KymcoForum.com
Scooters - 50cc => Super 9 => Topic started by: Triesandluth on December 28, 2014, 04:38:51 PM
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I bought it with these holes drilled. Before finishing the derestrict mod of cutting the useless tube I covered them, thinking it was a part of my lack of power. But I uncovered them before tube cutting.
Since then I haven't covered them back to see if there's a notable difference, but would there be? A lack of back pressure may cause issues?
The only thing I've noticed is that it gets a deeper, throaty sound with them.
My neighbors might appreciate the quieter exhaust lol. My tuning habits probably get on their nerves, between the impact and the revving.
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That's someone's attempt to make it go faster. But in reality it'll rob power because of back pressure. Weld em' shut.
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sound with holes, pardon the smoke, wasn't warmed or ran.
https://vimeo.com/115523502 (https://vimeo.com/115523502)
After covering
https://vimeo.com/115523560 (https://vimeo.com/115523560)
Gonna run up to the store in a few to see the difference, if noticeable.
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Oops. Didn't cut the recording when I thought. You get to see the rear of my beat up tao duster!
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I ran it a about three miles round trip. It seems to have made my initial rpms about 100-200 lower (maybe) , no real top speed difference. I'm going to run it some more the next few days. If I don't notice anything I may chip that back off. The sound was way meaner with the open holes at higher rpms.
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There's a possibility the person that drilled the holes up-jetted accordingly, and with them plugged it's too rich. It won't ruin anything if you leave it open tho haha.
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I had already went up to 85 mains from 82 that were in it after I finished your pipe derestrict mod.
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Still might already be too rich with the amount of "spooge" I was getting lol.
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I would say 95 is where you should be with the holes.
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I have one of those 1" HEADER PIPES W/ AN OPEN "SHORTY" MUFFLER. (sorry for yelling) The cat hit Caps...
It's running a 105 main jet.
Opening the exhaust ALWAYS increases power when it's jetted accordingly. The more air/fuel you can move thru the engine, the more power it makes. Magic!
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Yeah, I went up to 90 with the holes open (the closed sound wasn't doing it for me😉), threw in a newish plug, an iridium I stupidly bought 😓, ran it about ten miles, checked the plug later and there was almost no color change. Actually looked more white than before putting it in! I feel that was a false read, put back in the bpr7 and am going to stop to pick up a few plugs in morning.
I'll get that squared away before heading on my planned long ride. Not wanting to burn anything up...
Of course I then will be also trying to work in the 95 jet that I have, the highest ATM.
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If the 95 doesn't get it, you can always open one of the smaller jets w/ a torch tip cleaner. I have dozens of unknown size jets I opened up, or closed w/ solder.
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I'll have to get one off of eBay, unless one of the scooter guys around here have some. One two guys acted like I was a moron when I talked about upjetting, one guy that drag races didn't, and the old guy seemed impartial about it. Bad thing is that the ones that acted like jerks about it, one is an authorized kymco dealer and the other used to specialize in LC two strokes and is trying to get me to look at his s9 with bad crank bearing.
The plug chopping may need to wait, it's nasty out and not looking like it's gonna break today. But I've got nothing more interesting to do today. Sure as hell ain't gonna clean my house! 😜
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Hmm.. In an attempt to do the plug chopping I have ran wide open throttle for miles and this is all I am managing to get . Is it safe to say I'm lean and have been at risk of burning up? I'm going to go up to the 95 and see if that changes anything...
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Looks light.... Any other mods? Wouldn't be surprised if the previous owner drilled the airbox out either. What kind of 2t oil you using?
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No other mods besides the extra pipe trimming, per your thread, and those dumb little holes. The box is solid, I did cut back just a little more where it attaches under the body from the snorkel. Oil is Bel Ray si -7.
Just bought a torch cleaner kit and reamed out an 80 I had to go above 95. The 95 still looks about the same. Gonna give that a shot.
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Oh, when I bought it, there was no air filter (!!!) in the box. I keep forgetting. I put one from a gy6 in it that I had lying around. I put it in as good as I can tell for it to not let anything through and not be too open.
I really need to order one...
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Hmm i wouldn't think it would look that lean. Oh well you'll get it. Another more accurate way to make your own jets is by drilling, get an accurate micrometer(digital) and measure the bit at the shank, then drill it gently. The jet sizing is as follows, a 100 jet is 1.00mm a 95 is .95mm etc etc. Most decent hardware stores will have small size bits down to .5mm or smaller.
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Good call. Will do!
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Hmm, somehow I got carried away on the jet I was working on. Straight up drowned the plug. Maybe a 200😡
Tried a lot lighter on my 95, ran it on the stand and started to bog at 7k. Oops. Went light on the 90. Ran it with a new plug, it still looks the same.
Maybe my oiler shouldn't be wide open at wide open throttle? I really would hate to turn it back. Yet, the more oil makes it more lean, so I'm essentially burning up this expensive oil and not gaining the benefits? Whatcha think?
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The oil meter is not supposed to be open all the way at wot, there's a mark for where it's supposed to be set, in-between two lines. Also the more oil taking up space on each charge, the less room for fuel hence making it leaner. That's why race two strokers run as low a mix ratio as possible, more room for fuel!
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Ah... Okay. I'll look for the marks tomorrow. Maybe later, since I'll be kid free this evening 😄
How about my fuel grade? I've been running strictly non ethanol 93 octane
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There's an adjustment that has to be done on the oiler. You'll see a grove cut into the cam, and a line on the housing. These must be aligned at idle. The wot position is based on that.
Also the fuel is metered Before the oil is injected so adding more oil on an injected system does not lean the air/fuel ratio.
You can melt solder into the drilled jets to close them back up. I use the approx size sewing needle to keep the hole partly open when melting the solder in. The needle will easily pull back out when the jet is cooled.
