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Thread: Yamaha NXC125 20,000km

  1. #76
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    12th February 2004 - 10:29
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    bucket FZR/MB100
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    I'll see about putting a gopro on it this weekend but have attached a picture of the underseat storage in the meantime. there was nowhere else to put the Mikuni. It's just a bit bigger than the original 25mm CV carb
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  2. #77
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    12th February 2004 - 10:29
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    So funny. Another little trip down the motorway from Rosebank Road to Lincoln Road. Seems there is a road rule I was unaware of that says if you need to exit at the next off ramp that you need to be in front of any scooters on the motorway. One pushed in and another was looking to follow. A quick squirt saw the speedo past the oil change light and me 4-5 car lengths ahead in a space between cars. Both guys came down Lincoln Road and were looking to be somewhere near so I split to the front at the lights. At the green I gave it a bit of throttle to make sure I was clear of cars and totally unexpectedly the front came up and only went down when i closed the throttle about half way across the intersection. So much fun.

  3. #78
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    12th February 2004 - 10:29
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    It gets better with distance. Beautiful day for scooter ride so did the loop Glendene, Rosebank Road, Lincoln road and back home. Along Gt Nth Rd snuck to the front at the lights. Took off sharpish to get away from cars and the front came up, closed throttle to put it down and then opened it again and the front came back up.
    110-120K(oil change light) is about 1/2 throttle and easy as. It does pink hard in certain circumstances so I really need to get the Ecotrons ECU fitted so I can programme the advance. Spent time today making an enclosure around the carb under the seat. Just need the lid now and we can get back to using the underseat storage. Can still fit a helmet under there as well. I want to fit a bung to the exhaust for the lambda sensor and then we'll have a look at some dyno time.

  4. #79
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    12th February 2004 - 10:29
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    Tried getting the Ecotrons ECU to work in the scooter. Managed to get spark but couldn't change the timing using the standard Load/RPM table. Also had problems with it connected to the scooter battery and scooter ground. My ECU was one of the range that had contact between the leads on the board touching the case. Despite giving me the run around for a year denying there was a problem I finally figured a cure by completely isolating the case from ground. Later I trimmed the wires so they didn't touch.
    Anyway, i can't be bothered struggling with it any longer and will fit my Ignitech DC CDI and feed the MAP signal in on the TPS input. It should work OK but I'm thinking will need a bit of smoothing. I'm hoping to use a 3D map with the variable MAP signal being used in place of the variable TPS signal, versus RPM.

  5. #80
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    12th February 2004 - 10:29
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    Hooked the Ignitech up and ran it. I can map it OK and adjust the timing. The MAP siganl bounced around way too much to use so i pulled a hose off my vacuum gauges which has a little restrictor in it to stop the gauges fluctuating too much and that cured it nicely. Still using the standard ignition at the moment but should be able to get it fitted in the long weekend coming up.

    Oh yeah, damn, pesky speed cameras. Must have been parked in the church carpark just heading out of Henderson up the hill.
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  6. #81
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    12th February 2004 - 10:29
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    first - that speed camera is a new fixed jobby. From the lights it sits behind a "school" sign and isn't obvious.

    Ignitech is in and running the bike now. Set the idle timing to about standard and just added some advance as it revs. I haven't enabled the TPS/MAP input, just keeping it simple at the moment. It may be just a whisker harder to start but runs fine once fired up. Blips clean from idle which is 2000rpm and I think I'll add a bit of advance to make it real crisp. I've tried big throttle settings and the motor is a lot happier with no sounds of pinking. I'll add a bit more advance through the middle until the noises start up again.
    Ideally I'll be able to get it on a dyno. At the moment i have 10g rollers in it which seem to work fine on the road but for the dyno I'll put 12g rollers in so the variator tops out as early as possible. Then we will be able to see the power the motor makes at certain revs which is what is needed. It might even be worthwhile making some heavier rollers to max the variator out even earlier in the revs.
    Taking off from an intersection it isn't too hard to make the front feel light. It's the wrong word but the motor is feeling a bit "lazy" so I'm expecting good things once I get the timing right.
    The plug is looking text book light tan so the jetting is not far off at normal riding speed.

