If your going to run race fuel I would seriously look at VP MRX2. It will make about 7% more power due to its o2 content and it's distillation curve is matched to a two stroke.
661 Oil Test 32:1 vs 40:1 vs 50:1 ?
- Thread starter redbull660
- Start date
Help Support Arborist Forum:
KG441c
Keith
Im not following where we r suppose to think the piston is suppose to be perfectly clean on top without some depoists? Like I mentioned before the only way would be to use so much oil that it washes the depoists out but then u r getting tons of unburned fuel and oil out the muffler? Wouldnt it make more sense if u were getting a complete efficient burn from your fuel and oil at the right performance level that some depoists would have to eventually form on top of the piston?
Ron660
Addicted to ArboristSite
Thanks...good information. I read somewhere the oxygenated fuel may cause internal corrision issues. Truthful??
Yes, you are thinking correct. Some carbon on the piston top is expected when the air/fuel mix is correct. Too much fuel washes off the deposits and means the combustion temp it low. Google piston wash. The ultralight guys have great info on piston wash. It's not the oil that washes the piston but rather too much fuel.
whitedogone
Addicted to ArboristSite
Holy crap....THE oil thread to end all oil threads....not
Yes, it's very true if the oxygenate is ethanol. The VP fuel I mentioned uses MTBE, which doesn't cause corrosion of screw up tuning like ethanol does.
If the piston is bare metal clean it either hasn't been run long or nits way rich. Ideally the piston should be a light brown color with a small amount of wash where the transfers discharge. More common is a black dull black coating of carbon and a small amount of wash where the transfers discharge. On a saw these wash spots should be approximately the size of a pencil eraser.
The guys who claim bare metal are inadvertently admitting they can't tune a saw to save their lives.
One other thing to look for is mettalic deposits on the crown and combustion chamber. These will look like extremely rough texture, raised globules or balls. These are bad because they can heat up till the glow under heavy load and cause pre ignition. I recently tore down a 346 for a friend that was ran most recently on Klotz Super Techniplate. It wasn't as bad as I thought cleanliness wise, but the piston crown and head had alot of mettalic buildup.
FYI motul 800t has the highest mettalic content(as measured by the sulfated ash test) of any two cycle oil I have seen.
the metal content is from calcium based detergents and from ZDDP added as an anti wear additive. This is one example of why it's smart to match oils to applications.
My only point was that Ultra isn't necessarily a dirty oil, as RedBull suggested. I've personally never seen a bare metal piston crown in any saw, ever. I've also never used 100LL for any length of time.
Moparmyway
Its just a saw
- Joined
- Dec 2, 2012
- Messages
- 2,481
- Reaction score
- 3,399
Bare metal .................... 661
Attachments
Moparmyway
Its just a saw
- Joined
- Dec 2, 2012
- Messages
- 2,481
- Reaction score
- 3,399
Removing all doubt as to how little you can comprehend..Priceless epic
You think I have contradicted myself, but I have not....
Little run time...
Saying Ultra is dirty, then cheerleading H1R in a saw is a real joke..
I checked the VP website and it specifically says to keep that fuel cool, that could be a issue on a hot day.
I would leave it in a metal can and mix only enough to use at one time. But really the same goes for any race fuel. You really don't want all those low boiling point components evaporating off. This isn't as big of a concern with pump gas due to changes in regards to evaporative emissions standards, but it still isn't a great idea to let your fuel get warm.
KenJax Tree
Terraphobic
I've used VP T4 with good results, they also have T2 which is premixed 40:1. I would assume it has Motul oil in it like SEF.
I have had good luck with SEF and C10 mixed 40-1 with Stihl Ultra. That new VP fuel I will for sure try once I get my hands on some.
Any good racer will keep their fuel cool as possible away from sun light. Many of the race fuels you need rubber gloves to prevent it from getting on your skin.
Any good racer will keep their fuel cool as possible away from sun light. Many of the race fuels you need rubber gloves to prevent it from getting on your skin.
Moparmyway
Its just a saw
- Joined
- Dec 2, 2012
- Messages
- 2,481
- Reaction score
- 3,399
Been asking for an explanation for some time now .....................
Moparmyway
Its just a saw
- Joined
- Dec 2, 2012
- Messages
- 2,481
- Reaction score
- 3,399
Fuel and air are compressed before combustion, most of the fuel burns in its liquid (atomized) state. You would have us to believe that most of the fuel is turned to a vapor, then combustion occurs; this is incorrect and where you are wrong.
Under heavier loads, the motor requires more fuel due to more of the atomized fuel flashing off into a vapor from the additional heat generated.
Atomized fuel in its liquid state provides combustion, fuel vapors burn at different rates and contribute very little to the power that atomized fuel produces.
http://inventors.about.com/library/...be29d3fc-99b1-4f9c-9f2c-bfb8ea8161f5-0-ab_gsb
