KymcoForum.com
General => Technical | How To => Topic started by: jbcinzio on September 14, 2010, 11:14:55 AM
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Hey guys, just found a surprise restriction in the inlet hose that runs between atmosphere and the airbox on my Like 50 4T.
It's a black Collett that you can just pop out of tye connection on the airbox if you can get your fingers in there.
Has anyone ever seen or eard of this with other models?
Removing this effectively doubles the size of the smallest (most restrictive) point in the inlet.
Josh.
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..it's there on some...not on others...
..take it out!!..
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so is this on the agilty 50s also
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..again...some have it..some don't...
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I removed the collet from the air intake. After doing so the scoot is running like a dog. I have been trying to adjust the mix but can't seem to get it right. Particularly when cold it won't develop any power now. Not so bad once it warms up. If anyone else has removed the collet can you tell me how many turns you have set the pilot screw.
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Yes, you will need to upjet to compensate for the extra airflow. If you get a larger filter, you will need to upjet also.
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Yes, you will need to upjet to compensate for the extra airflow. If you get a larger filter, you will need to upjet also.
Thanks for that. 1000km service due soon. I will ask them to do that.
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Thanks for that. 1000km service due soon. I will ask them to do that
..or you could adjust it yourself and save some bucks....
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Thanks for that. 1000km service due soon. I will ask them to do that
..or you could adjust it yourself and save some bucks....
I've never tried that before. Tried googling for instructions but wasn't able to find anything. I thought the jet had to be replaced rather than adjusted? How do you know what size to use? I read about someone drilling it out but if you get it wrong, you're stuffed. Would be happy to give it a go if you want to advise :)
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In regards to the jetting/adjusting questions, there are a few things that probably need to be pointed out for all the newer members (Like me!) Although I don't always have all the answers, however I'm fairly well read, and am not afraid to research things, ask questions, and give things a go myself.
ANY intake/exhaust mods (eg bigger/smaller exhaust, pod filter, removing collett in airbox, and so on) will require:
1. A replacement jet (high speed jet, not the idle jet unless absolutely necessary).
2. Adjustment of the air/fuel mixture.
Here's how it works:
The Jet controls the flow rate of the fuel, in conjunction with the needle that runs through it.
The bigger the number on the jet, the more fuel it will flow.
If you increase the flow of air through the engine, you MUST increase the amount of fuel going in to it, otherwise the engine will run "Lean" ie; Not enough fuel mixed in with the air, and the engine will run very hot, possibly burning a hole in the piston (you don.t want this).
If the jet is too big, then it's not nearly as dramatic, except the engine will run too "Rich" (too much fuel mixed in with the air), resulting in loss of power, fouling of the sparkplug, and an engine that will run like crap.
Once you've put a bigger jet in, it's time to adjust the air/fuel mixture.
Now remember this: The mixture screw adjusts the amount of air coming in via a very small pilot hole to create a venturi effect. It does NOT adjust the flow of fuel. That is determined by the relationship between the Main (High-speed) Jet and the tapered needle that runs through.
Tighten (do-up) the mixture screw, you let in less air and a leaner mixture will result.
Loosen (undo) the mixture screw, you let in more air and the mixture will become richer.
A perfect mixture (air/fuel ratio) is called Stoichiometric (commonly called Stoich) and is an air/fuel ratio (AFR) of 14.7:1 ie 14 parts air to 1 part fuel, though this is damn near impossible to achieve.
Tuning any engine without an oxygen sensor/exhaust-gas analysis machine is damn hard, with most tuners relying on three things:
1. "Feel" of the engine eg smoothness, pickup (acceleration), sound, vibration etc
2. Temperature ie Leaner mixtures = hotter engine temps, while Richer mixtures = cool running's.
3. Spark-Plug Colour (Ok, Color for you USA scooter-nuts)
For more info on the correct colour of the carbon build-up on your spark-plug, i'm pretty sure I saw a link on here somewhere for an excellent guide....
Just remember, adjusting the mixture screw and riding around for 5 minutes at full throttle will NOT give you an accurate colour-change on your spark-plug. It takes a couple of hundred Kilometres and a wide range of engine load/s rev-ranges, stops, starts, start-ups and shut downs to accurately guage a PROPER colour-change on your spark-plug.
Happy Tuning,
Josh.
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Just remember, adjusting the mixture screw and riding around for 5 minutes at full throttle will NOT give you an accurate colour-change on your spark-plug
...WTF josh!!
...awesome post!!!!
:D
..dang...post the link to that!!!
..i'd save that in my favorites!!!
