KymcoForum.com
Scooters - 50cc => Super 9 => Topic started by: chaz35 on November 15, 2014, 11:35:06 PM
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Got 2003 S9 LC to run and drove around the neighborhood some. Runs OK, but appears lean, very slow to warm up, boggs at lower rpms. When it comes up on the pipe it takes off, but I hesitate to push it until I get a chance to test it out more. Air temp was in the 40's fahrenheit all day, so fairly cold.
Service manual says carb has #92/ #78 main jet (unlimited/ limited speed) and #35 slow jet. When I took carb apart to clean, jets didn't have any markings that I could recognize, so I don't know what I have. Also, the CDI green wire is connected, so I think it's still restricted. Scooter has nice expansion chamber, I think came stock with it. I think CVT has been opened, but didn't seem to slip that much, but really don't know if modified. I plan to keep stock airbox, because of nose concerns. I know from kart racing, the loudest engine sounds come from the carb, not the exhaust.
I did some research, I think I have Keihin PB16 carb and found I can order some jets from jetsrus, thanks to some postings on this site. Any recommendations on jets to order, main and slow? Assuming I have #78 main jet and #35 slow jet. Thanks
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I wouldn't mind knowing as well. Probably won't get around to upgrading the carb until spring.
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very slow to warm up, boggs at lower rpms . . . temp was in the 40's
Cold fuel related discussion (http://www.thumpertalk.com/topic/621041-2-strokes-loaded-up/).
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I don't know what to do, so ordering following: 90, 92, 95, 98 main and 38 slow jets.
My logic is, I think carb has 78 main jet/ 35 slow jet right now, because I think the cdi is still restricted (green wires are connected) and service manual says carb jets are 78 main/ 35 slow if limited. Unlimited should be 92 main jet/ 35 slow jet.
I saw post People 50 section where went from 70's main/ 35 slow to 90 main/ 38 slow and was easier to start and ran a lot better.
Once I figure out what my carb jets are I can go from there and order more jets if I needed. Cheers
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Ah. When all else fails check the manual! I think I'll go for the ninety two.
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I know slow jets not supposed to effect wot, but my experience, if you go up on the slow jet (idle jet), it will richen top end. So, I ordered a 90 main, because I also plan to go to a 38 slow jet. I am thinking it will run like a champ when I get the right jets in it. We will see. Cheers
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Definitely keep me posted. I would like to know the outcome so I can copy you. That's if I don't get to doing the bbk first
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By BBK do you mean aftermarket airfilter? I may do that at some point, but for now just want to get stock airbox to run right. Today it was warmer, and started up easy and ran a lot better, but I think still lean. I will post update as soon as jets come in and I can try them. Ciao
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Big bore kit. Make it seventy CC
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I know slow jets not supposed to effect wot, but my experience, if you go up on the slow jet (idle jet), it will richen top end. So, I ordered a 90 main, because I also plan to go to a 38 slow jet. I am thinking it will run like a champ when I get the right jets in it. We will see. Cheers
Slow jet and mixture screws both effect ALL throttle positions. Drastically at less than 1/4 and less the higher the throttle opening, but it does have an effect at WOT. have a peek at this: http://www.mopedarmy.com/mediawiki/images/thumb/7/72/PHBGGraph.png/286px-PHBGGraph.png (http://www.mopedarmy.com/mediawiki/images/thumb/7/72/PHBGGraph.png/286px-PHBGGraph.png)
It's for the Dellorto PHBG but the same principals apply to all pull slide carbs. Just look at that chart and picture it when your riding your scooter, if you can try to find the "transfer" where the jets change from idle, slide, needle, and main then you will have a much better chance of trying to successfully tune your carb. Depending on your bike if you can cover the air intake with your hand to determine if its lean, if it is your bike will pick up in rpm if its rich it'll start to choke out and slow down.
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Hey guys... I just posted earlier that the colder the ambient temp is, the denser the air mass. This alone creates a lean running condition on all smaller carbed engines.
Back on topic both of you can't really guess at what jet is correct. You have to go thru the trial/error process.
