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I have always used 20:1, ....
Try a few months with a leaded gas like Sunoco standard.
WTF!
I can really smell it. If this thread goes on any further we will all be using 8:1 with dino oil pretty soon, and be happy about the zero carbon!
7
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I have always used 20:1, ....
Try a few months with a leaded gas like Sunoco standard.
Hey Brad if you read this I had some extra time so pulled my 260 apart knowing for sur it's the only saw I have that has never seen anything but amsoil since new outside of my 200. Most of my other saws have probably seen ultra but anyhow the 260 is modded and no carbon buildup anywhere. Please don't think this is an amsoil plug but my 460 before it got crushed was nothing but stihl oil and was carboned just like the one in your photo. I know you mentioned amsoil as a possability so maybe this helps. For what it's worth there was some buildup on the crown on my 372 which has since cleaned up after switching.
I'm curious as to whether or not this is normal carbon formation on a piston crown. This is the P&C from my new MS440. It has only seen maybe a dozen tanks of fuel. The saw has not been run excessively rich, or lean for that matter. What's odd is the the combustion chamber and exhaust port are both clean. The carbon on the piston crown was extremely hard and very difficult to remove.
Most of you know that I run Klotz R50 at 32:1. My questions are this. Is this normal? If not, is this the result of running R50? Is it the result of running 32:1? What do the masses think. And please don't just blurt out, oh you're running it too rich. Give me a reason why you think what you do.
FWIW...Carbon seems to be heavier on the right side.
- Suggests xfers might not be firing simultaneously or the angle is off on the right side, because the piston crown is not being swept.
- You stated it's a new saw, but has it been modded?
BCMs answer was to not run premium unleaded or mid range unleaded road gas because of the deposits it leaves behind. Regular unleaded did not do this any where near as much. The techs would laugh when tearing down a motor and say "Oh yeah another Hi-test guy"
I was not advocating "special" gas for saws. As I said I've changed my thoughts on this subject completely. I used to run all 2 strokes rich on oil because that's the way my father taught me. Now I see over oiling as more of a danger than a help. It is an attempt to "save something to death" How many pistons have you seen with a big ugly score from a carbon chip that broke free and got wedged between tha piston and cyl wall. Carbon buildup is not good for any motor and it will not reach a point and stop building up. Carbon will adhere to itself better than anything else. In a water cooled 2 strokes it will eventually lead to "coking" which is a term used to describe severe carbon formations which will cause your rings to seize, break and you know the rest of scenario. Carbon is the "killer" of 2 strokes. I just thought it interesting that the guys "in the know" who routinely build and race 160 Horsepower, 180 MPH 2 cylinder motors would recommend a lesser grade of gas to help solve the carbon issue.
This is interesting,i had a chat to a stihl dealer saw tuner the other day about blow bye on a couple of my saws.I have always used premium unleaded fuel and Mobile 1 racing 2T at 40:1.He said that's the problem (premium unleaded) the saws are designed to run on 90 oct fuel and that the high energy fuels do more harm than good.
In one of your early responses, you indicated running 32:1 to get oil sealing compression increase in the hope of more power. Oil hurts combustion. When I corrected valve stem seal leak by. Fuel to oil ratio went from approx 150:1 to 600:1. I got a 10% increase in fuel economy. Simply better burning of the gas without oil. Same only more severe is occurring with 32:1. Synthetic oils have higher temperature capabilities. In other words, they won't thin out or burn as easily as Dino oil. Drop back to 40:1 or even recommended 50:1 since saws are generically capable of reaching very acceptable total life hours running 50:1 Dino.
GOOD LUCK. REPORT what we all hope successful resolution.
It appears that the piston head has dry soot while the squish area of the cylinder at the intake side is wet oily. If that is correct as expected the piston is running hotter than the cylinder. Why did you pull it apart? Just your curiosity? If you're into build and teardown, clean the carbon off and run a a few tanks at 40:1 and pull it down again. If it is substantially cleaner- just too much oil @ 32:1. If it is still carboned, especially on the piston head, possibly gas rich. Either way--rich on fuel means extra extra oil or OK adjustment on fuel means just extra oil. Either way means you shouldn't score a cylinder etc.
We certainly can't expecting a 2 stroke to burn as clean as a 4 stroke.
Are you hoping to optimize oil VS power output without trashing cylinder and piston? 16K + certainly requires good lubrication.
Good Luck.
Brad, if you like my 7901 will be coming apart soon and it's had a diet of 98RON fuel and Motul 8002T OR @ 40:1.
I'll post the pictures of the piston and chamber in this thread.
This is one of the best threads that this site has seen in a while. Sooner or later I'll finish up my inventory of MobilRacing MX2T, so it's nice to see what others are pleased with.
Im in the same boat as you, but im running out FAST!!! In fact, Ill be out by this fall. The motorcross buddy of mine is wanting me to try this....CASTOR 927
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