I have spark, fuel, and compression. But it won't start.

[gasbiketommy]

i just assembled my 66cc, I had it running, but it felt a bit held back and it conked out. I have spark, I have compression, and I have fuel, but it will not fire back up. I checked the magneto it is set properly,and I cut and made clean connections for my CDI. What is wrong, please help. I'll be going down hill, I'll let the clutch out the compression feels good, I'll give it gas but it won't fire and when I throttle down it won't start or rev.

 

[Frankenstein]

i just assembled my 66cc, I had it running, but it felt a bit held back and it conked out. I have spark, I have compression, and I have fuel, but it will not fire back up. I checked the magneto it is set properly,and I cut and made clean connections for my CDI. What is wrong, please help. I'll be going down hill, I'll let the clutch out the compression feels good, I'll give it gas but it won't fire and when I throttle down it won't start or rev.

When you say you have compression you know this because the head bolts are torqued down properly and you checked the compression or you have it like you can simply feel something that's resisting the rear wheel?

How about an air leak, a big enough leak on the carb or intake will make starting very difficult since it's so lean you can't get a burn going in the cold motor.

I would torque the head bolts to 15f/p with a real torque wrench, and check the snugness of the intake bolts, and check the carb is completely seated on the intake.

Out of curiosity does is make a kind of loud snap or pop sound while trying to start?

Check the spark plug too, you'd be surprised sometimes it's just that it wasn't installed tight enough, and it gets loose and leaks air into the head and fast/air out.

 

[crassius]

mag upside down, wires backwards

go thru the step-by-step on no start motors

 

[Frankenstein]

mag upside down, wires backwards

go thru the step-by-step on no start motors

He had it running before it stopped running, therefore everything would appear to be fine in the electrical department, only way it's the mag is if the Woodruff key is shorn or was never installed in the first place, but he did say he checked it so...

This sudden failure of a new engine kit sounds more like a sudden air leak/head warp.

 

[crassius]

said he worked on wires and checked mag - get a lot of repairs in because the stator was put on upside down

 

[DuctTapedGoat]

White wire, choke, head gasket, fuel filter, seals, plug chop

Check it all

 

[gasbiketommy]

I have an update, I took it to the top of a small hill, while going down it was popping, the muffler every few seconds was popping.

 

[DuctTapedGoat]

I have an update, I took it to the top of a small hill, while going down it was popping, the muffler every few seconds was popping.

White wire, choke, head gasket, fuel filter, seals, plug chop.

Quit dragging it up and down hills and do maintenance. I already mentioned common solutions to focus on.

 

[gasbiketommy]

I have the white wire clipped, I checked all the seals, I have a new champion plug and it's on tight, I am using an aluminum racing fuel filter, how could I tell if the head gasket is leaking, it looked uncorrupted when I checked it. Like I said before, I went through all of the electronics from properly setting the magneto to making fresh connections to the CDI. I have tried it with 2 different heads. I put lock tight on all my bolts and I ordered the HD bolt set. Double checked the carb, and all carb gaskets. Maybe it is the head gasket, even though its new could it have warped? Please don't think I was just trying to go down hill to force it to run, this morning i completely disassembled and reassembled the carb so I to it down the hill to be certain that I gave it enough revolutions to get the fuel where it needed to be.

 

[DuctTapedGoat]

There's been times I check the head gasket and it looks fine when it's really not.

I always got those symptoms from incorrect ground or I accidentally have the choke on. More often than not.

Oh, carb float is also on the list. I had one sink years ago.