This method makes your jets infinitely adjustable. Use plenty of flux, and pin the jet face up onto a board w/ your sewing needle.
If it gets sloppy, and the threads get soldered, just re-heat, and tap the jet w/ a screw driver to knock the solder off.
Using Electronics solder is best. It's thinner, and easier to control
This is a good method to get the correct jetting when you don't have a supply or the right sizes.
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So what would be the outcome of too much oil going in with the metered amount of fuel? Too much "substance" in the combustion area? Would it just burn up, or would it take over the fuel amount? Or vice versa?
I apologize for the daftness. I'm trying to wrap my head around this injection system mixing. I read plenty of things about premixing, but this just got complicated.
No wonder y'all just premix...
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It's not really that complex. 2t oil is flamable but not as much as gasoline, and even less than gas/air mixed into a vapor (air/fuel mix).
The oil doesn't really burn when injected in the correct amount. It needs to stay an oil to lubricate so the lower flash point makes it sort of evaporate off inside the pipe. That's why 2t bikes are always dirty/greasy.
The injector meters the amount for throttle position, and that is a VERY crude approx. of rpm. Too little oil, and cylinders/crank bearings suffer. Too much oil, and combustion temps fall.
Kymco does a good job of regulating the oil, and they use a decent/reliable oil pump. When it is adjusted correctly, and you are using a good quality injector oil... there are no real issues.
T%he only reason I removed my pump, and run Pre-mix is, I run high load cylinder kits. Let's say I am running 11k rpm at 900* f exhaust temp... I let off the throttle... The bike is still spinning wicked high rpm and the temp will rise. This is due to "soaking". The parts are hot, and the cooler air/fuel mix has been cut off. When I pre-mix there is a constant amount of oil, and most of that oil will remain in the crankcase simply because it is denser than the air/fuel. That iol can now be sucked up into the cylinder, and cool things down.
Your injector only gives what is needed according to the throttle position. WOT you get near 50:1 ratio. idle or closed position you get near 100:1. Even tho your throttle is closed you are still getting 100:1 (thru the pump) but there is no excess oil to cool the cylinder.
For an example... You will NEVER find any Pro Super Bike running an injected engine. They all run pre-mix.
Outboards get away w/ it simply because they are run at or near WOT all the time. They rarely throttle down.
Now the confusing part... Jetting for pre-mix requires you to use a larger jet (compared to injected).
The reason is oil takes up space. The jet needs to allow for the right amount of gas, and now you also need room in that jet for the oil.
See... It's really quite simple.
Don't worry about asking these things 8). It's how we all learn.
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Thanks! It seems I can read a million explanations of these things and still confuse myself. You dumb it down well for me! I guess it will just make more sense the more I get into it. Just a month ago I knew barely half of what I know about two strokes now.
The problem at hand now is restraining from starting the scoot up tonight and do a plug chop after I put the oiler into proper position, even if it most likely won't affect the outcome.
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Looking up "soaking" I found a page about octanes and two strokes.
http://articles.superhunky.com/4/370
Stuff that most probably know, but I gained a bit of knowledge from it.
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That's a decent article, and well worth reading.
Two stroke engines are so completely different from 4t's that they almost don't belong in scooters. Kymco (and others) have found ways to "tame" them to a level that they do OK for their intended task. OK but not great.
Lot's of us guys that have tuned these little engines have burnt up enough parts to learn the limits. I built my ZX for 1 mile runs, and nothing else. In fact I haven't ridden it in months.
The choices are, De-tune it for everyday street or keep it as is, and never get to use it.
I only bring this up to say... There are practical limits for 2t engines. The more you come across new phrases or peculiarities of these engines the more you will have to decide. Screamer or daily rider? where is the dividing line?
I'd have to say for ANY 50cc base 2t engine 70 mph @ 12k rpm is the limit for a daily driver. That is ONLY if you tend to ride around 55 mph @ 9-10k rpm, and ONLY if you hit top rpm/speed for short runs.
That's a great bike that can do this for a few years.
Keep reading up on the cool stuff, and figure out where you want your bike to be. Maybe get a cheap ass 4t China scoot to beat around on. You cant kill them, and they will also do 60mph. Much more reliably I might add. (lower rpm/less heat)
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I'm not going for 70 mph, that's for sure. My goal is to have it as a mostly daily driver, be able to not drop 15 mph on medium grade hills, and ride comfortably. That's where I believe I should do a sport bbk and tune it to just average capabilities.
I'm on my little Taotao right now, knees in the front plastic, being over six foot, and miserable, lol. Sad is that it starts every time, two kicks Max and can almost keep up with the s9.
I'm about to go look at another s9 and loads of parts that this guy has stock piled. He says he has a malossi bbk that I can get!
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That's your best bet. I have spares of everything... 3-4 of most parts.
This week I finished re-building both engines for the ZX. I put another JiangWayne 50mm kit on the stroker crank case, and the Corsa back on a stock crank. Both engines are geared, (Malossi primaries in one, and MHR secondaries in the other),and both running Jasil Vars, and Stage 6 clutches.
I figure each one will do 65mph but a very different rpm/power bands, and both of them reliable for street use.
Point is I am done w/ crazy tuning. A quick/reliable engine is more important now. At least I will get to enjoy riding.
I said this once before.
The only way to know the limit, is to exceed it.
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Point is I am done w/ crazy tuning. A quick/reliable engine is more important now. At least I will get to enjoy riding.
I said this once before.
The only way to know the limit, is to exceed it.
I've said similar, but about drinking. Replace the words "tuning," "engine," and "riding" with the word "drunk ::)
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;D ;D ;D ;D ;D ;D ;D ;D ;D ;D