YZ250 - tuning help

[mbrick]

klotz lists the flashpoint for all of their oils on their site. Highly recommended and they smell great.

As some others said, keep the 40:1 ratio and try a different oil. Let us know how it looks!

Oh and the dirt looks great, better get back out and ride more!

Edited November 14, 2018 by mbrick

[piltoyougram]

Klotz is the way to go! Try it.

[gspartsguy]

I have used Maxima 927 at 32:1 since the 80's with no problems on all of my motorcycles. I also try to ride WFO style as much as possible. That might be your problem, let that YZ run like it should be run WFO, lugging around on the trails is not what that YZ is designed for. Maybe you just need a trail bike instead.

Edited November 15, 2018 by gspartsguy

[Tahoe Gator]

I must be missing something running Yamalube R at 32:1 for woods riding. Not sure how much smoke there is. Too busy looking forward. Maybe I should try one of those “low flash point” premix oils. Maybe my silencer is going to be a morass of unburned oil when I get around to repacking it (or maybe opening it up here and there has been in my favor). Then again, I cannot recall a post of someone regretting running Yamalube in terms of longevity. And as simple as it sounds, running my can and tank to empty to switch isn’t so easy without lawn machines to burn it in. That said, “never know unless you try” I guess.

 

[kxrob]

6 hours ago, Tahoe Gator said:

I must be missing something running Yamalube R at 32:1 for woods riding. Not sure how much smoke there is. Too busy looking forward. Maybe I should try one of those “low flash point” premix oils. Maybe my silencer is going to be a morass of unburned oil when I get around to repacking it (or maybe opening it up here and there has been in my favor). Then again, I cannot recall a post of someone regretting running Yamalube in terms of longevity. And as simple as it sounds, running my can and tank to empty to switch isn’t so easy without lawn machines to burn it in. That said, “never know unless you try” I guess.

 

Yamalube 2r is not that high of flash point (255f) so not bad for trails , your jetting must be good if you don’t notice any smoke 

[kxrob]

11 hours ago, Donaldp said:

 right now I’m using BELRAY with race fuel and mixing it 60:1

 

What Belray are you using?

[LSHD]

51 minutes ago, kxrob said:

Yamalube 2r is not that high of flash point (255f) so not bad for trails , your jetting must be good if you don’t notice any smoke 

My bike is similar to Gators when I run Yamalube, no smoke. I have squish mod done and Zuk needle. Lately I have been running Silkolene and Amsoil Dominator. Still not issues. I run wide open during flat ground acceleration, so that helps. Repacked my silencer at 35 hours. Didn't need it.

[kxrob]

11 minutes ago, LSHD said:

My bike is similar to Gators when I run Yamalube, no smoke. I have squish mod done and Zuk needle. Lately I have been running Silkolene and Amsoil Dominator. Still not issues. I run wide open during flat ground acceleration, so that helps. Repacked my silencer at 35 hours. Didn't need it.

Good to hear , I did follow your thread on your jetting and watched you ride videos.

you ended up with a NECK needle yeah ?

[LSHD]

7 minutes ago, kxrob said:

Good to hear , I did follow your thread on your jetting and watched you ride videos.

you ended up with a NECK needle yeah ?

For a little while I ran NECK. Ultimately I settled on an NECJ and NEDJ, depending on the season. I used to want to run as lean as was safe, but now I just want good performance with acceptable spooge. Longevity is my goal.

[Donaldp]

3 hours ago, kxrob said:

What Belray are you using?

Si-7 Belray

[YAMAHA NICK]

My bike is similar to Gators when I run Yamalube, no smoke. I have squish mod done and Zuk needle. Lately I have been running Silkolene and Amsoil Dominator. Still not issues. I run wide open during flat ground acceleration, so that helps. Repacked my silencer at 35 hours. Didn't need it.

I have been running the amsoil dominator @32:1 with 30% vp t4 to 70% 90 octane ethanol free pump. Using a octane calculator and trying different ratios of vp I settled on the above mix. There is little to no spooge and it smokes a little less than average judging from all the other yz’s on the starting line.
I ran the 927 for a long time in multiple bikes. I believe the dominator to be a better premix for my riding and application.

[Doc_speeder]

To the OP:

How does the bike run?  Are you happy with it?  My YZ250X smokes too. It's a "2 smoke", so I don't worry about it because it runs awesome.

FWIW I run Motul 710.  It doesn't seem to smoke any less than when I ran Yamalube 2R, but I do get less spooge.

Just another thought...where is your ignition timing?  Timing can affect combustion temp and EGT, so in theory may affect the amount of smoke, maybe?

