Freshman Rider
Currently Offline
Posts: 94 
Likes: 3
Joined: Apr 30, 2014 2:44:28 GMT -5
|
Post by userix on Apr 18, 2015 2:36:44 GMT -5
I recently upgraded to a 180cc big bore kit for my GY6 ruckus and I am noticing the carb is constantly overfilled, which is evident by the excessive fuel pouring out as soon as I loosen the screws to the carb bowl and the fact the overfill tube is always full of gas. The scooter will randomly cut out when I am cruising mid-throttle. I am running an OKO 30mm D-slide carb, which is brand new, and I made sure the needle and seat are working properly.
I currently have a round Mikuni DF52-21-D dual output 35L/hr pump installed, with both fuel outlets T'd to a single hose that runs to my carb. Does the stronger vacuum pressure at the intake manifold of my 180cc engine increases the fuel pressure or flow rate the vacuum pump operates at?
The fuel delivery setup I have now is the same setup I used with my 150cc and I never ran into flooding or overfueling the carb. In fact, I had to use the Mikuni dual output setup because the rectangular DF-44 single output Mikuni pump wouldn't be able to provide enough fuel during WOT sessions. I would actually run the carb bowl dry only after a few minutes of WOT. Once i switched to the Mikuni dual outlet pump, I would be able to WOT all day and not starve the carb of fuel.
Now it seems with the 180cc build, it's the opposite problem of overfueling. The first thing i tried was installing a vacuum restrictor (basically a hose coupler with a small hole restrictor inside) inline between the pump and the vacuum nipple on the intake manifold. I thought by restricting the vacuum, it would lower the pressure or flow rate of the pump. Turned out it didn't change anything. Carb was still getting overfilled just the same. Again, i verified the needle and seat are working properly.
One friend recommended I switch my vacuum line to a smaller diameter line, but seeing how the vacuum restrictor didn't make a difference, I don't see how changing to a smaller diameter vacuum line would help either.
Would switching back to the single output 14L/hr Mikuni pump fix this issue?
|
|
|
|
Post by tvnacman on Apr 18, 2015 5:31:23 GMT -5
I think you need to have a look at the float in the carb, if it is adjusted where its filling the bowl too high it would yield the same symptoms your describing.
I'm not sure the way to adjust your carb without seeing it, and there is a way of testing the gas level height. clear tube in the bowl drain hold it up and let the bowl fill up the fuel in the drain tube will be the same as the height of the fuel in the bowl,
John
|
|
|
|
Post by dmartin95 on Apr 18, 2015 5:35:16 GMT -5
Do you have a tank on the bottom (in the floorboard) or up top?
IMO, if you have a floor tank, the simplest fix is to get an electric pump and a pressure regulator around 3 bar with a return fuel line. If you have a bottom tank, you will need a self priming pump with an inline check valve.
|
|
Freshman Rider
Currently Offline
Posts: 94
Likes: 3
Joined: Apr 30, 2014 2:44:28 GMT -5
|
Post by userix on Apr 18, 2015 15:08:57 GMT -5
I think you need to have a look at the float in the carb, if it is adjusted where its filling the bowl too high it would yield the same symptoms your describing. I'm not sure the way to adjust your carb without seeing it, and there is a way of testing the gas level height. clear tube in the bowl drain hold it up and let the bowl fill up the fuel in the drain tube will be the same as the height of the fuel in the bowl, John Yeah I checked the float height by taking off the carb bowl. It is set correctly. It's a oko 30mm d slide carb. www.treatland.tv/v/vspfiles/photos/OKO-30mm-black-2T.jpgThe carb is brand new and the needle/seat is fine. The float height is set correctly too. The only thing I can think of is the pump being way too powerful for my setup, even though the use of an inline vacuum restrictor yielded no difference. Theoretically, if the vacuum line was restricted to a very small diameter, shouldn't that reduce the pressure/flow rate of the vacuum pump? Logically, that's what I would assume |
|
Freshman Rider
Currently Offline
Posts: 94
Likes: 3
Joined: Apr 30, 2014 2:44:28 GMT -5
|
Post by userix on Apr 18, 2015 15:10:34 GMT -5
Do you have a tank on the bottom (in the floorboard) or up top? IMO, if you have a floor tank, the simplest fix is to get an electric pump and a pressure regulator around 3 bar with a return fuel line. If you have a bottom tank, you will need a self priming pump with an inline check valve. It's a honda ruckus gy6 swap. So the gas tank is in the floorboard, down low below the height of the carb. But the same fuel delivery I have now worked perfectly fine with my old 150cc stock gy6 engine. It never flooded the carb back then What's the difference between a floor tank and bottom tank? |
|
|
|
Post by dmartin95 on Apr 18, 2015 16:08:20 GMT -5
Do you have a tank on the bottom (in the floorboard) or up top? IMO, if you have a floor tank, the simplest fix is to get an electric pump and a pressure regulator around 3 bar with a return fuel line. If you have a bottom tank, you will need a self priming pump with an inline check valve. It's a honda ruckus gy6 swap. So the gas tank is in the floorboard, down low below the height of the carb. But the same fuel delivery I have now worked perfectly fine with my old 150cc stock gy6 engine. It never flooded the carb back then What's the difference between a floor tank and bottom tank? I'm unsure.... It could be the increased vacuum of the newer engine, or perhaps you un-knowingly repaired a vacuum leak when you did the engine swap..... In short, I don't know why you're getting too much fuel now.... Just a possible fix.... First thing I would try if I were you is to put the rectangular Mukini back on, and change your vacuum back to a single port....Try that and see if it stops drowning the carb.... |
|
|
|
Post by tvnacman on Apr 18, 2015 17:18:15 GMT -5
get a clear hose and get an external fuel bowl height. I now sell scooter parts because of defective parts being sold. New or old lets be sure they do and act as they should.
