Go Go Sundiro! 70cc Stage6 Sport Pro MKII build

[tsimi]

Do you have a W7 needle in there?
What's the slide number?

I use 37/95(summer season) and 38/96 (winter season) on my genuine Dellorto with a W7 needle and #40 slide.
stock airbox with snorkel out, no additional holes.

[lordverminaard]

Sept 26, 2017 20:12:56 GMT -5 tsimi said:

Do you have a W7 needle in there?
What's the slide number?

I use 37/95(summer season) and 38/96 (winter season) on my genuine Dellorto with a W7 needle and #40 slide.
Stock airbox with snorkel out, no additional holes.

Yep, W7 and #40 slide as well.

Interesting that your pilot is a bit smaller, though from how mine is behaving, that would make sense that the pilot is a little big.  Although your build is completely different than mine too but the two cylinders we are using should be fairly comparable.  I still think my pipe is holding me back a little as well.

I think I have another undrilled keihin slow air jet I can use as a pilot for further testing, lol.

As always, your input and opinions are much appreciated.

Brendan

[tsimi]

Yeah, my pilot is smaller then what others have used or recommended for similar builds. Most say you need 40 or a 42 pilot on a stock airbox but for me those never worked.
My mixture screw is 1.5 turns out.

To be honest it is very difficult to get a perfect carb setup from bottom to WOT.
I rather have a richer main but crisper pilot jet. I drive often in traffic and don't want that rich sputter at 1/8 to 1/4 throttle.

You just need to find what works best for you. You also can skip some of the problems at lower areas with lighter rollers, stiffer clutch springs or a good torque spring like the Malossi yellow.

[lordverminaard]

I tossed in the 40 pilot this morning before going to work- (nothing like rolling around the garage floor in my nice dress work clothes even!) and gave it a quick tune. Needed 3 turns out on the mix screw to get it to throttle up, so it's too lean. Also hesitates a bit on take-off unless I give it more throttle but it really feels better in the lower-mid range until the over-rich main kicks in and it sputters. I think I can drill it to 42 to test.

I'm feeling confident though so I went ahead and ordered a "real" 42 pilot and 93 main from Treatland. That should clear up my top-end sputter and finally get the low-end closer to what it should be. I guess I will hold on to my 95 main jet though, I have a feeling if I get a better pipe I will probably need it.

I really want to order my sliders but money is really tight right now. But this thing hits 50 mph on a not-so great tune so I am pretty happy with what I have accomplished for my first 2-stroke project.

Brendan

[spaz12]

When winter starts coming around you'll also need a larger main because of the cold, dense air.

[lordverminaard]

While waiting for the jets to come, I tore the panels and carburetor off the scoot and also decided to do something about the really loud muffler.  I have seen a couple posts of others doing the same thing to this style of pipe so I gave it a shot.  Removed the 5mm hex bolts, drilled out the rivets and it came apart pretty easy.  Didn't get a pic of it apart since my toddler was also in the garage with me and it was too much for me to keep track of him and also take pictures, lol.  But the packing looked like oil-soaked cardboard.  Yuck!  Packed it with some steel wool like so:






I wanted to remove the crappy looking blue finish but didn't really have time.  Popped some rivets back in and it was good to go.

My jets came the next day, (42 pilot, 93 main for those keeping track) so I put them in last night.  Also noticed some oil seepage around the idle screw on my carb, so I wrapped the threads in Teflon tape and it felt better.  Reset the mix screw to 1 and a half turns out, gave it a kick and it fired right up.  The first thing I noticed was "aw crap, the muffler is louder!!!"  Put the panels back on it, let it warm up and just gave it some blips in the garage, too late to do any test riding but it felt great.  I just needed to drop the idle slightly and it seemed good to me.

Fired it up again this morning (again, first kick), let it warm up for a good while before I left for work, and immediately I noticed it running much better in the low throttle-low rpm range.  (I try to putt slowly out of my neighborhood so I don't piss off the locals)  Darting through the side streets I was enjoying a much better,  MUCH more responsive throttle, and actually, the muffler sounded a lot better in the higher rpm range, not nearly as loud and shrill as it was before even if it is louder and deeper at idle.  (not a bad thing)

On one small stretch of 4-lane road, (with a 35 mph limit, hehe) I hit 52 mph in about 1/4 of a mile before I had to back off due to traffic.  Felt like I was getting pretty close to the top of the rpm range but I will need to pull the variator and check belt travel to know for sure.  But that's a new speed record.

The only running issue I am noticing is that it will still sort of sputter\miss\chop if I quickly roll into the high throttle position, the best way I can describe it, is that the rpms climb very high, then it sort of sounds like a "splatter" in the exhaust, then it clears up after a second or two.  If I roll into it slowly, it usually doesn't do it.  It was doing this before the jet change as well but much more pronounced.  I am thinking I probably need to lean out the needle a little more, but at this point I think I can probably live with it.

Either way, I am pretty happy with how it is running.

Also destroyed my 2nd cheap-o cell phone mount, nothing like trying to catch your phone with your feet while zooming through traffic.  I think one of those Koso clone tach\speedometers is probably in my future.

