Mixing Ratio

[dirtbikerida63]

I have a yz 125 and have to mix it 40:1, my brother just bought a yz 85 and has to mix it 38:1. If i just mixed my gas to run the 38:1 also would it damage the bike?

 

[atkkid250]

i am pretty sure it wouldn't

im pretty sure it wouldn't make much of any difference. why a 38:1? never seen that. with just that small amount different you probably wouldn't even have to change anything. I'm not very exact when i do my 40:1 so i end up with 43:1 or 37:1 probably sometimes, makes no difference

 

[outlawgrafyx]

isnt the stock mixing ratio 32:1??? 40:1 sounds a little thin...but depends on how you guys are jetted

 

[FruDaddy]

40:1 has worked for me for several years, with synthetic oil. 38:1 (if jetted reasonably) won't hurt the bike, but it will be a hair leaner. It will also be slightly more prone to plug fouling and spooge since there is more oil to be burned or deposited.

 

[Jaybird]

You are mistaking a 38 for a 32...but it is a moot point really.
Unless you are jetting the carb properly, I highly doubt your engine will even know the difference.

And, FruDaddy, .....nevermind...this is futile. :bang:

 

[FruDaddy]

And, FruDaddy, .....nevermind...this is futile. :bang:

I think that I know where you were headed, the words "slightly" and "hair" were chosen because I know how insignificant the changes would be.
I would check the jetting if I were going from 40-32; but 40-38, I wouldn't even give it a second thought.

 

[Jaybird]

Fru...if I go from 40:1 to 20:1, I am quite a bit leaner, yes?
And, am I more prone to plug fouling and spooge by doing so?

 

[FruDaddy]

I seem to recall, from reading on here, that the spooge comes from the oil not being completely burned off. I'm not looking to argue (this time), but if you have a counterpoint to give the OP, please do. I still live in the world of "pick a ratio and jet for it".

 

[IndyMX]

I've read on here, someone said they could run 16:1 with no spooge, when jetted properly.. It may have been Rich.

He might have some tricks us mere mortals don't possess.

 

[XR250rdr]

The difference between 40:1 and 38:1 is 0.16 oz of oil per gallon of gas. I highly doubt anyone's mixing procedure is that accurate.

I know Yamaha doesn't recommend 38:1 for the little YZ.

 

[FruDaddy]

I've read on here, someone said they could run 16:1 with no spooge, when jetted properly.

Exactly! The bike needs to be jetted for the mixture. If you change the mixture, but not the jetting, that's where the potential for inconveniences (like spooge) begins.

 

[arnego2]

Rpm

... the spooge comes from the oil not being completely burned off.

Hmmm, I believe that driving style also has a say in that matter. Low RPMs do more damage to the sparkplug than the difference of 0.1% to 0.5% in mixture. I drive a rm125 built in 1995 and I run it with close to 50:1 synthetic oil. Due to market shortage I cannot be too fusy about who produces the oil, I'm already happy I can get some somewhere. :ride:

I don't race in competition, though I use it mostly for Endurolike trips which I believe to be more fun than running around in cyrcles. :laugh:

best regards
Arnego2