  7. #82
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    12th February 2004 - 10:29
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    Still not seen a dyno but have given it plenty of full throttle runs. Got it so I can consistently hold it with the front light away from traffic lights. Have also given it a good full throttle burst and it went off the clock real quick and just kept going. I wouldn't say it is a lot quicker than the old motor, it's real hard to tell with the variator and the spread, but I suspect it's making good power, for a scooter.

  8. #83
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    12th February 2004 - 10:29
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    Arranged some dyno time at ESE on Saturday arvo and thought I'd swap out the 10g rollers for the 12g rollers. Took it apart and looked for the 12g rollers and couldn't find them. A couple of the boxes of rollers I got with the new transmission kit were 3 of one weight and 3 of another. Turns out I had put in 3 10g rollers and 3 12g rollers that were in the same packet. I've now replaced the 10g rollers with 11g rollers so not much of a difference but as good as I can make it for the dyno.
    Looking at it now I can see how it would be even quicker accelerating with a lighter set of rollers. It is quick even with the 2nd heaviest combination I had. Going lighter and letting it rev harder should be a real giggle. My son is taking it for a ride tomorrow with the 11g & 12g rollers in it. Will be interesting how it goes, especially at lower speeds like 50kmh

  9. #84
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    12th February 2004 - 10:29
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    On the road with the heavier roller combination it is a bit slower away from the lights. Once moving there isn't much difference, evidently. On the dyno the plot is very jittery and very difficult to determine a change. We played with the timing and ended up with a few more degrees from 8000rpm up. I took 1degree out after my son rode it on the road and he thought it pinked pretty good at certain revs and throttle.
    On the dyno the change that was really obvious was when I refitted the 10g/12g roller pair. As the throttle was opened from about 40kmh on a run there was a significant increase in power as it ramped up. Once at full throttle and spinning the roller up there was little to tell between the 2 setups.
    Theoretically with the lighter rollers the engine would rev harder at the exact same speed and the CVT would obviously be at a lower ratio. This seemed to be born out on the dyno with the engine limited to 8000rpm on a run with the 11/12 combo and sitting on 8500-9000rpm with the lighter 10/12 combo.
    I bumped the rev limiter up to 10,500rpm. This had the road speed going out to 170kmh on the dyno. It's very unlikely on the road for 2 reasons - it's not really making enough horsepower, and I'm not that stupid.
    The horsepower tailed off as the speed went up. I figure this is due to inefficiency in the CVT transmission. The transmission case gets too hot to touch in use so it sort of bears that out.
    We also tried a jet up and one down. There wasn't any real obvious difference. I will fit the Lambda meter and see what fuel ratio it is actually running and just tune for what is typically a good power setting, something around .8-.85.
    I tried giving it a handful from stopped on the dyno but it just spun the tyre and wanted to go sideways, hence doing runs from 40kmh.
    Back at home and I've been out riding. It does seem a bit more frisky, licence losing frisky. It launches off the lights and even with the speedo pegged it keeps on going real good. Not 600 good but OK for a scooter. I've also given it a couple of degrees extra advance around 2-4000rpm and it is back to being real perky when blipping the throttle. It'd be hard to mistake it as standard for sure.

  10. #85
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    12th February 2004 - 10:29
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    Lambda meter fitted and taken for a test ride. All warmed up at idle it is sitting on about 11:1 so a bit rich. Next time the carb is out I'll wind the idle air screw out 1/4 turn. Cruising around suburbia at 50K it's sitting on about 10:1 so proper rich. A touch of throttle and up to 60K and it drops to a more respectable 12-13:1. This is probably the reason it's so snatchy right down low, that transition from real rich to less rich when it perks up nicely. It's at hardly any throttle so probably a combination of idle air and pilot jet. On the motorway at a steady 80-100 it sits around 12-13:1 as well. Full throttle sees it moving around a bit but still on the slightly rich side so basically I don't think there's too much to do. I'll look at putting it on the rolling road I built and run it at a stable speed and load and see where it settles. One interesting thing is how lean it indicates when you close the throttle. Even at only 60k it goes full lean, something over 20:1 and as the revs drop to close to idle speed it jumps back to rich. Same on the motorway, closing the throttle fully and it goes super lean. Easing off it just varies about a bit. Probably because the main fuel source - main and needle, are closed leaving only the idle and pilot jet supplying fuel. With the motor still turning quicker than idle it manages to drag in air but not so much fuel.

