2 Q's in 1 post

[yfz450boy]

Hey guys! I have a headgasket question and a jetting recommendation question.
First, Which way does the headgaskets go on these 450's motors? I have searched the forums, service manual and my Cylmers manual with no luck. Unlike the base gasket, the headgasket will fit on either way. My tab of my headgasket right now is sticking out right underneath the bottom exhaust flange bolt.

Second, Im not the best at learning what jets you need, and whatnot but I have been reading posts and websites trying to learn more. But I want to make sure I somewhat do it right the first time.

Its a 2006 yfz450( 540ft Elevation) with

- Yoshi exhaust( shortened to 10 inches)
- Uni filter with box lid off
- 13:5 CP piston ( 2 comp. rings)
- stage 1 hotcams, intake and exhaust
- Trail tech lightweight flywheel
- running straight VP U4.4 racefuel 103 octane(r+m/2 is 114 I think) oxygenated, BUT plan on mixing 70% race 30% 93 octane if I can.

Has #165 main 48P 4th clip down on needle( no idea what needle) and I think my a/f screw was turned half way. Starts right up cold, off choke, and idles, Revs with no bog. Spark plug does look very dry when I pulled it out and checked though. It will not run on choke cold or hot. sounds like its running on a half a cylinder for ten secs then cuts right off. I did order a gytr jet kit and should be in tomorrow, so hopefully you all can point me in the right direction with the jets and clip notch on the new jet kit I got. They also told me that this fuel has like 22%oxygenation in it so you should richen it up some since it tends to lean the motor out some. Sorry for the long post. Thanks!!

[SuperCrew]

As far as your jetting give #185 main #55 pilot 3rd clip from the top and 1 1/2 turns out on the a/f screw a shot

[SuperCrew]

Also meant to say the tab should be located on the right side under the exhaust header

[SuperCrew]

Also one other thing that comes to mind since you said it runs for 10 seconds then cuts off.. check your cylinder wall for any type of scoring. If you notice some you could very easily have a bad lower rod bearing or crank bearings causing it to sieze up the piston. Kinda need some more details though such as when in dies will it crank back up or turn over at all. You said your plug is dry but what color is the prong white, black, or a golden brown. Have you checked your valve tolerances lately?

[yfz450boy]

Thanks supercrew! Ill give that jetting a shot and see what happens. As for the not running on choke problem, I was thinking that was because its already running so lean off choke. When you turn on choke it cuts the air down and give more gas right? As soon as you turn the choke on, it idles real rough, almost like a train chugging up a hill lol I highly highly doubt its anything motor wise. It doesnt cut off, off choke though. I rode it around for about 20 mins the other day. It has brand new crank, bearings, piston, cylinder been to the dealer to check taper, out of round etc. and same with the head. Do need to check the valves again though. Thanks man!

[yfz450boy]

Also forgot to mention that when I bought this quad, the timing on both cams were way off. I lined the the flywheel lines but the came dots didnt even get close to lining up with the top of the head. probably 2 to 3 teeth off. It did run pretty decent before the rebuild though, just a bad bog, and when it stalled, hard to start back up. Some guy the previous owner knew had messed with the carb to get it to run as best as he could, so the carb was set to run with that timing.

[SuperCrew]

Originally Posted by yfz450boy

Thanks supercrew! Ill give that jetting a shot and see what happens. As for the not running on choke problem, I was thinking that was because its already running so lean off choke. When you turn on choke it cuts the air down and give more gas right? As soon as you turn the choke on, it idles real rough, almost like a train chugging up a hill lol I highly highly doubt its anything motor wise. It has brand new crank, bearings, piston, cylinder been to the dealer to check taper, out of round etc. and same with the head. Do need to check the valves again though. Thanks man!

Yes when you choke it your taking away air from the motor and adding more fuel into the equation so if it is lean it should actually do a little better with the choke on. Make sure to check all the jets you pull out to see if they are stopped up at all. Also one you adjusted the cams you did verify the valves were adjusted correctly?

[yfz450boy]

Alrighty. When I had the head off of it, I put the cams back in the head and put the cam towers back on and torqued them to spec. So I measured the valve clearance with the head off.

[SuperCrew]

Did you make sure the piston was back at top dead center before reinstalling the head. Just trying to rule out any obvious causes

[yfz450boy]

yes sir. Timing is dead on. starts right up cold/hot off choke and runs awesome. Well cant say awesome, because i haven't cracked into it all the way yet but it feels like it.

[SuperCrew]

Trying the jetting I suggested and see if that will help out. If not let us know

[yfz450boy]

Alright so finally got the wheeler put back together. Changed the headgasket, checked valves again and made sure several times the timing was dead on. Put the 185 main in, 55 pilot, and 3 notches down on the new gtyr needle.

It still doesnt like choke at all. If its cold and you try to start it on choke, it just backfires and shoots a flame out of the muffler, or just sits there and cranks over. Itll start right up off choke cold like it did before and rev right up as if the motor was warm. When I turn it on choke when its running, it either cuts right off, or starts running rough and it doesnt want to start back up afterwards right away. Ive tried it with the air/fuel screw all the way in and a couple turns back and get the same response out of it.

So Im thinking of two possible problems right now, could it be the Tusk air/fuel ratio screw letting air get by? If its a cause, itll be fixed cause I have a R&D one coming now. I also have a FCI intake on the way now. And the other problem is, at the bottom of the carb bowl, theres that little allen bolt, I guess its a drain bolt. Well long story short, there was some fuel dripping from it eariler, and when I had the carb off putting the jets in, you could blow through the opening ( looks like a hose can fit on it) on the bottom of the bowl. So now im back to square one. Once I start mixing the gas, I have a feeling its not even gonna wanna run.

[yfz450boy]

Well I installed the R&D fuel screw and changed my pilot from 55 to 52. Still wont run on choke, oh well. If you ride it and crack into it through the gears, sometimes it will cut off and not wanna start right back up. Also sitting there idling, it revs up the best with no bog or cutting off when you go to hit the throttle if the r&d screw is set all the way lean. Start to richen it up, it tends to cut off more or sputter when you hit the throttle. Any ideas?

[manny530]

didnt read all this but from the title of the thread i have to say:
2 girls 1 cup > 2 questions 1 post...........................just sayn

[yfz450boy]

hahaha didnt even notice it.