John
|
|
|
|
Post by urbanmadness on Apr 18, 2015 18:33:37 GMT -5
Sounds like the float is set too high... Or the needle and seat are bad, or dirty. The needle should be able to handle the increased pressure without issue as long as it's not ridiculously high and these vacuum driven pumps don't generate that kind of pressure.
I'd change back to the stock carb (for diagnosis purposes) and see if it's still flooding out. I bet you it won't.
|
|
|
|
Post by tvnacman on Apr 18, 2015 19:17:15 GMT -5
Sounds like the float is set too high... Or the needle and seat are bad, or dirty. The needle should be able to handle the increased pressure without issue as long as it's not ridiculously high and these vacuum driven pumps don't generate that kind of pressure. I'd change back to the stock carb (for diagnosis purposes) and see if it's still flooding out. I bet you it won't. 2nd this |
|
Freshman Rider
Currently Offline
Posts: 94
Likes: 3
Joined: Apr 30, 2014 2:44:28 GMT -5
|
Post by userix on Apr 30, 2015 3:09:19 GMT -5
I recently just started having this bog issue only when I crack the throttle wide open from idle. It happened halfway through my ride. The first half of the ride, I could WOT from idle and the scooter pulls perfectly. Everytime I go WOT from idle, it bogs for 1 sec, then it will take off. I pulled the plug and noticed the plug is carbon fouled (dry, sooty deposits). I'm guessing it's super rich and I need to rejet to a smaller jet size. Is this the cause of the bogging shown in the video? Other than the bog described above, I can WOT fine after I get the scooter moving at speed. Current Jetting: 135 main/ 48 pilot, OKO 30mm D-slide carb.  |
|
|
|
Post by geh3333 on Apr 30, 2015 15:11:25 GMT -5
I recently just started having this bog issue only when I crack the throttle wide open from idle. It happened halfway through my ride. The first half of the ride, I could WOT from idle and the scooter pulls perfectly. Everytime I go WOT from idle, it bogs for 1 sec, then it will take off. I pulled the plug and noticed the plug is carbon fouled (dry, sooty deposits). I'm guessing it's super rich and I need to rejet to a smaller jet size. Is this the cause of the bogging shown in the video? Other than the bog described above, I can WOT fine after I get the scooter moving at speed. Current Jetting: 135 main/ 48 pilot, OKO 30mm D-slide carb. Wow , id go with a 125 main and I'd also drop the pilot some also. |
|
|
|
Post by ital on Apr 30, 2015 16:51:22 GMT -5
I had bogging that would eventually go away after running for 30 minutes, but eventually it kept getting worse. I was able to fix it by doing a valve adjustment.
do you have a uni air filter installed as well?
|
|
Freshman Rider
Currently Offline
Posts: 94
Likes: 3
Joined: Apr 30, 2014 2:44:28 GMT -5
|
Post by userix on May 1, 2015 3:11:24 GMT -5
I had bogging that would eventually go away after running for 30 minutes, but eventually it kept getting worse. I was able to fix it by doing a valve adjustment. do you have a uni air filter installed as well? It's weird because the bogging only started happening halfway through my ride. I could WOT from a standstill with no issues. Yeah, I am running an UNI filter. In the very beginning, I was running a velocity stack alone, but I kept getting bogging from 1/3 to 1/2 throttle. I later found out that when I put my hand up to the carb to partially block airflow, it immediately got better. So I realized the carb was getting too much air. Though it runs awesome from 1/2 and up. I would love to sport the velocity stack alone, but I couldn't cruise at a constant speed without it bogging out. |
|
Freshman Rider
Currently Offline
Posts: 94
Likes: 3
Joined: Apr 30, 2014 2:44:28 GMT -5
|
Post by userix on May 1, 2015 3:22:55 GMT -5
I recently just started having this bog issue only when I crack the throttle wide open from idle. It happened halfway through my ride. The first half of the ride, I could WOT from idle and the scooter pulls perfectly. Everytime I go WOT from idle, it bogs for 1 sec, then it will take off. I pulled the plug and noticed the plug is carbon fouled (dry, sooty deposits). I'm guessing it's super rich and I need to rejet to a smaller jet size. Is this the cause of the bogging shown in the video? Other than the bog described above, I can WOT fine after I get the scooter moving at speed. Current Jetting: 135 main/ 48 pilot, OKO 30mm D-slide carb. Wow , id go with a 125 main and I'd also drop the pilot some also. Just went for another ride today and I continued using the 135 MJ. The bogging at WOT from idle is still there, but when I pulled the plug today and checked, the insulator and electrode tip are a nice chocalatey brown. But the threads near the insulator is still black. Does the carbon build up on the threads mean the pilot jet is too big? |
|
|
|
Post by ital on May 1, 2015 8:45:24 GMT -5
Wow , id go with a 125 main and I'd also drop the pilot some also. Just went for another ride today and I continued using the 135 MJ. The bogging at WOT from idle is still there, but when I pulled the plug today and checked, the insulator and electrode tip are a nice chocalatey brown. But the threads near the insulator is still black. Does the carbon build up on the threads mean the pilot jet is too big? To me that sounds like you have too small of a main jet. When I installed the uni filter I had the same issue, it would bog on WOT throttle and gain speed if I did not accelerate as much. I went from a 108 main jet to a 130 main jet with uni filter only. I think you are running lean. I am on stock carburetor 24 mm so not sure what to advise you on jet size. Good luck!! |
|
