tuning help???

[wolfe 21]

Hello,

I've got an '04 400ex that has been setting since september '09 (Lost my job and health coverage) and have recently gotten it back out to get going again. I started it and let it run occasionally, but not nearly as frequently as I should've I'm sure. Anyway, now that I'm trying to get it going again it doesn't want to run well at all. My motor, jetting exhaust are all stock (38 primary, a/f is 2.5 turns, main is stock as far as I know) with a K&N filter and pre-filter the only mods. I have a 40 primary setting on the shelf to be installed, just haven't done it yet. Wanted to get it running right first.
My problem is when I start it, the bike will only idle for about 30 seconds unless I have the choke on full. With choke, it idles fine and will rev well. Have had the carb out and apart to clean it up twice, and the only thing I've modified is that I took out the little plastic disc that sits inside the float bowl because it was holding my floats shut and not allowing fuel in (I believe it's called an anti-buffeting plate or some such; not on parts diagrams I've found). Anyway, it sounds like I've got a miss or backfire as when I let off the throttle it sputters and without the choke the motor will not accelerate and just bogs out when I give it any throttle. I've checked the Fuel (bowl full), gets spark because it runs, exhaust is tight (replaced gutted stock exhaust with stock exhaust) and carb and intake clamps are tight. Also, it makes no difference if the airbox lid is on or off.
I'm down to either tearing the carb apart again or taking it to my local shop and paying to get it fixed (not relishing this on $8/hr). Any help greatly appreciated.

James.

[tri5ron]

does it have FRESH gas in the tank, or is it the old stuff from letting it sit ?

have you looked at the spark plug ? is it a nice cardboard brown color? or does it look more ashy/whiteish ? sooty black?

How long did it sit?
Have you recently cleaned the air filter?
Did you flush out the tank AND petcock AND fuel line when you worked the carb ?

Have you checked for any cracks in the rubber intake boot ?

Is your battery fully charged ?

[wolfe 21]

lots of new things to check I guess. No, I did not check the petcock or tank when I cleaned the carb as it still has the majority of a tank of gas in it from the last time I rode it. Does gas go bad even with fuel stabilizer in it. It's been sitting for about 14-15 months, but has only started giving me trouble when I tried to start it in the last couple months. Air filter was cleaned last fall and hasn't been ridden since, though I did oil it before trying to start it up the last time.

I guess tomorrow I'll pull the plug, empty the tank and carb and get some fresh fuel. If that doesn't solve it, I'll check the boot for cracks. How would the battery effect running (Will crank fine and fires, just will not continue running). Anything else to check (my buddy's warrior had some clutch safety switch that prevented it from running right; do 400's have anything like that). Plug should be a light tan/brown color correct. Fouled out is black (shouldn't be as only give about 2 pumps before starter) and lean is white and ashy?

James.

[tri5ron]

Depending on where you are located,
and what the local formulation for fuel is in your area,
(yes,... it is different in some areas than in others),
untreated gasoline, sitting in sealed fuel can, at a constant reasonable temp., is good for about 6 months max.,
and about a year if treated with a stabilizer.

any longer than that and your just pushing your luck.

sitting in a vented floatbowl, tiny fuel line, vented fuel tank, changing temp's,..... Probably not as long.

re-clean your airfilter, due to the oils become gummy when allowed to sit for extended periods of time, and use that old gasoline as some weed killer.

Clean out your petcock, and In-tank filter.

Flush the fuel tank with some fresh fuel, and you will probably have solved your problem, ...
(providing you did a good job of cleaning, and clearing out, any gummy gunk when you cleaned the carb.)

p.s.- it wouldn't hurt to get a new sparkplug, but isn't absolutely necessary either.

[wolfe 21]

I live in Ohio, so if the fuel is like everything else in this state I'll be lucky to get 6 months out of the treated variety.

Gonna have to wait to check the wheeler out, it took a backseat to another of my hobbies today. Will hopefully get back to it middle of the week when next time off comes around (3rds suck; seems like all I do is work and sleep and I still feel like a zombie half the time). Will drain and replace fuel, clean tank and filter and replace the plug. Everybody agrees NGK is the best right (not like the which tire or oil debates)?

James

[DragonGunner]

You didn't mention if you tore down the acclerator pump on the carb...or I missed it....if you didn't this is probably your problem..I can a 400ex carb that sat for yrs..I cleaned it up an it still ran like crap, the diaphram in the accerlerator pump was crusted up from dry gas...I cleaned an then it ran like a top....my friend had a banshee that sat for months...he said he tore his carbs apart an clean 3 times...I went over..he was using compressed air to clean his carbs.....lol....you are using alot of carb cleaner......right?

[wolfe 21]

Yeah, no compressed air for me. So far I've used 2 cans of Gumout Carb&Choke on the thing, though this time around I'll pay special attention to the pump diaphram.

James.

[wolfe 21]

well, pulled the tank and drained and flushed it today. checked the Petcock, filter and fuel line and checked all my connections and the rubber sleeve on the carb and didn't see anything loose or cracked as far as I could tell. Tried to pull the plug and can't get the thing out. What size socket do I need for that?

Anyway, put in fresh fuel and tried again. Still only runs with the choke on full. If the choke is off and I hold about 1/4 throttle it will idle there and sputter a little, but as soon as I let off the throttle and try to get back on, it just sputters and dies. It also sounds like it's sucking air somewhere, but I can't find any leaks. Any ideas? I'm getting tired of screwing with the thing right now. Seriously considering trading for an EFI Z400. :eek:

[CJM]

18mm socket, must be a thin wall tho.

The carb is probably not on the boots right, check to make sure they are tight and on properly.

Im betting its cause your sucking in air somewhere.

[wolfe 21]

Yeah, I thought I'd need an 18 mm. The only one I have available is plain deep well, so pulling the plug will have to wait until I get the correct tools (family of domestic cars and trucks means mostly SAE toolsets).

I guess I'm tearing the carb out again, this time I'll pay special attention to the carb boot and the filter connection. Makes sense I guess. An air leak would lean the mix out, having the choke on full should counteract that by restricting air into the carb and dumping extra fuel into the mix, correct? Any other suggestions to check while I'm in there. Could out of spec valves be causing my ill running (they probably need adjusted by now)?

James.

[CJM]

Doubt the valves are gonna be that far outta spec but it never hurts to try.

Look specifically at the boot thats bolted to the engine, as time wears on it can wear out and crack since its just rubber.

You are correct in thinking its lean due to the air getting in there, and putting the choke on does restrict the airflow.

[fearlessfred]

how did you detemine that the float bowl is full.the reason i ask is because you stated that you removed the baffel that sits below the main jet,in order to adjust the floats. you should not have to do this to adjust the floats. im thinking maybe you have allready cured the orginal problem and created another one. a simple way of checking level is by holding the floatbowl on by hand and letting it fill then turn fuel off and and then ckecking to see if it is half full ( when the bowl is installed the level is even with were the bowl meets the carb) just an idea please take no insult by anything said

[wolfe 21]

No offense taken, I'll take any ideas that may help. I assume the bowl is full because I turn the petcock off and then opened the drain screw on the side of the bowl and watched the fuel run out the little hose in front of my swingarm until it stopped (5-10 seconds). I don't know that the floats are at the correct level, but I never messed with them so I assume they are. As to the baffle, I removed it from the bowl because after I cleaned and reassembled it the first time the baffle wedged the floats in the closed position and was allowing no fuel into the carb. Probably should have looked further before taking it out as now I don't know where it's at (someone else "cleaned" my garage and now I can't find a thing).

james.