Project 49

[90GTVert]

I don't see much point in other CVT mods really. If I tried to mod the torque driver it would just get into a higher gear if I'm lucky, and then it couldn't pull that. Straight cut grooves may be good in the torque driver, but it seems like that would be really tough to make both grooves work in perfect symmetry. I looked at the vari and decided NO WAY. It's very time consuming and last time I did it I got amazing belt travel... but a couple of rollers flew out of the variator and all the time was ruined. The Hoca from Parts For Scooters at around $50 is a better idea than that for all but the most determined tuners IMO. Even with all the modding, I never could make a stock vari handle the Venus' power and gearing well. The Hoca worked well.... till I modded it too. lol I tend to mod stuff till they either snap belts or wear them fast. Usually run strong that way, but it's terribly expensive and it's no fun pushing the scoot home or calling for a truck.

[90GTVert]

Since I'm doing some free mods and I've never really messed with the ignition timing on my 2Ts much, I might as well try it. I started out by taking out the engine so I could fit the big degree wheel (most accurate) and setup a timing pointer and mark the flywheel.




I removed the stator while it was easy to get to and used a utility knife to etch a centerline on each of the stator's mounting holes. These marks will allow the stator to be put back to stock timing easily.




I made a mark roughly following the curve of the stator to help me as I drilled a few holes to slot the stock stator. After drilling the holes I filed to create slots.




Once the slots were done I installed the stator in the stock timing position. I made plenty of room for advance. Rotating the stator counter-clockwise will advance timing.






That's all I have done now. The engine is still on the workbench and I've got a couple of things to fix on top of getting it back together. The positive terminal broke off of the starter (that's a 1st for me) so I'll replace it with another I have here and a wire lost a connector on the CDI. Whenever it's all back together I'll get stock timing numbers and then try advancing it. I've heard of a lot of the ATV racers liking to advance timing, but nobody ever gives a base timing figure. I'll try to get some numbers instead of just telling you it's advanced.

[byte]

This gonna be interesting.... I know someone who uses up to 37 degrees advance , then 15, then 12, on a selettra ignition.

But be cautious. This mod is extreme in gain and aftermath.

[90GTVert]

I normally mess with the big minarellis and they will spark knock with stock timing. That's the big reason I haven't tried it. I'm so used to them that I thought when I pushed compression I'd start having issues for sure. Even running hot with high compression I never heard anything, so I'm hoping there's a bit of room here while still being safe. Unfortunately the CDIs I use only retard 3-4 degrees total from idle to 10,000RPM. I tested that on Project 90.

[90GTVert]

I got the engine fixed up and reinstalled. Checked timing as set in the stock position. It's 13° BTDC (Before Top Dead Center) at 2,000RPM. Then I rotated the stator counter-clockwise as far as I could with the slots I had made.






Now timing was at 28° BTDC at 2,000RPM. That sounded really excessive to me considering it only retards a few degrees max. Oh well, gotta try it anyway. It was obvious that it was revving quicker off idle on the stand and the scooter jumped a little more than normal when the clutch grabbed. Looked promising there, but I was expecting it to sound like ball bearings rattling in a tin can when I tried to ride it with 15° of advance.

I only took a quick run down the road, about 1 mile WOT each way. I didn't hear any knock. That really surprised me. I think I might blow up a 90cc with that kind of timing. lol It seemed like it got going just a little quicker right off the line and if I was on and off the throttle it kicked in a little harder. At the RPM at which the engine normally operates, I don't know that I could tell a difference. If anything I think it may have struggled just a little more to pick up RPM up top. Not really sure.

The one bad thing I know for sure is that it ran hotter. Temp was over 340F in just that quick trip.

I think I'm gonna back it off some. Not exactly sure what's a reasonable level. I could go to 20° and it should retard to 16° or I could go to 16 and it would retard to about 12°. The latter sounds most reasonable to me, but I'm really not sure how much it'll take.

[90GTVert]

Jun 25, 2012 16:02:18 GMT -5 byte said:

Brent I suggest 16° with that ignition to be on the safest side. I'm excited on how it will perform on a tuned pipe.

Well, you're late. lol I just got in from setting it at 20° to start with.



