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| 150cc GY6 and Under Engine Tech GY6 and Smaller Technical Discussion Forum |
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#1
08-25-2010, 09:51 AM
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thought I was running lean but rich? HOWHIT Gy6
Well I installed the 2 1/8'' uni and opened the exhaust up a bit, I know I needed to rejet but I put a new plug in it and rode it for 15 mins to get an idea. I pulled the plug and it was just as black as the one I replaced. I put in a different automatic choke and it rode a little better but still not right (still popping at WOT) before I replaced the automatic choke it would back fire like 5 times when I let off the gas after the motor was warmed up. What could cause my crossfire to run rich rather than lean? A neighbor thats an engineer also said it smelled rich when I rode by. The stock carburetor only has adjustments for idle speed and no air/fuel mix screw. With the aftermarket intake I think it would be foolish to get smaller jets considering I should be running slightly lean. I'm beginning to think that this popping through the intake/carb is a leak of some kind rather than going lean @ WOT. Any help would be great.
Last edited by Beefcake; 08-25-2010 at 09:57 AM. 
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#2
08-25-2010, 10:30 AM
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on my punisher with the gutted exhaust or one of my freeflowing exhausts any time i let
off the gas at wot it talks like a two stroke period if you are too rich like it sounds like you need to start working on your jet sizes smaller. any freeflowing exhaust will talk to you when you let off the throttle. give your jet size & elevation and i can get you close
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olderthan 2008 tomberline punisher 1500 spring 12g sliders 30mm cv pumper carb uni filter no rev cdi polaris xlt snowmobile shocks for front w/550 magnum springs & blaster fronts on rear and another buggy built working on mods gk-13 white spring 17 gram sliders so far
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#3
08-25-2010, 10:37 AM
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It's not exactly a free flowing exhaust I just made the tip on the end of muffler 1''. The header pipes and muffler are all stock. And what gets me is that if it were as rich as the spark plug show wouldn't it backfire? It's showing symptoms for both a lean and a rich engine.
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#4
08-25-2010, 03:32 PM
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One thing I noticed today while tinkering with it was that @ idle w/ the fuel on it was very choppy and sounded like it had a real lopey cam in it. I let it keep idling and I cut the fuel off and 2 minutes later it was idling perfect except for it being slightly high (it tried to take off on me). I was thinking maybe the electric choke I put on it was bad too. Is there any way to bypass this electric choke to see if it runs any better? I feel like the motor is trying to flood itsself which is making me believe the auto choke is the problem. Like the motor is constantly getting the extra fuel from the auto choke never closing or something. I tried to make a video of it doing this but youtube couldn't recognize the format or something. If anyone has an ideas as to what my problem could be let me know
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#5
08-25-2010, 05:52 PM
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The choke is pretty straight forward. You need to rejet on the main. Poppiing under WOT and a black plug = too rich. Find out what jet is in it and step down a few sizes.
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#6
08-25-2010, 07:06 PM
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I figured with the aftermarket uni and opened exhaust I would have to increase the jet size. I'm gonna open my carb up tomorrow and see what size is in it. So what your saying is that a black plug couldn't mean bad choke?
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#7
08-25-2010, 07:47 PM
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A choke would cause that but it would be running so bad at all points and typically when it is warn it would just die. The proper way to test that plug is to get a new one that's nice and white. Got make 3 or so wide open throttle passes and then pull the plug and see what it looks like. They do make a manual choke kit. Call tom at sycpowersports (click banner at top) and he can get you the manual choke.
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#8
08-25-2010, 08:57 PM
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video of it idling rough...
here is a video showing how it idles, kinda rough compared to when I first got it
http://www.youtube.com/watch?v=Tq4bdBBiIOs brand new plug installed that morning, checked it a little while ago after riding it all day and it was jet black. I guess I do need to get smaller jets which is confusing as hell because right after I installed the uni it ran awesome but it popped through the intake or carburetor and you guys suggested I increase the jet size to fix the popping. It had lots of low end and mid-range and now its like it only runs right at WOT while still popping through the intake. Could I possible have a clogged pilot jet and the main jet is still too small? I guess I'll know tomorrow when I remove the carburetor and check what the stock jets are. Last edited by Beefcake; 08-25-2010 at 09:08 PM.
