Kymco bet and win 250 carburetor jets

[zombie]

2005 GV my oem Keihin CVK30 has 38S / 102 stamped in to each jet.  Due to a hesitation that I have not been able to fully get rid of even after 5+ cleanings (improved but not gone) I experimented with different jets from jetsrus and found that increasing the pilot jet to #52 seems to get rid of the hesitation completely.  #58 was too big and seemed to result in an overly rich mixture and smell from the exhaust.  #42 was not enough of an increase over stock.  Also, I have the pilot screw mixture set 3 turns out.

Sounds like your idle circuit is not working.I'd pull, and Completely break down the carb. Spray Carb Clean thru ALL the ports, ans go back to the OEM jet.

[zombie]

There you are... I replied to the post in the other thread.

Fantastic Post!!!   Well done sir!

[zombie]

You all have gotten way too good at helping people here. Now I have to step it up, and get rid of this little Chinese kid that types for me.
I'm keeping the Irish one that gets my beer tho.

[BettinANDlosing]

The correct Fuel screw setting for almost any of the CVK carbs is 2-1/2 turns out. And I think a few of you have it backwards, on the CVK carb the "air/ fuel" screw is actually a fuel screw, clockwise leans the mixture out, anti-clockwise makes for a richer mixture. Base setting should be 2-1/2 then adjust from there for best idle and throttle response.

[zombie]

Spot on.

[OGBillyT63]

 Update on my 2006 B&W .   I have now been running my scoot up to this date with just the use of manual choke that Iinstalled in place of the bystarter and it has worked out great so far.  So my question ,  does  the bystarter circuit and idle circuit feed into basically the same main passage in the carb and if so why can't I just leave it the way it is and just open the manual choke just enough to keep it at idle and set the idle mix screw at 1/2 turn essentially bypassing the clogged idle circuit altogether? 

[mrbios]

I recommend watching my carb videos.  They will show you exactly what to do to get the carb back to oem original condition and you can put the auto bystarter back on.  To answer your question - choke passage is separate from the pilot jet / idle screw circuit.

Kymco Grandvista / Grand Dink / Bet & Win:


Carburetor Cleaning & Theory three part series:

[OGBillyT63]

Thanks mrbios for the info.
OK , I took the carb off once again and I drilled out the brass plug and ran a thin wire (very thin wire ) through to where I could see it in the pilot jet hole along with spraying with carb cleaner so hopefully this will clear the idle circuit as you showed in your video .  One question though ,   What is the charcoal canister purging that I saw on the close up of the carb openings in video 3 ?  Is this something I need to do or just clean everything out with the cleaner and then blow it all out with compressed air?     

[mrbios]

Thanks mrbios for the info.
OK , I took the carb off once again and I drilled out the brass plug and ran a thin wire (very thin wire ) through to where I could see it in the pilot jet hole along with spraying with carb cleaner so hopefully this will clear the idle circuit as you showed in your video .  One question though ,   What is the charcoal canister purging that I saw on the close up of the carb openings in video 3 ?  Is this something I need to do or just clean everything out with the cleaner and then blow it all out with compressed air?     

Your welcome OGBilly!  Glad you made use of the videos.  Yes you are right to descirbe the wire as a "very thin wire"  I think the passage is too small and makes the carb prone to clogging if the scooter sits.  The set of 4 carbs in the video the passage is about 5x as wide as our scoots making cleaning easier.

Charcoal canister purge - No need to clean it.  it works the same as all cars (carb & fuel injected).  Basically, the EPA does not allow the vapor from warm / hot gasoline after the car / scooter is run and then parked to vent to the atmosphere.  So the vapors vent to the charcoal canister.  Once the motor is started a valve allows clean air to enter the canister and get sucked into the carb / motor to be consumed by the motor.  It is important that the vacuum line leading from the canister to the carb be sealed - no leaks and if it is disconnected then the carb hose connection must be capped off.  So just treat it the same as any other vacuum lines - no leaks as leaks lead to lean burn.

