Topic: testing a motor with no wiring harness???

[amemoryoncelost]

 So I have two CB400Fs. One is my runner(kinda) and needs some work. Needs a full tune up, has the usual oil leak from the cylinder(oring or gasket, not sure). The bike does get me from point A to point B, but I've been looking at getting another bike so I can go through and make it get above 65mph and do some long rides to the mountains. So I ended up tracking down this second bike. The wiring harness is cut out, had 12,000 miles and the engine is clean, kind of jealous because it looks better then the engine on my runner bike. It looks so nice, I wonder if it's a good runner or not. The PO said he never had it running outside of some serious jerry rigging with a boat battery and jumping the starter solenoid or something. He also said it didn't run well and that the carbs probably needed a cleaning, which they do look pretty gross from the outside, so I can only imagine what they look like once they get opened.

 So I want to figure out a way to find out if this motor on this "junker" would be a good donor to my runner and while I'm using that engine, go through the actual engine and do a full rebuild and take my time with it. Is an engine swap easy enough to where I should just pull them both and swap them to try it out? Some way to rewire just enough to start the bike and do a compression test? I have a wiring diagram, I'm just not sure exactly what's needed.

 Any help would be great. It's finally starting to get nice and would be so nice to get some wind in my hair and no oil on my shoe.

thanks!

[scondon]

 A fully charged 12v battery supplying power to the starter motor is all you need to do a compression test. I've only done this once years ago so forget the exact +/- connections but it's really easy and straightforward, find the leads to the starter motor and connect to battery leaving the ground as a loose contact so you can stop the motor fast by pulling the ground as needed.

[jbswearingen]

And you can just as easily do a compression test with the kicker.  No need for the starter.  You'll just have to kick it a bunch of times.

[amemoryoncelost]

okay cool, not sure why I thought the kicker wouldn't work. I'll try the kicker first tomorrow and if that fails, I'll try doing it with a battery.

thanks.

[jbswearingen]

okay cool, not sure why I thought the kicker wouldn't work. I'll try the kicker first tomorrow and if that fails, I'll try doing it with a battery.

thanks.

Doing it with the kicker won't fail.  And there's no possible risk of overheating the starter in this manner.

The exercise will do you good, anyway!

 

[gregk]

I went through the same exercise this winter with a 400 that I had bought as a parts bike.  No wiring harness  etc.  I posted a topic on the site and found that it was easy to hot wire the bike, same as we used to do with our old cars.  Positive wire to the coils and connect the grounds.  hooked up a battery out of my gold wing and shorted out the starter solonid.  After cleaning out the carbs the bike fired right up. 
Fair warning!  I now am in the process of fixing up my parts bike, trying to find all those parts i ripped of to fix the other 400.  Its an endless circle.

Greg

[upperlake04]

  I've only done this once years ago so forget the exact +/- connections but it's really easy and straightforward..

   Thats not very complimentary Mr. Condon 

[amemoryoncelost]

 I was going to steal the exhaust and gauges and other goodies, but I think I'm basically only going to swap out the motor if it ends up being in good shape and possibly starting slowly on a rebuild of that one. The original 77 I have is basically complete, there are a couple of issues here and there, but I shouldn't need to steal much from this parts bike that may end up being a runner at some point.

 So on a compression test, all four plugs out, wide open throttle and kick it over until the gauge stops moving right?

 It's been awhile..

[amemoryoncelost]

 Just tested the motor, all had around 143psi in each jug with no plugs in. With wide open throttle I had more towards 150 if that makes sense. I did it with both since I couldn't remember if you hold it open or not. Looks good so far. Not sure what else to check before I do a swap. Tranny clicked through most of the gears with it sitting on the stand, not sure if it should easily click through all or not. Other than that, guessing I might just try and do the swap and see what happens? hah

[rbirkhan]

143-150 psi your good to go it will be higher when its running with hot oil and a few miles to clean out the cob webs. Sounds like you have a good engine.

[amemoryoncelost]

 Yeah, I figured as long as I didn't see anything +/- 15, I'd be good. I'm nervous to test the "running" motor and think I might just swap it and not do it, lol. What I don't know won't hurt me right? Actually, I'm gonna go pull the engine out of the one I was testing and get it all ready, clean it up as best as I can and if I get really bored, pull the other one as well and do a compression test before I disconnect everything just to know what I'm looking forward to when I do actually rebuild that engine. I'll post some pics of the engine I'm pulling once it's out.

[amemoryoncelost]

 Got it out, followed the directions from the shop manual. Had to take a few other things out, but for the most part, went pretty smoothly until I was actually taking it out, which I did alone. Twisting and turning, but finally popped out of there, oil everywhere, yeah! Gonna spend some time cleaning it up before I dig into the other bike. I think I'll start a thread for the build now to keep up with the progress instead of spreading it across four or five threads..