50cc weird compression

hey guys I am new here and I have a question about a moped I am working on for a friend. she said that she was riding it and it just stopped. then it was siting for like 2 years in a garage and now it is at my house. I figured that the carb was just dirty. but when I dump fuel in the intake it does not go. I checked for spark and it has good strong spark. so I take off the intake manifold and I put fuel in there, well it went everywhere. so I put my finger over it to act as a choke and I feel a lot of pressure and suction. and when I put my finger over the spark pug whole I feel much less compression than at the intake. what do you think my problem is? I was thinking timing chain skipped, but I wanted a second opinion before I dig in.

Re: 50cc weird compression

What kind of moped? You say timing chain, if it's a moped it doesn't have a timing chain unless it's an ssr Lazer or Indian. It sounds like you might have a scooter. Either way not telling us the make/model doesn't help us help you

Re: 50cc weird compression

Dirty30 Dillon /

If your feeling for compression on the exhaust stroke it will feel weak.

Also, feeling for compression is a pretty un-helpful way of measuring it. Grab a compression tester and see what do.

Re: 50cc weird compression

so it is a znen zn50QT_11. Ill have to go buy a tester. and after taking a closer look I think you are right that it is an ohv engine. (edited)

Re: 50cc weird compression

Dirty30 Dillon /

You're working with just a generic, Chinese-manu'd GY6 motor, there are much better sites to be probing for info.

That said, the quality on these is low and there are numerous items that could have failed

Re: 50cc weird compression

At least you got the "fastest" of the shitty Chinese 4 stroke 50s. Znen has the "best" QMB engine so far.

Re: 50cc weird compression

Check the exhaust valve clearance

Re: 50cc weird compression

{quote}Check the exhaust valve clearance{quote}

thank you, that is an Idea I have not thought of. it does have less air out the exhaust. what should the clearance be?

Re: 50cc weird compression

> Josiah Nowak Wrote:

> -------------------------------------------------------

> {quote}Check the exhaust valve clearance{quote}

>

> thank you, that is an Idea I have not thought of. it does have less air

> out the exhaust. what should the clearance be?

I would think .005" - .006" ( that's INCH ) should do .

Better a little too loose , than too tight . (edited)

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