Pilot jet: After fully applying the cleaning methods in the videos I reinstalled my original pilot jet #38 and the scooter worked fine and no longer felt like it wanted to stall on take off (especially when cold).  However, I feel the scooter benefits from a larger pilot jet because it provides smoother off-idle hesitation-free acceleration.  So I recommend purchasing a few sizes from an aftermarket vendor such as #42, #45, #48.  I currently running #48? and thinking about cutting back to #45.  Mid range feels much stronger and fuel economy might be reduced by 1 or 2 mpg not sure.  I tried increasing the main jet but decided #102 (stock size) is best and there is noting to be gained.

Please continue to post results and I hope you get your scoot running great like mine is.  I just passed 14K miles.

Paul

[BettinANDlosing]

Your welcome OGBilly!  Glad you made use of the videos.  Yes you are right to descirbe the wire as a "very thin wire"  I think the passage is too small and makes the carb prone to clogging if the scooter sits.  The set of 4 carbs in the video the passage is about 5x as wide as our scoots making cleaning easier.

Charcoal canister purge - No need to clean it.  it works the same as all cars (carb & fuel injected).  Basically, the EPA does not allow the vapor from warm / hot gasoline after the car / scooter is run and then parked to vent to the atmosphere.  So the vapors vent to the charcoal canister.  Once the motor is started a valve allows clean air to enter the canister and get sucked into the carb / motor to be consumed by the motor.  It is important that the vacuum line leading from the canister to the carb be sealed - no leaks and if it is disconnected then the carb hose connection must be capped off.  So just treat it the same as any other vacuum lines - no leaks as leaks lead to lean burn.

Pilot jet: After fully applying the cleaning methods in the videos I reinstalled my original pilot jet #38 and the scooter worked fine and no longer felt like it wanted to stall on take off (especially when cold).  However, I feel the scooter benefits from a larger pilot jet because it provides smoother off-idle hesitation-free acceleration.  So I recommend purchasing a few sizes from an aftermarket vendor such as #42, #45, #48.  I currently running #48? and thinking about cutting back to #45.  Mid range feels much stronger and fuel economy might be reduced by 1 or 2 mpg not sure.  I tried increasing the main jet but decided #102 (stock size) is best and there is noting to be gained.

Please continue to post results and I hope you get your scoot running great like mine is.  I just passed 14K miles.

Paul

Better yet, rip that cheap emissions system off!!!!!!!!!

[OGBillyT63]

 After watching Paul C 's you tube video about different levels of cleaning carburetorsi I decided to drill out the brass plug which gave me access to thoroughly clean the idle circuit with the use of a very thin wire.  I put the carb back together and plugged the hole I made with JB Weld and let it set for a day and then reinstalled the carb.  I started up the scoot and got it warmed up and then pushed the manual choke all the way down essentially stopping the choke circuit,  and to my delight it didn't stall out as in the past.  So once again thanks for your help Paul C..  I'm still running with the 38 slow jet for now ,but I may experiment with larger slow jets later.  The idle screw is now at 2-1/2 and it seems to be happy there.  Also checked my valve clearances since I had the seat off and set them at .1 mm .  So I ordered a new bystarter since I broke the original trying to get it out of the socket  when the brass plunger stuck in the hole so the only way to get it out was to pull on it when the plastic parts fell apart.  .
Thanks all for your help.

OGBillyT63

[mrbios]

...
Thanks all for your help.

OGBillyT63

Your very welcome.   

I went through all the same stuff and I stumbled on the idea of drilling the pilot jet plug for direct access.  Want to share it with my fellow scoot enthusiasts to show that carbs still work great and the problems with them can be put to bed once and for all.  When the "lambs stop screaming" (silence of the lambs movie) you many want to bump up the pilot jet in time - you will be very surprised how nicely it improves off idle and early mid range power.  But the most important problem is solved and all with the best performing stock / oem parts.  No dangerous lean burn and endlessly aggravation off idle hesitation.  For me it has been about 2.5K miles and not a single hesitation.

Long live our affordable and dependable Kymco scoots!   

-Paul