[HSV-DirtRider]

So I am going to go in a different direction with my post... Have you checked the clutch side crank seal? It could be pulling in gear oil and burning it. If still smoking a lot check that out and replace the seal. It is about $7 or $8 at Rocky Mountain and doesn't look that hard to replace.

[Grinson]

23 hours ago, LSHD said:

Yes, folks will chime in. I'm thinking you aren't a pro racer with a team? Stick with 32:1. Better power. Better longevity. Allows you to use jetting tested by so many of us on TT who also run 30:1/32:1.

Far from pro racer. I just hit the trails for fun. I was running 32:1 but switched to 40:1 thinking it may solve my smoking "problem" - never even thought I may be using the wrong oil for my application!

[mlatour]

You may be tempted to try a few things like premix ratio and jetting but,

start by only changing one variable, the choice of premix.

High float level is also often a contributor to a rich running engine.

Even brand new, many Yamaha 2-strokes are set higher than specs.

[Grinson]

On ‎11‎/‎15‎/‎2018 at 6:09 AM, Doc_speeder said:

To the OP:

How does the bike run?  Are you happy with it?  My YZ250X smokes too. It's a "2 smoke", so I don't worry about it because it runs awesome.

FWIW I run Motul 710.  It doesn't seem to smoke any less than when I ran Yamalube 2R, but I do get less spooge.

Just another thought...where is your ignition timing?  Timing can affect combustion temp and EGT, so in theory may affect the amount of smoke, maybe?

I haven't checked timing, would it be a scenario where advancing the timing would increase combustion temp?

I feel the bike runs well, idle doesn't hang, and it never bogs. I do need to ride WFO more often though. I found this Google Docs oil-comparison table and can see that the Yamalube 2R isn't nearly as high of a flash-point as others, so could definitely be my riding and timing.

I've actually replaced the clutch side crank seal, and then was wondering if I had messed up the install, so I checked how much oil I drained last time and it was exactly 750ml, which means it shouldn't be leaking tranny oil into the crank.

[mlatour]

Many YZ250's (also the X) also suffer from very wide compression squish band

(the clearance between the edge of the piston's circumference and cylinder head)

which makes for incomplete combustion and, requires a tad richer than ideal jetting to prevent detonation.

Search the Yamaha 2-stroke forum, it's a very common topic as with switching to the Suzuki spec needle.

 

Commonly not a problem on the YZ125, but correcting the squish height made my already crisp running engine run even better

and, less sensitive to ambiant temperature changes (same pilot jet now covers a wider temp range)
 

Advancing the timing adds some low end grunt but at the risk of detonation.

Retarding the timing smooths out the power 'hit' and, can increase top end/overev capabilities.

Edited November 16, 2018 by mlatour

[jaguar57]

I think it's nonsense to talk about the oils flash point temp. why? Because that reflects how much "lightening additive" (something like a very light kerosene) there is in the mix to lighten it up to make it more pourable. That's typical with synthetic oils. The only flash point that's important is that of the base oils and they are pretty much the same except for the cheaper group 1 oils some mixes have.

So forget "flash point". It means nothing because they don't list the base oils flash point. the kerosene-like additive with a low flash point quickly vaporizes and leaves the base oils on the parts. It is their flash point that would have any importance and that isn't listed in the specs.

For competition riding use a castor blend or a synthetic blend (combo synthetic and mineral oil) so you can have the fuel/oil ratio close to 30:1

For trail riding use a synthetic oil so you can have a high fuel/oil ratio.

Check out all the info on the subject at www.dragonfly75.com/moto/oil.html

[Kinger317]

^[emoji106]

[kxrob]

2 hours ago, jaguar57 said:

I think it's nonsense to talk about the oils flash point temp. why? Because that reflects how much "lightening additive" (something like a very light kerosene) there is in the mix to lighten it up to make it more pourable. That's typical with synthetic oils. The only flash point that's important is that of the base oils and they are pretty much the same except for the cheaper group 1 oils some mixes have.

So forget "flash point". It means nothing because they don't list the base oils flash point. the kerosene-like additive with a low flash point quickly vaporizes and leaves the base oils on the parts. It is their flash point that would have any importance and that isn't listed in the specs.

For competition riding use a castor blend or a synthetic blend (combo synthetic and mineral oil) so you can have the fuel/oil ratio close to 30:1

For trail riding use a synthetic oil so you can have a high fuel/oil ratio.

Check out all the info on the subject at www.dragonfly75.com/moto/oil.html

I wouldn’t say it means “nothing “ , I agree that the term “flash point “ may not be the best way to distinguish between premix oil that burns away at lower combustion temps and castor based oils that require higher combustion temps to burn off completely.