 14.2 @ 14,000RPM (16* @ 13,500RPM) | 2.13 | 2.11 | 3.15 | 4.6 | 6.00 @ 56.20 | 6.88 | 9.57 @ 66.54 | 003 = 17* @ 13,300RPM and 12.2 @ 14,000RPM (15.5* @ 13,500RPM) | 2.17 | 2.17 | 3.26 | 4.76 | 6.09 @ 56.16 | 6.92 | 9.64 @ 66.76 |
I was happy to see a bunch of good times. Lots of 60fts around 2.12-2.13. 2.12 was the new best then I did the 2.10. There may be more there if I make the clutch more aggressive and it stays down without slipping. There was a side wind that wasn't helping me and the CVT seems wrong because I was 14,000+ at the end of the 1/8 mile and I think that may be why MPH is lower than I'd expect from such strong runs. I'm definitely curious what happens if I get RPM to stick around peak better so I'll probably put 001 back in and see what I can do with the CVT at some point. Either less shim or more slider weight most likely. I think more personal bests may be coming. You could spend an endless amount of time playing with the adjustable ignition, and that is where I think a lifetime supply of dyno time would come in handy. I could possibly up the lower RPM advance a little and see some benefit at launch, but I don't want to push it into detonation when I'm cruising around part throttle. Speaking of that... the detonation gauge randomly started working a couple of times. I think related to me leaning on the gauges to keep the front down. Unfortunately it didn't stay on the whole time and I wasn't about to touch the sensitivity dial to try to adjust it. Looked like possibly a useful tool from what I could see. Sadly mine is basically junk and a waste of time and money other than 5 minutes out of today. A couple of quick shots of T2 from other people at the car show... 16:34 youtu.be/6IVv4rmv4YQ?si=fIwmZQzHgN91CHra&t=9931:49 youtu.be/XNIB__qm50w?si=hjTlPTWdPpwk0yZ7&t=109
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Post by 90GTVert on Oct 25, 2024 8:33:52 GMT -5
I took the big steel disc that is a flywheel weight off yesterday. Might as well try it and see how snappy it is and if it can make some quicker 60fts and overall times. The negatives that I expected were trouble starting and possibly idle quality (needing to set the idle higher so it won't shut off). I could deal with that for a few test runs at least. It definitely went back to being harder to start. Starting is usually 1-3 kicks and it took at least 20 I'd guess. Idle was OK, but I turned it up a tiny bit just in case... especially since it would take more kicks if it shut off. I was totally surprised when it fell on it's face after it got moving. RPM dropped into the 12k range, and in a perfect world I'd keep it between 13.3-13.7k all of the time. I had a tailwind on the first pass and sometimes RPM changes after the first run anyway, but it felt roughly OK. I turned around for another pass and let out partway through because I thought something was wrong. I got into it some more, but RPM was out of the power whether it was an acceleration pass or just hitting it from a roll. My first thought was that the flywheel weight must provide some momentum when RPM comes up from the clutch working off the line and then without the extra flywheel mass RPM drops. I believe that to be the wrong idea because if it were purely carrying momentum from the clutch, it shouldn't make much difference when I'm moving and the clutch is engaged... but it did. Cruise RPM and everything was lower. It was as if I put heavy sliders in it. So much for just removing the flywheel weight and instantly going quicker. This didn't make sense to me. I remove flywheel weight and it makes the bike more sluggish? What?!? Something must be wrong. I put the flywheel weight back on as what seemed like the simplest path to verifying that it was indeed the weight disc making all of this difference and it went back to normal. Mind blown. I just wanted to take 2 bolts and and do some fast passes on a windy day and I wind up learning something... or at least with something to think about. My current theory is that there must be some sort of correlation between flywheel or total crank weight/mass and roller/slider weight. It appears that I'd need to reduce slider weight to get RPM back up if the flywheel weight is removed, so less weight for less weight. When installed, more weight for more weight. I talked to hypervertical and he said he tried adding more weight to the flywheel before and had to increase roller weight. He also noted that it was slower with more flywheel weight and more roller weight though. I think of the sliders largely as related to RPM. They're just pushing outward to close the pulley based on how heavy they are vs how strong the contra spring is. In addition, they seem a bit torque sensitive. It could be contra spring differences or something else happening, as I've never tested it specifically, but generally I've had to use heavier rollers with higher output engines. As an example; I had to use much heavier weights in a 103cc stroker that turned ~9,000RPM than a 70cc sport kit at the same RPM. This adds some new layer that I don't really understand, but then thinking about my stroker argument... maybe it wasn't the torque output. Maybe it was because I put a heavier stroker crank in so I've seen this effect all along and thought it was the wrong thing? It gets