Topic: What tests can be done on a motor outside the frame? Some Results

[manjisann]

This is kind of a continuation of my other thread: http://forums.sohc4.net/index.php?topic=74448.25  . I'm going to put the spare motor I have on an engine stand tonight, clean all the pine needles and dirt off it, change the oil and check the valves. The condition of the engine is unknown as I got it when I bought a frame to fix a buggered one, and I've never done anything with it. What should I check and what tests can I do with the engine out of the frame?

Thanks all,

Brandon

[Gordon]

You can do a compression test or a leak-down test.

[scottly]

I would hook a battery and solenoid up to the starter and do a compression test. Also, either monitor continuity to ground on the oil pressure sender with a meter (continuity=no pressure, open=pressure), or screw in an oil pressure gauge.

[manjisann]

I have a Harbor Freight Compression tester, but no leakdown unfortunately.

Will a compression test work if there are no exhaust pipes hooked up?

Thanks,

Brandon.

[scottly]

Yes

[scottly]

I would also squirt some oil in the spark-plug holes before spinning the motor to make sure the pistons have some lube.

[manjisann]

Do I have to have the solenoid in there, or can I just hook the battery to the starter long enough to do the compression test? Sorry, I'm looking at the 650's wiring diagram and having a hard time figuring out how to hook the solenoid up and get it to work without the wiring harness.

Brandon

[Gordon]

The solenoid is just a switch and isn't necessary for running the starter motor.  Hook the negative cable from the battery to the engine case and then when you touch the cable from the starter to the positive battery terminal it will turn over the motor, as long as the starter motor works. 

[manjisann]

The solenoid is just a switch and isn't necessary for running the starter motor.  Hook the negative cable from the battery to the engine case and then when you touch the cable from the starter to the positive battery terminal it will turn over the motor, as long as the starter motor works.

Sweet, that's what I was hoping to hear, thanks 

Brandon

[manjisann]

I got home and blew as much of the crud off the engine as I could and checked each plug hole with a flashlight to try and see anything that might fall in. I pulled off the other valve covers and everything looks good. The plugs came out easily which was a pleasant surprise. I checked the oil level and it was full, yeah, I have no idea how old it is, but it wasn't jet black, or some strange color and since I'm just doing a compression check I figured I'd be ok. I checked cylinder 1, 100 (I'm using a harbor freight gauge, so the values won't match honda's), put the plug in and checked cylinder 2's, 100, and then the plug that is underneath the charging rotor popped out and oil blew onto my pants. I had taken the rotor's cap off a while ago to scavenge some parts and hadn't put it back on, oops. I'll put it back on tomorrow and check 3 and 4, but I'm somewhat hopeful that they'll be good.

A question though. All the plugs were sooty, which doesn't worry me too much, but plug 2 seemed a wee bit oily and did smell of oil. When I did the pressure test the tester came out oil free, AND it did test the same psi as cylinder 1. Is it possible to have a bad ring or valve seal but still get good pressure tests?

Thanks,

Brandon

[scottly]

I would call those encouraging results. The blown-out oil galley plug proves you have oil pressure. If the other two cylinders are close to the same readings, bolt it in and see how it runs!!

[manjisann]

Haha, Scottly, Terry in Australia said pretty much the same thing in the other thread. I'm gonna check the other two just to be sure, give her a good cleaning, and do as you say and bolt her in. I'm actually a little hopeful that she'll run with only a tune up and fresh oil

Brandon