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OT but you guys are the best.... 2 stroke jetting for "oil Pool"

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I read an article a couple years back about when jetting a 2 stroke to jet for oil pool around the cylder head (or something like that). Was interesting.

Back then I didn't have a 2 stroke but now my son's riding and would like this info again.

Anyone have any info? Did I dream this or something because it just kind of disappeared.

Note. Cross posting to jetting & General forum.

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I've never heard of an "oil pool". However, on snowmobiles, the common jetting procedure is look for "piston wash". Would this be what they were referring to? PW is basically a reference to the cleaned-off areas on the piston crown, which are adjacent to the transfer ports. The fresh charge of air/fuel will keep these areas "washed" clean of soot. As the engine is jetted richer, these washed areas become larger. Leaner jetting = smaller PW. A lean jetted engine will have almost an absence of wash and have a piston crown which is almost entirely soot covered, at which point you are flirting with buying some new parts.

Dirt bikers do not talk about this procedure, however, b/c visability to view thru the spark plug hole is usually very restricted. Snowmobiles are have historically very easy to view from the top of the engines, although recent year's new design snowmobiles have restricted access.

Hope this helps.

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Bazooka-

Interesting stuff!

Not what I was thinking about however.

Funny, the carbon thing sounds kind of backwards.

Seems like too rich would leave alot of carbon somehow (cause all the fuel wasn't getting burnt. Guess I've got my wires crossed again.

Thanks for the interest.

Eddie

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Eddie,

Yes, it does sound backwards at first, until you think about that these washed areas are kept clean by the incoming oil/fuel mixture. Too rich will have plenty of carbon build-up towards the center of the piston, but that takes some duration of running to accumulate and that's not what we are looking for. What we are watching for, is a light coating of soot covering the piston. Adjusting the jetting will make this soot coating come and go with a single run. Change the jetting and try again.... and again... :applause:

If this sounds over-anal, yes it can be. You should see some of those snowmobile guys watching their jetting. Open the hood, pull the plugs, shine a little flashlight at the piston, and then pull off the carbs (PITA on some sleds). Take a run and try again and again. In comes a cold front or big temp change and they are back at it. Freaks, they are, maybe. To their defense, engine parts aren't cheap and it sucks getting towed home. Plus, there is some HP on the table w/o spot on jetting, and sleds are basically on a dyno on a WFO run accross a frozen lake. To each their own, I guess. I jet mine for -10 on good gas and then live with it when it's warmer. Unless, of course, I have a score to settle, then out come the smaller ID brass parts for some spot on jetting. :eek:

Here's a link to some further explanation-

http://www.snowtechmagazine.com/articles/2001/baseline/baseline.php

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