Finished top end build, won't start.

[CalvinB]

bought a BBK and Big carb kit from Taz/ Chop (awesome guy to deal with). tore the engine down and just got it back together last night. Long Story short, I have strong spark, I have fuel to the carb, and the compression is strong. If I kick the motor a few times, I will get a loud puff out of the exhaust, like it wants to fire, but it never does. I tried for 3 hours off and on last night, with just about every combination of carb adjustments, and now my leg is tired, any pointers? My buddy got a Yamaha Razz this week and I want to ride with him this weekend!

TLDR: read the manual cover to cover, used search function, BBK, 21mm carb, have fuel to the carb, strong spark, 125lbs compression, puff but no start

[CalvinB]

Thanks, the carb is together right and the slide moves freely. I didn't think to prime the carb, I'm used to VW's and I just keep cranking and use copious amounts of starter fluid and it usually goes pretty quick.

[Dr_Craw]

another option, put a small amount of premix fuel into the chamber using the spark plug hole

[johnny248]

Might sound like a dumb question, but is the bowl actually dull of fuel? Just wondering if there was enough vacuum applied to the petcock to fill the carb?

[CalvinB]

the bowl is full of fuel, I bought clear fuel lines and I can see that they have fuel in them.

Ive tried priming the carb, and I don't know what else to do. I've given it 100+ kicks and no signs of life so far today. No puffs, no nothin.

[johnny248]

Ok, lets start from the top.

The engine ran, then you installed a BBK, manifold, and carb?

You fuel/air, compression, and timing to run.

You said you have good spark, there is fuel in the carb, and 125psi. Is fuel getting into the intake, reeds, and engine? Is there fuwl in the cylinder? Plug wet?

Is would make sure fuel is flowing through the carb into the intake. It should be wet in there. If you have fuel and have kicked it that much, the plug should be wet if the engine is creating crank case vacuum and the fuwl is getting through the reeds.

Is it possible your new piston is facing the wrong direction? I don't know what kit you have, but the piston should have some sort of intake cutout/port that might cause an issue if it is facing the exhaust side.

[CalvinB]

The piston is facing the right way, the plug is wet. I just let it sit for a bit and kicked it and about a foot of flame shot out the pipe but it didnt turn over.

when i bought it 2 weeks ago it ran like a top, i put about 150 miles on it in a long weekend and then it sat for a week before I rebuilt it, but thats about it. the old top end looked pristine and the carb was spotless

[johnny248]

That is good I guess. The plug is wet, fuel is getting into the cylinder. Not to question your info, but you are positive that the compression is 125psi?

From there it would lead me to believe that there is either a problem with the ignition system, or that the carb is so our of whack or not working right so that it is flooding it with way too much fuel.

If you pull the plug, and ground it to the head while kicking it over and over, is it sparking in every rotation? Just asking because I have seen these things have an issue where the CDI has gone bad from poor grounding, or no grounding, or who knows actually, but it would actually cause an issue where it will spark once on the initial kick, but then it wont spark after that. For instance , kick-spark, kick kick kick, no spark. Almost as if it won't recharge for the next ignition.

Does the electric starter work? Easy to just hold the plug against the head and hold down the starter button to observe.

If the ignition is firing like it should, I would maybe try bolting the old carb and manifold back to see what it does.

[patthesoundguy]

A bad ground in the harness can get issues like that. But my first thought is replace the plug. I have had bad plugs do that. Also double check the jets carb make sure they aren't loose and the float level as well.

[CalvinB]

the lady said the starter was burnt out and the had tried a couple batteries with it, so i yanked it and the battery. I stuck a drill on the starter pinion and im using that now because my legs are tired. it sparks right at the timing mark every time it goes around.

at this point, with the flame spitting and all im sure it is getting way too much fuel. i just dont know how to remedy that. i cant put the stock carb back on because its a very very different size anf the stock manifold reed block broke getting it off.

[johnny248]

Was that a new carb? Maybe try closing the pilot completely and seeing if you can get it to start? What size jets are in it?

Also, just a thought. Getting that throttle cable correct with the am carb can be tricky sometimes. I'd the handle bars turn it can throw it off also. Is it possible that the carb slidw is not closed completely whole trying to start it?

[patthesoundguy]

Yes Johnny is right check those jets and that's a great call on the idle air screw. You shouldn't have to kick that thing over that your leg wants to fall off. If everything is kinda close it should start pretty easy. May the force be with you, I know we are with you on this

[johnny248]

Yeah, that's what's throwing me off. You can usually get these things to start if the carb is anywhere even close to being in the ball park of being right.

[CalvinB]

i screwed with it for 45 minutes this morning and nothing. Then I raged for a while. My wife came out to help because my legs were getting tired. She kicks it 3 times and vroom. I let it die, she kicks it one more time and vroom.

I have no idea what was wrong still, but I knew I married that woman for a reason.

Thank you all for your help, I have no idea which one of you was right, as I did all of the above, but I'm sure it was one of those things.

[Just Joel]

Never mind... Congrats