Replaced Carb and Exhaust now won't start

[saminaustintx]

Hello all,

I have found this site extremely helpful through the naked conversion of my sunny 150cc. The scooter was running perfectly fine and I decided to upgrade to a new 24mm carb and a 130 main jet, I also cut off the old muffler and put a new slip-on on. I finished the install and went to start it and it will crank but not fire. I tried for about a minute and a half with not even puttering, checked for spark and it was fine. Pulled the fuel line off at the bottom side of the filter and it flowed without a problem. Should I just tr some starting fluid and see if it will kick over? Any advice is appricatied, its a 2012 with about 2k miles. Valves also adjusted recently, oil change, etc.

[edfr]

Did you check for spark on the motor? Also the new carb, turn the fuel ratio screw clockwise until it stops and turn it out 2 1/2 turns, open the CARB drain hose and stick it in a container and crank the motor over fuel should come out as you crank if it does the carb is getting fuel.

Also you need to make sure that the BUTTERFLY is not completely closed some of the carbs come with the IDLE SPEED SCREW out and not adjusted to have the BUTTERFLY a hair open. If closed it will not start. So when you attempt to start it twist the throttle just a little and see if it attempts to fire. If so then give the IDLE SPEED SCREW 1/16 or so clockwise turn.

I also have to tell you the 130 main jet is WAY TO BIG, the 24mm carbs come with a #35 Pilot and anywhere from a 103-105 main jet. If you add a free flow filter and free flow muffler you need no bigger than a 115 main jet and that may be to big.
Lefty

[saminaustintx]

Thanks for the input.. i have indeed checked for spark against the valve cover. Throttle twists easy so don't think its that. When I get off work I'll try to open the drain valve. Idle speed screw is good, if it's not getting fuel (my assumption as no puttering even cranking at full throttle) then what would be the next trouble shooting step? As said before it was running just fine which is why this is really puzzling. Thanks again!

[edfr]

Well they do need some backpressure is the muffler you put on just a straight through pipe or what.
The throttle twisting easy is not what I meant. The Throttle when you twist it OPENS the BUTTERFLY that is all it does.

If your getting spark and all you did is put on some kind of muffler. Then I would suspect the CARB when you changed the jet. Take the VACUUM line from the INTAKE MANIFOLD the other end of it and get a CUP paper cup or plastic not foam, put a TEASPOON of gas HOLD the VACUUM Line up and squeeze the cup to make a point and pour the little bit of gas STRAIGHT into the motor hook the hose back up and give it a shot. IT SHOULD Attempt to start and fire it may start and die. BUT then we will know no gas is being sucked into the intake from the carb.

Is that all you did or did you do other stuff?
Lefty

[skuttadawg]

This is why it is best to only do one thing at a time in case it does not work . I would look for a leak around the intake and double check the vacuum lines and on the bottom of the carb turn the drain screw to see if anything flows out of the bowl .

Try reinstalling the old carb and see if it will start

[saminaustintx]

Just went home for my break and did a quick check. Didn't have a hose hooked up off valve head so did that, but no difference. The muffler is a flow through design, but I ran it on open pipe for a short run last week and it did fine. Going to try the drain screw later and see whats up, I suspect that as there shouldn't be any leaks as everything is relatively new.

Carb with uni filter and muffler were only mods done.

How exactly do I check the butterfly? Just see if it moves when I twist the throttle?

[skuttadawg]

You Tube has lots of self help and how to scooter videos

[wilds]

Check the valves again...

[edfr]

So you ran it with no muffler last week only with the header pipe on is that what you mean?

If you ran it hard it could have already burned your exhaust valve, check your compression.
Hold the Trottle wide open and crank it when you check the compression.

The valve hose is just a VENT for the motor that will not cause anything. But since you found one hose disconnected maybe you connected the fuel line to the wrong place or Vacuum hose to the wrong place. Can you take pictures of the carb area and hoses.
Lefty

[saminaustintx]

Feb 15, 2013 0:52:56 GMT -5 edfr said:

So you ran it with no muffler last week only with the header pipe on is that what you mean?

If you ran it hard it could have already burned your exhaust valve, check your compression.
Hold the Trottle wide open and crank it when you check the compression.

The valve hose is just a VENT for the motor that will not cause anything. But since you found one hose disconnected maybe you connected the fuel line to the wrong place or Vacuum hose to the wrong place. Can you take pictures of the carb area and hoses.
Lefty

Just a quick ride around the block until i realized how loud it was.

[edfr]

I would first check your compression and let us know what the reading is. It may have burned your valve already.
Lefty

[saminaustintx]

Intake elbow was loose...tightened it up and runs awesome. Thanks everyone.