Patxipt

I have my share with Sanye engines, both 2 and 4-stroke designs. But this SC of mine is making me think.

The engine is fairly new, has had around 1 liter of fuel through it (bought it as "run only 2 times"), and as with all my four strokes, ASP FS30 and FS52, more specifically, I'm using FAI fuel.
I ran the engine last Saturday for around 200cc worth of fuel on the bench. A pain to hand start (like it's sibbling, the ASP FS30), a high idle and shaky mid-range - still needs some hours to be fully broken-in. But it spit a lot of oil, darkish colour oil out of the rocker cover, while the CCV was sipping oil out, and when primed for hand starting it blew oil right through the front bearing (it's sealed on the outside) until it sputtered clean.
Today I took it apart to check it inside, and it looked good, the crankcase vent nipple isn't clogged, the cam followers were filled with dark oil (as was the inside of the rocker/valve area).
A new run on the bench (trying to hand start it) resulted in back and forth crank movement, like a 2-stroke predetonating until it resumes correct rotation, and lots of oil being expelled by the front bearing.

I just can't see what could be possibly wrong with the engine, especially the oil issue! It definitely needs running-in to bed things out, but otherwise..?[&:]

gkamysz

My Feedback: (19)

Typical poor valve guide fits in the Sanye 30 four stroke. I bet if you try to wiggle the valve stem in the guide, there will be visible movement. That means far too much. The exhaust valve to guide clearance must be particularly large in your engine this is where the dark oil is coming from. The high pressure in the exhaust is forcing it into the rocker well. Poor hand starting is also indicative of this issue. The valve guide fit is poor resulting in poor valve sealing. My solution was to scrap the engine in frustration.

Patxipt

That sure makes sense. Will give it a wiggle tomorrow morning and let you know.
A new head is 30 pounds from Just Engines, which equates to half what I paid for the engine... I'll have to give it a good thought, as the engine is mint [sm=disappointed.gif]

jaka

Hi!
Typical symptoms of running no nitro!
The remedy is easy! : Use 5-10% nitro!

Patxipt

Jaka, I run the same fuel on all my engines and they all run well without these symptoms, so this is not the cause. Nitro gives a bit more power and helps tune an engine, but good engine tuning is itself an art with no nitro.
What I find is oil leaking in large wuantities through the rocker cover as well as through the front bearing when primed.
I'll keep this one as spares for my ASP FS30.