Jonway YY250t - 2 years later, still not running... By johnny3d (Read 13,525 times)

[johnny3d]

I've just recently moved up into the mountains of South Dakota (about 15 minutes from Sturgis). I've noticed that my Jonway YY250t is idling really rough and that the idle adjustment doesn't seem to be functioning properly.

If I turn it down low, it drops the idle down below were it should be (about 1000rpm). If I turn the idle adjustment up, it'll get up to about 1200rpm and instead of continuing to go up it'll start making a 'popopop' kind of sound and will jerk a bit. If I crank the idle adjustment screw up all the way it'll idle smoother but too high...

I think the problem is that I need to adjust my air/fuel mixture screw, but I'm not 100% sure where it is on my carb. I think I've found it (down out of reach facing down on the back of the air/fuel output side), but if that is it, I can't figure out how to reach it to adjust it while it's running.

I made a video so you can hear it somewhat. Hopefully it helps. If there is something else or another video you would need to help me figure this out, please let me know.

Here is a video I made quickly so you could hear the problem: Link

[johnny3d]

[replyingto=johnny3d]johnny3d[/replyingto]I'm pretty sure I know which is the air/fuel screw...

Since I won't be able to adjust that while it's running, how many turns out should I be setting it for about 3500-4000 ft above sea level?

[alleyoop]

Hi
It is running RICH if it is smoking at low idle, that is why if you idle it up it clears out it then Sucks in more air to match the amount of fuel.

And yes your correct the Fuel Ratio Mixture screw is UNDERNEATH by the intake manifold PITB TO GET AT) but you can get one of these and it works great.

Alleyoop




To adjust your carb here is how-to:
If your carb has a SCREW near the INTAKE MANIFOLD side the Carb has a FUEL RATIO MIXTURE Adjustment screw.

Turning the Fuel Ratio Mixture Clockwise LEANS it Turning it Counter Clockwise RICHENS it.

The Idle Speed screw is on the Throttle Control Wheel that the Throttle Cable pulls on. The Idle Speed Screw usually has a SPRING under it to keep the setting. Turning that Clockwise RAISES the Idle and Turning it Counter Clockwise LOWERS the Idle.

Most of your 250+ scoots come with 30+ mm Carbs. The procedure is the same just that the Fuel Ratio Mixture Screw may be in a Different place. They also have a ACV Valve that looks like a flying saucer attached to the front top of the carb. Other Carbs usually have them on the right side by the Throttle bracket.

[red]IF YOUR CARB HAS A SCREW ON THE AIR FILTER SIDE GO SEE 2TS CARB TUNING.[/red]

[red]Follow this procedure to tune the carb: Take your time 1/4 turn to much in either direction makes a big difference.[/red]

ADJUSTING YOUR FUEL RATIO MIXTURE:









[red]YOU WANT THE HIGHEST RPMS OUT OF THE AIR RATIO MIXTURE SCREW:[/red]

Start your scoot and Get The Engine Nice and Hot about 5 minutes so that the Enricher IF it has one is no longer Allowing Extra Fuel to come in. Then do the following to fine tune the Fuel Ratio Mixture:

[blue]FUEL RATIO SCREW:[/blue]

FIRST TRY RICHENNG THE FUEL MIXTURE FROM ITS CURRENT SETTING:

1. [red]RICHEN THE FUEL RATIO MIXTURE:[/red]

Turn the Fuel Mixture Screw COUNTER CLOCKWISE 1/4 of a turn and wait 10 seconds to let the engine catch up with the new setting.

a. If the RPMS go up REPEAT #1 UNTIL the RPMS GO DOWN OR NO CHANGE(then go to b).

b. TURN the Fuel Ratio Mixture Screw CLOCKWISE 1/8 and that should be your highest Fuel Ratio Mixture setting—GO TO #3.


[green]******[/green]If on the FIRST 1/4 TURN from the STARTING Position IN #1 ABOVE the RPMS GO DOWN OR NO CHANGE , turn the Fuel Ratio Mixture Screw Back the 1/4 turn to the Starting position and wait 10 seconds until the engine catches up -- GO TO #2[green] ******[/green]


2.[red]LEAN THE FUEL RATIO MIXTURE:[/red]

Turn the Fuel Mixture Screw CLOCKWISE 1/4 of a turn and wait 10 seconds to let the engine catch up with the new setting.

a. If the RPMS go up REPEAT #2 UNTIL the RPMS GO DOWN OR NO CHANGE(then go to b).

b. TURN the Fuel Mixture Screw COUNTER CLOCKWISE 1/8 and that should be your highest Fuel Ratio Mixture setting—GO TO #3.