First things first. The ideal position for your idle MIX screw is 2.5 turns out. This is a fuel metering screw so turning clockwise is leaner, and counter is richer. Depending on where your bike idles/snaps the throttle best will tell you if you need a larger pilot jet. If it responds better at three turns go bigger.
That jet does carry over into the main circuit when running on the main so it will affect the rest of the jetting.
I would buy a set of jets from 86/88/90/92/94, and a set of pilots from 38/40/42. At a few bucks each they will come in handy.
Get 3-4 new spark plugs as well.
Determine the pilot as suggested, and install the largest main. IF the bike runs but bogs some ,try compensating w/ the idle screw. Down to 1 turn out is acceptable. From there it is just a matter of finding which two jets work best together, and nearest the 2.5 turn setting.
The extra plugs are to verify the overall mix ratio by doing a few "Chops". Ride at WOT for about a mile, and hit the kill switch/or key to shut down. Pull out the plug, and look deep inside the insulator for a coffee colored ring. A FULL circle is what you want. NOT black or tan but a rich coffee color.
Black means the main is too rich/tan too lean.
You should also try to do this at an avg temp for your area. Set it correctly at 40* F, and the bike will be rich in warmer temp.
Hope a bit of this helps.
The cdi I forget what derestricts them... I think it was combining the two green wires but that might be the ZX. There is info on that cdi here on the forum. You might have to dig for it.
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Wires unplugged derestricts the rev limit.
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Is that the one w/ the bullett connector in the green/yellow wire?
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I don't think so, I'm thinking of the ones that are in like the early people 50 and sing it has two solid green wires looped into the cdi and connected with a bullet. I'm not 100% it's the same on his super 9 but knowing Taiwan it prolly is.
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Well I know the solid green is ground. The bike may not fire w/out it but no biggie... Just re-connect it.
I seem to remember the S9 had a simple bullett connection right at the cdi that you just pulled apart. That was one model, either AC or LC I forgot. The other you have to buy an adapter/cdi to de-restrict.
If the bike has no obvious pull apart connector.... Racing Planet has the proper kit for the bike you have, and I think they are around 50 bucks now. They used to be about 100 more.
Either way as I remember the pipe hits at 7.5k/peaks at 8.k. The power stops at 9k. but you should be seeing 60mph by then if not a bit more.
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good info, still waiting for my jets to come in... My CDI has green wires connected with bullet connector, 03 S9 LC. Cheers
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Two green wires disconnect to derestrict!
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Got jets and installed 38 slow, 90 main. Was hard to start, because it flooded engine. Took me awhile to realize engine was flooded, but once I did, I got it started (start with throttle open).
Not there yet, but definitely runs better. I am going to run it a little more and separate the CDI green wire before I change the jets again. Then, will probably go back to 35 slow and try 95 main.
I was able to determine I had 35 slow 82 main jets in original carb. I got as used scooter, so maybe changed from factory, but that's the way I got it.
Also, I bought after market jets, which are OK, but pretty hard to read marking. Next order, I will probably pay a little more and get OEM Keihin jets. Ciao
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You're on the right path. Have you also re-adjusted your idle mix screw? That will make a world of difference.
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Yes, have been playing with air screw adjustment, doesn't appear to do much with my carb. Service manual says if 1/2 turn on air screw doesn't effect idle, may have some other issue? So, I guess my carb is not working right in that regard.
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That adjustment should kill the engine if it is too far out of adjustment. If it has no effect the circuit is clogged.
Before messing w/ any more jets you have to repair that or nothing will ever work out right.
I use Chem Dip for stubborn carbs. Its about 40 bucks for a gallon can but IMHO it's worth every penny.
Tear the carb COMPLETELY down, and soak it directly in the gallon can (it's like a paint can) for 48 hours. Use rubber gloves, and DON"T open that stuff indoors. It stinks for months, and the smell never fully goes away.
Clean it all under running water (outside), and follow that up w/ a can of spray carb cleaner to blow out all the ports.
It will be like a brand new carb for 1/2 the price.
The bonus is the chem dip lasts for years, and you can do any number of carbs for other people to re-coup the cost.I charge 20 bucks to dip a lawnmower type carb, and all I do is soak it, and hand them back the parts. If I didn't trouble shoot the engine I will NEVER touch any part other than cleaning it up.
