All 2st Jetting Chat - Need Help? Post Your Questions Here

Thanks for the suggestion...by heavy float, do you mean one that fills with fuel? I removed it and it seemed to be fine, with nothing inside. I also double checked float height and confirmed shut off by blowing into the fuel intake and that seemed to be fine also. Of course, it hard to be sure without changing it. Maybe tomorrow I will swap carbs and see what happens just to make sure I have a carb issue. I have a big riding weekend planned and either my son or I will need to ride this bike. Do you see any harm in running it with idle screw in?

The black floats are actually a closed cell foam, over time the foam will break down and absorb fuel like a sponge. This usually takes a long time but Alcohol in fuel and other additives can cause this to happen faster. As for the needle it can get a wear ring on it where it contacts the seat and will not always leak when testing it with the carb inverted but add a little vibration of a running bike and it bypasses just enough to cause idle problems especially bouncing around on a rough downhill section. Sometimes it's worth a shot to just replace the needle and seat.

I would almost consider this a routine maintenance item. Replace the o-ring that seals the seat while you're in there, too! Never hurts.

thanks guys, I will see about replacing those parts. I was reading on TT about a guy who had a leak in the seal between the jet block and carb body. He had very similar symptoms. Ever heard of such a seal? Ive never had the carb down that far.

+1 on that, I cured my YZ125 by replacing the "O" ring that goes around the seat.

Doug,
I do not seem to have an oring at that location. Are you talking about the rubber tipped needle that shuts off fuel to the bowl, or the jet needle? I don't have an oring at either location.

The seat can be removed from the carb body, there is a screw that acts like a hold down tab. The seat is made of brass and has an "O" ring around the outside. This is how the Mikuni on my YZ was. I have seen other seats that were screw in with a gasket and not an "O" ring and also seats that were machined in and part of the carb body but those were usually on cheap chinese bikes. Your carb model might differ from what I've described.

can you clarify which needle seat please. thanks

The float needle and the seat that the float needle seals against.

thanks. Mine is brass, but appears to be bonded in. I see no way of removing it in a gentle manner. no oring there either. I sprayed some carb cleaner around the needle and nothing leaked past, so I am assuming it is good. I removed the cast piece which holds the jets from the carb body and found four o rings connected together which are looking pretty flattened. I am sure those will be difficult to source, so I carefully installed some rtv in there and will let it cure over night before running gas through it. I have been planning a riding trip for this weekend for a while, so Im hoping that cures the issues. I will report back when I return.

RTV, teflon tape and pipe dope type sealer are bad hoo-doo around fuel systems. It's probably too late since you've already applied RTV but it will probably turn gummy from fuel and let go and get lodged in a passageway somewhere and turn your carb into an unfixable piece of junk.

thanks for the encouraging words, but Im assuming that the dc730 for aircraft fuel systems I used should be fine

This will help anyone jetting a conventional carb.
http://twostrokemotocross.com/2009/12/carburetor-theory-and-tuning/

Just a follow up for those owning PWK airstriker carbs and having problems with the idle circuit and excessive fuel consumption as well as crazy amounts of spooge. After fixing the gasket between the jet block and carb body (best to replace the gasket, but I used an expensive fuel safe rtv,) I put about 100 miles on the bike this weekend and the issues seem to be cleared up. I now suspect the same issue on my 165 with the same carb as symptoms are similar.
BTW, A big thanks to lankydoug for all his help on this board

Does anybody have a 6DEY15-74 needle that I can try/buy? Or a place to get one? I know I can buy one from Husky (8B00H1785, supposedly), but I was looking for another source...

I have a 13' wr300 could anyone tell me what a #5 slide will do? I have a 440 main, 50 Pilot, #5 slide, Clip set 2nd from bottom on needle, 1.5 on air. The idle is real low and cant be turned up anymore, the plug is black pig rich. I ride 0-3000' and it's like 100 heat index tight woods hare scramble racing and have a gnarly pipe running pump 91 gas 40:1 amsoil I have the GAY needle. Halls told me to use 430 main, 45 pilot, #4 slide (dont have) clip in middle, air at 1.5.

My problem is I'm stuck with the #5 slide this weekend and I'm thinking I might leave the main at 440 raise clip to middle and lower pilot to 45??? Not sure what to do??

I have a 2009 WR300 with the aftermarket carb, PWK?, FMF Gnarly pipe and a fresh top end. I am an older rider too so I tend to ride more in the low to mid range, just being honest. I find the bike a challenge to start (could be a function of the short lever and the fact that I'm old), it burbles in low-mid range and was getting major splooge. I lowered the needle one clip and much of the splooge went away, still some burbles in mid range. Still harder to start. I live in the midwest i.e. Wisconsin so temp in summer is 70-85 typically. I am also new to this carb so unsure about the one screw on the side versus the typical slide adjuster idle screw and the air screw. I would be grateful for any ideas on settings and or starting routines. I am finding that holding it wide open when hot is the trick for starting then. Thanks for any assistance.

Here is a suggestion for a starting routine: http://www.cafehusky.com/threads/dead-starting-a-wr300-nothing-to-it.33579/

Another suggestion that may help is buy a 38mm Lectron and put your old carb on ebay. I dont know much about jetting but was able to dial in the lectron to run better than stock in minutes. Not a salesman just my 2cents

Turning the air screw counterclockwise will let more air in the circuit and lean it out a bit. The air screw setting should end up between 1 1/4 - 2 1/2 turns out when ideal. If you have to back it out farther then that it means you need to go to a smaller sized pilot jet. I've found that the perfect pilot usually requires 1 1/2 turns on the air screw.

If you have to raise the slide way up by turning the idle screw way in that is also an indication of a rich pilot circuit.

Hey guys just brought a new (to me) 2004 wr125

took it for a spin on the weekend and it didnt run as well as i would have hoped.
symptoms, plug indicates running rich, fowled a plug, has bugger all power untill power band then takes off like a rocket!!
and a few times it felt like it had no fuel at WOT wouldnt do anything then close throttle for a bit then crack off she goes again......

carbys the standard 38mm TMX
needle 6DJ8-59
pilot jet 27.5
main jet 190 - this is a plastic jet, weird??
emulsion tube 633 R-5
air screw 1.25 turns out
float level 17-18mm to top of point from base.

running motorex oil at 40:1 (dealers recommendation) previous owner ran 50:1 ipone
far amount a spooge after ride, not worried about it if bike ran properly :P.

any advice guys btw im in Sydney Australia and ride anywhere up to 1000mtrs above sea level..
cheers