Backfire in carb?

[GAZ-V-21]

As most of ya know i jetted my carb the other day and changed spark plug it runs great but when i first start it after sitting overnight its been harder to start than before jetting im needing to use choke. Also after it starts for the first couple seconds there is a couple little backfire sounds coming from carb any ideas what might be causing this? Also there is no backfire from pipe so im good there.

[GAZ-V-21]

It only does the backfire once or twice right after startup and when revving engine.

[TheAwesomehonda]

Is it like a cough/spuder coming from the air filter?

[GAZ-V-21]

No farther up than filter sounds like it inside the carb but ya is like a cough/spudder only happens the first time i start it after sitting over night if i shut it off and start again it dont do it. Also ive been needing to use choke first time i start it.

[TheAwesomehonda]

Originally posted by GAZ-V-21
No farther up than filter sounds like it inside the carb but ya is like a cough/spudder only happens the first time i start it after sitting over night if i shut it off and start again it dont do it. Also ive been needing to use choke first time i start it. I get that spuddering to when I start mine cold but it goes away in 10 to 40 second depending on how cold it is but idk if you could change your jetting in any way to fix this. I don't think it is anything to worry about if you can start it and i doesn't do that when its warm but that doesn't answer your question.

[01boneless]

Originally posted by TheAwesomehonda
I get that spuddering to when I start mine cold but it goes away in 10 to 40 second depending on how cold it is but idk if you could change your jetting in any way to fix this. I don't think it is anything to worry about if you can start it and i doesn't do that when its warm but that doesn't answer your question.
dude your gonna have to stop telling people not to worry about stuff. this is the same backfire that caught my filter on fire and just about burnt my airbox.
TO THE OP in my case my quad was a little rich thus causing it to flood when i tried to start it. the backfire was from the fuel combusting. you have to be real rich to actully have a fire like i did but imho ur a tad rich. but sometimes being lean can cause a backfire aswell ...do a plug reading and report back

[TheAwesomehonda]

Originally posted by 01boneless
dude your gonna have to stop tellong people not to worry about stuff. this is the same backfire that caught my filter on fire and just about burnt my airbox.
TO THE OP in my case my quad was a little rich thus causing it to flood when i tried to start it. the backfire was from the fuel combusting. you have to be real rich to actully have a fire like i did but imho ur a tad rich. but sometimes being lean can cause a backfire aswell ...do a plug reading and report back That is probobly my problem to but it seems to be common on the 400ex when you first start it to spudder. Mine even did it when it was all stock so how do you explain that? haha I'm not sure how bad his spuders though.

[01boneless]

Originally posted by TheAwesomehonda
That is probobly my problem to but it seems to be common on the 400ex when you first start it to spudder. Mine even did it when it was all stock so how do you explain that? haha I'm not sure how bad his spuders though.
400's come lean from the factory :blah:

[TheAwesomehonda]

Originally posted by 01boneless
400's come lean from the factory :blah: I'm confused, are you saying the spuddering is being caused by leak or rich? Cuz my 400ex is surely not lean.

[01boneless]

Originally posted by TheAwesomehonda
I'm confused, are you saying the spuddering is being caused by leak or rich? Cuz my 400ex is surely not lean.

i thinks its to confusing. OP read your plug. i think u may be a little lean a 152 shouldent be rich.

[quadracer556]

Originally posted by 01boneless
dude your gonna have to stop telling people not to worry about stuff.

i see people get banned all the time for less serious offenses than giving someone blatantly retarded *** backwards advice yet this kid is still rolling around somehow.guess that settles it,here its dont take sh** and give it right back...banned. not know wtf your talking about,back nothing up with facts and offer only opinions.....sweet,ur good to go.what a joke.dont bother replying awesomehonda,no one cares about your jabber anyway and certainly not me.