I've only ran it down the road the same distance as before. It's so windy (storms coming in) that I can't really say what the result is for sure. It feels stronger than stock and stronger than 28° to me just taking off. Once up to speed the wind is messing with me. 36MPH one way, 45MPH the other. I will say it pulled through to 8100RPM at 45MPH easier than I've seen even with a tailwind, but this might be stronger than any winds I've had yet? Other good news is that the CHT was not elevated on this quick trip. I'll take it on a longer ride this way whenever I can and conditions are more stable so I can tell something.

[90GTVert]

Well, now I don't know exactly what I wanna do. Remember I said the drive face mod made the RPM drop too much on the "shift" in the torque driver. Nope. The new torque driver does that. I guess I took a little too quick of a test ride and then moved on, but it's still doing it. It feels obviously quicker taking off with the timing... but it's slower to 35. I've tried a torsion control and different contra springs and another stock torque driver and it always shifts like that. I think the first one had worn in a way that actually smoothed the shift out. Now I'm really regretting the decision to go with a TD that I could see was worn when I want to be consistent. Not too bright.

[90GTVert]

Tried the old TD again. Still didn't do that odd shift where it falls out of power again, but compared to the ones in good shape it struggles for top speed more. I've gone from just under 17 seconds 0-35MPH to over 18 seconds with an engine that definitely feels like it's taking off quicker. I already screwed the times up on the first run, was hoping to keep them consistent. :no:

[90GTVert]

I set the timing back to stock and got it set up to run 7500RPM around 40-41MPH and then went for a test run late last night to the spot where I've done most of the 0-35 vids. That spot's about 10 miles from my house. When I left it revved as normal, shifted and fell to 68-6900RPM, and eventually made it to 38-40MPH cruising speeds. By the time I got to the spot to make some test runs it was acting different. I couldn't make it to 35MPH on the whole little street that I did the tests on. Made it to 33 I think at best on any run before I had to stop for a stop sign and a grassy hill on the other side of it. On the first run it was shifting and dropping to 6400. By the time I made a couple more attempts it was dropping to 6200 on the shift. I rode back home. Worst I saw was 6100 on the shift. It also dropped 100-200RPM at cruise speed. If it would drop 500 here and 500 there instead of 700 here and 150 there it'd just make life too easy I guess? lol With it dropping so much it struggled more on inclines too. It was 96 degrees outside when I left at 9:15PM last night, so I thought maybe the heat was really taking it's toll... even though my CVT cover is really open.

I took the scooter on a quick ride this morning. RPM dropped to 6200 at the shift and was still 100-200RPM low at speed. I did a 0-35MPH pass on a random flat stretch and it took 24 seconds. Pretty horrible.

I had switched around different 1000RPM contras to try and fine tune the cruise RPM. Not sure if the one I used was new and had to "break in" somehow or what's up. I'll have to work on tuning it a little better and then the game plan is to get a new baseline 0-35 time to compare to and redo a couple of free mod tests.

Only I would start out at 17 seconds, then go to 18, then drop into 16, and then all the way up to 24 seconds. lol Now it runs like I expected a 49cc to.

[2strokd]

Try one if you can?..

www.partsforscooters.com/169-281_Hoca_Torque_Spring_Base?sc=11&category=74117

[90GTVert]

I dunno if I really have a problem. I just think it's working like it should. I believe the old TD had worn in a way that smoothed out the shift. Woulda been a good thing had it not starting doing weird things and causing it to kinda get stuck and resist it's higher cruise speeds more.

The main reason it sucks is it throws off numbers and it woulda been nice to say it went ____ seconds stock and here's a progression and this did that. I guess if I get it in tune now though, it'll basically just be stock and tuned since I hadn't got far. I could take the modded clutch off, but I doubt I will. I did show a clear result on it already. I may revisit compression. The fact that it struggled to top speed with the old TD and I had noticed it struggling more at speed with raised compression makes me think that coulda just been the old TD. My goal now is basically to be accurate, even if that means being slower than before. I don't honestly care how fast this engine is, as long as anyone reading/watching and I can learn from it.

I would like to try that sometime though. From the Malossi TC with and without I could only tell one difference... the added height of the TC made it rev 1-200 RPM higher. Seems like it's main use for now would be fine tuning.