Brendan

[repherence2]

get a cylinder head temp gauge and a tachometer from TTO. they make tuning a lot easier. I tune air/fuel screw first during idle, the amount of turns in or out on the screw will point you in the proper direction to get the right size pilot jet. once air/fuel screw is adjusted, I tune for WOT and shoot for a temperature of 350. I keep testing jets at WOT until I find the size jet that will allow me to hold the throttle open all day long and not go past 350 on the flats and 375 on the hills.

[lordverminaard]

I know that a CHT and tach would have told me a lot about tuning right from the very start but I never seem to find the good deals on these things like some people can find, and I don't really have the extra $40 - $45 each for a couple gauges. I scan ebay on a weekly basis to try to snag up a used unit but so far nothing.

A CHT would help a lot with the current issue as well, this morning (again before work, haha) I swapped rollers to yet even lighter ones, three 5g weights. I also moved the carb needle up one clip in hopes of clearing up some cutting out issues at half-throttle and greater which seemed to me as a rich condition. I only really made it a couple blocks before I turned around and came back home, it was 100 times worse, starting at even 1/4 throttle and WOT was not even possible.

I can't really figure out what happened, the cutting out it was doing seemed like a rich condition to me but maybe it wasn't? Either way, pretty frustrated, (especially since changing needle position is a giant pain) that I thought I was on the right track with jetting and now it seems like it's wrong again.

Back to the garage!

Brendan

[repherence2]

try tuning the CVT with all 5g or 4g rollers, all 6 of them. it will keep your CVT rate at a constant. you're fooling around with too many variables all at once. I traveled down the same headache road as you are. if your bore and pipe combination is around 8000-9000 rpm, put the 5g x 6 rollers in. if your bore and pipe combo is supposed to rev above 9000, put the 4g x 6 rollers in. Keep the CVT constant until you get the carb in tune.

I totally understand where you are coming from in regards to obtaining a temp gauge. I was the same way. I got mine over a year after getting into tuning. and a tach long after that. but, what I have found is that a temp gauge makes tuning the carb a lot easier. a tach makes tuning the CVT a whole lot easier once the carb is tuned.

[lordverminaard]

Apparently the koso variator likes really light weights as someone else mentioned, I had 6x6g weights in it to start, and I was blaming the tune but it was shifting way too early, and that is with a NCY yellow contra spring too.


I fooled around with it last night, pulled the plug to have a look and this is what I got:






Keep in mind I used a flash on that pic, but maybe a little lean?  Either way I have not noticed any detonation during any rides, even when it was very warm out.


I decided to swap out my CDI since the cutting out I was noticing was very much like a hard ignition cut.  I put the "new racing" cdi back in, and didn't touch the carb jetting.  Fired it up and it was running pretty good.  I fattened up the idle a little, let it warm up a while, and gave it a couple full throttle rips on the stand, no cutting.  (yesterday it would not take full throttle on the stand without cutting out)  It was too late to ride it though.

This morning I decided to try and ride it to work again, and I had basically no problems.  I noticed a slight burble in the higher throttle ranges (1/2-WOT) if the RPM's weren't up, but I didn't get any ignition cut.  The 3x5g roller weights seemed pretty good too, accell is better but I really didn't get a chance to test top speed due to traffic.  I still get a pretty significant flat spot right off idle, maybe I can turn the mix screw back in a little.

We will see how it does going home.

Brendan

[lordverminaard]

Time to dig this project back up for 2018.

I basically haven't touched it since mid-October of last year until recently. The weather here has been very inconsistent but during one of the warmer weekends we had, I rolled the bike out and tried to fire it. I just hooked it up to a jump box and cranked it over and eventually it fired up. I only let it run a couple minutes and shut it down, didn't have time for a test ride. A week or so later, I decided to give it a go around the block after checking tire pressures, etc... and I couldn't get it to start. So I hooked the jump box back up to it and when I turned the run switch on, I immediately noticed that I didn't have any lights and the starter wouldn't do anything. Guess I have to figure that out before I do anything else this year. I took the dash panels off, and did some more testing with a multimeter and it looks like the kill switch is working and the ignition switch is working. Maybe a fuse blew out somewhere?

Plan this year is get it tuned right and probably try and sell it. I'd like a Stella\Vespa project or possibly a Ruckus, or maybe an older Honda scoot. Also thinking of a Typhoon. I also really want to get my KZ400 running or I might even sell that too.... Not sure what I want yet, it is early still!

[oldgeek]

If it has an AC lighting system, as many scoots do, the lights do not come on until the stator is producing voltage.

If the starter will not turn, check the brake lever switches as they are in the starter enable circuit. There should be a fuse at the battery, if it blows, the starter will not work.

[repherence2]

Not to be an A--hole but was the key turned to the "ON" position? There has been many times where I stood there kicking on the kick starter, only to realize that I didn't have the key turned to that "ON" position.

[benji]

Mar 20, 2018 21:22:55 GMT -5 repherence2 said:

Not to be an A--hole but was the key turned to the "ON" position? There has been many times where I stood there kicking on the kick starter, only to realize that I didn't have the key turned to that "ON" position.

or the spark plug hooked up/installed, or fuel in the tank, or the Killswitch set to off...etc. I do all of these almost weekly, if not more often.

[Corrosion]

My questions: A projected nose spark plug on a performance 2-T? Is it a Squish type head? What number plug is that?