Kymco bet and win 250 carburetor jets

[OGBillyT63]

Can anyone tell me the correct size jets for a 2006 Kymco Bet and Win 250.  Mine has a 35 slow jet and a 102 main jet.  I have seen specs that say 38 for the slow jet and 108 for the main jet.  So what size should they be?

Thanks all.

[ophelia]

The official service manual says 38 slow jet and 108 main jet. That sounds like one size up for both jets from what you're using now. Are you at higher altitude?

Is your Bet and Win 250 running just fine?

[OGBillyT63]

I live near Valley Forge PA so I don't think altitude is a issue. I bought it used , Dec 2013 .  I was having problems with stalling out when coming to a stop and and some hesitation on initial throttle up so I took the carb apart for cleaning thinking that could be the issue. While cleaning I looked at the jet sizes and discovered that they were different than those seen in several specs.  Could that difference in jet sizes be an issue?  After reinstall I am still having same issues.  My next steps are to check bystarter then valve clearances and cylinder compression.

Thanks

[rice10562]

I have a two brothers cf250 on my bike I am using 38 slow and 125 main but I haven't put on a breather filter yet my bike came with a 35 and a very small 102

[OGBillyT63]

So rice10562,  What do you mean by two brothers cf250?  How did your bet and win 250 run with the smaller jets ?  I haven't tried mine with larger jets yet.   How did you end up with using a 125 main jet and how does it run with that set up?

Thanks

[ophelia]

Did everything else check out okay on your bike? My Bet and Win 250 had 16000 km when I sold it. Never had any running issues, but it was my daily commuter. Throttle very crisp, hardly any warmup time. For all I know, it might have come with the smaller jets.

Check all hoses and connections in case you have a vacuum leak making you run lean? I can send you the service manual if you need a copy.

[OGBillyT63]

So far I have put the 38 pilot and the 108 on the main jet  after another carb cleaning and checked the bystarter which checks out OK hooked up to my battery and on the carb .  I also drained the gas it came with and filled the tank up with 93 octane gas.  The bike is outside with a cover on it surrounded by snow and I have not had a decent warm day here to reinstall the carb to check the newer jets,  so once I do that I'll see how it runs and if I still have a problem  I'll go on to checking out  for vaccum leaks, then valve settings and then cylinder compression.  .I do have a service manual.   I will keep you posted.

Thanks again all!

[rice10562]

The exhaust I have on it is this one Honda CRF250R V.A.L.Eâ„¢ Slip-On Exhaust Systems: made by twobrohers they usually go in ninja 250 bikes but I got a sweet deal on a used one so i cut the original exhaust off made a bracket slipped it on the exhaust manifold then tested for back pressure then I welded it on since it is a bigger exhaust I needed more gas on high end for it to run right with out being to lean once I change the air filer to a breather filter I might have to up jet again

[OGBillyT63]

After reinstall of carb with 38 slow jet and 108 main jet , new irridium dr7iex-9 ngk plug, new gas ,new fuel filter, I started my scooter up today.  After adjusting the idle knob and idle mixture screw  I got it to keep running .  After warm up I pulled the plug that i just installed which was sooty on the end . I then checked the compression with WOT and cranking it over where it reached 180 on the gauge,  which seemed good to me.   I reinstalled the same plug after wiping off some of the soot and restarted and turned the mixture screw in thinking that it should lean it out some and as I turned the screw clockwise it did'nt change how it ran.  There is no hesitation when throttling up,  but sometimes acts like it is going to stall out at sitting idle.   I have not had it out on the road yet for a run,  so all my tests have been with the scoot on its stand.   Still need to check for vacuum leaks,  but a vacuum leak would make it run lean , right?

Thanks all.

[ophelia]

I think the service manual suggests an idle mixture screw setting of 1/2 to 1/4 turns out from fully seated when used with the #38 pilot jet. Start there.

If 1/4 turns out is still too rich, then go back to the #35 pilot jet and start with 1.5 turns out, adjusting up to 1/2 turn more inwards if too rich or 1/2 turn more outwards if too lean. Use how well the bike takes to throttle as your indicator. Slow to return to idle, slow to rev up or high idle after revving = too lean; too fast of a rev drop or stumbling idle = too rich.

[OGBillyT63]

Today I took all the air side apart ( air cleaner , the tube and air box that runs from the front to the air cleaner compartment ,  the oil evaporater tube coming off the valve cover,  drip tube form that tube),.   When I took the air box off  which sits up front there was evidence of a mouse nest ( pieces of fabric , wood shavings etc,  which one mechanic found in the air cleaner compartment right after I bought it .   So the mouse went into that compartment , then through the 1 1/4 inch dia tube , then through the air box and built a nest in front of that. I figured I would check the bystarter so I took it off and measured the length of the plunger before warmup.  After all that I started it up with out the air cleaner in and the other tubes off and it started up fine,  so I reinstalled all the air air cleaner system and it seemed to run ok still. I was going to take the bystarter off to remeasure after warm up , but could not pull it all the way out,  which I assumed meant that the plunger went down as it was supposed to do,  so I re installed.    I then rechecked the mix screw and found that I could turn in some more from where it was and after turning in I found that it did change how it ran .  I now have it at at about 3/4 to 1 turn out from seating and it seems to be running ok now,  but I need to take it out on the road once the snow an ice are off the roads to see how it performs .   

Thanks again!!

[OGBillyT63]

Update on carburetor on my 06 Bet and Win 250. 
I found a manual choke to replace the electric bystarter and installed it  and finally had some warmer weather to take it for a run.  I found that the scooter runs great with the 38 slow jet and 108 main jet with the choke is still engaged. However if I push the choke cable all the way in even after warm up it will stall out .   I'm thinking this could be a sign that the idle mixture screw is not working properly,  especially since after seating the screw and backing it out 1to almost 4turns doesn't seem to change the idle and I think the fuel should be coming from idle mix screw  after the choke if shut off ,  so hopefully that will clear up after some riding.  If not I'll take the carb apart and make sure the idle mix line is clear and see if it changes anything .  So for now I'm adjusting the choke as I ride.

 

[ophelia]

It sounds like the idle circuit on your carb is still plugged somewhere. You may have to clear the passages that the pilot jet and the idle mixture screw sit in. Try some compressed air.

[OGBillyT63]

 Update:   Since I last posted I put seafoam in my gas tank and adjusted the manual choke that i installed as I rode in hopes that the idle mixture circuit would clear up eventually.  So today I went for a long run and when I got back I pushed the choke all the way in to see if it would idle and not stall out.   To my surprise it kept running at idle while just sitting on the stand,  so I'm thinking it is at least starting to clear up.    Kinda made my day .

[mrbios]

... So what size should they be?

My 2005 GV uses 38 / 102.  Due to a hesitation resulting from a clogged passages as a result of sitting I experimented with different jets.

Increased the pilot jet to #48 seems to get rid of the hesitation completely.  I set the pilot screw mixture set 1 1/2 turns out.