What oil is best? and what ratio?

[full chizel]

The benchmark is Motul 800 off-road. That said, we are on oil number 2 so....

I was wondering if it was off-road or road racing

 

[full chizel]

I thought I listed it as the Off-road in my testing. Musta forgot.

you probably did and i missed it

 

[andyshine77]

RA100 all done. 8 hours and 55 minutes wfo. Shortly after the shutdown thick red oil started dripping out of the air filter housing and running down the gas tank.

So a lot if spit back. Likely from excessive skirt wear. Could also be from tuning real rich, because of tuning the engine under excessive load. That could potentially account for a lot here, like trying to tune a saw with a really long bar, you tend to end up tuning too rich. Maybe I'm thinking too much.

The slow down speed up could be from soft seizing, I've actually felt that before while running a saw, not a good feeling.[emoji15]

 

[Keith Gandy]

Great! 58 and raining now. Probably another 40 minutes give or take b4 its oot of furl.

So a lot if spit back. Likely from excessive skirt wear. Could also be from tuning real rich, because of tuning the engine under excessive load. That could potentially account for a lot here, like trying to tune a saw with a really long bar, you tend to end up tuning too rich. Maybe I'm thinking too much.

The slow down speed up could be from soft seizing, I've actually felt that before while running a saw, not a good feeling.[emoji15]

I didnt figure it would make it through 100to1

 

[andyshine77]

I didnt figure it would make it through 100to1

I thought it would after seeing trimmers do OK for years running on 100:1 in commercial use. Now in a ported 390xp making stumps cuts or milling it wouldn't, but that's not what this is about, and unless you have money to burn I don't see anyone doing that, although it would be awesome to see.

 

[andyshine77]

I think most of the top tier stuff will.

In a trimmer I agree.[emoji111]

 

[andyshine77]

Not a fan of its smell. Its similar to 800 off-road smell but just enough different to be kinda sickening.
Just to be clear, that's based on using it at 40:1 in something else not being tested to death. It runs great on it.
The test unit has very little smell at the 100:1 ratio. I could smell the hotness of the engine over the RA at that ratio.

You would like K2 than, even at 32:1 with the engine warm the smell is light compared to oils like 800 or R50.

 

[mdavlee]

Not a fan of its smell. Its similar to 800 off-road smell but just enough different to be kinda sickening. And I like the 800 smell.

Just to be clear, that's based on using it at 40:1 in something else not being tested to death. It runs great on it.
The test unit has very little smell at the 100:1 ratio. I could smell the hotness of the engine over the RA at that ratio.

I didn’t care for red armor smell either. The last fuel I mixed was VP and Mobil old stock. I’ll probably go across the highway and buy some saber since I can’t find my gallon of Klotz

 

[Keith Gandy]

I didn’t care for red armor smell either. The last fuel I mixed was VP and Mobil old stock. I’ll probably go across the highway and buy some saber since I can’t find my gallon of Klotz

Still liking the Klotz Original? I hear folks talking about it but I never had an issue with the original

 

[CR888]

Synthetics are stinkie...

 

[mdavlee]

Still liking the Klotz Original? I hear folks talking about it but I never had an issue with the original

That’s what I’ve been using. Even some 1.5 year old canned gas mixed with it.

 

[Ron660]

Some are for sure. None have approached the level of stink the orange bottle Stihl achieved for my nose. I can't stand that *s-worde. Thank God its all used up now. It was free. I'll turn it down if ever offered it again. I Like the smell of Saber and Motul 800 off-road.

800 smells even better mixed with 110 Sunoco 110 octane. The Sunoco 110 octane is purple in color. After mixed I call it Purple Haze.

 

[Keith Gandy]

Through the exhaust port. Some bubbly crust forming in the bottom corners of the port. Hard to see but its there.
4th pic shows varnish like deposit on the intake side of the cylinder.
View attachment 234963 View attachment 234964 View attachment 234965 View attachment 234966 View attachment 234967

Step down exhaust? Ive never seen the original RA formula make this buildup in the exhaust

 

[Keith Gandy]

Not sure what you mean by step down? There isn't a cut out in the ceiling to start blow down early if thats what you mean.

In pic #3 it looks to be a step down from the exhaust port floor , goes in a distance, and then is lower from that point to the exhaust port exit. Keeps the exhaust floor high, prevents freeporting, and gives volume in the port

 

[Keith Gandy]

There is no step, just a gradual slope. A rectangle funnel from piston out if you will.

Gotcha. My eyes were playing tricks! I had a stepdown in a ported 390xp that worked very well

 

[Keith Gandy]

Yes its as you described on the RA100 test mule. It steps down from the port opening.
Why it is there had not even occurred to me till your description. I was focused on the picture taking. Makes sense. It's like exit of a Venturi giving space for gasses to expand as they travel outward.

Ok I was fixing to go to the eye doctor!!!

 

[Keith Gandy]

When you start talking port design and what not it's outside my knowledge. I have years of experience with repairing / working on stock 2 strokes but have very limited knowledge on port designs and what each style does what and why. I'm a thumper guy. I get 4 strokes.

Id love a XR Thumper to trail ride

 

[Keith Gandy]

And when I say I get 4 strokes, thats is the modding of as well not just the repair and operation. I understand how a 2 stroke works but outside pipes and reed changes on bikes from the past, the rest I just never delved into once I discovered the Honda XR 250 in 87.

Mine was a cr125, kx125, cr500, yz250, and the last was a CRF450F. The HotWheels YZ250 was my favorite

 

[andyshine77]

When you start talking port design and what not it's outside my knowledge. I have years of experience with repairing / working on stock 2 strokes but have very limited knowledge on port designs and what each style does what and why. I'm a thumper guy. I get 4 strokes.

The idea of the step, is to create a low pressure area to draw the gases out. It works well too. A steeply downward angled port works somewhat similar.

 

[Keith Gandy]

The idea of the step, is to create a low pressure area to draw the gases out. It works well too. A steeply downward angled port works somewhat similar.

I figured the slope was the same but just not as drastic of a pressure drop as the step. There is a pic somewhere here on the 390xp stepdown in mine. It worked well