fresh rebuild spittin fire

[jasonwayne222]

ok my friend just got done rebuilding his 04 with stock bore piston hot rods crank stock stroke and I believe the piston is just a little higher comp. than stock. So anyway it idles great but you try to give it gas and it just spits fire and sputters

Whats the deal? I dont think its a bad exhaust leak because it doesnt do it on decel it does it on excel. it just spits fire and sputters at the same time. also the header pipe glows red hot just through the bend but its at night and i heard thats normal for this bike

any help is appreciated

[700xxmaniac]

did u rejet it

[jasonwayne222]

havent tore into the carb to find out yet, but thats my next move to see whats in there.

The bike was a friends project who recently died. So my buddy got the bike and finished puttin it back together and were tryin to get it right.

[jasonwayne222]

would this be a rich condition

[jasonwayne222]

cleaned the carb but didnt use carb dip yet but its still spittin. The carb has factory jets so maybe I need to jet it. The header was glowing red all the way to the muffler so that means its lean right

[yfzrider690]

Umm ya, it's way lean. I wouldn't start it again until you get some jets, you're gonna seize it. These quads come lean from the factory and need to be rejetted even if there still stock. Stock jetting is 42 pilot and a 155 main. I would go with a 48 pilot jet and a 175 main to start. And set the needle on the 3rd or 4th clip down from the top. If you are running the stock needle I would get the ncvq needle, it's out of the yz dirtbike. Also set you a/f screw to 2 turns, it should run a lot better. Don't clean the slide with carb cleaner, it will eat the coating off and cause it to stick which will mess up your idle.

[jasonwayne222]

ok thats what i was thinking, its actually my buddys quad and i kept tellin him tonight that I think it needs bigger jets but he wasn;t so convinced for whatever reason, I actually have a 400ex which is pretty subpar but better than nothing. So it being way too lean will cause it to spit fire like that hugh. Ive only had that problem on decel from an exhaust leak. but it makes since as to why the pipe was gettin hot all the way to the muffler, not enough fuel to cool it

[yamaha_maniack]

ya dont run it anymore because you will run the risk of overheating and seizing the piston and you will need a whole new block.. running too lean will cause extra heat and not enough cooling and that is why it got red all of the way up to the can...

I would suggest rejetting for sure. Good luck!
Later

[jasonwayne222]

It was one tooth off on the intake cam on the timing. I figured thats what it was but my friend who owns the bike was sure it was right but anyhow we got it runnin good but the carb still needs to be dipped in carb bath because its just not right yet but we got the main problem fixed

[700xxmaniac]

wow ur lucky ur vales didnt hit ur piston.

[yfzrider690]

Originally posted by jasonwayne222
It was one tooth off on the intake cam on the timing. I figured thats what it was but my friend who owns the bike was sure it was right but anyhow we got it runnin good but the carb still needs to be dipped in carb bath because its just not right yet but we got the main problem fixed

I wouldn't dip the whole thing in carb cleaner. If you get the slide with that stuff it will eat the coating off and cause it to idle funny and will have to replace it.

[jasonwayne222]

ya i know how to use it, i only put in metal parts, and my buddy had cleaned it with carb cleaner spray before we knew what it does to the slide and it was sticking but we fixed that.