even more complicated to me when I start to wonder about heavier pistons and the forces against them and so on. I do still think engine output matters though, because you can add power with something like ignition timing or jetting and need to make generally minor adjustments to roller weight because RPM goes up with more power. Still, I'm not exactly sure why more crank/flywheel weight has to equal more roller weight to maintain RPM. My brain is stuck on the idea that roller weight should largely be due to fighting the contra spring even though I know things like engine setup, drive boss length/shimming and pulley angles can change it. I'm guessing there's some physics stuff going on with the force/inertia/momentum changing with more crank weight and how much roller weight is needed to control that the same way... but that has to be some complicated math when you add in contra spring force and all of the other factors. Physics and engineering geniuses; speak up. On to the more fun side of things... Wind was 10-15MPH continuous with up to 25MPH gusts and I took full advantage of it. I was looking at the wind map on my phone to find roads where I'd have a direct tailwind. LOL It feels like cheating... but then if you go to the track and have the same tailwind, to my knowledge they don't disqualify your time if you set a record so this can surely count for personal bests. Just know that in normal conditions my best runs are more likely 9.6 or so in the eighth and high 6 0-60s. It still feels really good to see lower numbers though. Now if I could find a mountain AND a strong tailwind... LOL These are also the first times I've ever seen a full 70MPH in the 1/8. The more I try to fine tune, the more I seem to learn. The dragy has done that. It was bad enough with my own time keeping, but now I get all of these details and it's so easy to use and it starts to become an obsession. Much of it frustrating. The idea that you can never lock in the right tune for long due to belt width changes is the most annoying, I think. Luckily, I'm still not pure drag. I understand that real world nobody notices the difference if I go 9.5 or 9.7. Even I can't tell, but that damn dragy is right there to let me know if I'm slow. LOL Even worse it that I get more annoyed than ever that I don't have a dyno or easy access to one because there's stuff that it would be nice to sort out there. I've just never had luck with the build material sourcing at any reasonable price. Even when I'm planning piecing together another RC-One based engine, I could try to divert funds toward dyno stuff... but if I have to choose then the higher power faster setup wins because I like to learn but ultimately I enjoy fast scooters... especially when I could have 2 scoots with these engines. It hardly seems like life could be better than that. Well... 2 RC-Ones and a dyno... Santa Claus? Are you out there? I can make some pretty good cookies and (if you ignore the constant wheelies and racing) I've been a good boy.
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Post by zekefab on Oct 25, 2024 17:59:38 GMT -5
What are your weights in sliders currently?
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Post by zekefab on Oct 25, 2024 18:09:38 GMT -5
I had recently had an issue where it was breaking up bad down low and cleared up with throttle but I quickly noticed ect clime fast with every pull. pulled the head off and saw traces the oring was giving out in one spot. Thinking that was reason for the break up and maybe because my squish was on the tight side at .52, I took small cut on the lathe but I didn’t measure it (I probably should have). After putting it back together it still broke up down low. Came to find the ground connection at the coil was wiggly loose. Clamped it to a tight fit and zero break up.
It was gonna bug me not knowing the squish as I only took a hair off….. it’s at 1mm!!!! but it still runs very strong hitting the low 80s mph. So I’m gonna leave it and ride it. Maybe it will give me a little better longevity?
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Post by 90GTVert on Oct 25, 2024 19:06:33 GMT -5
What are your weights in sliders currently? 6.25g with a Polini 36kg spring
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Post by oldgeek on Oct 25, 2024 20:53:52 GMT -5
The optimal CVT setup for a 150lb rider should differ from the optimal CVT setup for a 300lb rider on the same scooter correct? I think it is correct because rider weight, available torque from the motor and the torque driver setup are a big factor in the CVT setup, along with variator weights and the contra spring to a lesser extent. Focusing on the torque driver, the force applied by the belt to spread it and the resistance the torque driver has to that force is difficult for me to understand. If you have ever played with a torque driver that does not have a contra spring installed and wrap a belt around it, you may understand what I am trying to describe. That part alone boggles my mind. Throw in belt width, belt length, shimming, how much travel you have left in the CVT after it gets you in the correct RPM range and a couple other factors I likely left out or dont know about........ Almost rocket science IMO
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