Modern Buddy

I have a 2013 Buddy 50 . It used to run great. Now it won’t start. I have a spark, new carb, new plug, new reeds and compression is about 90 psi. I also replaced all the hoses. It has absolutely no vacuum. I can’t find a leak.
Any suggestions?

You're saying you have no vacuum going to the petcock. How many miles on the bike and where are you?

So…you’re saying there’s no fuel? Are the two hoses to the fuel petcock, vacuum and fuel supply, connected correctly? Does fuel flow when you suck on the vacuum hose? Et cetera.

You have to start from there and work downhill to the spark plug.

DeeDee wrote: ↑Wed Apr 16, 2025 1:59 am You're saying you have no vacuum going to the petcock. How many miles on the bike and where are you?

I have no vacuum at the intake manifold. No vacuum anywhere.I have compression but no vacuum. Someone mentioned it could be some seals in the engine e somewhere.

reed valve? oh, never mind you said you changed them. you have compression so, you have to have a vacuum leak somewhere. a really large one at that!... wait... what about exhaust restriction? drop the pipe. no air out, no air in.

I’ll try that. Thanks.

Well, That wasn’t it!!

Did the scoot suddenly just die on you?
Did it slowly lose power and then die?
What prompted you to do all this stuff in the first place?
Just trying to get a better understanding as to what happened.

You could do a leakdown test. Check this Modern Vespa thread for an example:

https://modernvespa.com/forum/topic187155

You'd want to pull the carb, block the intake manifold and vacuum port, as well as the exhaust port. You could leave the plug in if you pressurize the system from the intake side.

There are seals on both sides of the crank, but there's also an O-ring under the autolube pump that seals the crank chamber. Make sure the autolube pump is clamped down tight.

sc00ter wrote: ↑Wed Apr 16, 2025 10:38 pm Did the scoot suddenly just die on you?
Did it slowly lose power and then die?
What prompted you to do all this stuff in the first place?
Just trying to get a better understanding as to what happened.

I died on me last year. It would start, I’d go around the block, and it would die. I replaced all these parts because I’m trying to eliminate things it could be.

Same amount of time from start to die? will it start right back up?