2004 400 ex

[Camaden]

I have been having trouble starting this thing, it has had about a 1/2 of a tank of gas ran through it, and the last few times I tried starting it, it backfired horribly. Yesterday I tried firing it up again and finally got it started only to have it back fire more so why it was idling I reved it up a few time nothing big and noticed about 6-8 inches of the pipes right out of the head were cherry red, what would cause this? Its under warranty but I have a few days before I can take it in so I was just wondering...

[nosliw]

any mods to it?

check the bolts or studs or whatever connect the headpipes to the head, they might be loose- letting air in.

[Camaden]

None yet just got it for xmas like I said only 1/2 of a tank of gas has been used since new. But will check the bolts to make sure they are tight. The dealership was supose to do this but I guess it could have come loose, ill check.

[Camaden]

Everything seems tight any other suggestions?

[cals400ex]

make sure both the air boots (the one that connects the carb to the head and the one that connects the carb to the air box) are tight. also make sure neither of them have rips or cracks in them. look close, they are hard to see sometimes.

[balls2da-wall]

did you break it in properly?

[Camaden]

Break it in it doesnt have but maybe 2-3 hrs on it, and it wasnt whipped on by any means, at least not yet:D My cousin said I might hae a valve problem do you guys think this could be true?

[balls2da-wall]

I say you must have got the 1 out-of 1,000,000 defective hondas:D take it to the dealer and see what they have to say.

[400ex28]

Just take it to your dealer

[397ccEX]

my cousins dirtbike does this and the dealer said it was normal

Originally posted by 397ccEX
my cousins dirtbike does this and the dealer said it was normal normal for a yamaha dirtbike

[Camaden]

okay I talked to the dealer and they said it was normal and that most riders dont noticed it cuz they are on the 4 wheeler. He also said the pipes can get up to 800 degrees. This sound right to you guys?

[balls2da-wall]

pipes do glow red...more so in the winter because the engine is leaning out a little more than in summer...hard starting is normal on a cold engine for a 400ex. As for backfiring...ive never had it backfire...I have had it make a chuging sound until its up to operating temp.

[Camaden]

Thanks, maybe it was just backfiring because the spark plug was fouled..