YZ250 - tuning help

[Grinson]

Hey everyone,

Earlier this year I purchased a used 2013 YZ250 on Craigslist. The bike had been modified for trail riding and had about ~100 hrs on it (came with hr meter). The engine is stock, except for a rekluse, 10oz FWW, aftermarket pipe & silencer, and a Lectron (which I installed, purchased from a fellow forum member). I put in a fresh top end and now have about 30 hours on it.

Ever since I've had the bike it has smoked. The smoke is the more bluish color, which tells me it may be jetted too rich, however I haven't been able to tune it out and am wondering if this is something I should continue to rack my brain about, or if I should just leave it since it seems to run just fine.

It smoked just as much with the stock carb as it does with the Lectron. This past weekend I tried a couple settings on the Lectron (leaned the metering rod a quarter turn here and there) - however, I found that it still smoked just as much when it was leaned, and had to richen it to fix a hanging idle.

Could I be missing something? I measured the oil during my last change and it came out at 750ml, which tells me it can't be a bad crank seal.

I started with Yamalube 2R @ 32:1, and went to 40:1. I only ride trails, and will try to open it up every once in a while to get the engine hot and burn off any excess. 

Here's a picture my wife snapped this weekend, shows what the smoke looks like. This is after riding for a while so the bike should be at operating temperature - don't mind the crappy wheelie 

Thank you in advance for your help!

 

[mlatour]

IMO the Yamalube 2R flash point is too high for your usage, 

'opening it up' once in a while doesn't remotely compare to constant corner to corner WOT accelerations and higher combustion temps of motocross.

 

For recreational trail/off-roading, try a lower flash point premix like Amsoil Interceptor or Lucas.

Edited November 14, 2018 by mlatour

[Grinson]

38 minutes ago, mlatour said:

IMO the Yamalube 2R flash point is too high for your usage, 

'opening it up' once in a while doesn't remotely compare to constant corner to corner WOT accelerations and higher combustion temps of motocross.

 

For recreational trail/off-roading, try a lower flash point premix like Amsoil Intercetor or Lucas.

Thank you for the tip! I wondered if that may be the case. I've heard people talk about Motul, and the local bike shop pushes it quite a bit - I think its the Motul 800 - good for trail riding?

[mlatour]

Like your current Yamalube 2R, Motul 800 is also a high flash point oil, better suited to racing applications.  (say like Amsoil Dominator)

 

Motul 710 is more in line with the ones I mentioned, favoring cleaner burning.

Typically, most low flash point premix oils will also mention 'can be used in premix or oil injected applications'

 

For anyone who disputes Interceptor or any low flash point premix oils don't provide enough protection,

my recreationally but still pushed to 10500rpm MX track ridden YZ125 is going on 7 seasons / 100+ hours on it's original bottom end.

Edited November 14, 2018 by mlatour

[YZDOC]

5 minutes ago, mlatour said:

Motul 800 is also a high flash point oil, better suited to racing applications.  (say like Amsoil Dominator)

 

Motul 710 is more in line with the ones I mentioned, favoring cleaner burning.

Typically, most low flash point premix oils will also mention 'can be used in premix or oil injected applications'

I've never checked but 2S is used in injection bikes. Does it have a different flash point that 2R oh wise one? 

Also for OP, if you change oils, be sure to drain out the existing fuel mix before trying new. Some oils do not play nice together and will make gumbo in the power valve. Also, replace saturated exhaust packing as needed. 

[mlatour]

Tough to find infos on the Yamalube 2S but I would imagine so.

 

IMO, 2S versus 2R would directly compare to Interceptor versus Dominator.  (710 vs 800 as well)

Intended usage, particular base oil viscosity and blend of additives favoring clean burning versus film strength / maximum protection etc.

Edited November 14, 2018 by mlatour

[Grinson]

Man, I'm going to feel silly if it just ends up being the Yamalube 2R.

Any other low flashpoint oils out there?

[mlatour]

Pick something that's available to you locally, you mentioned the Motul brand, try the 710 and not the 800.

As Doc suggested fully drain your old gas/premix before switching over.

Don't change your premix ratio, stick with 40:1

 

It may not fully stop the smoking but at least you're on the right track with a better suited oil.

 

The exhaust pipe might also be full of un-burnt premix and your type of riding never gets it hot enough to burn out.

If so, it may require removing the pipe, adding a bit of kerosene inside and leave a propane torch pointed in the inlet for an hour or so.

