wfo bog

[skid jackson]

06 gasser 300

my bike has a bog from about 1/2 - 3/4 throttle to wfo

Riding today I noticed that the bike ran pretty good up to about 1/2 throttle. After that it fell flat on its face with a big bog at about 1/2 throttle and beyond. I don't spend much time above 1/2 throttle on this bike .. so I don't know if this is new or something that has been around for a bit. Its got a 178 main and guys generally run anything from 175 to 182. I have run a 180 before. I played around with the needle slot and got nowhere. I started with it in the 3rd slot, then went to the 4th to see if I could richen it up a bit. It ran like crap. I then went up to the 2nd slot and it ran nice and crisp almost a bit lean but still went flat with a bog after 1/2 throttle. just a bigger main jet?? air screw was 1.5 turns out. temp was about 55/60 maybe even 65 later in the day. mix is about 36/1 gas half old half new. cck needle. bike hasn't been used since mid july. temps were around 60 degrees

btw I rode a buds 06 300 and his bike was a rocket, jetting was spot on. He could not remember what was in it but he did say he used the ltr jet kit. He was actually the one to point out the bog. He thought it was going lean up top and I needed to go up on the main jet.

 

[EtienneNZ]

Read a few forum entries lately and you may first want check out your tail pipe and make sure it is not blocked or in need of a fresh packing. Good luck.

 

[moto9]

06 gasser 300

my bike has a bog from about 1/2 - 3/4 throttle to wfo

Riding today I noticed that the bike ran pretty good up to about 1/2 throttle. After that it fell flat on its face with a big bog at about 1/2 throttle and beyond. I don't spend much time above 1/2 throttle on this bike .. so I don't know if this is new or something that has been around for a bit. Its got a 178 main and guys generally run anything from 175 to 182. I have run a 180 before. I played around with the needle slot and got nowhere. I started with it in the 3rd slot, then went to the 4th to see if I could richen it up a bit. It ran like crap. I then went up to the 2nd slot and it ran nice and crisp almost a bit lean but still went flat with a bog after 1/2 throttle. just a bigger main jet?? air screw was 1.5 turns out. temp was about 55/60 maybe even 65 later in the day. mix is about 36/1 gas half old half new. cck needle. bike hasn't been used since mid july. temps were around 60 degrees

btw I rode a buds 06 300 and his bike was a rocket, jetting was spot on. He could not remember what was in it but he did say he used the ltr jet kit. He was actually the one to point out the bog. He thought it was going lean up top and I needed to go up on the main jet.

If I remember correctly, bog is too rich, usually you can tell a lean condition because it will ping.
Easy way to tell though, check the plug color.
If the bog is 1/2 to wfo that's tuned with the MJ and the needle.
Drop to the next leanest MJ, clip in the 2nd slot from the top and see how it runs, if it's getting better then your going the right direction.
Keep dropping the needle or go leaner yet on the MJ until it's running good with the clip somewhere in the middle, so you still have some adjustment both ways.

Check the plug color a few more times.

 

[iancp5]

If you've not changed anything, it could be too lean. If it's really bad, i.e. just dies at 1/2 throttle I'd check for muck in the main. Also check for air leaks in the inlet and that the fuel tank vent is clear. Possibly crankcase if a seal has gone. The only way I can think it might rich bog all on it's own is; filter very clogged or float holed but the latter normally spews fuel out the overflow too. There are more failure modes that go lean I think.

 

[einsteingarage]

Skid in my 300 I have

42 pilot
175 main
needle in 3rd clip

here is the key-- You need to get the optional needle from a 2001 yz250 I will try to find the part # for you.

It made all the difference. Straight hard pull to WOT no bogging

 

[skid jackson]

Bike had been sitting for a few months .. figured maybe the main jet is gunked up .. so I drop the drain plug. As i'm unscrewing it I hear something rattling around in it. I get it off and look in the bottom and there is my main jet!! In all my years of riding I have never had a main jet come off!! Oh Well nice that it was an easy fix .. and the bike ran great all day!! Still a bit rich off idle though!! The last time I rode it was pulling arrows at the rocky .. all those rocks must have rattled it loose!!

einstien ...
I'm running 42 pilot
178 main
cck in second slot
air screw 2 turns out

bike ran good today, I'll have try a 175. tempted to put the ltr needle back in just to seee what its like

funny how the bike ran quite well with no main jet until that circut come on!!

 

[stainlesscycle]

.. so I drop the drain plug. As i'm unscrewing it I hear something rattling around in it. I get it off and look in the bottom and there is my main jet!! In all my years of riding I have never had a main jet come off!!

i've had that unfortunate occurrence once. i double check every time i change a main now...

 

[iancp5]

Bike had been sitting for a few months .. figured maybe the main jet is gunked up .. so I drop the drain plug. As i'm unscrewing it I hear something rattling around in it. I get it off and look in the bottom and there is my main jet!!

Now you have to resist the temptation of doing it up too tight!

 

[moto9]

Bike had been sitting for a few months .. figured maybe the main jet is gunked up .. so I drop the drain plug. As i'm unscrewing it I hear something rattling around in it. I get it off and look in the bottom and there is my main jet!! In all my years of riding I have never had a main jet come off!! Oh Well nice that it was an easy fix .. and the bike ran great all day!! Still a bit rich off idle though!! The last time I rode it was pulling arrows at the rocky .. all those rocks must have rattled it loose!!

einstien ...
I'm running 42 pilot
178 main
cck in second slot
air screw 2 turns out

bike ran good today, I'll have try a 175. tempted to put the ltr needle back in just to seee what its like

funny how the bike ran quite well with no main jet until that circut come on!!

So, it was a little on the rich side..Ha...at least it was an easy fix!