32:1 or 40:1

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speedtrip
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32:1 or 40:1

Post by speedtrip »

Wondering what most folks here run. I use 32:1(as per the manual) But the end of my tailpipe is oily and black. I get a few drops out of that drain plug in the stock muffler when I take it out. That fuel/oil calculator is way cool too.
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Post by scheckaet »

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Post by speedtrip »

Thanks man!
I think I just gave myself the hint that I should use the cool search function on this forum. I know it gets a bit tedious to see the same question or topic over and over. There is a lot of good info on this site. Glad I found it! I could spend hours here! Thanks again! :grin:
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Post by skipro3 »

Just keep asking. We will keep pointing you to the right info if we can. Otherwise, we'll make up something to sound smart!!

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Re: 32:1 or 40:1

Post by Mr. Wibbens »

>|<>QBB<
speedtrip wrote:Wondering what most folks here run. I use 32:1(as per the manual) But the end of my tailpipe is oily and black. I get a few drops out of that drain plug in the stock muffler when I take it out. That fuel/oil calculator is way cool too.
That's more of a jetting thing, but even if you have your jetting close and you run a lot of tight ****, you are gonna get the spooge!

Or if you run Toulene, the drips may get worse as I've recently discovered
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Post by canyncarvr »

A couple of things to consider:

Spooge is not a premix issue (like Wibby said).

The more oil you run (jetting corrected), the more power your bike will make.

If your oil manufacturer does not recommend a ratio for your bike, use the BIKE manufacturer's rec. That's a general rule of thumb...most oil mfgs. DO specify. Maxima (SuperM for example) recommends 40:1 for a 200cc bike.

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Post by speedtrip »

Spooge is not a premix issue?!

OK, so if I fattened up my jetting a bit much all around with a richer pilot, main and needle and air screw tinkering, I could finetune with premix ratios? As long as I was providing the motor with enough lubrication to keep it running well.

It just seems to me that a thinner ratio would be less oily and that it would effect what I am seeing at the tailpipe.

I appreciate any enlightenment!
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Post by Mr. Wibbens »

>|<>QBB<
speedtrip wrote: It just seems to me that a thinner ratio would be less oily and that it would effect what I am seeing at the tailpipe.
You'd actually be running richer :wink:
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Post by Indawoods »

Yes... and Spoo is unspent fuel....
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Post by speedtrip »

richer? with 40:1 compared to 32:1?

splain that one to me Lucy.

wait; more molecules of fuel in the same volume of charge?
A combustion chamber filled with unignited mix.....more oil displaces fuel amount? more oil = less fuel?

You made me think, now my head hurts :blink:
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Post by speedtrip »

when i put in my new Wiseco piston, I swear, somewhere along the process, I read to run 16:1 for the first hour. That was possibly advice from Wiseco themselves.
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Post by KDXer »

RICH or LEAN refers to the amount of GAS being delivered to the engine. More oil would mean less gas in X amount of gas.
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Post by fuzzy »

[/quote] I read to run 16:1 for the first hour[/quote] That's fine, but be sure to richen it up (stock jetting would be OK as it's real rich just about everywhere in the world). Warm up for first 15mins, and then flog it for the next 45 being sure to get a good amount of top-end and engine braking during the 45 min cycle.
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Post by canyncarvr »

>|<>QBB<
speedtrip wrote:richer? with 40:1 compared to 32:1?

splain that one to me Lucy.

wait; more molecules of fuel in the same volume of charge?
A combustion chamber filled with unignited mix.....more oil displaces fuel amount? more oil = less fuel?

You made me think, now my head hurts :blink:
Surely you've got it at this point? From the last part of the above it seems plain...but, to hit the broad side of the wall...

40:1 is forty parts gasoline (presumed for ease of explanation. Could be part kerosene, xylene, toluene, C12, etc. etc.) to one part oil.

32:1 is..obviously...a whole lot LESS gasoline to that SAME part oil!

40:1 is MORE RICH air/fuel-wise than is 32:1.

Your 'thinner ratio' (Again..presuming 40:1 to be your 'thinner' compared to 32:1) is MORE GASOLINE per unit of measure.

Using the terms richer/leaner in regard to premix isn't the best idea. Too easy to confuse the words with air/fuel.

Re: 'What happens when I run a richer fuel mix?' means...well...who knows WHAT it means.

You can finetune with premix ratios. Pretty easy to get confused doing so, though. Consider: Your bike runs noticeably better at 32:1 than 40:1. Does than mean that the 32:1 premix (more lean air/fuel-wise) indicates the bike likes less gasoline? Needs to be leaner jet-wise?

Or...does it mean the additional oil in the 32:1 premix ratio gives you a better piston-cylinder seal...a better RING seal thus higher combustion pressures thus thus and thus?

Which?

Choose an oil and a rec'd mix ratio. Jet your bike via carb adjustment to be 'correct'.

Re: The 16:1 part on break-in...

Some folks still say that...more folks don't. Like Fuzzy said...keep the important part, air/fuel ratio in mind.

Oh..if I recall (**edit**did check the link below to have bradf set me straight...again..) correctly a change from 40:1 to 32:1 is a .6% reduction in air/fuel expressed in a gasoline volume change. Of course, air/fuel is not expressed that way, is it!:hmm:

'I'm running one ounce of fuel to four gallons of air!'

Uh...no.

http://www.kdxrider.net/forums/viewtopic.php?t=3570

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Post by skipro3 »

>|<>QBB<
speedtrip wrote:richer? with 40:1 compared to 32:1?

splain that one to me Lucy.

wait; more molecules of fuel in the same volume of charge?
A combustion chamber filled with unignited mix.....more oil displaces fuel amount? more oil = less fuel?

You made me think, now my head hurts :blink:
You've got it!!!
So, with less oil and more gas, you are running richer. Not only that, but the oil viscosity plays a little role too. Less oil and your premix is 'thinner' viscosity-wise and so more gets through a jet opening. So now, if you are experiancing spooge, it seems pretty obvious that it is not unburned oil, but is unburned gas. It's a fact that some riders experiance less spooge when they upped their oil in the gas.

As CC noted, it is possible to change your "jetting" by adjusting your oil/gas ratio. Also.......... pump gas is very inconsistant from one station to another, one brand to another, heck, one delivery to another. This can result in obtaining a batch that doesn't burn well for your bike, will look like it's rich by causing more spooge, and yet is really lean because that gas, turning into spooge, is not burning and is leaning out your air/fuel mix.

Does that make your head feel better?

If so, then start tackleing the concept that fuel is pushed upwards in a dirtbike carb from the bowl via the ambent air pressure in relation to the vacuume of the intake stroke and that the float level will change the overall vertical rise that the fuel needs to overcome.
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Post by canyncarvr »

Re: 'Not only that, but the oil viscosity plays a little role too.'

:hmm: But....but...with more oil, shouldn't the fuel be slicker and so flow easier?

Just fussin' with 'ya.

THIS is important, though. Seems to be overlooked often, but it BEing overlooked makes it no less true:

'...will look like it's rich by causing more spooge, and yet is really lean because that gas, turning into spooge, is not burning and is leaning out your air/fuel mix.'

Man, have I seen that! Lean enough to overheat, detonate and leave the plug spotless..but the exhaust spattered like a champeen!!

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Post by speedtrip »

Wow! I swear I get it now! It tooka while for me to wrap my brain around the concept. Oil/fuel air/fuel oil/fuel air/fuel.

Makes a guy want to mix several batches and go riding!

Thanks Guys I really appreciate the time you all took. And the sharing of knowledge
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