GAZ do a plug chop and report back with what it looks like....and whatever you do dont listen to the your fine just run it guy.lol wtf

[GAZ-V-21]

I will check the plug tonight and let ya know thanks guys

[GAZ-V-21]

I hope its just something simple kind of worried now

[01boneless]

Originally posted by GAZ-V-21
I hope its just something simple kind of worried now
it will be prolley a small jetting adjustment

[kt1148]

subscribed. mine does the same thing sometimes. would like to know what you find out.

[GAZ-V-21]

Ya its weird only does it one or two pops then runs great

[TheAwesomehonda]

Originally posted by kt1148
subscribed. mine does the same thing sometimes. would like to know what you find out. I'm with you on that. @GAZ-V-21 So how cold has it been when your starting it and does this? Does it do it when its 20degrees F and 80F? Also how long does it have to be choked for and full or half choke?

[GAZ-V-21]

I would say its been around 60 degrees ive only tried it full choke its weird cause it only happens after sitting overnight if i go out and start a few hours later it does not need choke and does not backfire in carb

[TheAwesomehonda]

Originally posted by GAZ-V-21
I would say its been around 60 degrees ive only tried it full choke its weird cause it only happens after sitting overnight if i go out and start a few hours later it does not need choke and does not backfire in carb Oh its that warm well that isn't so common. Mine does it mostly when its real cold like 40 degrees or less. Yeah there right you may have a little jetting problem.

[GAZ-V-21]

Here is link to vid of my 400 and what its doin
https://www.youtube.com/watch?v=ftatHuQIwCw&feature=youtube_gdata_player

[GAZ-V-21]

Here is new spark plug i put in the tip is pretty dark for being new
<a href=http://s1095.photobucket.com/albums/i465/GAZVATV/?action=view&current=IMAG0178.jpg target=_blank><img src=http://i1095.photobucket.com/albums/i465/GAZVATV/IMAG0178.jpg border=0 alt=></a>

[GAZ-V-21]

This is my 400 and what its doing
https://www.youtube.com/watch?v=ftatHuQIwCw&feature=youtube_gdata_player

[JOHNDOE83]

I have a few odd questions that might solve your issue?

How high does your oil read on your dipstick?

How much does the oil reading change after you warm up the motor?

It's very odd that a 155 main and a 42 pilot are to rich for a EX even a mostly stock one, exhaust maufacturers recommend a 155 for all stock EX with a aftermarket slipon.

Try going 3 to 3.5 turns out on your a/f screw and see if that does anything, if it were to rich you wouldnt need the choke to start it cold.

Also check out the FAQ section here www.jetsrus.com

[GAZ-V-21]

After warmed up it goes on full level on dipstick not sure bout when its cold but ill check later. What could it be with oil?

[quadracer556]

for the plug chop did you run it wide open for a few seconds then cut the power while it was running wot?hondas are typically cold blooded so if you did the above procedure and the ceramic on your plug is golden brown then you should be good to go.my efi 450 perfectly tuned backfires when i run it cold.im not saying totally ignore it but there's only so much you can do and expect especially if your plug looks good.

[GAZ-V-21]

Plug is black

[CJM]

I think he has an air leak somewhere, exhaust, headers, at the carb possible.

[01boneless]

^very possible check between the carb boots air filter ect did u put on a new exhaust crush gasket? also really your plug is dark but idk think its real rich you can see some light areas. push the free play out of your throttle lever and start in in the mornings giving it gas while u try and start it could be flooding it out. was that plug after a ride?

[GAZ-V-21]

I dont know if this means anything but when i gapped plug i gapped it wrong way wrong sticker on frame says gap at 0.6-0.7 millimeter i gapped it at .065 inch. Could that make it harder to fire and keep pushing fuel causing backfire?

[01boneless]

Originally posted by GAZ-V-21
I dont know if this means anything but when i gapped plug i gapped it wrong way wrong sticker on frame says gap at 0.6-0.7 millimeter i gapped it at .065 inch. Could that make it harder to fire and keep pushing fuel causing backfire?
it may..dont even gap the plug on ngk im pretty sure they come
pre-gapped but i cant see that causeing your problem

[JOHNDOE83]

Originally posted by GAZ-V-21
After warmed up it goes on full level on dipstick not sure bout when its cold but ill check later. What could it be with oil?

