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Bogs when I open the throttle fast.

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Ok so my bike has this bog that is pretty annoying. When the bike is at an idle, it will bog if you open the throttle all the way to fast. It is still rideable but sometimes when it happens it is always at the wrong time. My plug is lightly oily and black. I already cleared my jets and cleaned the carb.

Thanks guys.

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You're running rich man. When the temps change you have to change your jetting although you can easily take away that bog (rich) by leaning out the air screw. If you know where your air screw is at on your carb turn it counter clockwise in 1/4 turns until it revs perfect. Turning this screw clockwise will rich the mixture and worsen the bog.

If you find that you go more than 2.5 turns out on the air screw you need a leaner pilot, and if you're less than 1 turn from closed you need a richer pilot. Leaner is physically a smaller diameter pilot jet (less fuel) richer is a bigger diameter pilot jet (more fuel) If it bogs on the top end then you'll need a leaner main jet. Main is the jet for the top end. Pilot is for the very bottom, but air screw adjustment could easily solve all of it. I highly suggest you get or download a manual and :read:

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I beg to differ !!!!!!!!!!!!!!!!!!!!

Firsly a bog / dies from idle will mean its lean ! from memory I think you should have a 36mm Keihin fitted and I think they had a 50/55 pilot fitted and I always found these to rich, so maybe someone has changed it and gone to far, also you may just want to lift the needle a notch and see if that helps .

If its been fitted with a 38mm they can be a bit of a pain to loose the bog/die from idle as the poor little motor cannot suck that hard from idle but you cannot notice any bog when riding as the revs are always much higher.

Post what carb/brass you have as this will help people to help you:thumbsup:

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What? A bog, die, all of that is THE symptom of being too rich? Too much fuel right?

Please explain how a bog means it's too lean? If a bog is lean then what is the symptom of rich??? Makes no sense to me.

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oily plug, your probably on the rich side, if you have your pilot dialed in already, try dropping the needle a clip or two and see if it makes it better or worse

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Ok guys i just got the bike and have not checked the sizes. I am aware that these were jetted rich from the factory though. This bike had 2 owners before me. The one i bought it from installed v-force 3 reeds and had no clue what jetting even was and said he probably moved the needle the wrong way. The owner before that installed an FMF fatty and he probably re jetted. How do v-force 3 reeds effect the jetting?

And also when i open the throttle fast it it will bog till it dies not bog for a second then rev. Hope this helps.

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they dont, neither does the fmf pipe imo, I have never rejetted for either on a two stroke

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what's in the bike, that's what your starting with

I prefer to setup the pilot first, it's the easiest imo, then needle then main, sometimes I have to adjust needle again after the main

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Ok I guess I know what I'm doing this weekend and the rest of the week.

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Well both. Check what you have in the bike and what your manual calls for at your altitude and temp...Also other things to definitely check is how many turns out you are on your air screw...A quarter turn on that can GREATLY effect off throttle performance. Also check which clip position your needle is at. There are 5 positions, 3rd is dead middle and is the best. Set those 2 first, then start changing brass.

Still waiting for an explanation from this fellow who says a bog is lean?

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I am here !!!!!!

A bog from idle is a lean condition not a rich condition ! if you crack the throttle hard from idle on a smoker and it goes baooooor and dies it is lean, the motor sucks a huge gob full of air and dies, if you replaced the carb with say a 30mm item it would never happen

I dont want to argue with anyone but I have not ever come across a rich bog and die , weather gets colder bike gets leaner

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True on your last statement, but how come when my bike would have a bog off throttle leaning out my air screw (more air) fixes the bog and the throttle is then crisp and clean???

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True on your last statement, but how come when my bike would have a bog off throttle leaning out my air screw (more air) fixes the bog and the throttle is then crisp and clean???

Well god knows lol maybe the slide cutaway needs to go leaner (higher number). we also must remember what works for some will never work for others! I have spent the last few days jetting two identical husky wr 125s and on the stock mikunis one loved a rich setup the other a leaner setup, I changed the carbs to pwks and instantly got two bikes that now became identical to jet, still scratching my head over the mikunis as I swapped them from bike to bike but still they acted diferently hence the swap :):lol::banghead:

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Well god knows lol maybe the slide cutaway needs to go leaner (higher number). we also must remember what works for some will never work for others! I have spent the last few days jetting two identical husky wr 125s and on the stock mikunis one loved a rich setup the other a leaner setup, I changed the carbs to pwks and instantly got two bikes that now became identical to jet, still scratching my head over the mikunis as I swapped them from bike to bike but still they acted diferently hence the swap :):lol::banghead:

that's because the tmx carbs that come stock on the wr's are crap compared to the airstriker.

my 250 would literally start fouling plugs whenever a cloud would pass over with the mikuni. since switching to the pwk it's just a clip adjustment winter/summer and otherwise it's spot on all the time.

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Okay guys, I have a93 cr125, and I feel it's jetted pretty dang good. When it was warmer 65+ we ran 165/50 on 2nd clip. Now that it's alot cooler, around 40. We're running 168/50 on middle clip Position. Runs great. Both settings with mixture screw at 1.5 turns. When temp drops to Around 30 I have the same prob as OP. So when it's does it's bog it must be cause itso cOld and the air is so dense right? Making pilot lean?

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I'm sorry guys, but is a PWK carb? I know I should know this but.....

pwk is a popular keihin carb on 2t's. mikuni makes a tmx or twx, can't remember which, that is the comparable carb from it's line.

the pwk also known as the airstriker has proven to be the easier to jet carb and is a common after-market upgrade for bikes that come with the mikuni.

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Okay guys, I have a93 cr125, and I feel it's jetted pretty dang good. When it was warmer 65+ we ran 165/50 on 2nd clip. Now that it's alot cooler, around 40. We're running 168/50 on middle clip Position. Runs great. Both settings with mixture screw at 1.5 turns. When temp drops to Around 30 I have the same prob as OP. So when it's does it's bog it must be cause itso cOld and the air is so dense right? Making pilot lean?

Now to me you are bang on with your thinking! the only other cure would be to try a richer slide but again this from memory is a 5.5 and that is about right ,plus the cost of a new slide if it is not the cure is pretty expensive!

I have been useing KTM noz type needles latley as they taper more so give more fuel at 1/2 to WFO with some very good results in the colder weather.

I still think the bog is more slide / needle than the pilot as that is the easy part to dial in

Would like to know if a 52 pilot would cure it though or go in on the air screw half a turn

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