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#9
08-25-2010, 09:06 PM
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Nice job. I've heard plenty that were worse than that. I don't think your choke is a problem at this point. You may be able to smooth the idle a bit with tweaking but like I said, there is much worse idles than that. You need to rejet. it is possible that the person before you jetted it or something. Post what size jet is in it now and I could advise but with experience in jetting, if it is popping at wide open throttle and say I had a 28 in it right now, I would put a 25 in it and re-run it.
Some carbs respond massively to small jettings. Others, like what is on the ASW machines, respond mild with heavy jet spreads.
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#10
08-25-2010, 09:43 PM
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It had a stock air box when I bought it but it was broken which led me to buying the uni, so it should be stock crossfire jetting. So your saying I need a smaller pilot jet and main jet? I'll make another video tomorrow of how it accelerates and the sound it makes @ WOT
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#11
08-25-2010, 09:52 PM
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on your rear rail you can see that you are running to rich-i would start from what is in
the carb jetwise its possible the guy you bought it from changed it or the carb came from another buggy let us know what you have pilot & main jet wise and your elevation and we can probally help.
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olderthan 2008 tomberline punisher 1500 spring 12g sliders 30mm cv pumper carb uni filter no rev cdi polaris xlt snowmobile shocks for front w/550 magnum springs & blaster fronts on rear and another buggy built working on mods gk-13 white spring 17 gram sliders so far
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#12
08-25-2010, 10:00 PM
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It is very rare to actually have to mess with the pilot. just deal with the main. you need a smaller main.
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#13
08-27-2010, 01:00 AM
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BuggyMaster do you think this kit would have all the jets required to find the right smaller jet? It the only package I could find that had jets from 100 to 115. Fairly cheap too considering some sites I've found charge $7-$8 a piece + shipping for a single jet and they don't sell the smaller jet sizes. Steep price for a piece of brass that doesn't even weigh a gram. Heres the link
http://cgi.ebay.com/ebaymotors/Carbu...item45f480c261 Also I was wondering if a clogged air filter could cause it to run rich? The guy at the Honda place told me my uni was oiled from the factory and it wasn't, so I searched google for substitutes for uni oil and I found out gear oil worked the best so I used that. Maybe I put just a tad too much gear oil on it and its just not flowing well? It was a uni PK-92 and its for a street bike not an off road vehicle. I'm thinking the street bike filters have smaller pores or something and don't need to be oiled. I'm going to try running it without the filter tomorrow on some paved roads with a clean spark plug and see if it still comes out black. Last edited by Beefcake; 08-27-2010 at 01:09 AM.
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#14
08-27-2010, 08:43 AM
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i use nothing on my uni filters except uni-oil or k&n oil.i would get a uni or k&n kit
clean the filter then reoil it. gearoil is not a good solution.check when you pull the uni off you may need to reclean the carb again. do this first then see if you need to rejet
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olderthan 2008 tomberline punisher 1500 spring 12g sliders 30mm cv pumper carb uni filter no rev cdi polaris xlt snowmobile shocks for front w/550 magnum springs & blaster fronts on rear and another buggy built working on mods gk-13 white spring 17 gram sliders so far
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#15
08-27-2010, 11:34 AM
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First uni filters do not come oiled you have to oil them. I would pull the filter and get you a can or two of break clean to clean the gear lube, making sure all oil is removed. I will bet this is your problem. Try removing the air filter and see how it idles, but don't run it without the filter for long. The gear oil is very thick and will plug the filter. You need to use filter oil weather it is uni or k&n oil but only filter oil. The stock jet in the carb can be anywhere from a 108 to 114. My experience when installing a uni and opening the exhaust as you had done is installing a 123 or mostly 125 jet. The buggies come from the factory running very lean so when you remove the restrictions on int. and exh. you need to richen the main jet. Now to check the plug you will need about 1200 foot run and bring your plug wrench with. You will pedal to metal from a dead stop and travel about 1200 feet about 4 phone poles. With foot still to floor turn off ignition until engine stops, let off throttle and pull plug to read. If you coast to a stop removing foot from throttle you will get a false reading since the engine will return to the idle circuit. You want the full throttle reading first, adjusting jet size until plug shows dark brown to gray in color. When this is acheived you would than fine tune the idle circuit which should be just fine since the engine is basically stock. TOM
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