In the spring I get 3-4 carbs a week to soak.
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Good tip on cleaning carb.
I didn't read your post before I changed out slow jet back to 35 and changed main jet to largest one I have 95. Had a little trouble with air leak where airbox mounts to carb. Runs pretty good now, doesn't lay down when I give it some gas, still maybe needs larger main jet.
The 38 slow jet I got was aftermarket and maybe defective. Seemed to be as lean or leaner than 35 slow jet, so I put the 35 slow jet back in. Still haven't tested starting with cold engine. Still have top of airbox disconnected so I can choke it if engine tries to die before it has warmed up. If still doesn't start and stay running without having to choke, I will probably order another 38 slow jet, but this time Keihin OEM, not aftermarket.
Carb is responding to idle speed and air screw adjustments now. I don't think it's dirty, runs too well for that, plus I already cleaned it really well, soaked it in some brake cleaner for several days, took that long to get it clean. Cheers
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That all sound good except, if you leave the air box out.
That HAS to be installed just as if the bike were 100%. If you have to choke it by hand then there is an issue that has not been resolved.
Take out the auto choke, and turn on the key. Within 2-3 minutes the choke should move about 4mm out from the cold position. If it doesn't then a new one is about 5 bucks on FleaBay. If it does then perhaps the choke circuit is clogged.
Something smaller than a grain of sand will (in some cases) cost you your bike. Lot's of people sell then because of a piece of debris the eye cannot see.
You're on the right track for sure... Just keep hitting it, and eventually it will listen. (I learned that by being a dad) LOL just a little...
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cleaning carb . . . soaked it in some brake cleaner for several days, took that long to get it clean
Alternative jet cleaning strategy (http://www.urbanscootin.com/forum/viewtopic.php?p=129434#p129434).
One vibration configuration (https://www.youtube.com/watch?v=R1DtY2VwSyY) to clean alloy castings.
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Ono issue w/ the ultra sound guy... All the parts have to be taken down. The rubber seals are a buffer. PLUS the chemicals are NO GOOD for plastic/rubber.
Otherwise it is a GREAT idea. The same result can be achieved w/ a stainless stock pot, and a piezo tweeter. The higher the frequeccy the faster the action.
Use METAL clamps to attach a tweeter to any stock pot, and leave the stereo on over night. the high frequency will clean the parts using only water.
Once again I am simplifying... but the idea is there. Take a baking dis (stainless), add 10 piezo's, and in an hour any metal comes out like new.
That's a GREAT post Tortoise. The more ideas the better.
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My airbox is in, just the tube from the opening attached to the inside of the left body panel is disconnected. It doesn't run any different than when completely connected, just allows me to easily choke the carb.
Good test on the autochoke. I think it's working OK, because engine settles down after it runs awhile, like the choke is off.
Yes, it's fun to see improvements. I really enjoyed minibikes and I am an expert on Honda G100 clone engine, can make them really sing. Hope to be able to do the same with scooters.
Cheers
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Now I follow you on the air box deal... All is well again in Kansas.
That also helps make sense of your suspect defective jet.
Something that really helps verify /modify jets is a 4 dollar set of Torch tip cleaners. It's something I have done for years, and works a charm. tey are perfect for cleaning out jets, as well as opening them up to larger sizes. If you go too big you can always re fill the hole w/ solder, and begin again.
I use this method to dial in the jets, and later on replace them w/ appropriate sizes. I did this for years as I said. Now I have dozens of jets on hand from continuous modifications.
Here's a look...
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I looked at buying a set of torch tip cleaners, but couldn't figure out what size to get. I have a set of micro drills I used to drill jets for 4cycle engines. I was thinking about using to drill out 2 extra main jets I now have. I plan to use the micro drills to measure Keihin main jets, see if my drill set is in the right size range, then may drill out jets to next larger size.
I started scooter this morning, didn't pass keep running test. Real easy to start, but still needs a little choke to keep it running for the 1st few seconds, then it's fine. Oh well, will keep trying until it starts right up and keeps running like it's supposed to.
