G1 Won't Start In Reverse

[kwest0425]

I've got a strange problem. Yesterday, my 1981 G1 ran great. Now it won't start in reverse. Starts fine in forward. Turns over just fine in reverse so I'm thinking the reverse solenoid is OK. I haven't had a chance to check much out but I'm thinking either: I have a bad main switch or the timing has shifted badly.

Any other thoughts???

-kwest

[GMB74]

That's an odd one. Start off by checking for spark when cranking for reverse. Look the engine over for rubbing wires and loose connections that might show up only when the engine is turning in reverse.

[kwest0425]

Update...

Thanks GMB74 for the reply.

I checked for spark and sho' nuff... spark in forward, no spark in reverse. After studying the electrical diagram, I saw that the ignition switch changes the direction current flow thru the magneto's pulsar coil depending on whether your starting in forward or reverse. Ahhh, I thought. This is probably related to my problem. Metered everything and found nothing. Grounds were ok. Switch seemed to be doing the right thing. Pulsar coil was 15 ohms.

In the process of checking the pulsar coil, I decided to check the magneto charging coil. My meter indicated a dead open, but that made no sense. It shouldn't start in forward or reverse if the charging coil was bad. I check, double checked, and checked again, but I still came back to a bad charging coil.

I removed the engine cover on the flywheel side and started to unbolt the fan to see what I could see. In the process, I was moving the flywheel back and forth and noticed the 4-wire cable harness coming out of the magneto was flopping around. I was thinking, that's not suppose to happen. I put my meter back on the charging coil and start moving the flywheel back and forth and saw the resistance of the coil go from open to 348 ohms and back to open. Obviously, something (either the whole magneto plate or the charging coil has come loose...I suspect the plate).

My current theory is that something has come loose and in the process has broken one of the harness-to-charging coil connections. When the engine cranks in forward, the connection is made. When cranked in reverse, the connection is opened.

Since I didn't have my big sockets and flywheel puller with me, I couldn't go any further, but I'll post another update once I get a look behind the flywheel.


-kwest

[chuddly]

good deal...sounds like you have narrowed it down. and good job of hunting AND thinking. That seems to be a skill that is lost to alot of people

[sho305]

Sounds like you found it. While you are in there you can advance the timing lol.

[kwest0425]

Update #2

Got the fan/flywheel off and saw the magneto had come loose and was flopping around. My own fault, I replaced the crank seals last year and I guess I didn't get it tight enough when I put it back on.

Anyway, I did a little more checking and found that the black wire (ground) on the the magneto harness was broken at the magneto end. Fixed that, put everything back together and it runs great.

Does anybody know if your suppose to put 'thread lock' on the magneto screws? I was reluctant since I had such a hard time getting them out when I did the crank seals.

thanks all.

-kwest

[GMB74]

Well, the good thing about putting loctite on the mag screws is they won't loosen up again. The bad thing about it is those screws won't loosen up again. Unless you are addicted to tinkering with your timing, you should be able to set it and forget it. If you use blue loctite on the screws that should keep them in place, but you can still get them out with a little difficulty if you need to in the future. The worst part is the original screws are phillips head and difficult to grip when loosening. If you can get some allen head screws of the proper size you should be golden. Make sure the screw heads clear all moving parts.

[sho305]

Old thread but some tips: If you work on things with phillips screws (like motorcycles) get a manual impact driver, its a thing you put a socket on or bit holder and hit with a hammer (3lb works wonders). They are only 10-15 bucks, you turn it to load in the direction you need and whack it. They will bang the screw out without stripping it because it hammers into the screw at same time it turns. Also great for removing stuck smaller bolts most have 1/2 or 3/8 socket connection on them and come with a large bit holder, its larger size than cordless drills use.

Another tip that might work is if I want to lock a bolt but not use loctite I often use silicone, or silicone gasket maker. It will make the bolt not turn by hand but does not lock it at wrench torque. So even if it comes loose they don't rattle out.

[Soul Searcher]

Another tip on Phillips screw heads. If the Phillips screwdriver doesn't fi the screw head. It's not a Phillips screw head, it's a JIS (Japan Industrial Standard) screw head. Use you favorite Search Engine, it will show you the difference. They will keep you from stripping the screw heads.

[TheGDFP]

My favorite thing to do with Phillips/JIS screws, is toss them in the scrap pail and use hex heads :)