ATV Connection

uchi · #1 (**permalink**) 05-01-2008, 07:05 PM

hey guys, ive tried searching but i cant find the answer. firstly ive got a 2003 honda 400ex. i bought it used from the dealership so im not sure of whats been done to it aside from a pipe, filter and i drilled out the airbox. ive found that if the bike sits for a bit its hard to start and it wont idle at all for a few minutes on its own no matter where the choke is set to. but heres the issue i have now, yesterday i started the bike and it was sounding poppier than normal, it ran for a minute and then died and wouldnt start again. its got a full tank of premium and i checked the its getting fuel. i just ordered a sparkplug tool so i can change the plug but the ignition wire is giving off a strong spark. im hopeing its just the spark plug but if not then what else could it be? ive read about the kill switch being a culprit and i cant find any documents that talk about bypassing it. its definatly something id like to get rid of. also if you guys could point me to a FAQ section on here or perhaps a post thats gots some tips and tricks for this thing id appreciate it. thanks for your time

Bounce400ex · #2 (**permalink**) 05-01-2008, 07:43 PM

If you're getting spark it's not the kill switch. You might have leaned it out when you drilled holes in the airbox and fouled the plug. When you do something that changes the fuel/air mixture the carb needs to be tuned. Running lean is not good.

uchi · #3 (**permalink**) 05-01-2008, 07:46 PM

thanks for the reply, i wont know until i get the tool to check the plug to see what its runnign like. i havent ridden the atv since drilling the holes, only run it a few times but it hasnt left my garage. do you happen to have a diagram or perhaps a link telling me how to fatten up the air fuel mixture a little to compensate? also assuming i can do so without re jetting, how can i tell when ive added enough fuel?

uchi · #4 (**permalink**) 05-01-2008, 09:29 PM

just to add, fouling a plug would mean ive dumped too much fuel on it, so i think if anythign it may just have built a nice white crusty layer of crap on the plug. hopefully thats all it is

Basstromboon · #5 (**permalink**) 05-02-2008, 12:19 AM

let us know. Just curious

uchi · #6 (**permalink**) 05-02-2008, 12:22 AM

will do, the sparkplug tool should be in tomorrow the store said and if not then by tuesday at the latest. which sucks because it means i miss a day of offroading this weekend.

uchi · #7 (**permalink**) 05-06-2008, 10:06 AM

well after a headache ive got it sorted out, kinda. the 18 mm plug wrench had to be ordered, so it came in on saturday, was a little too long and kept hitting the bottom of the tank, so a hacksaw fixed that problem. i yanked the plug out and it was completely black. turns out the local place and the parts store dont have the proper plug for my 400 so i had to order 1. went home cleaned up the plug as best as i could and she fired up. runs like crap but it runs, so im jsut waiting for my new plug, supposed to be here today

josh_13 · #8 (**permalink**) 10-27-2008, 10:55 AM

well the other day i went to ride my 400ex and i had been riding it just about all day, electric start isn't workin right now so i pushed it off and it cranked, i turned it around and then it died and wouldnt start back. i put new gas in, cleaned the carb, cleaned the jets, it was getting spark, put a different spark plug in, and still wouldnt start. can anyone give me some help b/c now i'm lost

70judge920 · #9 (**permalink**) 10-27-2008, 12:14 PM

hi josh I just worked on a 2000 400ex it had fuel ,compression,spark but would not start,I found that the timing chain had worn,and had jumped a number of teeth I put a new timing chain in ( $100) set the valve lash now it runs great.I heard this is a common problem,hope this might help