Still no luck. It doesn't turn over. I checked for spark again and all 4 plugs are sparking. Just to confirm, the cylinders are 1-2-3-4 when you sit on the bike. Wires, blk/w is to 1 and Y/bu is to 4. Bl/w is to 2 and bu/y is to 3. I checked the fuel pump by removing the hose that leads to the carb and there is fuel pumping. The choke was on. I thought maybe I flooded the engine but I smelled all the plugs and no gasoline. I'm assuming it's the carb, and it maybe needs a thorough clean. This is a little more complicating than I thought but if you guys have any other ideas, let me know. Thanks.

 

Ok. So I took the carb off the engine and as soon as I flipped it upside to rest on the bench, gas started to poor out of the breather tubes. So, gas is getting into the carbs. I cleaned the jets with carb cleaner as best as I can again, but I'm concerned it might not be the problem.

 

So, you use the starter to crank the engine, you have a spark and fuel to the carbs but bike won't start. Is that correct?

 

That's correct. The chamber between the carb and engine is dry as bone too. How does the carb know when to spray fuel into the chambers?

 

Basic internal combustion...
a) Suck. The intake valve(s) open. The piston pulls the air/fuel mixture in as it drops in the bore.
b) Squeeze. The intake valve(s) close. The piston rises in the bore and compress the air/fuel mixture.
c) Bang. The sparkplug sets off an explosion and drives the piston down. This is called the power stroke.
d) Blow. The exhaust valve opens and allows the spent combustion gasses to exit.
Repeat a-d.
Air, fuel, and spark all have to be present.
It sounds like your carbs are not metering fuel into the engine. I would recommend cleaning and balancing them.

 

Carb does not know.
The engine is a big air pump. Air/fuel gets sucked into the engine as it rotates. Refer to Thrashers previous post. Could be valves need adjustment, compression is low or a blockage in the exhaust. I would check all of those things. If the valves are not closing all the way, then you will not have good compression therefore no fire. I recently had a 50cc 4 stroke scooter that was very hard to start. Did a valve adjustment and it started right up.
This is a very basic example, as our bikes are way more sophisticated, but the concept is the same. Do we assume that your bike's engine is in decent shape? Are you sure that you got the carbs reinstalled correctly? Maybe you have a big air leak between the carb and engine. Maybe a big rats nest in the exhaust pipe or a plugged air filter? Can you feel air pushing out of the exhaust when you crank the engine?
Carbs are usually the problem for everyone who has starting/performance issues. Keep checking things and posting the results.

 

Hi guys. Thanks for the quick and helpful responses. I guess it's not safe to assume anything on this bike except for what I can see. I'll try to do a compression test and balance the carbs first. I do feel and hear the air coming out of the exhaust. I tried cranking the engine without the air filter too. There should be a DIY for balancing carbs some where on this site in search I'm assuming. I'll keep you guys updated.

 

Are you cranking it from the battery only? Sometimes the battery just doesn't have quite enough power. Try using jumper cables from a car when you are trying to start it. Even the worst balanced carbs will fire once in a while.

You can try squirting a little gas in each cylinder and then see if it will fire.

Spark, fuel, compression and air. Something is missing.

KongBastard

 

Yes. I'm cranking it from 2 newly charged motorcycle batteries. I'm still thinking it's a fuel problem and that it is not getting into the cylinders to fire.