Back to stock muffler and now wont run!

[maplechill]

i have an '04 400ex. when i got it there was a White Bros muffler on it. the guy i bought it from said it was re-jetted when the muffler was put on and those were the only engine mods to it. engine ran like a top. 2 pumps on the throttle lever, hit the button, rock and roll.

well, the muffler wasn't mounted quite right and is now junk. i bought a stock exh and put the stock muffler on it. it ran for about 2 min then quit. now i can't get it to start at all.

the service manual says to just go up one size on the jet for a muffler upgrade. doesn't seem like a jet one size larger would keep it from running at all w/ a stock muffler.

i'm taking off the carb tonight, but wondered if anyone out there could give me some pointers. any help is greatly appreciated. oh, and i've only run 91 octane ethanol free gas with it. i've gone through a couple of tanks so i don't think it's a bad gas issue.

[Thumpin440ex]

The main jet really has no effect on idle.. Did you change that or a secondary or pilot?? Are you sure it still has gas, or you didn't turn the fuel off?? Did you make sure the carb was put back together correctly?? The stupidest thing can make these not run.. LOL



John

[maplechill]

yeah i know what you mean. carbs can be very touchy. I didn't change anything with the carb. according to the guy i got it from it is only jetted for the muffler. no other changes.

it def has gas and the fuel is on. i took the plastic nut off the bottom of the carb to look for sediment and it was super clean.

i've been driving it for a couple month's w/ the White Bros muffler and haven't had any problem what-so-ever. started and ran like a champ. after that one broke off, i replaced it with a stock muffler. no other changes at all. it idled for about 2 min then quit and now won't start.

[chronicsmoke]

I've never heard that before.. have you tried bumb starting it?

Where abouts are you in Upstate NY?

[maplechill]

i live in Mineville. a small town about an hour south of Plattsburgh

[4strokernow]

Check to see if you have spark, my cdi went on me and I had a similar question a while back, I put in a new cdi and she fired right up. Just throwin that out there...

[AtvKid4Eva]

it should still start if it ran fine before putting the stock pipe on. If jetted wrong it might run rich or lean but still should start.

Make sure you didn't bump a wire or something during install. Might just be a coincidence lol.

[maplechill]

it did run for about 2 min with the stock muffler, then it died and wouldn't start again. i can get it to turn over if i choke it and hold the throttle open. it just runs for a second or 2. revving way up like it's burning a bunch of fuel then dies right off.

i thought there might be a restriction in the muffler so i took the muffler cap off (2 of the 3 friggin bolts broke) and core was fine. is it possible that there is still a restriction?

[Thumpin440ex]

No something is def not rite.. The stock muffler is not going to cause the bike to not run, even if it is still jetted for slip on or full exhaust.. I would start going back over my steps, possibly pull the carb again to see if it is infact back together correct.. If you have spark, then you are not getting fuel..


John

[dxcody]

well you said it ran for about 2 minutes, may try to replace your plug, i know it takes more then 2 minutes to carbon faul a plug but since you switched back to the stock pipe it would have been running a hair rich and POSSIBLY fauled out the plug.

My buddies 450r did that (he didnt switch back to the original pipe) but he went out one day and fired up his 450r and it ran for about a minute and just shut off then it didnt start again. Turned out his stator was bad.

But in my opinion it kinda sounds like the plug maybe. Cant hurt to try.

[CJM]

You sure you have enough gas in the tank? Gas is on or on reserve? Its getting spark and the carb is getting fuel.

What does it do when you crank it, try and turn over or just crank and crank and crank?

[maplechill]

good idea. i should get another plug while i'm at work.

[maplechill]

Originally posted by CJM
You sure you have enough gas in the tank? Gas is on or on reserve? Its getting spark and the carb is getting fuel.

What does it do when you crank it, try and turn over or just crank and crank and crank?

yup the tank is almost full and the gas is on. the spark is what im questioning now. i'll check/change the plug tonight. God i hope it isn't the stator...

when i try to start it, it just cranks and cranks and cranks.

[dxcody]

Any news?

[maplechill]

last night i got home and decided to crank it over and see what happened. it ran for about a minute and then stalled out same as before. i took the airbox lid off and it would idle, but if i hit the throttle it would bog and die. from what i know, the main jet really only comes into play at half throttle and up.

so i turned off the fuel and loosened the clamps on the carb to turn it to the side to get the cap off the bottom. i took the main jet out and it says 152. the manual says it should be a 148. unfortunately i didn't have one and have to pick one up today.

is it likely that the main was all that was changed with just a muffler added to it?

still have to drill out the little 6mm screws and tap them for the end cap.

[maplechill]

ok this is weird. i just called a Honda dealership and they said all they had was a Keihin kit and the closest they can get to a 148 is a 147.5. they have to order a 148 by the oem number which will take them a week.

does that sound right? why wouldn't a kit come with a 148?

[dxcody]

Yes, if it was jetted properly then the main jet would have had to be bumped up a little bit. PM me your address and i will send you the main jet you need for the cost of a postage stamp if you need it. I got like 4 of them. I actually have 3 full carbs. So if you need me to i will.

[maplechill]

OK! i got it figured out and running great. after changing the spark plug, putting the stock main jet in, and checking compression. i had the fuel turned to 'on' and opened the drain screw on the carb. fuel came out slow at first but started to flow better.

then, on a tip from my bro, i turned the valve to 'res'. it f'n POURED out! so i took the gas tank off and drained it into a tank through some paint filters. you would not believe the crap that came out! all kinds of dirt and even a couple pine needles. looks like the previous owner was using dirty funnels to fill the tank.

so i cleaned the the tube screen w/ carb cleaner and flushed the tank. after i let it dry out in the sun, i put everything back together and it runs like a champ! i didn't dyno it or anything, but i swear it runs better now that it is cleaned out and is back to the stock jet and muffler. well, kind of. i do not run with the cap.

thanks very much to all that gave suggestions here.