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Thanks Slinger', I've just noticed the confusion surrounding the "Black Art" of tuning popping up in the forum a bit lately.
Always happy to help :)
Josh.
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Hey guys, just found a surprise restriction in the inlet hose that runs between atmosphere and the airbox on my Like 50 4T.
It's a black Collett that you can just pop out of tye connection on the airbox if you can get your fingers in there.
Has anyone ever seen or eard of this with other models?
Removing this effectively doubles the size of the smallest (most restrictive) point in the inlet.
Josh.
Do you have a picture showing this ?? Not sure if i have this on people s 50 2009
Stefan
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Here's a link to a plug chart i found using google,
http://www.4secondsflat.com/plug_chart.html (http://www.4secondsflat.com/plug_chart.html)
hope it helps
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Great very informative post, however I think there is one line that is confusing:
Tighten (do-up) the mixture screw, you let in less air and a leaner mixture will result.
Loosen (undo) the mixture screw, you let in more air and the mixture will become richer.
Its my understanding that letting in less air will mean more gas to air ratio and a richer mix &
More air will result in the opposite or a leaner mix.
This is very important when adjusting the mixture screw, just want to make sure nobody screws it up.
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asources, you more than likely have this(black Collet) in your air box lid. Like I said it is in the air box lid. Remove it and look in the hole on the bottom(where the air comes in to the lid). You'll see a rubber tube. You can remove it with a little bit of twisting and pulling. You'll get a lot more air to your engine after that. You may have to mess with your idle a little after(no big deal).
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Great got it ... but ... power change all the time ...
Where is this %/$%/$%/ mixture screw ... will have to play with it until i change de main jet ...
I have a people s 50 4T 2009 ... picture of it ??
Stefan
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Yes more air flow is more power all the time
Asources, don't get frustrated there is typically only two external screws that control the way the carb functions. One is the idle speed the other is the idle mixture. THATS IT. Im pretty sure 99% of the time the idle speed screw is larger than the mix screw. On my 2 stroke people the mix screw is on a slight incline(angle) and the idle screw is perpendicular. Yours is 4 stroke so it could be different.
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Tighten (do-up) the mixture screw, you let in less air and a leaner mixture will result.
Loosen (undo) the mixture screw, you let in more air and the mixture will become richer.
ianmac, you are correct. The quote above is somewhat incorrect. Clockwise is less air and counter clockwise is more air but is also incorrect because Less air equals rich. More air equals lean. It's just common sense people.
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Yes more air flow is more power all the time
Asources, don't get frustrated there is typically only two external screws that control the way the carb functions. One is the idle speed the other is the idle mixture. THATS IT. Im pretty sure 99% of the time the idle speed screw is larger than the mix screw. On my 2 stroke people the mix screw is on a slight incline(angle) and the idle screw is perpendicular. Yours is 4 stroke so it could be different.
Thanks ... but where are those screws ... i have to look from the side of the pipe pr the sire of the air box ...
Do you have a picture of it ?
Stefan
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Those are just IDLE mixture screws, they have nothing to do with the amount of air/fuel that is going into the carb when you are riding the throttle
You are going to need a new main jet.
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No pics sorry. Screws are on the air box side of of the bike. There is probably a rubber shroud around the carb. Usually there is a small hole in the shroud to access the idle speed screw.
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..old post i ran across...
..doesn't the mix screw adjust fuel delivery, not air during idle?
..if so, then clockwise would create a leaner fuel mix due to the restriction of fuel, not an increase in air..
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Ok, did a little research and found a good resource. Check out the link.
http://www.mypage.tsn.cc/rdd/TT/contents/CARB/dellorto/dellorto_3_4.html (http://www.mypage.tsn.cc/rdd/TT/contents/CARB/dellorto/dellorto_3_4.html)
Apparently it can work both ways, just depends on the carb. An air-adjusting screw is always usually upstream from the slide. A mix-adjusting screw is always usually downstream from the slide.
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..yeah, and that is a excellent link btw....
..judging from the location of the screw on these kymcos, i'd say it adjusts fuel delivery...
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Yep, my stock ppl carb and my dellorto both have adjustment screws downstream. So they would be fuel adjustment not air. :-[
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Here (http://translate.google.com/translate?js=y&prev=_t&hl=en&ie=UTF-8&layout=1&eotf=1&u=http%3A%2F%2Fscootergrisen.dk%2Fscooterhjemmeside%2Fkarburator.php&sl=da&tl=en) are an almost complete walkthrough on the Constant Velocity Karburator (refered to as CVK), which is on the 4-stroke engine. The link i have given you is translated by google translate from danish to english, so translation might not be flawless. ;D