spin me up

Was trying to do a compression test. Engine is pulled from frame and in a stand, electrical system is also ripped loose. So I need to jury rig the starter solenoid to spin the starter.

Hooked up the fat red wire on the solenoid to my battery pos terminal, and the fat engine ground wire to my batter neg terminal. Tired bridging the two pin connector, but that did nothing. Maybe I'm bridging the wrong connectors? Basically need to close the same circuit(s) the key & start button would, but don't know which plug terminals on the solenoid would do that.



And yes, the engine is in neutral. It will spin if I directly feed the starter 12 volts, but switching that on and off gets kinda.... sparky.

 

With an engine out of its frame, I would use a good battery with the positive post connected directly to the positive of the starter, and the negative post of the battery the ground of the engine. As sonn as you close the circuit, the starter will turn. There is no need to go thru the solenoid, key switch, start button and so on, as long as you make sure the trans is on neutral, there is no problem.

You should disconnect your TCI to preserve it.

 

OK - disconnect your battery ground from that solenoid!

A solenoid is just a switch (of sorts). There are the two big bolts which are either side of the switch. One of those big bolts should connect to the positive side of your battery. The other big bolt should connect to the positive lead of your starter. Your battery ground should go to the frame/engine. When you supply voltage to the solenoid (the two smaller bolts) it energizes the coil and closes the switch (if you will) which then allows voltage to be passed to the starter.

 

Quick and sparky method: run wire from battery positive to one pin and hook another wire to the other pin that is long enough to reach battery negative. When you touch the wire to the negative terminal( or anything grounded Be Careful) the starter should spin.

Correct remote start button method: run wire from battery positive to one pin in the connector, run another wire from the other pin to one side of a momentary contact button. Run another wire from the other side of the button to battery negative. When you push the button the starter should spin.

 

x2 on what quebecois59 said - even better yet

 

No problem except I want a way to close / open the circuit that doesn't shoot sparks around and try to weld the contacts together. I'm looking for a way to control the high amperage draw the starter creates using the solenoid, rather than playing doctor VonFrankestien with my new battery. If I was REALLY smart, I'd also wire a fuse in somewhere.

As for the tci - when I said "ripped loose" I meant entirely loose from engine and frame. The TCI is in a box on the other side of the garage, along with the rest of the electrical system, so no concerns there. Literally all I have in the setup is the engine, battery, and that solenoid. Once I establish the engine has good compression, get the valves adjusted, get the carbs set and installed, etc, then I'll wire it all up again (either in the frame or by mocking up grounded mounting points on the engine stand for stuff like like the coils) and see if it runs. First things first.

 

If you re-read my post, you'll see that's exactly what I did.

A-HA! That makes sense - I was just bridging across the smaller bolts, not supplying current to them. Yeah, I think that will solve the problem if I just push current through there. A bit more complex than I'd planned (probably want a fuse on that low current circuit) but easily managed if I buy a switch, some wire, etc. May have what I need already. Thanks!

 

Deuh! Once said the engine is out of the frame, I should have noticed the TCI has to be somewhere else for sure!

Why are sparks flying around a big concern?

There is no Frankenstein skills involved in what I suggested, you hook your cables, the battery spins the starter and the engine for 5-6 revs, you disconnected one cable, starter stops spinning, you note the meaurement for that cylinder, then you do the others the same way.

 

Mostly because I don't have any alligator clips or other way to quickly establish / break a high amperage connection. I'd be messing with pressing the actual wires against the terminal and trying to get solid contact while taking the reading. Requires to many hands, to many things to go wrong (like say it spark welds and I can't get it loose, and then spins until the battery is drained... or worse, until the starter melts down.)

Best case scenario, by the time I'm done the battery terminals and wire ends (where the bolt goes through) would be covered with spark scars, which (besides looking ugly) effectively promote corrosion and reduce contact. Why deal with that mess if I can avoid it by using the switching mechanism that is (literally) MADE for the job?

I've had enough bad experiences jamming live wires onto a load with that I just don't like the idea if I can avoid it, especially in cases where there's potentially double digit amps flowing through the circuit. Lots of amps = lots of heat at any localized area of high resistance (eg, the small contact point between wire and battery terminal when initially making contact). Last thing I need is a 55 amp short setting something on fire.

 

don't use the threaded stud on the starter, the arc will bugger up the threads. bolt a wire on it and leave that on, make the neg connection on something thats out of sight. think jumper cables

 

I thought you had booster cables with good "jaws" at both ends.