have stock carb, what jets to order?

[chaz35]

good info, still waiting for my jets to come in...  My CDI has green wires connected with bullet connector, 03 S9 LC.  Cheers

[BettinANDlosing]

Two green wires disconnect to derestrict!

[chaz35]

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

[zombie]

You're on the right path. Have you also re-adjusted your idle mix screw? That will make a world of difference.

[chaz35]

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.

[zombie]

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.

[chaz35]

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

[zombie]

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...

[tortoise]

cleaning carb . . . soaked it in some brake cleaner for several days, took that long to get it clean

Alternative jet cleaning strategy.

One vibration configuration to clean alloy castings.

[zombie]

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.

[chaz35]

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

[zombie]

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...

[chaz35]

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

[zombie]

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?

[chaz35]

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