If the oil level is to high it will pop, puff and spit at certain RPMs.

Unless you removed 5 bolts to change your oil you may not have drained all of it and adding the factory recommended amount may be to much "just throwing that out there".

If the plug got that dark that quick "assuming" you did a correct plug run or even ran it around for 20-30mins I would say you either accidently used mixed gas "if thats possible" or your needle would be way to rich, possibly even oil burn on the plug.

To many questions without me actually being there.

If you just run a ATV around idleing and going low speed then turn it off your plug will look like that also.

A proper high speed run for a plug reading will burn off all that black carbon and left over stuff and leave a new plug white with no color and a older plug porcelain chocolate brown.

Either one will be blackish if just idled to a stop.

Also check for air leaks.

[JOHNDOE83]

Also theres new ways to jett without doing plug chops.

A plug chop is actually cutting the plug open to read for main jett setting at WOT.

[GAZ-V-21]

Originally posted by JOHNDOE83
If the oil level is to high it will pop, puff and spit at certain RPMs.

Unless you removed 5 bolts to change your oil you may not have drained all of it and adding the factory recommended amount may be to much "just throwing that out there".

If the plug got that dark that quick "assuming" you did a correct plug run or even ran it around for 20-30mins I would say you either accidently used mixed gas "if thats possible" or your needle would be way to rich, possibly even oil burn on the plug.

To many questions without me actually being there.

If you just run a ATV around idleing and going low speed then turn it off your plug will look like that also.

A proper high speed run for a plug reading will burn off all that black carbon and left over stuff and leave a new plug white with no color and a older plug porcelain chocolate brown.

Either one will be blackish if just idled to a stop.

Also check for air leaks. cool thank you for help im hoping it might be that i gapped the plug way wrong it was supposed to be gapped at around 0.6 millimeters i gapped it at like .065 inches which is way off.

[GAZ-V-21]

[QUOTE]Originally posted by GAZ-V-21
[B]cool thank you for help im hoping it might be that i gapped the plug way wrong it was supposed to be gapped at around 0.6 millimeters i gapped it at like .065 inches which is way off. I have not been able to give it a 20-30 min good run just some laps up and down alley for a couple minutes at a time.

[GAZ-V-21]

Just took seat off and started it does sound like air leak but cant tell exactly where from

[GAZ-V-21]

Found it bottom of the hose from airbox to carb had gap in it was not all the way on just got it on right and no air sound. I hipe this was the problem. What do ya think?
<a href=http://s1095.photobucket.com/albums/i465/GAZVATV/?action=view&current=IMAG0180.jpg target=_blank><img src=http://i1095.photobucket.com/albums/i465/GAZVATV/IMAG0180.jpg border=0 alt=></a>

[01boneless]

bet that was your problem!!!!! good find!

[Drfat400ex]

Well there ya go! Myn did a little bit of spuddering when I was running a 158 and should have been doing a 152 lol. Also when you gunned it at about half throttle it would plane out then just be like WAAAAAAAAAAH like a two-stroke lol quite an experiance running a rich quad for a while.

[GAZ-V-21]

Thank you guys for giving me the info to know what to look for and saving me from causing some serious damage you guys are awesome.

[CJM]

If that doesnt work, take some carb clean and spray around the engine-if it idles up you found your leak.

[GAZ-V-21]

Will do im gonna let it sit for the night and see how it acts on a cold start tomorrow again thank you guys for all the help ive learned alot this past couple weeks all from you.

[TheAwesomehonda]

That video does make it sound like a intake leak. Those rubber boots get bridle and then come off the carb ez if they aren't real tight.

[GAZ-V-21]

Ya i think i just didnt get hose hooked all way onto carb after jetting it the other day.