[kxrob]

@

Amsoil Interceptor - 183 F

Amsoil Dominator- 194 F

Amsoil Saber Pro - 237 F

Maxima Formula K2 - 240 F

Maxima Super M - 280 F

Maxima Super M Injector - 220 F

Maxima Castor 927 - 420 F

Maxima Bio 2T - 180 F

Motul 710 - 190 F

Motul 800 - 485 F

Motul Bio 2T - 255 F

Motorex Cross Power 2T - 230 F

Lucas Semi Synthetic - 182 F

Bel Ray H1R - 435 F

Bel Ray MC1 - 208 F

Bel Ray Si7 - 194 F

Castrol Power RS- 163 F

Castrol 2T - 194 F

Red Line Two-Stroke Racing Oil - 221 °F

Edited May 17, 2016 by MistrRoboto@Grinson

[Grinson]

10 hours ago, kxrob said:

@

Amsoil Interceptor - 183 F

Amsoil Dominator- 194 F

Amsoil Saber Pro - 237 F

Maxima Formula K2 - 240 F

Maxima Super M - 280 F

Maxima Super M Injector - 220 F

Maxima Castor 927 - 420 F

Maxima Bio 2T - 180 F

Motul 710 - 190 F

Motul 800 - 485 F

Motul Bio 2T - 255 F

Motorex Cross Power 2T - 230 F

Lucas Semi Synthetic - 182 F

Bel Ray H1R - 435 F

Bel Ray MC1 - 208 F

Bel Ray Si7 - 194 F

Castrol Power RS- 163 F

Castrol 2T - 194 F

Red Line Two-Stroke Racing Oil - 221 °F

Edited May 17, 2016 by MistrRoboto@Grinson

This is great, thank you!

[RidingWithStyle]

We ran klotz with 20% castor 40:1 and had great results. It smells amazing as well. Currently run golden spectro 40:1.

[Animatrix86]

We've ran Golden Spectro at 50:1 in all our two strokes for a lot of years.  Never had any issues.

[kgmkgm]

I do crosspower 2T on my ktm 200, and it doesn't smoke too bad. It's at altitude so I usually have it decently rang out, not just blipping the gas, unless its a really hard trail. What do you guys think?

[powdermuncher]

Any good oil will be no problem at 50 to 1 in trail-riding applications.  High flashpoint oils will not burn just migrate into your exhaust packing and make smoke when trail riding. The high flashpoint of  amsoil saber is able to run at 100 to 1 it does not burn of as easy so sticks around longer. 

A budy just got a trials bike with fuel injection , they recommend saber at 120 to 1  for that aplication that runs even colder egt's 95% of the time.

[Tahoe Gator]

The exhaust pipe might also be full of un-burnt premix and your type of riding never gets it hot enough to burn out.

If so, it may require removing the pipe, adding a bit of kerosene inside and leave a propane torch pointed in the inlet for an hour or so.

 

 

Am I missing something that pointing a propane torch into a silencer full of kerosene seems like a dangerous idea?

[mlatour]

Not really, it's not under pressure so can't 'explode' but just like lighting a bond fire or BBQ, be careful!

 

Slosh 1-2 ounces of kerosene (or diesel) in the pipe beforehand so it can soak into the carbon,

put it on the ground away from anything combustible and point the stinger end downwind,

set it afire by the inlet end and keep the torch pointed inside to maintain the burn rate high.

 

After 30 minutes or so, the oil will have burned out,

if you insist on a thorough cleanup, any leftover carbon will scrape out quite easily by

spinning a length of metal coat hanger wire inside, mounted in a cordless drill.

(bend a small 1/4" 'hook' at the end of the wire)

 

Same goes for perforated silencer cores before repacking.

 

 

[Christo6060]

19 hours ago, Grinson said:

Thank you for the tip! I wondered if that may be the case. I've heard people talk about Motul, and the local bike shop pushes it quite a bit - I think its the Motul 800 - good for trail riding?

I use motul 800 works great for me, and smells great too!

[Grinson]

I found this site with some good info on 2-stroke oils: http://dragonfly75.com/motorbike/oil.html with the flashpoint on some others not listed above.

I'll make the switch to a lower flashpoint oil, likely Motul 710. I recently replaced my packing so hopefully that should still be fine. Definitely a relief that the excess smoke is likely just me not knowing which oil to get rather than having bought a lemon!

[Donaldp]

I kinda had a test bike and tried all the different oils (premix) and the top name oils gave me the best performance and wear and tear AMSOIL being the best for me but the real change came when I started trying different gas, pump gas forget about it, try to use racing fuel or ethanol free gas, right now I’m using BELRAY with race fuel and mixing it 60:1, I know everyone will probably be chiming in on this but I’m running clean and no wear yet, the only reason I’m running this is I met a pro hard enduro racer and he said that’s what his team runs so I Thought my slow ass will try it, good luck to you , everyone seems to have the best ideas but you’ll have to try what works for you.happy trails

 

[LSHD]

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.