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MagnumSturd

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All, I am running a 38mm PE keihin carb on my 90 warrior. My jetting is a #160 main, #50 pilot and AJM needle on the second notch. My problem is my plug is covered with black soot. At idle and with a short rev there is a lot of black smoke coming from the exhaust. If I put in a brand new plug just let it idle and then pull the plug it's still getting covered with ashy soot. Would this be my pilot jet to big? Would moving it down to a #48 or #45 solve this? The bike seems to be running really hot. Also when starting the carb sometimes pops or backfires? I have an open air box with a K&N filter and a supertrapp exhaust. I could move the needle clip up to the first notch to lean it out but think its more on the idle to 1/4 then 1/4 to 3/4. Thanks for the reply.
 
I thought black soot means running rich too. It's not oily at all but real sooty. All around the bike runs good. No problems at WOT. But she is running hot! That is why I was thinking the pilot, because it's idle to 1/4 smoking the most. After a good cleaning of the carb she fires right up. After making some adjustments to the needle clip position either up or down and turning out the air screw nether seems to make any immediate improvement to the plug. If the main jet only controls 3/4 to WOT and the needle clip position is not making major differences then what now? Thanks for the help.
 
i know that but if it pops through the carb its lean, when i bored my carb i richened it right up but it still on the lean side. Its runing hot? how hot? can you put your hand near the motor really close with out touching it or does it burn your hand
 
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Gets super hot fast. A five minute warm up and its burning. That says lean right? But if it's lean shouldn't the plug be white? So confused!!!
 
YAMAHAULER said:
usually black soot on the plug means she's running rich
Click to expand...


That's why I asked how it ran otherwise. Ya know, surging at WOT, loading up, etc... You may want to try jetting back to the stock warrior specs and get a baseline, then go from there. It would atleast save you the headache of throwing different jets at it, somewhat hoping to stumble onto the solution. Just a thought.
 
I just tried moving the clip on the needle to the top position to see the results. It fired right up. At idle the smoke definitely cleaned up. I turned up the idle so she was reving up a bit. Then closed the air screw until she started to bog. Doing small slow adjustments it rev'd at its highest about 2 1/2 turns out. Even backing it out more she stayed at that same rev. I bet I could have pulled it out with no difference? I pulled the plug and way less soot. After replacing the plug I let it warm up then gave her a couple hard rev's and now it seems to be smoking more at 1/4 to 3/4 throttle. I have to get it rideable to really see how she runs. Is running on this clip position bad? The getting hot issue seems to be more exhaust. The head I can get close with my hand. The exhaust has been hotter than usual? All though the gas is fresh, I think she hates this new gas. I have owned her since 1990 and never had issues with this same set up back in the day. I have a few ATV's and they all seem gas fussy these days. Anyway, thanks for the thred. Info. Welcome.
 
Yes, I was talking about the stock warrior carb specs. From your 1st post it sounded like you had just gotten this bike/carb. I didn't realize you have been running it this long. So it ran fine until now? You're sure the air filter is clean? You have a deffinet rich condition, so getting that problem solved is a must before you can take it any further. By you moving the clip to the very top of the needle, you leaned out some of the idle circut, and really leaned out the mid range. That right there tells ya that you have a rich condition, since it is running better. If you suspect gas to be part of the problem, drain it and put in some GOOD 93 octane gas and see if that helps. I would just go over EVERYTHING you can think of before going to extremes, if she ran good until now there's probably something out of place. But, assuming your jetting is off, I would drop the pilot jet a little (since lowering the needle leaned it some) and drop the main down. Does the engine surge at wide open throttle? If so your main jet is too large and needs to be swapped out for a smaller unit. Just go one size at a time until the surging at full throttle stops, that is a pretty good way to get the main jet right.

One other thing, do you still have the instrutions for that carb? Or, can you get them? Wish I was there in person to help ya.
 
That seems like a good plan. Unfortunately this atv has not been used much over the last few years. Maybe a few times. So it hard to give you the total story on how it's running. I bought myself and my wife a couple 4x4 ATV's and last year got my 8 year old a brand new LT80. But seeing her tearing it up already is making me realize how much Im missing the warrior. I will say ever since I put this carb on its run rich. But never this rich. I do remember last summer when I rode it last my buds telling me riding behind me sucks stink'n of fuel and exhausty and i remember it was loading up and hard starting. I will get her all back together, order some jets today and take her out for a run to see what's it doing now.
 
If it hasn't been used much, clean the carb. Could be some trash tucked away somewhere. I'll try to look at those instructions before I leave work. If not will look at them when I get home.
 
Those instructions are pretty much the standard way to go about adjusting carbs. If I were you, I'd clean the carb for good measure and see what happens. From there you know that it is good and clean, hopefully runs a littler better, and can make a better decision on what jetting changes you need to make.
 
Damn, I know somebody on here is Running that carb! I just can't think of who right off. I'm pretty sure there are some threads on the 38mm Keihin here. Do a search for that info. Basically though Pat is right, 1st off it has got to be clean. Do a couple real hard wot runs, shut it down, roll it into the driveway/garage, whatever & pull the plug, see if it's black. Yes, chopping the threads will give the real story but just checking the plug will get you in the ballpark & that's what we're after right now. You can always check the plug per the throttle range that you're running in, it'll take some time but you'll find it. 1st things 1st, clean it, ya think it's clean? Clean it again. Also make sure that your fuel line isn't goin to **** from inside out, ethanol fuels do nasty things to some fuel lines. Sorry, I know some of this is all redundant.
 
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