40:1 bad for engine?

[millak]

Hey, I have a 2004 yz250 and pretty much every tank of fuel I have a different fuel ratio, someone told me to go down to 125 mills of oil per 5 litres, making 40:1, is this bad for your engine in terms of not enough lubrication? I know recommended is 32:1 but he said that just gunks everything up(I have really soggy muffler packing which I am replacing)-i run castrol active Jaso 2t, which is mineral(not synthetic)

Thanks!

[1987CR250R]

NO!  Run whatever but jetting is what gunks up your muffler, not your oil ratio.

Edited November 14, 2013 by 1987CR250R

[BDubb106]

I run 40:1 in all my bikes except for the 125. I run 32:1 in that because of how often it is held WFO. 32:1 got me the correct amount of oil in the case. 

 

Take a chop stick and place it under the crank. you want 2-3mm of oil to show on the stick.

 

Change your jetting to suit your ratio, don't change your ratio to suit your jetting.

[707ktm]

I run 40:1 in all my bikes except for the 125. I run 32:1 in that because of how often it is held WFO. 32:1 got me the correct amount of oil in the case. 

 

Take a chop stick and place it under the crank. you want 2-3mm of oil to show on the stick.

 

Change your jetting to suit your ratio, don't change your ratio to suit your jetting.

Umm...

[BDubb106]

ummm what?

[707ktm]

ummm what?

Chop sticks? Really?

 

 

I use bamboo shoots to measure crank case oil.

[BDubb106]

Lol I couldnt think of anything else to use as an example. I use chopsticks because I like chinese! Whats wrong with that

[Bremer120]

Lol I couldnt think of anything else to use as an example. I use chopsticks because I like chinese! Whats wrong with that

What's *wong* with that

[jamracing]

Oil ratio can also be determined by your riding style. Motocross or desert racing (open throttle for long periods) will warrant a lower ratio. I would run 50:1 on my ktm125 for woods riding, and I run 40:1 in my yz250.

[AzMatt]

I run 32:1 if I'm gonna be on the main jet all day, sometimes a bit more if it's really sandy. If not I run a bit less. If you're not WOT all day you should be fine

[numroe]

millak, I think that Castrol Active mineral JASO FB oil is pretty good. I used a couple of liters of it, and the motor was perhaps quieter than using Castrol TTS synthetic. I only switched to TTS because it's blue and I didn't want my clear tank to discolour to brown too soon.  TTS is supposed to keep the top end and PV parts clean, and I think TTS certainly does do that because my head and piston crown are spotless with a nice gold/tan color. I was shocked to see how clean they look. I think my jetting is good, not lean or rich.

 

Take a chop stick and place it under the crank. you want 2-3mm of oil to show on the stick.

I agree that's a good test.  A similar test is to see how long it takes to clear the case out after warming it up a little and when the motor has been sitting for a few days. If it takes too long to clear the case and great plumes of smoke come out, then I believe that indicates too much oil for how the bike is being ridden.  Some of us might use more oil for better engine life and accept that means more frequent silencer repacking. Just a choice.

 

IMO, Oil ratio depends so much on how the motor is used. The amount of surplus 2S oil in the crank case seems like a good guide.

 

I run 32 to 40:1 for MX riding and 50:1 for trails. Using Castrol TTS. I have a 295 and only rev it in short bursts. I ran the current rings in using 25:1 and the compression today is excellent. But when I ran 25:1 it took ages to clear out the case. Almost embarrassing amounts of smoke.

Edited November 15, 2013 by numroe

[jamracing]

millak, I think that Castrol Active mineral JASO FB oil is pretty good. I used a couple of liters of it, and the motor was perhaps quieter than using Castrol TTS synthetic. I only switched to TTS because it's blue and I didn't want my clear tank to discolour to brown too soon. TTS is supposed to keep the top end and PV parts clean, and I think TTS certainly does do that because my head and piston crown are spotless with a nice gold/tan color. I was shocked to see how clean they look. I think my jetting is good, not lean or rich.

I agree that's a good test. A similar test is to see how long it takes to clear the case out after warming it up a little and when the motor has been sitting for a few days. If it takes too long to clear the case and great plumes of smoke come out, then I believe that indicates too much oil for how the bike is being ridden. Some of us might use more oil for better engine life and accept that means more frequent silencer repacking. Just a choice.

IMO, Oil ratio depends so much on how the motor is used. The amount of surplus 2S oil in the crank case seems like a good guide.

I run 32 to 40:1 for MX riding and 50:1 for trails. Using Castrol TTS. I have a 295 and only rev it in short bursts. I ran the current rings in using 25:1 and the compression today is excellent. But when I ran 25:1 it took ages to clear out the case. Almost embarrassing amounts of smoke.

