Which spark plug for a Jonway yy250tt? By miky6719 (Read 1,972 times)

[ellpee]

Feb 18, 2014 6:35:24 GMT -6 miky6719 said:

Ok, i removed the filter box but it is ok, so the problem is another. I think there is an electrical problem, false contact, but do not know where it can be.

Thanks

(1) You report a good, strong spark at the plug, so I don't see how it can be electrical.

(2) You report no problems with the air filter.

(3) You report smelling and seeing gas in the cylinder when you crank the engine, so the fuel pump is working and gas is getting through the carburetor to the cylinder.

So to my understanding, it has to be a matter of the gas/air mixture, in other words, carburetor settings. I'd suspect TOO MUCH gas for the amount of air coming in. If so, you need to find the mixture screw and turn it a little at a time until the engine will start. (Clockwise to reduce the amount of gas, if I recall correctly, at least on my scooter.) Believe I've read here that the best technique is to turn it COMPLETELY clockwise, therefore no gas at all, then back out about two full turns and try it. If it starts, then experiment with 1/4 turn at a time in either direction until you get the smoothest running.

I guess it's also possible the valves are out of adjustment, I have no experience there so others will have to comment. Oh, and another possibility that occurs to me is that the "enricher" that squirts in extra gas for starting is defective, and is squirting in TOO MUCH gas. To check that you might unplug the wire from the enricher briefly and crank it a couple times, and see if there's any difference.

By the way, when you say "won't start," do you mean no firing at all, or when you crank the engine it tries to fire but won't "catch" and stay running.

[miky6719]

Thanks for reply, when i crank the engine it tries to fire but won't "catch" and stay running. If i try to unplug the wire from the enricher but where is this wire?

Bye

[alleyoop]

Ok, lets find out if it is to much gas. Take the Air Filter cover off and Air Filter OFF and try to start it.
Alleyoop

[ellpee]

Feb 19, 2014 11:50:50 GMT -6 miky6719 said:

Thanks for reply, when i crank the engine it tries to fire but won't "catch" and stay running. If i try to unplug the wire from the enricher but where is this wire?

Bye

So when you crank it, it goes " ... rrrr-rrr-rrr-putt-putt-rrr--rrr --putt--rrr-rrrrrrrrrr"? That's what *** I *** understand under "tries to fire." As opposed to just "rrrrrrrrrrrrrrrrrrrrrr," with no "putt-putt" whatsoever. Just want to be real clear about what problem you're having.

As to the enricher, ON MY SCOOTER it's a black thing that looks a bit like a spark plug and screws into the top of the carburetor; it has a couple wires going into it. Where exactly to unplug it I don't know, just have to follow those wires down to wherever they have a connector on the end.

[miky6719]

Hello, the sound of my scooter when i crank the engine is in attachment:

Recording20140224_001.amr (36.66 KB)

Thanks 

Bye

[richardthescooter3]

The enricher (auto choke) allow extra gas to come into carb at the beginning of starting your scooter, as the scooter warms up, the needle in the enricher closes off the extra gas, so it if want to test the enrich, take out hold thumb over hole start your scooter and watch the needle come out, its working.

[ellpee]

Feb 25, 2014 2:39:08 GMT -6 miky6719 said:

Hello, the sound of my scooter when i crank the engine is in attachment:

View Attachment

Thanks 

Bye

Very cool -- don't think I ever saw a sound file posted before! And as I listen to it I don't hear any firing going on at all, even though you say you are seeing a good, strong spark at the plug, so my amateur guess would be that your fuel/air mixture is WAY off. Either way too much gas or way too little. Since you also reported smelling and seeing gas in the cylinder after cranking, I'd be inclined to suspect too much rather than too little. So, unless others here with more experience than me want to suggest otherwise, I'd say find the mixture screw on your carburetor, screw it all the way in, then back out about two complete turns. Then try to start the scooter and see if you notice a difference. It should at least TRY to fire. If not, there's something else going on and I am at a loss what it might be.

PS -- since you're in Italy this may not apply, but in USA the mixture screw on these carbs often has a plug to keep people from changing it, due to our sometimes strict emissions rules. If you want to make the adjustments I describe, you may find out that you have to first remove that plug. Unfortunately I can't even tell you where the mixture screw is located; I have basically the same scooter, a Roketa, but have never (yet) had to tinker with the carburetor mixture.

[miky6719]

Hooray I found the problem!!. It was the switch on the side stand, the bolt was partially unscrewed so it was not a good electrical contact, for the first time what it is on, but then with the vibrations, the contact is open the scooter would not turn on anymore. Thanks for your help!!
Now I have to solve the problem fuel gauge but I'll open a new post

Hello