  11. #86
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    12th February 2004 - 10:29
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    Time ran out and I never got it on the rolling road so I've only made adjustments to the idle mixture. When I checked the idle adjustment on the carb it was 1 turn out from bottomed. This idle adjustment is for fuel not air so I gave it a 1/4 turn in. The AFR went to 12-13:1 so looking good. The only problem is that when giving it really small amounts of throttle it was going lean, really really lean. I turned it back so it was only about 1/8th of a turn in and this seemed to work OK while still making it a bit leaner. I still wasn't completely happy with how it felt so went back to the original setting. It was here that I checked how far off bottoming it was and found it was 1 turn out. The instructions say it should be 1-3 turns once adjusted. I have a few pilot jets so will try one smaller and make the adjustments again. It might make the progression just off idle a bit better. It still barks when you blip the throttle but i haven't ridden it on the road yet so don't know how it takes throttle if I have it leaned off. The WOF is due which will be interesting.

  12. #87
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    12th February 2004 - 10:29
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    That didn't go so well. Bit noisy, even with the decibel killer insert, the throttle cable a bit stiff. Cable is all sorted and the stock muffler is all but refitted. With the taller big block none of the mounting holes line up so the pipe has been cut and I now need an adaptor to fit over the cut ends and join them up. The header pipe is way smaller than the port but I ran it like that with the last motor and cam. Be really interesting to see how it goes.

  13. #88
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    12th February 2004 - 10:29
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    WOF all sorted. Son had ridden with the stock muffler and reckoned it went OK. I just got back from a ride and it is OK. Did my usual test loop to New Lynn, Rosebank Road, NW motorway to Lincoln Road and home. Pretty happy puttering about at 50-60k though it feels richer than ever. Launches off from the lights but I'm guessing it is missing a bit as it doesn't pick the front up like it was. On the motorway it was no problem getting the speedo round to the oil change light and just cruising happily at that. Giving it a handful resulted in a bit of pinking. It might be more obvious as it isn't being drowned out by the exhaust. It also might be worse because of the restrictive stock pipe. The header is at least 2-3mm smaller diameter than the port. As OK as it is I'm going to put the other pipe back on but leave the decibel killer fitted as it knocks the noise right down with no obvious detriment to power.
    It's a bit of a "stealth scooter" as my son has called it. Nearly as quite as stock but still goes like the clappers.

  14. #89
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    12th February 2004 - 10:29
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    Starting has slowly been getting more of a problem. The starter one-way clutch was slipping worse and worse. I had a look and it was past it's best-by date for sure. Another one was ordered and when it turned up it wouldn't go on the boss in the crankcase that it rotates on. There's a roller bearing that goes on a hardened sleeve on a boss in the crankcase and the starter cog rotates on that. The trouble was that the boss the bearing was supposed to fit in was something like .15mm smaller than it should be. As is usual with bearings it looked hard, as in hardened. Anyway, chucked it in Kev's 3-jaw chuck and checked runout. It was only .02mm so we decided to not mess trying to get it better. The whole thing is not that precise anyway. A new ceramic bit was fitted to the boring bar, speed 1500rpm, and away we went. Very impressive cutting hardened steel at speed. Took it out to precisely where Kev thought it would work and ended up with a very nice finish. Good enough finish for intermittent use anyway. Brought it home and fitted it together and it works great.

    Seems I might not need that new battery that is now on the way.

  15. #90
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    12th February 2004 - 10:29
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    Went for a ride in the weekend with my son on his Yamaha Scorpio. He followed the whole way up through Swanson to Taupaki and then Blossoms Cafe. The Scorpio is good for 18hp(claimed) and he was saying the scooter walked away from him in places despite him being in the right gear and giving it a handful. He's done a bit of racing so knows what you need to do to get along. He doesn't weigh much either so all the better. Away from lights on the way to Swanson he reckons no way he was staying with the scooter. No surprises really.
    Starting is way better with the new clutch and gear and it still goes off the clock plus a decent bit more so it's still fun to ride.

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