YZ250X Bog/blubber

[Miles Holt]

13 minutes ago, kxrob said:

you haven't ben around here long have you ? , everyday there are posts on yz250x jetting not even being close to right ,

to the OP , A xxxW needle imo is not a good choose at your elevation as the needle is to rich straight off the pilot, couple that with a rich pilot ( you should be at a 42ish for your elevatyion ) would still be blubbery

Thanks! Could too rich of a pilot cause a sudden bog hesitation like I said above? 

I think reguarless what i mix, there is still a issue in the carb area which is why I came here to see if anybody can help or has had a similar situation. 

[mrdsee]

20 minutes ago, kxrob said:

you haven't ben around here long have you ? , everyday there are posts on yz250x jetting not even being close to right ,

 

Yeah, just 59 years, about 40 of which have been on YZ's. I stand by my assertion that stock jetting is "nearly" perfect from sea level to about 3000ft within comfortable air temperatures(60-80 degrees). Adjustments needed when going out of this range. Use the factory jetting charts.

[Christoffer Brandel]

1 hour ago, Miles Holt said:

Thanks! Could too rich of a pilot cause a sudden bog hesitation like I said above? 

I think reguarless what i mix, there is still a issue in the carb area which is why I came here to see if anybody can help or has had a similar situation. 

The kind of bog you described in the OP has happened to me a few times in the past. 

In my case it's been the sparkplug almost getting fouled, and like you I fixed it most of the time by clutching and revving it out. 

But I doubt the pilot will cause that scenario at 3/4 throttle. Your plug did look good, although IMO just looking at a plug doesn't give you much more than if your oil is getting burned up or not (the brown color is left overs after the premix). Although if you say it run good it probably isn't to lean. 

My guess is that you would benefit from a #40 powerjet, together with a leaner pilot. This will affect the main some and you might need to up it a size or two.

Just my 0.02$

Edited March 19, 2018 by Christoffer Brandel

[kxrob]

Yamaha needles are known to have a lean bog just off idle as there dual taper . I would look into a Suzuki needle and look through the yz250x jetting thread

[biglake]

I'd lean the needle 1 clip position or run a needle that's 1/2 a clip leaner.

It's pretty odd IMO to lean everything but the needle when the needle has the biggest effect at 3/4 throttle where your having issues.

[2strokeYardSale]

1 hour ago, Miles Holt said:

If you are suggesting that my main is too lean, it could not be with how it runs currently, plugs look good, and bike runs bad with a larger main.

I was. We live and ride at the same altitude (presumably at similar temps) on similar bikes .(I have a non-X with a milled head.) I'm not saying you should use my exact jetting, I'm just very surprised that we are so far apart on the main.

 

[Kinger317]

I've never heard of a main jet in the 150s on planet earth. There must be something else going on, I don't care what oil you run.

[mrdsee]

Xlnt info on myths about 2 stroke oil, and why I run 28-1 on my YZ144 race bike and 30-1 on my YZ250's.

http://www.off-road.com/dirtbike/tech/twostroke-fuel-ratios-premix-myth-vs-reality-54169.html

[celler]

9 hours ago, mrdsee said:

Xlnt info on myths about 2 stroke oil, and why I run 28-1 on my YZ144 race bike and 30-1 on my YZ250's.

http://www.off-road.com/dirtbike/tech/twostroke-fuel-ratios-premix-myth-vs-reality-54169.html

I have a recent story to go with this. I recently sold a 250rr Beta that had about 300 hours on it. The buyer then turned around and sold it to another party and asked if the new owner can contact me. I said sure.  It was a great bike. New owner gets ahold of me and asked me some general questions and said he just loves the bike.  Said he was was going to run Ams Oil at 80 or 100:1. I said I never ran ratios that lean. I ran 40:1 and before that I ran 32:1.  40 years of dirt biking on 2 stokes. He contacts me and says the motor made a large clanking noise and he stopped. Said the bike would run but was clanking.  I said it  sounds like a Rod failure. I asked him when it failed. He said he was going down a road at 85!  This Beta was geared down from stock so it had to be really spinning. Low oil ratio and extended high RPM....Yep that could do it.  I told him the only rod failure I had was same conditions. running down a road at max RPM for miles on a KX 250 that was known for losing the lower rod bearing.  I was considering a lighter oil ratio on my next 2 stoke since KTM started recommending it and MX action said they had a lot better luck with the KTM jetting mixing per KTM guidelines. That is no longer a consideration for me.

[EmpireofDerp]

85mph at 80:1 lol. That's the perfect recipe for blowing up your 2 stroke. When i got my YZ i was coming off 10 years of superbikes, took it out on the dunes and did the same thing, wide open on the flats for like a minute, BOOM.

