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View Full Version : Popping on Decel


BoneStockHonda
03-07-2012, 11:05 PM
05 400ex completely stock motor.

The quad ran fine for years then one day it started popping through the exhaust on decel, mainly from higher rpms. I tried adjusting the valves twice since then but its still popping.

A friend of mine told me he had a similar problem before on a 4 stroke dirtbike and it ended up being a leak in his exhaust somewhere. I find this kind of hard to believe but I checked the exhaust for cracks while on the quad and didn't see anything. I was going to pull the exhaust off and check for cracks and replace the gaskets on the exhaust if there's no cracks.

I just wanted to get some input on what the problem could be before I start getting into it. I was also thinking it could possibly be carb related because of the all the ethanol **** in fuel now.

Any ideas what it could be?
AtvKid4Eva
03-08-2012, 05:36 AM
your friends right, a leak int he exhaust will cause this. Check and make sure your exhaust o-rings are still good and no air is getting out there. Also check where your carb bolts to the motor and the airbox for a loose boot or a tear. My brothers 426 did this and we found out the exhaust stud nuts were loose. if none of these are the problem then it is carb related.
ggodfreyX
03-09-2012, 11:13 AM
If you haven't changed the jetting and previously the quad ran fine this is likely as AtvKid stated, an air leak in the exhaust or intake. Confirm that both carb boots are tight and on sufficiently. Use WD 40 to check for air leaks while the quad is running. If you spray around the intake or carb and there is an air leak the engine will respond. If you spray around the exhaust you can look for bubbles. Start with the exhaust and do it as soon as you start the quad so the exhaust is not to hot or it will bubble anyway.
BoneStockHonda
03-22-2012, 12:19 PM
Well I finally got around to looking into it. I pulled my heat shield off and I think I found my problem lol. I already lined up a stock header for $25. Now my question is should I buy or it? Or will this happen again and I'm better off welding it?
BoneStockHonda
03-22-2012, 12:20 PM
Also what kind of metal is the stock header made from?
01boneless
03-22-2012, 12:26 PM
ive never seen one crack there..:/ but a new header should fix it..also it looks like you have a MAJOR oil leak around the base gasket
Thumpin440ex
03-22-2012, 12:42 PM
Originally posted by 01boneless
ive never seen one crack there..:/ but a new header should fix it..also it looks like you have a MAJOR oil leak around the base gasket


INDEED


John
HondaRacing83
03-22-2012, 01:51 PM
My 05 hasnt done that yet lol. A new header will fix it, might as well grind the inside welds off that new one before you put it on. I hope mine doesnt do that.
BlasterEaten250
03-22-2012, 01:52 PM
Mine cracked there after 10 years of riding. I bought a used one and its been fine since.
TheAwesomehonda
03-22-2012, 01:59 PM
WOW i've never seen a stock header crack like that eather. I thought there more heavy duty then that but i guess not. Also I've got a nice stock header.
BoneStockHonda
03-28-2012, 03:49 PM
Originally posted by 01boneless
ive never seen one crack there..:/ but a new header should fix it..also it looks like you have a MAJOR oil leak around the base gasket

No leak that's just some cable lube from spraying my clutch cable down there.

So I guess the route I'll go is a new header since this seems like a rare problem.

Thanks guys.