SLOPOKE21 Posted July 8, 2010 Report Share Posted July 8, 2010 So I got my cub back together and I went to texas to ride for the 4th. I went from about 1500ft to 3800ft elevation. I had to replace my flywheel and stator before I went so I did not get to ride it in cali before my trip so I don't know if this was happening before the elevation or not. I get to the dunes and make a pass to see how everything was going and I notice that when I let off the throttle it seems like my bike is running out of fuel and still idling really high. I blip the throttle a bitand it seems to calm it down. It is dumping raw fuel out the pipes but with the high idle after a run I was scared to lean it much. I did drop my powerjets from 157.5 to a 155 but it didn't seem to help. My carbs are 39 pwk's with .120 dump, .110 mains, air screw 1.5 out, stock needle with clip in center, and 62 pilot. I also have one float removed as well. My question is am I running out of fuel at the end of my run or the fact that I'm super rich doing this? Quote Link to comment Share on other sites More sharing options...
okbeast Posted July 8, 2010 Report Share Posted July 8, 2010 With a .120 dump a .110 main sounds really small. I'm not up much on the alky tuning but I would think a .115 or .118 main would be closer to correct. Quote Link to comment Share on other sites More sharing options...
sheefreak Posted July 8, 2010 Report Share Posted July 8, 2010 So I got my cub back together and I went to texas to ride for the 4th. I went from about 1500ft to 3800ft elevation. I had to replace my flywheel and stator before I went so I did not get to ride it in cali before my trip so I don't know if this was happening before the elevation or not. I get to the dunes and make a pass to see how everything was going and I notice that when I let off the throttle it seems like my bike is running out of fuel and still idling really high. I blip the throttle a bitand it seems to calm it down. It is dumping raw fuel out the pipes but with the high idle after a run I was scared to lean it much. I did drop my powerjets from 157.5 to a 155 but it didn't seem to help. My carbs are 39 pwk's with .120 dump, .110 mains, air screw 1.5 out, stock needle with clip in center, and 62 pilot. I also have one float removed as well. My question is am I running out of fuel at the end of my run or the fact that I'm super rich doing this? A high idle would indicate a the pilot or midrange ckt being lean. W/a 62 pilot, and clip in the middle, you should be nowhere near lean. As a matter of fact, opening that dump up to .120 will make your midrange real rich at the middle clip. This is why you are spraying raw fuel, it is not because of your power jet. To start pulling off your PJ in neutral, you would have to hold the throttle open way to long prolly blowing the smiterines out of your motor. I would start by raising your clip one notch to lean it up. At your elevation, you may need to run it as lean as it will go(closest position to blunt end of needle). I also believe your pilot is too big...55 should be fine. On the top end, i have never messed w/PJ's that are metered by jets. As long as you are a hair rich on the bottom end though, your spark plugs will tell the story. If you don't know how to read an alky plug, you need to read up. And last but not least, you need to either run a pump or billet bowls on a cub motor. If you run any distance at all, it will suck those bowls dry and you will never figure out your jetting. There is a lot more to talk about, but I am at work and have to go. Good luck! Quote Link to comment Share on other sites More sharing options...
RadarRacing Posted July 8, 2010 Report Share Posted July 8, 2010 I second the main being small. "110" you should also have a needle specifically for alky. Not whatever comes in the carbs when new. It sounds like a lean hang to me. You said it blows raw fuel out of the pipes, are you talking about WOT, 1/2 throttle riding, blipping the throttle off idle? I ride at 1/3-1/2 throttle or so in 3rd with a slight load on the motor and then blip the throttle with the clutch in, hopefully it takes a cpl good raps to clear out. Depending on how you ride can also get a lean cond at the end of a run if you just let off the gas and don't pull the clutch in with the motor turning high rpms, it will be very lean for a second and can high idle.Don't do that if you were but probably not just a thought. Quote Link to comment Share on other sites More sharing options...
SLOPOKE21 Posted July 8, 2010 Author Report Share Posted July 8, 2010 Well before I mess with it to much more I'm gonna put a pump on it and see if that takes care of it before I start racking my brain with the jetting. Quote Link to comment Share on other sites More sharing options...
AKheathen Posted July 9, 2010 Report Share Posted July 9, 2010 i've not messed with alky or those carbs, but just an idea- are you sure the idle is not set too high, but with the mixture off at idle? i'd think if the bowls were running low, they would fill back up really quick once you get out of it, like within 1-2 seconds max. if it is happening, and the bowls don't fill that fast, change the needle seat over to a larger one. i know there is sdiffernt ones to choose from for mikuni carbs, for higher flow rates. also- simple one- make sure the fuel cap isn't restricting flow... Quote Link to comment Share on other sites More sharing options...
SLOPOKE21 Posted July 9, 2010 Author Report Share Posted July 9, 2010 so what you guys are telling me is to lean up my pilot and drop the needle down a little bit?? your right it does take a long time for the fuel to reach my pj's, but if im at WOT is it really going to matter how long it takes for the fuel to get there? also there is no kind of cutting out or anything in 5th. i have never really wound it out to far in 5th but i have a 2-5 override and 14-41, and most of the time once i hit 5th i let out of it. my plugs dont look to bad either. ill see if i can get some pics up of them to see what you guys think. i am new to alky as well so i am still learning a lot. the bike pulls really hard no bogs off the line seems to clear out fine even though it doesnt really seem to load up like some other bikes i have seen. before i took the bike to texas i never noticed the raw fuel coming out and i didnt seem to have this running out of fuel problem so if anything i would figure that i should just drop down the pj's right? i only went down one size and it didnt seem to get any better so maybe its just low on fuel in the bowl and the pilots dont have enough fuel and its throwing it off?? Quote Link to comment Share on other sites More sharing options...
J-Madd Posted August 4, 2010 Report Share Posted August 4, 2010 Did you ever get this figured out? What do you mean by "stock" needle? Exactly what needles are you running. That makes a huge difference. Quote Link to comment Share on other sites More sharing options...
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