Backfire, die, wont start

[Vampire2800]

Let me begin by apologizing for this thread if it's redundant or if someone else already posted something similar. I try to research all my questions before asking it publicly & I usually succeed in finding the answer. This one, not so.

=> 4 days ago I changed the oil & put AMSOIL 20/50 synthetic (per some dealers request in Tulsa). I previously ran Yamalube 20/50 non synthetic

=> Immediately noticed "the bog" which was not present before

=> My son & I were out riding just a few minutes ago when I started to notice a backfire every once in a while. The back fire started happening more frequently the longer we rode. I made a few more laps around the field behind the house, came up to the driveway, reved it up, let off the accelerator, it backfired all the way down the RPM range & died. Fired it up a couple of more times & it did the same thing. I do know that something sounded different near the end of our ride (as the backfires got worse.) I can't explain what sounded different, but something did.

=> Now, no starty-start.

I pretty much rely on the posts on this forum for support, tips & help as I live in northeast OK & the closest repair place is an hour or more away. Ya'll ALL do a superb job in the maintenence of ATV's & the attitude is unrivaled when it comes to members on this forum. I think I speak for EVERYONE when I say, "Hats off to every one of you on here for your help & support in the past."

WTF. This thing is like a boat. ( B.O.A.T. = Break Out Another Thousand)

Would changing the oil back to Yamalube 20/50 fix it? I'm afraid to do a whole lot right now in fear that I will make the problem worse. Any suggestions would be greatly appreciated & abliged. Thanks in advance.

[mxpimp2000]

the oil isnt going to make ur bike do this. start by trouble shooting ur prob.

1. spark plug
2. dirty carb
3. air filter not clean
4. bad gas (water in gas)

my bike done this kinda but it would start up. i done the zip tie mod and changed my main jet 1 size and boom it ran awesome

if its not starting id start with the spark plug see if its firing, check the color of the plug also white=lean, black=rich, brown=perfect, if its not shot and its gettin fire then move on to the carb/gas and air filter

[Vampire2800]

Will do, thank you sir

by the way, I just spent 7 months in KY. Bowling Green/Owensboro/Madisonville/Hopkinsville. All the counties west of Barren over to Trigg & up to Henderson & Daviess counties. I work for State Farm. We were there from the ice storm & wind storm. Then got sent to Louisville for the flood for a couple weeks. Got back home almost a week ago.

Thanks for the help!

[mxpimp2000]

yea we had a bad ice storm no doubt.

ur welcome

thanks

[Vampire2800]

I did all that was mentioned above with no success. I took the oil filter off and put it right back on & the quad fired right up. Still has the bog with lots of backfires, but runs for now. I know it sounds wierd, but I think it has something to do with the synthetic oil or the filter. The filter is that HiFlow thing that comes in the black & green box. So, any more suggestions? I'm gonna go back to the Yamalube today & see if that fixes anything. Also, when I let off the accelerator, it slowly throttles down & hangs at a slightly higher RPM than idle. It eventually goes back down to idle, but it takes about 20-30 seconds. Any advice is very appreciated. Thanks in advance

[daddio]

Has the quad been sitting for a while?
If sounds like the carb is dirty, or has bad fuel in it or water.

Do not clean the slide with the spray type carb cleaner, though.

[Vampire2800]

Well, it sat for 3 months, then I got back home & we rode for the weekend. It rode fine then. So, I went back to work in KY & came home a week ago yesterday (3 1/2 weeks without it being started). The first thing I did was change the oil & that's when this crap started happening. It seems like the slide is sticking also. What do you suggest I clean everything with? By the way, the "post idle bog" is still present. Did the zip tie mod & everything. I don't know about any leak jet on there, but I finally got the plug to be the right color.

My setup is as follows:
Main = 165
pilot = 45
NVCQ clip in 4th position
elevation is at 758'
zip tie mod
pretty sure the cam mod has been been done also
fuel screw is 1 turn out
K&N air filter, clean, no lid, with the little black sock over it
New 91 octane fuel (from the Conoco up the street). I also put a little Sea Foam in it to help cleanse whatever carbon build up there might be in there.
GYT-R slip on (needs a little more packing, though).
Renthal handlebars

I stuck my finger in the carb yesterday & it came out clean. Had to press the throttle to open the valve & my finger came out the same color as when it went in.

If there's any more info that you need to make a proper assessment, just let me know. Please keep in mind that I'm fairly new & learning from ya'll.

Thanks in advance, Jeff

[Vampire2800]

Sorry, it's a 2005 Yamaha YFZ 450 SE (possibly an R, not sure how to tell)

A small puff of black smoke out the exhaust when hammered on means lean, right? Screw in or out?

And the bog I'm referring to is not the typical "hammer the throttle & it bogs & dies". That's not it. It bogs when you barely press the throttle. The throttle (thumb) may move 1/16"-1/8", but as long as your press it harder than that it does just fine, no bog. It's a pain in the John Brown hind parts when trail riding, though because a lot of the time you need to have consistent throttle pressure just above idle & the dad-gum thing wants to try to die on you. Sucks, but I am optimistic!