Questions about Jonway YY250T By goodrosnemesis (Read 1,265 times)

[goodrosnemesis]

Two questions:

First, my scoot is backfiring a LOT when I am decelerating. It didn't do that until recently, and it seems to have come on gradually. I'm starting to worry that it is damaging the muffler. How can I fix it?

Second, I am leaking gear oil constantly. It seems there is a little relief tube that runs from the gear box up to the top of the air intake, and it the past when I have pushed too much gear oil into the box, it squirts out of the tube, which terminates under a little hood at the top rear of the air intake. Is there a gasket or something that goes on the gearbox? It usually leaks about three or four drops when parked over a span of about 12 hours, and the oil drips from the very bottom of the gearbox near the rear tire. I can post pictures if you really want to see it.

Help!

[Alleyoop]

Backfiring means it is running LEAN, first check the FLANGE where it connects to the motor. Many times with vibration and movement of the motor and or the muffler is loose it will loosen the nuts on the HEADER FLANGE that holds it to the motor and it leaks. It may have even lost one of the nuts holding it. It could have blown out the gasket also check for any air leaks around the carb area the Air Filter tubing cracked, air box cracked etc.

As for the blow by of tranny gear if you overfill them they will blow it out. As for the drips it could be the drain plug that is leaking and in need of a new gasket. Just to NOT over-tighten otherwise you will strip it the case is aluminum and they strip easy.
Alleyoop

[goodrosnemesis]

Thanks for the quick reply! I will dive into it tomorrow and let you know what happens.

[kibora]

Hello,
I also have a question.
And FYI, I am writing for my husband, who is not proficient in English.

My husband was going for a drive in our neighborhood on his 2009 YY250T Jonway (which he bought two weeks prior) after getting his motorcycle permit, going at 20~30 mph. It was at night and he didn't notice there was a pothole until it was too late, so he ran over it. A few seconds later, he had to make a left, so he was entering the left lane when he heard some metal dropping sound. Then as he stopped, his engine sounded like it was powering down (think of a computer shutting down) and died. He tried to turn it back on, but it failed. He dragged the bike in a safe place, then went back to where he was to see if there was a metal piece anywhere, which he did not find. He actually went back out there now to see again, so I'll update if he finds something.

This was on Wednesday night and it still is not working now. When we try to turn on the ignition, it sounds like how it normally does when first starting without the actual catching. Also, it sounds like the fuel is running, if that makes sense? It sort of smells like fuel when we try to turn it on. Any suggestions or thoughts as to what in the world is going on?

We are total newbies when it comes to scooters and have zero experience in mechanical work, but we are willing to learn if someone is willing to coach us...! Please help!

[kibora]

He found a piece that seems likely to have come from his Jonway.

i13.photobucket.com/albums/a252/fishieobGod/metalpiece.jpg

Any help will be greatly appreciated

[borris120]

Alleyoop,
I was wondering about your description above as you were mentioning that the engine was running LEAN. Given that it is only occurring while goodrosnemesis was DECELERATING, would that not be due to the engine running RICH? As excess fuel which does not combust has the chance to do so in the flaming mixture which winds up in the exhaust system. When deceleration occurs, the throttle is closed so more fuel can make it into the mixture than air, correct? It would seem like two factors indicating rich mixture combined would lead to the backfiring. I am by no means an expert on the notion, so please explain if I am missing something. Personally I would think the motor is running rich and combined with deceleration the backfire would seem evident. I understand engines well enough, but sadly most of my training has been on engines which are other-than carbureted.

Boris

[termigator24]

My jonway yy250t will turn over but not crank, I can spray eather in the muffler and it wii crank for a second then go dead. Please help.

[kz1000st]

First, please don't jump in on someone elses thread, start your own. Second, you have a clogged jet, a clogged fuel filter or a vacuum issue. 250 scooters have vacuum operated pumps and you're not getting fuel to the carb or through it. Pull off the fuel line to the carb, hit the start button and see if it squirts. If not something is up with your pump, if it does the problem is in the carb.

[serpic0]

I had mine backfiring and all I had to do was turn up the idle, I have a tach on this scooter which I didn't have on my old one so I set the idle speed with the tach, but anyway I set mine to 1500 rpms and have not had it back fire since, the other things people had said are also possible, but try the idle first, if you don't have a tach set it as high as you can go before the clutch/drive moves ie; rear wheel