Saw carb tuning help

noah9988

Active Member
Joined
Jul 3, 2021
Messages
228
Each wing should reach about half way across the piston. Maybe not all the way, your intake system and porting will determine how far. They should reach about 2/3 the piston in the forward to back position. Again has to do with intake and porting, plus squish distance. The squish area of the piston when set right is relatively cool, and clean. There will be a little junk, we are burning stuff in there after all. When in perfect tune, the residue on the piston crown, should wipe off easily. You were way to rich from the air leak, so your wings should have a carbon hunk around them. An running a bit extra oil, if the right amount of fuel, should still leave relatively easy to clean residue. The oil is what keeps the inside of the chamber clean. It carries away all the junk. So these guys that run 50:1 and higher, are losing the ability to carry junk from the fuel and air that makes it in, away. Idc if you use saber or whatever that says you can go 100:1. it doesn't carry the junk away, there is not enough oil to do so. So instead it hangs out and wears parts down till it finally gets spit out, or sticks to something in the chamber. If you don't get a little drip, drip from the pipe when you come to ride it after sitting over night, you are to low on oil. There shouldn't be a big puddle, but a few drips, maybe a quarter sized puddle or smaller under the exhaust tip if you run a stock muffler.
Obviously my engine was not running correctly, when I've had it running like a top it doesn't build up hardly any carbon on the piston, just a brown film. The combustion chamber usually doesn't have anything in it either. This time it had a little black chunky crud. I've used conventional supertech (walmart) at 32:1 and that built up a lot of carbon, similar to what it looked like this time.

The cylinder I was using also had the center bridge part of the transfer port removed (g4 cylinder). I didn't notice any performance difference, if anyone's wondering.

All a part of doing stupid stuff in the name of science!
 

Karl Snarl

Well-Known Member
Joined
Sep 20, 2019
Messages
5,691
Obviously my engine was not running correctly, when I've had it running like a top it doesn't build up hardly any carbon on the piston, just a brown film. The combustion chamber usually doesn't have anything in it either. This time it had a little black chunky crud. I've used conventional supertech (walmart) at 32:1 and that built up a lot of carbon, similar to what it looked like this time.

The cylinder I was using also had the center bridge part of the transfer port removed (g4 cylinder). I didn't notice any performance difference, if anyone's wondering.

All a part of doing stupid stuff in the name of science!
That film is how it should be, just a residue. An walmart oil is good stuff and will run the same if dialed in. I used it for years and got the brown residue, very little carbon. Maybe it was starting to happen then , and you may have thought it was the oil. I still run walmart oil if I have no lucas and castor. I use only walmart oil in my weed eatters. One of them is 15 years old, only used walmart oil, it runs the best of all my eatters, even better than the electric one. lol. Not defending walmart, but their oil is made on the same lines as everyone elses, and uses an additive package really similar to lucas land and sea.
 
Top