Compression check

I just bought an XJ700N parts bike and want to check the compression. All the wiring harness is gone but the engine and carbs are intact. I don't plan on using the engine, but want to at least check the compression. It was running, but parted out due to electrical issues. Anyway to hook up a temp switch to the starter to turn it over?

 

Anything that you can jumper the terminals on the solenoid with, if the battery connections and solenoid are still there.

Otherwise all you need are a battery and jumper cables; connect one cable (-) to ground, then the (+) side to the big terminal on the starter. It'll spin.

Be sure the throttles are held wide open.

 

jumper cables hooked to a battery pos to the stud on the side of the starter negative can go about anywhere else that makes a good contact. quick and easy. Or use the solenoid to wire in a switch leave the normal heavy gauge wire running to solenoid and then to the stud on the starter, make sure the engine (or frame if it is still in the frame) is grounded back to the battery. Then wire in a switch: power from battery to switch to the small positive wire on the solenoid then small negative on the solenoid back to the battery.

 

Thanks. I think all the wiring harness is gone. I have a battery and jumper cables. Does it need to be a motorcycle battery or will it be ok to use an auto battery?

 

For simply spinning the starter, 12V is 12V.

I generally use a motorcycle battery; I just pull the one from my bike.

But I doubt you'll hurt anything using a car battery for that short of a time.

 

Bummer. I got home and got the bike in the garage for a good check and the starter is gone. I bought the bike for the carbs and forks, so the engine and other parts are just extras, but it would have been nice to do a compression check. Guess it's just a parts engine now.

 

So pop your starter off and swap it over for a New York minute. Two, three bolts and the one cable and that's it. That way you don't chance condemning a possibly solid mill to the scrap heap.

 

sounds like a plan. I don't have any need for the engine but would not want to sell it unless I can vouch for the compression.

 

Another "crazy" idea would be to secure the engine (if not in the frame), and pull the side engine cover off. Use an electric drill with a socket bit, and the right sized socket to crank the engine. It doesn't have to be fast, but fast enough to get a few good rotations.

 

Another "crazy" idea would be to secure the engine (if not in the frame), and pull the side engine cover off. Use an electric drill with a socket bit, and the right sized socket to crank the engine. It doesn't have to be fast, but fast enough to get a few good rotations.

 

Doesn't sound so crazy to me. I'll give it a try if I have then right socket. A strong variable speed drill should work.

 

If I remember correctly, it is a 19mm socket.

 

You would need a 19 mm open key, so I doubt a 19 mm hexagoanl socket would work.

 

Yes, I forgot it's a square head and not a hexagonal head. I wonder if a 12 point socket would work better than a 6 point socket?

I saw that there are square sockets that are made: http://www.alltiresupply.com/p-GP-4319S.html

However, I don't know if you want to spend $16-$20 for a socket you may only use once.

Another option might be to get an old socket or cheap socket (goodwill/Salvation Army, Harbor Freight, etc)...and cut relief notches out so that it is a reversed spanner wrench.

If I'm not making sense, another way to think of it would be a socket almost big enough to slide over that has four notches cut out for the corners so that the socket can fit over the square head.