well you could have a bad coil or stator.
just simply wnet out. sometimes this happens. though nt normally while tuning the carb.
but they can be unpredictable if they are going to go out.

use a meter and check for voltage at the coils' power wire.

not the coil wire that plugs onto the spark plug.


it could bne as simple as the spark plug cap coming loose as well so check that.

i'd love to spend 5 minutes with it.

at my shop i specialize in hard to fix problemsn and performance mods, (thus the reason i like to diagnose on here.)

check the coil for power and get back to me.  

Embush,

My daughter is 15 yrs old and she is not new to the motocross/quad scene. She has been riding bikes and quads since she was about 8 yrs old. She has been racing in Dade City, FL for the past 2 yrs and I would consider her an average rider at best. She loves to ride and knows her limits on the track. She became too big (tall) for the her Blaster last year and complained of the lack of power/balls and handed it down to her 11 yr old brother. We currently have 4 bikes and 5 quads in the garage and yes her 450 is the baddest one of the bunch. She gives it hell of the track and I am aware of the dangers involved in racing quads. Hell, I will admit, her bike scares me sometimes when riding around our property but it is what she wanted and she is very responsible. She always rides with full gear and kill switch attached. She has flipped & wrecked a few times but she always gets up, brushes herslef off and gets right back on. She is the daughter (tomboy one day/ prom queen the next) that I always wanted.

Thank you for your concern,

Steve  

Wofl1

I have absolutely no idea on how to or where to check those. My friend, who is an auto mechanic, suggested checking the resistance on this and that but I do not have an ohm meter and have no idea on what or where to check. Is there a simply way to check. Heck, I dont even know where there items are...

You would happen to be coming to Florida for spring break would you?????  

no darn it I went to california for a month long vacation here while back.

planning one for the summer and need to get back to florida, (especially since i have vacation property there in Bonifay florida.)

I know you said central  but
what part of florida are you in?


the coil"
the thing that the spark plug wire is mounted on.
you should have either one wire, or two.
if you have one wire then that is the wire you test.
if you have two wires then one wire will run to a bolt on the frame and will be the ground, so test the other wire.
if we know it is getting voltage to the coil and the coil is still not putting out a spark then we need to look at the stator.

reason being, when the magneto contact passes the stator contact it lifts the ground wire on the coil, (or engine if only one wire) causing it to spark everytime the magneto passes the stator in time with the piston and compression stroke.

also check the magneto and stator contacts for rust or dirt, this could cause a weak or loss of spark.


check the wires coming from the stator.
there should be 4-5 wires coming out of the left side cover from the stator.
trace them down, make sure they are connected well, and none of them broken.

check the connectors on the sparkplug wire.

the "spark plug cap" is the cap on the end of the spark plug wire that fits over the spark plug.
make sure it on tight, it should screw down onto the plug wire.

I'd love to be there right now, i am positive i could get it running for ya and tune the carb.

right now i couldn't get away from here for more than a day or two. if you are in central florida then it's probably about a 16 hour drive for me one way.

and good grief the gas prices are nuts.  

Ahhh,

Just typed a book in reponse and it didnt post. must have timed out.

I live in Winter Haven which is dead center of the state. I looked up Bonifay and thats just past Marianna where my father and his family is from. Very rural area.

My fingers are tired but if I read your post correctly then I need to check the wire on the coil for fire. There are 2 wires and I will verify a good ground for the one. While the plug is in the bike and the coil secured on the plug, check for spark while trying to start. If NO spark in wire then the coil is bad. If there IS spark then I need to move on to the stator and/or connections.

I did check the coil wires last week but wasnt sure what I was really looking for and didnt know one was a ground. I cannot recall if the plug was in or out of the bike as at one point I had the plug laying against metal looking for spark.

Can a dealer usually check just the coil if I were to bring it in? I would had to buy a non-returnable electrical part that I didnt need.

If I do get spark and move to the stator and the 4/5 wires do they all have spark when trying to start?

When I mentioned my spitting issue with a mechanic at the dealer he suggested 2 things (other than filter). the air/fuel screw and the coil. If I recall correctly, he mentioned $90 for a new coil, $35 for a used on on ebay.

I will check tomorrow night and let you know the outcome.

Thank you again for your help.  

not the spark plug wire. there will be either one or two wires going to the back of the coil. opposite end that the spark plug wire comes out of.

if you have two wires coming out of the back of it one of them should go to the frame as a ground, and the other should be the power wire.

(a coil magnifies voltage, so that 12 volt power wire suddenly puts out at a higher rate so that the spark will be strong enough to jump across the gap in the spark plug.)

test the power wire for voltage, if you don't have voltage there then we are looking at the stator or the cdi.

most likeloy if youa re getting power to the power wire of the coil but no voltage at the spark plug wire, chances are the coil is bad.
but it could be the stator or cdi as well.

most likely the stator.

do you have anyone with the same bike?
if so see if they'll let you test your coil on their atv.
it won't damage their atv to try it out and see if it works on their atv.

same for the cdi box.

to check the sparkplug for spark.
remove the coil wire and the spark plug.

place the spark plug into the spark plug wire, lay it against the engine so that it will ground itself.
(but not so the electrode on the end of the spark plug is close enough to the engine for the spark to go there.)
turn the engine over and see if it sparks at the electrode.  

I have a quick question and Wolf1 you really know your stuff. This should be a breeze for you.
I just purchased a 2008 YFZ450 and i'm thinking about putting on a Dr D slip on exhaust and a pro flow kit. Do i need to jet it? I'm a noob to the whole jetting thing.
I will be riding at Glamis and other areas in So. Cal. Your input would be greatly appreciated.

Thanks,  

You would have to re-jet and readjust the carburetor.

you should be fine as long as you buy an exhaust that comes with a jet kit included.
most companies have done the research and know exactly what jet kit you'll need.

and adjustment isn't too horrible.  

Ok ,Ive Tried to adjust the mixture screw and it did nothing. The air box lid is off and im runnig a 170 ,45 with the needle on clip 3 NVCQ (im pretty sure). It came with GYTR Jet kit i bought, and its at 1 1/2 turns out on mixture screw. Do you think that the reason its poppin and shooting flames out is because that its getting to much feul and its causing it to do that? Im not sure im lost!! please help me out. I know somethings not right just cant figure it out.  

shooting flames... um yeah it's most likely getting too much fuel.

and probably the popping is post ignition in the exhaust pipe.

basically the excess fuel puddles in the exhaust pipe and combusts when it hits the hot pipe.  

So What  Should I do Lower the Main Jet Or Go Bigger On Pilot Or change The Needle I Really dont know ive been messing with this thing for a very long time and cant figure this thing out and i have no clue on what else i should do  

first try lower the needle to the top groove.
tha should make a significant difference. try to tune the carb with the needle in the top groove. if it starts running too lean or gets worse try the second groove. and then retune
if no change that way you'll to change the jets.

it is cuts out then it is too lean
if it bogs down then it is too rich.  

Wolf you seem to be the man!!! I hope you can help. I have a 08 yfz450 m160 pstock, neddlestock put yoshi full system and motoworks intake. will run like a raped ape with choke on full otherwise runs and idels like poop!! I'm at 4000' elevation thanks  

air box lid is off  

anyone got any suggestions I would greatly appreciate it skip from utah