Before I changed main jet from 82 to 95, used to start immediately 1st try then die, especially if you gave it a little gas. With larger main jet, I will try giving it a little gas when 1st start it, see if that will keep it running. Ciao
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Most of these scooters will die if you open the throttle while cold. Just the first few seconds really.
If yours starts right up but dies as it warms then the choke is not passing enough fuel OR you might have a small vacuum leak that is allowing extra air into the cylinder. MOST of the time the Crank seals leak but after that it's the Intake/manifold/cylinder base.
Do you have access to a leak down tester? Perhaps a hand type vacuum pump?
Where are you located?
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It used to start right up and die pretty quickly or die immediately, if I gave it a little gas. If I choked the airbox it was OK.
I think I may have it tuned just right now. Main jet is pretty fat and I can give it gas at initial start and it revs, doesn't die. So I changed my start routine, and I tried giving it a little gas at start and worked great. Being positive, I connected the airbox tube, so it's all hooked up now. No more choking? We will see. I am guessing gas mileage will be lousy, but I am OK with that.
I am hoping to have it registered and legal next week so I can ride it out of the neighborhood, see what it can do. Guy I bought it from didn't have title, has been a fair amount of paperwork to get a new title. Cheers
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keep us updated...
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Yes, please do. I've been following this thread. I have the 35/82 setup right now and am waiting for my new jets in the mail. I'm eager to know what effect it will have for my top end.
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I am still having some issues with it starting up and continuing to run. I ordered some Sea Foam and plan to add some to gas tank, hopefully will help. I am pretty sure it is the auto petcock being cranky, and think it will get better as I ride it more. I recently unplugged the CDI green wire and it doesn't cut out at approx 40mph anymore. I took it out tonight and think I hit pretty close to 50mph. It runs nice, but gas mileage is not so good lol's.
I also ordered some Amsoil Interceptor oil. Did some research and seemed to be the oil to get.
I rode a stock 05 Piaggio Typhoon 50cc 2T tonight, maybe buying another scooter. Nice scooter, but my S9 is a rocket compared to this one. I wonder how much $'s would take to get it run like my S9? Cheers
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You're getting it by yourself. That's a great thing...
2 stroke scooters are a royal pain in the azz.
The funny thing (for me) is you have one of the bikes that there are no real after-market parts for. The flip side is it runs better than the ones that there are parts for.
To get a Pig to compare you have to put about three grand into one. The S9 will beat them at every corner (OEM), and still be worth as much at trade in, and more as a re-sale.
Keep the 9, and at least have a "Buffalo Nickel" at home. They don't make them anymore. For 50cc's they were too fast for the American/Imperialist pigs!(I'm honorary non whatever)
I mean they are good scoots.
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I've tried to upjet. Tossed in a 90. As I was nearing top speed it straight up died. Changed down to 85. Then it started the good ol die while idling fuss again. Sigh. Only after it runs wide open. Hell, I should've left the vacuum leak I had from the reed cage gasket. Didn't die then...
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Stay w/ the 85 main, and go up on the pilot jet. There is some "bleed" from the main at idle so the bigger main (90) was allowing more fuel for idle.
I have a Vacuum leak tester if you want to borrow it. I can send it out to you, and then you can forward it to Bet & loosin for me.
It's impossible to tune if there is a leak somewhere.
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I changed back to the 82 today. I'll probably try the 85 after I get new pilots, and have a good day to plug chop. I also set the float a bit higher. I almost thought it was solved, ran it to the store, making sure to stop completely at signs, etc, to let it get to the dying point and it seemed fine, even with my lowered rpm I set to after reading some other threads. but I gave it a little longer of a wide open run, just joy riding and it tried to quit on me pulling in to a lot. A few throttle bumps until it leveled out kept it running. Then driving it home it seemed fine, pulled into the car port and let it run. Stayed fine... I need to order a set of pilots, I only ordered mains.
I also readjusted my air filter a bit, opened up the port under the body a bit more, just for peace of mind, and made sure everything was sitting well.
It's been so cold that even if I were able to tune properly it would be in vain after winter. But I wouldn't mind testing it. I guess if you want to message me on details to work this out that would be great.