Running a different oil ratio for break in is not necessarily a good thing... When you run a super low ratio (more oil), you actually lower the amount of gas, creating a leaner situation, raising engine temp etc...

[numroe]

Running a different oil ratio for break in is not necessarily a good thing... When you run a super low ratio (more oil), you actually lower the amount of gas, creating a leaner situation, raising engine temp etc...

Yep. My motor was jetted slightly rich, so it worked out perfect with extra oil in the mix. Motor was probably too cool, if not ideal. Today I often struggle to start my 295 because the comp is so high. And I thought I was good at starting high comp motors.

Also, in my experience, the jetting impact of oil:fuel ratio changes (on air:fuel ratio) is over rated. One clip pos of jet size change makes a much more noticeable difference to engine temp and response than changing from 25 to 40:1 oil. I'm not claiming oil mix makes no difference, but I do believe it's a small difference, and often irrelevant.

Edited November 15, 2013 by numroe

[BDubb106]

Running a different oil ratio for break in is not necessarily a good thing... When you run a super low ratio (more oil), you actually lower the amount of gas, creating a leaner situation, raising engine temp etc...

 

 

Yep. My motor was jetted slightly rich, so it worked out perfect with extra oil in the mix. Motor was probably too cool, if not ideal. Today I often struggle to start my 295 because the comp is so high. And I thought I was good at starting high comp motors.

Also, in my experience, the jetting impact of oil:fuel ratio changes (on air:fuel ratio) is over rated. One clip pos of jet size change makes a much more noticeable difference to engine temp and response than changing from 25 to 40:1 oil. I'm not claiming oil mix makes no difference, but I do believe it's a small difference, and often irrelevant.

Both of you are actually correct IMO. Different strokes for different folks. 

 

The misconception that oil ratio can be changed to clean up jetting just boggles my mind. I see it way too often on this site. You are probably doing more harm than good going that route because if you can't jet for the ratio you are running what makes you think it is jetted correctly for a different ratio. People just need to understand that both play a role but in the end it all comes down to jetting. You could run 1:1 if you jetted it properly. You need to know WHY you are changing ratios.

Edited November 15, 2013 by BDubb106

[primerib108]

My theory is i would rather have too much than too little oil. I am sure there are a few who disagree with that though lol

 

I jet for 25:1 and ride trail mostly but occasionally hit the track and go on a hill climbing adventure. I like to be on the pipe more than lugging it so that is a consideration. I can tell there is a difference in the top end condition between the 25:1 to the 32:1 I used last year. My powervalve has little to no carbon on it and I can wipe clean the internals with a paper towel.    

[jrg446]

Hey, I have a 2004 yz250 and pretty much every tank of fuel I have a different fuel ratio, someone told me to go down to 125 mills of oil per 5 litres, making 40:1, is this bad for your engine in terms of not enough lubrication? I know recommended is 32:1 but he said that just gunks everything up(I have really soggy muffler packing which I am replacing)-i run castrol active Jaso 2t, which is mineral(not synthetic)

Thanks!

No. I run 40:1 in my YZ125 and have never had a problem. I check my spark plug after every ride to see if the jetting needs to be changed for certain weather but other than that it should be just fine. I ride 90% motocross and some trails and havent had an issue yet.

[arnego2]

I like the highest oil mixture possible just as my bearing last way longer when running 20 - 25 :1 vs 40 - 50:1 Bearing love oil.

That apart more oil lets those rings seal better.

[BDubb106]

No. I run 40:1 in my YZ125 and have never had a problem. I check my spark plug after every ride to see if the jetting needs to be changed for certain weather but other than that it should be just fine. I ride 90% motocross and some trails and havent had an issue yet.

Looking at your spark plug is a bad idea if you are using pump fuel... too inconsistent! It will never give you a good reading! 

[geoffro]

I used to run my CR 125 40:1 for mx and that was on a very sandy track. It was full synthetic and got a season out of top end and bottom end perfect. Although I am not the fastest...Too much oil over-rated, I think for Ktm at moment 50:1 suggested from factory.

[millak]

Well I ride a lot of trail, but also love just blasting WOT down the straights for up to 10 seconds at a time, and apart from that i'm not really in the power band much unless I am on the up ramp of a jump, so I do a lot of trail riding, straights, hill climbs and jumps,

e.g. today, it was pouring down with rain, but I went out anyway, and mostly stayed on the main straight's because everything else was muddy, so spent ages in the powerband, but as per normal, mostly just cruising,

so when I started this thread I was wondering about a ratio that wont let me wear down my engine too fast, but wont gunk everything up in the process, now I know it is my jetting, in about 2 weeks I will have a fresh wiseco top end and muffler packing so I wanted to change it and look after them.

thanks for all replies! will continue to run approx. 36:1 I reckon, and tbh I have no idea about jetting,any links to help out?

thanks!