[90GTVert]

I swapped to 4.5g sliders and RPM is just a tad above 7500RPM at 40MPH. It still drops off bad on the shift, but at least now it's 6500ish instead of 6200. The worn TD was more like 7000RPM drop off. I know 500RPM doesn't sound like much, but this stock motor really struggles to pull through that 500RPM, so it slows everything down a lot. Gotta say, if I were confident in my abilities to machine each groove symmetrically, a straight groove TD would be high on my list for free mods. I'm not a big fan on street 90s because of their sacrifice of low cruise RPM and sometimes top speed... but 90s don't struggle to get the 35MPH either. I think this would do 40 still with a straight groove TD, but should be much quicker getting there. Also it looses a little of the hit on the initial launch with these lighter sliders.

I took a quick ride just as a preliminary test, 7 miles. In that time I didn't see the RPM drop off and it's quite hot out. Hopefully the contra has broken in, seated, heat cycled, or whatever the hell it did last night and it's done now. Depending on the weather, I might get out for a timed run in the usual spot tonight.

[2strokd]

Ya know, my Cobra acted real weird once after a CVT clean-up. Shifted weird, then after it warmed it short shifted and held lower RPM,s at speeds i never recalled before. Dropped right outta the power (7,200-7,700RPM or so on mine) bad and never would lift' back in it.

I decided i would look at it the next day. I suspected the TD was binding. Rode it the next morning anyway and the problem went away as i rode it. Weird, but i wasnt complaining.

My sons 49cc Mina shifted much smoother with the Hoca rear pulley. I believe its in the middle slots. I know, again, not stock though. He has the solid Malossi torsion plate too.

[90GTVert]

I'm gonna start pulling my hair out any minute now. lol Rode last night. It shifted 6500 leaving. It shifted 6500RPm at a stop sign 9 miles toward the spot I've been doing 0-35 vids. At a red light 11 miles from home it started shifting at 6300. That's about as low as I saw, but it also lost a little RPM cruising. I don't know if I've ever been more ready to get back home and off of a scooter. I did at least barely make 35MPH in a test run before slamming on the brakes because I was out of room. No idea what the time is. I didn't check the cam cause I'm not happy still.

So now I think I wanna pretty much do-over the baseline tune, since I think it acts like a stocker really would. I'll be swapping out the modded clutch for the stocker with 1500RPM springs and going back to whatever works with stock for a new starting 0-35 time. I'd really like to have something that can be followed with relative ease for the condensed thread rather than a roller coaster. That would also mean doing over the with and without spacer test and everything I've do so far pretty much. Not something I'm looking forward to, but good solid results will be worth it in the long run... I prob won't support me decision when I'm doing this all over though. lol I apologize if I'm making this as-I-go thread weird or hard to follow.

So I started out this morning by trying a different 1000RPM spring. It was just too soft with 4.5g weights. Then I tried a 1500RPM spring. It's about the same as one of the 1000 springs. Nice. At that point I came in to get something for breakfast, and instead sat down to type this. lol

I'll work at it and get a result that I'm as pleased as I can be with. Then I'll start do-overs. :doh: I'm still quite angry with myself that I didn't just replace a TD I knew was worn from the start and all of this would have been avoided.

[90GTVert]

I was gonna change some stuff around in the CVT and then thought, why not go all the way and make the best result possible. So now it's all stock again and I'm dreading riding it. lol I gotta take a bit of a ride cause I wanna get another fuel economy number that's accurate as it's setup. I think it's gonna suck. It was bad enough with sliders and a stiffer contra. I guess I'll delete most of P49's youtube vids soon too. Just rather have accurate info out there and not confusing bits of wait is it 17 or 30 seconds to 35 stock? lol

I'm trying to figure out a test spot now that's closer to make life much easier. I chose the last cause even though it's far away I never see cars there and there are lights at night and it seems flat. I could go out at 2PM or 2AM and make a few passes with no one else around. Not sure where I can have that very close. Lights won't really matter if it's close enough, cause I can get out for a quick ride a lot easier and won't have to wait for night when someone else can take care of my grandmother.

Bare with me. As boring as I'm sure this all is, I'm hoping it's all worth it when the numbers flow instead of leaping wildly around.