[red]IF YOU GOT TO THIS POINT AND NOT INSTRUCTED TO GO TO #3 THAT MEANS THERE WAS NO CHANGE IN RPMS FROM DOING #1 or #2 ABOVE, IT IS TIME TO CLEAN THE CARB:
YOU NEED TO CLEAN YOUR PILOT JET AND PASSAGE AND AIR PASSAGES AND THEN START FROM #1 AGAIN.[/red]

3. [blue]IDLE SPEED SCREW:[/blue]

The Idle Speed Screw on a Carb that are on most 4Ts you will find on the right side on the THROTTLE CONTROL WHEEL. It is the screw with a SPRING on it.
To Lower the IDLE you turn it COUNTER CLOCKWISE to Raise the IDLE you turn it CLOCKWISE.

If after adjusting your Fuel Ratio Mixture your idle is to fast Turn the IDLE SPEED SCREW COUNTER CLOCKWISE. For the 50s-150s they like to idle around 1500-1800rpms, for the 250s+ they like to idle from 1800-2000 rpms, pick the smoothest idle with the rear wheel not spinning ---GO TO #4.

4. [blue]TEST YOUR ADJUSTMENTS:[/blue]

Now give the Throttle a QUICK twist and the RPMS should climb up quickly without hesitation or bogging and come down to where you set your Idle at---GO TO #5.

5. NOW take a ride and try it out, the Fuel Ratio mixture may need a tweak in either direction now that the motor has a load on it.

The tweak will be minor maybe a ¼ turn richer or leaner IF it acts up with a load---GO TO #6

6. When it acts up BACK OFF the throttle about ¼ of an INCH AND HOLD IT THERE:

a. If the motor speeds up it is LEAN you need to richen it up a little.

b. If the motor settles down and or stumbles and then settles down it is RICH you need to LEAN it out a little.
GO TO #5 AGAIN.

[blue]Problems with the IDLE:[/blue]

1. Give the throttle a quick twist:

A. If the rpms drop below idle speed, then recovers (or stalls), it is RICH —Turn the Fuel Mixture Screw Clockwise ¼ turns at a time and go to #1.

B. If the rpms do not drop quickly to the idle speed but hang and drop slowly it is LEAN —Turn the Fuel Mixture Screw Counter Clockwise ¼ turns at a time and go to #1.

[johnny3d]

Thanks for the reply. I didn't have one of those fancy tools you showed up there. Looks cool though. I loosened the carb and turned it a little so I could turn the screw a bit. I turned it 1/4 turn and then put everything back. When I tried to start it, it tried and tried but no spark, no fire, no start... So I turned it back how it was before and tried to start it again... same result. Currently it's sitting out there charging the battery (I have a battery tender installed in it). I'm at a loss since everything is essentially the same as it was before only now it won't fire up and even run rough.

[alleyoop]

You probably flooded it when you turned it sideways. Take the PLUG OUT and crank it a couple of times and the gas should out.

You need to do this while the motor is running so Tomorrow go to a Harbor Freight or Home Depot or some hardware store and pick one up.
If your going to own a scooter you need the right tools otherwise you will just make things worst than they already are.
Alleyoop

[johnny3d]

I assume you mean the spark plug when you say to take the plug out? Not trying to be dense or anything, just want to be sure.

I'll look for one of those tools today. I'm still not certain how I'm going to adjust that screw while it's running even with that tool. The air box blocks most of the access to it. Or do you have some trick to reaching that with the air box still on?

[johnny3d]

Worked on it some more today. Bought an equivalent of the tool you showed up there (the ratcheting offset screwdriver). Mine looks a little different, but it's essentially the same. I took out the spark plug and turned it over for a few seconds, but no gas came out of the hole. The spark plug was pretty black on the tip. It looked just like what a picture of a plug from a rich running engine would look like.

I put the plug back in and tried to start it... no luck. I pulled the air box off, adjusted the air/fuel screw a bit, put the air box back on, and tried to start it again... no luck.

My plan is the following: I'm going to pull the carb out (partially... enough to get at the screw easy but not so much as to need to disconnect everything from it). I'll put the screw all the way in (but not tighten) and then back it out 1.25 turns. I have read that 1.5 turns out is about factory average so 1.25 should give me a little leaner than normal setting to account for the altitude. I'll put the carb back in place. I will also buy a new spark plug. I'm concerned that the one I have in there right now is too fouled up to get a good enough spark to fire. I'm planning on picking up an NGK Iridium DR8EIX spark plug. I'll install that. Then I'll put the airbox back in place and try to fire it up.

