Bench Testing 717 Engine

[bordercollie]

Hey folks, I've posted here before and just signed up for the premium membership.

Anyhow I bought a used engine via ebay and I would like to test the compression outside the boat. I'm thinking of rigging up a quick platform using 2x4's, bolting on the starter, attaching the intake and oil line(s).

I don't have the engine right infront of me but I recall at least 2 separate oil line hook-ups (1 on the carb, and 1 under the exhaust) and I think there was a 3rd??

Anyway, for purposes of testing compression do I even need to attach the lines? Could I just fill the crankcase with oil (does the crankcase usually fill with oil or is it "dripped" in via the carb? and maybe a few shots of oil in the spark plug holes.

I would rather do the bench test outside the boat b/c if this engine doesn't pass this simple test there's no point going through the bother of putting it in the boat.

Thanks!!

 

[USAF_Pride]

You don't need the oil lines hooked up to do a compression test. You might want to put a little bit of oil in the cylinders to make the rings seal a little better tho.

 

[RodInEscondido]

Hey folks, I've posted here before and just signed up for the premium membership.

Anyhow I bought a used engine via ebay and I would like to test the compression outside the boat. I'm thinking of rigging up a quick platform using 2x4's, bolting on the starter, attaching the intake and oil line(s).

I don't have the engine right infront of me but I recall at least 2 separate oil line hook-ups (1 on the carb, and 1 under the exhaust) and I think there was a 3rd??

Anyway, for purposes of testing compression do I even need to attach the lines? Could I just fill the crankcase with oil (does the crankcase usually fill with oil or is it "dripped" in via the carb? and maybe a few shots of oil in the spark plug holes.

I would rather do the bench test outside the boat b/c if this engine doesn't pass this simple test there's no point going through the bother of putting it in the boat.

Thanks!!

2-stroke engine; lube oil is mixed in the gas normally via the oil injectors, but for testing and initial use while insuring the oil injection works a 40:1 gasil mix will be good.

I would recommend doing an initial compression test before putting oil in the cylinders because the readings will probably be significantly different. According to much research here it seems that the most correct compression reading for comparison is after running the engine and letting it cool down ... an option you do not now have.

No need to connect oil lines for this quick test; but if you desire, check the service manual for the oil connection to the bottom of the engine, connect a clear piece of tubing to it and fill with proper oil until the level gets above about halfway up the engine (insure you have the correct line, one connection to the lower part of the engine is the pulse line connected to the fuel pump on the carb).

good luck,
Rod