[jmd426]

54 minutes ago, celler said:

I have a recent story to go with this. I recently sold a 250rr Beta that had about 300 hours on it. The buyer then turned around and sold it to another party and asked if the new owner can contact me. I said sure.  It was a great bike. New owner gets ahold of me and asked me some general questions and said he just loves the bike.  Said he was was going to run Ams Oil at 80 or 100:1. I said I never ran ratios that lean. I ran 40:1 and before that I ran 32:1.  40 years of dirt biking on 2 stokes. He contacts me and says the motor made a large clanking noise and he stopped. Said the bike would run but was clanking.  I said it  sounds like a Rod failure. I asked him when it failed. He said he was going down a road at 85!  This Beta was geared down from stock so it had to be really spinning. Low oil ratio and extended high RPM....Yep that could do it.  I told him the only rod failure I had was same conditions. running down a road at max RPM for miles on a KX 250 that was known for losing the lower rod bearing.  I was considering a lighter oil ratio on my next 2 stoke since KTM started recommending it and MX action said they had a lot better luck with the KTM jetting mixing per KTM guidelines. That is no longer a consideration for me.

80:1 sabor in slow trails sure.

85 mph down a gravel road, dam people do some silly stuff

 

[mrdsee]

Yeah, the factory recommends say 30:1 and racing engines are run even richer. Yet there's those who roll the dice at 80:1 or even leaner... All in the interest of what? Less smoke(gee, a 2 stroke that smokes, certainly a engine that smokes can't be right!) Perhaps some oil coming out of the muffler? Can't have that on my vanity bike! Must be clean clean clean!

What could possible go wrong?

Of course if one never winds their bike up, does nothing but lugs and bogs the bike it could last....a while.

But then one jumps on it, and kaboom, bye bye parts, and hello wrenches and wallet raiders.

Over 300hrs with one recipe, and then another chef changes a winning recipe. One created by factory and racing engineers, and gets 3 minutes.

Go figure!

Edited March 20, 2018 by mrdsee

[RawbW]

48 minutes ago, mrdsee said:

Yeah, the factory recommends say 30:1 and racing engines are run even richer. Yet there's those who roll the dice at 80:1 or even leaner... All in the interest of what? Less smoke(gee, a 2 stroke that smokes, certainly a engine that smokes can't be right!) Perhaps some oil coming out of the muffler? Can't have that on my vanity bike! Must be clean clean clean!

What could possible go wrong?

Of course if one never winds their bike up, does nothing but lugs and bogs the bike it could last....a while.

But then one jumps on it, and kaboom, bye bye parts, and hello wrenches and wallet raiders.

Over 300hrs with one recipe, and then another chef changes a winning recipe. One created by factory and racing engineers, and gets 3 minutes.

Go figure!

I don’t get it either. At 32:1 my bike doesn’t even smoke when it’s warm, and doesn’t give me any spooge.

[mrdsee]

2 minutes ago, RawbW said:

I don’t get it either. At 32:1 my bike doesn’t even smoke when it’s warm, and doesn’t give me any spooge.

Sounds like a case of proper jetting, along with a bike that's ridden like a 2 stroke should be.

[celler]

Only reason my 2 stokes smoke is because i run a fat pilot.  I find the power is better (Does not matter how hard you whack the throttle open under any load and it pulls with no bog) and it can save you from seizing when your ripping wide open and then chop the throttle quick.

[Tahoe Gator]

On 3/18/2018 at 6:11 PM, Miles Holt said:

So I picked up the YZ250X not that long ago. I live and ride between 4000-6000ft. I run Amsoil saber at 80:1

Is Amsoil Saber some magical premix that works twice as effectively? Or actually 250% as effectively (80 / 32) I should say?

Otherwise, I don’t see how the Yamaha engineers could be so wrong on suggesting 32:1.

How many of us use torque wrenches and precisely follow the specific torque specs in the manual? I wouldn’t over- or under-tighten a bolt 250% off it’s spec.

 

Edited March 20, 2018 by Tahoe Gator
torque example

[Christoffer Brandel]

I am just gonna put this here. 

[3rdMoto]

 

[mrcribbs]

#8 slide, 40 power jet, Suzuki needle, correct main and pilot, corrected squish, and power valve mod. No more issues.

[LSHD]

22 hours ago, RawbW said:

I don’t get it either. At 32:1 my bike doesn’t even smoke when it’s warm, and doesn’t give me any spooge.

Plus you get better mileage and more power at higher oil ratios. I think up to something like 26:1 it just keeps making more power.

Edited March 21, 2018 by LSHD