I did pull the plug after a couple attempts and I did notice that there was a small amount of gas on the plug and it smelled of fresh gas. The amount on the plug evaporated almost instantly. It didn't seem like an excessive amount of gas to me.

If there is anything else you think I should consider or anything you think I ought to do, please let me know. I have a battery tender installed in the bike and the battery has been kept topped off during this process.

Right about now I'm seriously missing my old 50cc carb... it was so easy to get at that screw. Keeping that one tuned up was so simple. Thanks again for your help and suggestions so far.

[johnny3d]

Attempted to clean the current spark plug using some naptha and a bit of cloth to clean up the black soot. It being Sunday, I couldn't get to the store. I tried adjusting the air/fuel mixture screw all the way in (not tight) and then backing it out 1 full turn then 1.25 then 1.5 then 1.75 then 2 full turns out. I took out the spark plug a few times to check and there was definitely gas getting into the chamber, but no telling if it was too much. So far, it hasn't started...

All in all I'm starting to lose hope that I'll manage to get it running again.

[alleyoop]

Ok, so it is getting gas, BUT is the SPARK PLUG FIRING? So if you have a spare SPARK PLUG Just take the BOOT OFF THE PLUG on the motor and put the spare plug in the BOOT and then hold the metal part of the plug against the VALVE COVER OR MOTOR and CRANK IT and see if the SPARK PLUG IS FIRING. You should see BLUEISH SPARKS when it is firing.
Also DO you have the KILLSWITCH IN THE FUN POSITION? if it is not in the run position the SPARK PLUG WILL NOT FIRE.
Alleyoop

[johnny3d]

I do not have a spare spark plug to try it with. I only have the one plug on hand. I tried pulling that plug and putting it against the valve cover with it in the boot and it produced no spark when I had my wife hit the starter. So if that works, that means I'm not getting power to the spark plug and/or that spark plug is simply dead. I should be able to buy a replacement plug tomorrow either way.

The kill switch is definitely in the "fun" position. When I put it in the "no-fun" position it won't even attempt to turn over the engine.

[alleyoop]

Good, so know we know why it will not start, unfortunately it could be many things.
1. Plug is bad
2. BOOT CAP is Bad
3. Bad Coil
4. Bad CDI
5. Bad Pickup Coil
6 Bad Stator

Hope you have a multi meter some of the items can be checked some cannot.
The boot cap you can look inside and see if the clip that grabs the plug is intack
You can also check and make sure it is screwed onto the WIRE itself good. The Boot cap can be replaced they just screw onto the wire. Check the wires that connect to the COIL itself make sure they are on the COIL CONNECTORS and nice and tight and not broken or touching. After that you will need a mulit meter.
Alleyoop

[johnny3d]

Well... bought a new plug this afternoon. It wasn't the plug.

I'll end up picking up a multi-meter in the next few days. I had one but it got ruined a bit ago and I hadn't gotten around to replacing it yet. I unscrewed the plug boot and it looked to me like it was getting a decent connection there, but still no spark.

The thing that gets me is that I hadn't done anything in particular with the electrical system aside from disconnecting the battery. All I had done was adjust the carb a bit... So frustrating and it's going to cost me at least another $30 (for the multimeter) just to figure out where it's actually not functioning.

[alleyoop]

Well hopefully you did not connect the battery back up wrong because that will blow
some major parts like the R/R and CDI.
Alleyoop

[johnny3d]

I'm pretty positive that I did not hook the battery back up the wrong way or even short it out. I'm always really careful about that kind of thing.

The gauges come alive, the starter turns, and it sounds like it is trying to start, but no "fire" sound coming from it. I've been hunting around on the web to see if I could find a shop that would take a look/work on it anywhere near me... so far no luck.

[alleyoop]

You can do just as good as a shop would, the shop usually do not have a good enough mechanic to diagnose and or test the Electricals. They would start replacing parts which you yourself can do just as well. If you want you can do the same thing Which are the most likely culprits, one is the COIL and the other the CDI and those are plug and play just unplug the old and plug in the new. After that then it can be either the PICKUP COIL and or STATOR.
So you can spend the money on the two new parts and It will be cheaper than JUST THE LABOR from a shop.
Alleyoop