Changed main jet to 125 and still rich?
 

Guys,

2012 ASW Carbide 150cc.

I put a homemade intake on and changed the main jet from stock 111 to 125 as recommended from Tom at SYC. See pic of the intake. Couple of questions.

1. Took a heck of while to get it running, and once I did, I needed to turn the idle screw 2 full turns UP to get it somewhat steady without stalling. Is that normal?

2. Pulled the plug and I think the colour is OK when compared to the old one I had in there at stock. See pictures - the one on the left in the socket is the new plug with larger jet and intake. BUT, it smells rich. Any help here?

3. Although the test runs were on pavement, I didn't really notice any power increase. Might be different in the trails maybe?

4. The small 1/4" line that runs from the head to the stock air intake, what do you do with that. Just leave it hanging? Seems to be pushing air, not pulling.

The spark plug on the right is good the one in the socket is very rich. Put the stock jet back on and see if she behaves better. If you did nothing to ur exhause you may not need a bigger jet. Your home made intake looks good its not to long. If she still acts up check for air leak around the carb. Area. Spray cab cleaner around intake and manifold and see if idle changes, if it does you have a leak.

Thanks Eddie. I'm running stock exhaust. I'll check for leaks and drop down a jet size to see what happens. I tried the intake once with the stock jetting, and it bogged out under load. So, that's what I moved it up from 117 to 125 on SYC's recommendation. Maybe I need to go down a size?

I would put the stock jet back in and see if you can adjust the bog out with the pilot screw. You should not have needed to adjust it in that much with just the filter change, had you gutted the pipe, maybe so. Do you have jets in between the 117 and 125?

Not sure about the carb internals, but the howhitt I have you can adjust the needle setting as well, perhaps the stock jet and move the needle up a notch, if possible. Thats what I did, and it ran ok except I couldn't get the pilot figured out.

You said ur exhause is stock. If your gonna let more air in thru ur filter than you need to let air out thru exhause. By gutting or performance pipe but first try whats mentioned above.

ASW engines are unique. They come with a very light main (I thought they were 114's actually) and will typically gladly accept a 125 even in stock form as a means of protection from running lean and killing the engine. Now this assumes that you have the stock carb on it because it's their carbs that were unique. Something in the actual fuel porting within them. I've had others that came with a 108 main and if you put a 111 in it, it chokes all over the place.

One of our threads from long ago, likely in the tech section (I'll see if I can find it) shows some controlled changes to our engine and then measured results, both on the track as well as with wideband 02 readings. The best bang for the buck was an aftermarket exhaust, a UNI intake, and some clutching mods. Remember also that you are dealing with a 150cc engine. Want to really feel a difference seat of the pants? Put a 250 in it.

I would try the 117 jet. That worked best in our blue buggy when going from a 114 main with a uni filter ported head and stock pipe. I used the vent line from the valve cover to the oil separator box on the old stock air box and put a vacuum fitting into the rubber intake boot. I didn't like the idea of crank case fumes venting from the line and thought that by putting it in the intake it might decrease some of the positive crank case fumes.

On my Carbide, I went from a 108 to a 135 and runs fine now. Did the normal, UNI, HH exhaust, coil, sliders and yellow spring and can tell a difference but nothing to jump up and down about.

Guys, thinking I need to adjust my air / fuel mixture screw also. Little bit of hesitation or flat spot at 1/4 throttle.

1. Does the A/F screw change change the amount of air or amount of fuel?

2. By re-jetting the main up to 125, do I need to turn the screw in or out?

Yes; but a/f screw should be ur last alternative imo.if the problem starts at 1/4 throttle then it may need needle adhustment. If you decide to mess with the a/f screw first close it bbut make sure you count the turns when closing it. For any reason ur adjustment fails you can always put it back the way it came from stock a heads up...

Eddie, m

Thanks for the info. I'll be sure to mark and count for stock settings.

First off, eddie is right that you should turn the screw in until lightly seated (while counting the number of turns it takes to get there). If your adjustments are unsatisfactory, you can always go back to the original setting.

1. The air/fuel screw lets an already mixed amount of fuel and air into the carburetor to be mixed with the fuel coming in through the pilot jet.

2. Since the air/fuel screw mainly works with the pilot jet (idle to 1/4 throttle), the main jet will have a very minimal effect on its setting.

In my experience, the air/fuel screw can tell you how close your pilot jet is. To set your air/fuel screw: warm up the engine to operating temperature, turn the air screw in or out until you reach the highest idle (or if there is somewhere to hook up a vacuum gauge, the highest vacuum). Once you reach the highest idle, that is your optimum setting. Then turn the screw back in until lightly seated while counting the number of turns. The screw should be somewhere between 1 and 2 turns out from lightly seated. If it is less than 1 turn, the pilot jet is too big. If it is more than 2 turns the pilot jet is too small. Once you reach the highest idle, or vacuum, adjust the idle back to standard with the idle adjustment screw.

Guys,

Finally did a proper full throttle run & spark plug check. Looks pretty good I think. What helped A LOT was I plugged a 1/4" line that ran from the old airbox directly to the intake between the head and carb! Once I plugged it the RPM's shot up. As soon as I adjusted the idle back down, it was purring wonderfully

FYI, i adjusted the A/F screw about 1/16th out and that go rid of the slight hesitation also.

Here's some pictures of the plug and the line I sealed. I'll have to seal it better than tuck tape, but it did the trick for the time being.

The vacuum leak explains alot of the issues were having, and the plug looks good to me, a nice chocolate color is what you look for. Now go drive that thing like you stole it!:hooaray:

Thumbs up to you danp. :)

Thanks for all the help guys. Taking my oldest out tomorrow. He freaking loves it. Then again at 4 years old anything with a motor is awesome. ;)

Next, I need to check my sliders. Have a feeling one or two aren't seated right because it seems to jump up to full rpm quickly but the speed seems like it needs to catch up.

Hey Danp, I am running lean with stock main jet (108). The hose I have left over (after removing airbox) comes from the engine head ( wear valves are). I think that is just a vent or breather.
I line you taped up comes from the manifold. mines is still on. There are two lines coming from gas tank fuel line which feeds in carb. and then that line below it which connects to manifold. I think it creates the vacuum to pull fuel to carb, maybe??

mine
 

here is mine.
Sideways of course

I see. It looks like you have a fuel shut off. And didn't need that y connector.

I had two lines. One breather and one line the went directly into the intake after the carb. Once I plugged that the rpms shot up because it was getting a little less air.