No vacuum?

[GoodDerf]

First thank you to everyone who has helped me so far, hopefully this is the last question I have before I get my spree running again .

At this point I have assembled everything after cleaning it, along with putting on new seals, grease and spark plug. However now I cannot get the engine to pull a vacuum on the line. If I suck on the vacuum line fuel comes out easily, but when I hook it up to the carb, fuel does not flow.

I have tried other means of temporarily starting the engine such as carb cleaner and priming the carb or cylinder with fuel to no avail. Before it broke down my spree could get up to 35 or a little above on flat road according to the speedometer, so I have assumed so far the problem isn't compression.

So any ideas at all on what I should do next, because at this point I really don't want to take this in to get it fixed. I personally cannot accept defeat this easily.

[Wheelman-111]

Greetings:

If it's fully assembled, pull vac on the petcock line and count to 20. The carb bowl should prefill. The running scooter may have enough vacuum to maintain its own flow, but it can take time cranking on the starter if the bowl's empty when you begin.

If it stalls out in 30 seconds or so, a common cause of low vacuum is a reedvalve seal issue. Simple vacuum leaks, like around the reedblock gasket or the carb insulator can decrease vacuum too.

Hopefully it's not a case of very low cylinder compression (bad) or crank seals leaking. (very bad, at least in terms of the work involved to disassemble and address.) None of this is insurmountable if you get to know these endearing little beasts and think about what's going on in there.

[GoodDerf]

Maybe I did not prefill the bowl enough.

I have searched the site, and have not been able to find step by step how to do a compression test without the motor running. Honestly hook a compression gauge to the cylinder means nothing to me.

Onto the next one how would I diagnose bad crank seals?

[Wheelman-111]

Greetings:

Google Harbor Freight tools. Search "compression tester" on that website. Find the one for $9.98.

Remove your spark plug. Screw the end of that tool into the hole. Open throttle. Crank until the needle rises no more. Read. Should be well-north of 100.

[GoodDerf]

That is what a compression test is? . Had I known that I would have done that a long time ago. I think I have a tester actually lying around in one of these tool boxes.

*Update*
So I didn't have one, but I picked one up from autozone as a loaner that was brand new with the plastic still on it. So I took off my spark plug, screwed in the hose attached the gauge and pressed the little yellow button. But nothing happened, not even the smallest twitch of a hint that the needle wanted to move.

I put my hand by the muffler because I could audibly hear the air coming out of it and confirmed it by feeling the air coming out. So I am guessing that I did something wrong in testing. Right now I don't have the carb on, but to my knowledge that shouldn't affect the test. Any ideas?

[Bear45-70]

Me thinks you need to pull the head to see if the piston, rings and cylinder are OK? I doubt it from your no PSI compression test.

[GoodDerf]

I have pulled the head and looked at the piston in the cylinder, it looked OK from above. I did put some ceran wrap rubber-banded around the cylinder to make sure there was some air being forced out. I just find it hard to believe that an engine could be running seemingly fine and then it just dies and has no PSI yet it is still pushing air out of the exhaust. I am not saying it is in great condition but a reading of 0 is what is making me weary that the test is correct. I mean shouldn't there be SOME psi when there is air being forced out of the exhaust?

[Bear45-70]

Does the compression tester needle even bounce off of zero when cranking the engine with the throttle full open? If it doesn't I would suspect a bad tester.

[GoodDerf]

There is no bounce, nothing, not even a hint at it thinking of moving. I don't have the carb on at this moment, and I didn't try it with the throttle open because I didn't think about it honestly. If either of those would make a difference then it was probably my fault. Though I am not sure about the tester I mean I took it would of the packaging meaning it is brand spanking new and hooked it up to my cylinder, always possible you never know.

[Bear45-70]

No carb is the same as WOT. But if the needle doesn't bounce at all then that is pretty amazing unless the tester is bad. There is a valve in the end of the tester that screws into the head. Try it on a different engine.

[GoodDerf]

I will definitely try it on a different engine tomorrow to make sure,this is the tester that I have in my possession.

[Wheelman-111]

Greetings:

I agree that a compression of "0" is very unlikely. Plastic shred covering the tester's inlet? Bad connection somewhere? Gauge "Made in China?!". Just because it's new doesn't prove it's good.