400 problem

[Honda4LifeWes36]

Well heres the story.

Unloaded my quad at the local track to make a couple runs. Did a couple little runs (not going fast or nothing). Realized I was getting low on gas so I switched it over to reserve and did a few laps and decided to load it up. One of my buddies came and said he had some gas that I could use, so I put that in. I accidently switched it to off and started it and it was a loud backfire and just shut off. I, then, switched it to ON position and nothing. Its a really loud cranking sound like the carb is getting no gas but really I don't know. I pushed it down the hill and nothing. Maybe sounds like I have no back pressure??

WHAT HAPPENED?!?!

[trailrider894]

I would perform a cylinder leakdown/compression test. Check your sparks plug gap, all the little things. It really sounds like something is up on the inside.

[trailrider894]

What aftermarket mods are done to it? and has it ever been rebuilt?

[Honda4LifeWes36]

No rebuilds. Just little stuff.

Nerfs
White Bros Exhaust
KN Air Filter

Nothing big to the engine. No aftermarket cams or nothing.

I really don't wanna spend big money on it but it looks like I'm gonna have to. Its weird though because I was just taking it nice and easy and then the gas ran out and now it won't fire?!

[Honda4LifeWes36]

Also the guy the gave me gas was for his 4 stroke dirt bike but you think it would be pretty much the same or Ok for my quad.

[trailrider894]

Well, try to crank it over, and tell me if there is back pressure. ( just put your hand over the exhaust and feel ) He might have been running a high octane fuel or something...

[bherriman]

Make sure the backfire didn't blow the carb. off the intake boot...this happened to me and I was looking all over for what was wrong thinking it jumped time and what not..all it ended up being was the carb was blown off the boot.

[slightlybent47]

Check everything but look at the plug and change it, it may have just fouled the plug.

[tri5ron]

Originally posted by bherriman
Make sure the backfire didn't blow the carb. off the intake boot...this happened to me and I was looking all over for what was wrong thinking it jumped time and what not..all it ended up being was the carb was blown off the boot.
X2

[Honda4LifeWes36]

Alright thanks guys. I'll check that out today and let you know.

[Honda4LifeWes36]

Hardly if any back pressure when I tried to start it with my hand behind the exhaust...

[trailrider894]

I am gonna put my money on a top end rebuild. Rings or a piston, could be a head gasket too... Stuck exhaust valve or intake valve. The list is long...

[Honda4LifeWes36]

wow guys im sorry but im gonna feel dumb when I tell you this.

I was going to replace the spark plug first and found my old one just laying loose in the boot. put the new one in and tightened her down and she fired up.

I'm so sorry and stupid about that. I thought it was something way worse but I didn't check into it yet.

[trailrider894]

Lol that would explain the loss of compression... XD

[togup]

i blew a spark plug out of the cylinder once ,thought i blew up the motor

[tri5ron]

Originally posted by Honda4LifeWes36
wow guys im sorry but im gonna feel dumb when I tell you this.

I was going to replace the spark plug first and found my old one just laying loose in the boot. put the new one in and tightened her down and she fired up.

I'm so sorry and stupid about that. I thought it was something way worse but I didn't check into it yet. HAHA ! that's funny !
Don't feel too bad though, I've heard of more than one guy on here who have just about drained the battery dead, trying to start their bike,.... Only to discover that the emergency kill switch was in the off position !
(Yes,.. I would be one of those guys too.... DUH !)

[clemsonteg]

Originally posted by tri5ron
HAHA ! that's funny !
Don't feel too bad though, I've heard of more than one guy on here who have just about drained the battery dead, trying to start their bike,.... Only to discover that the emergency kill switch was in the off position !
(Yes,.. I would be one of those guys too.... DUH !)

When I was doing plug checks when I was rejetting mine I kept leaving the boot off and trying to restart it.

[Honda4LifeWes36]

Yeah it was the first time it ever happened to me (blowing the spark plug off)

That must've been what the loud backfire was when it ran outta gas. WOW.

I was about to order a whole new top end!

[IMSROLL450R]

Originally posted by Honda4LifeWes36
Yeah it was the first time it ever happened to me (blowing the spark plug off)

That must've been what the loud backfire was when it ran outta gas. WOW.

I was about to order a whole new top end!

Haha add this to my checklist..... so funny.

Glad you figured it out.

[MidnightBlade]

same happened to me, i kept hearing this ticking and had som major loss of power so i thought it was valves. took it to my friends opened her up and the valves were perfect, meanwhile when we turned the motor over to get it to TDC i saw the spark plug wiggle a bit. i tightened the spark plug and she ran like a champ.

i would also be one of the ones who cranked till the battery died to find the killswitch was off, or the plug boot was off. :grr:

[skullracer34]

i have a ? on jetting a 05 450r carb on a 400ex stock bore i have a full exaust procom cdi box and a webb cam degreed 7 degrees i have a 48 pilot 190 main and a/f 2-1/2 out needle is set 2 notches down from top it runs strong on top end and mid but when i rev it up and let off it pops and cracks out the exaust i put a 50 pilot in it but it seems a little big any suggestions will be helpfull from you guys that have done this


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[skullracer34]

i finally got it figured out on my jetting thanks everyone on your intell