Javier-RCU

My Feedback: (6)

Hello friends,

Yesterday I bought an NIB OS 25FX from a local hobby shop. When I came home instilled some after run oil drops and installed a prop.

I begin to turn the prop by hand, but when piston is in up position, there is a lock something like a short stroke, then I need to apply some force to complete the turn.

I did put apart the cylinder head and cover plate and inside the engine seems to be new. When I release the cylinder head screws, this lock or short stroke disappear.

There is something wrong with this engine, should try to break in or should to return to store?

Thanks in advance.

Javier

Hobbsy

My Feedback: (102)

Perfectly normal for that engine. The cylinder is tight at the top becoming a perfect fit at operating temperature.

Dr1Driver

This engine is normal. It's an ABC design. Aluminum piston, chrome plated brass cylinder liner. This type has the liner ground in a taper, with a slightly smaller diameter at the top. When the engine heats up, the top of the liner expands to the proper clearance. You MUST break in this engine in an only SLIGHTLY rich two stroke mode. It MUST come up to operating temperatutre to properly break in.

Dr.1

piper_chuck

My Feedback: (12)

From the owners manual (that paper thingy that many people toss aside and ignore) on page 7: With these engines, the piston will feel tight at the top of its stroke when the engine is cold. This is normal. The piston and cylinder are designed to achieve a perfect running clearance when they reach their intended running temperature.
Why did you start disassembling a brand new engine? With many warranties, this could give the manufacturer an excluse to reject a claim for warranty work. I'm not saying yours needs warranty work, or that OS would reject a claim, but in general, it's not a good idea to disassemble a new product if you think it's broken.
Already answered by others, this is normal. I do suggest putting the engine back in the box and not touching it again until you've read the owner's manual.

Javier-RCU

My Feedback: (6)

[/quote]
From the owners manual (that paper thingy that many people toss aside and ignore) on page 7: With these engines, the piston will feel tight at the top of its stroke when the engine is cold. This is normal. The piston and cylinder are designed to achieve a perfect running clearance when they reach their intended running temperature.
[quote]

You are RIGHT!

Some times one think that knows all... This is my first experience with a little engine. Your advice is well accepted!

Javier

Rv7garage

My Feedback: (10)

I JUST LIKE HOW YOU CORRECTLY USED INSTILLED AND INSTALLED IN ONE SENTENCE [8D]