1973 GT80 Ignition woes

[inteva6184]

Hey guys I am new to working on dirt bikes and this spark issue is driving me nuts. I bought the bike needing a piston long story but the guy said it was running before he pulled the cylinder jug. So I put it all back together and now no spark. I installed a new coil and still no spark. I then did a continuity test on the ignition switch. It has a 6 wire connector and two other wires. I checked every one in all three switch positions. The only one two wires that showed continuity were two black ones. I am lead to believe I may have a switch issue and would love to just jump wires to know if its the issue but I have no idea where to start? So any info on that would be great and I any other info on testing the ignition system would be great too. I am a little confused on testing the magneto and filing points. So any info you guys can provide would be great. Thanks

 

[inteva6184]

Here is a quick update I read if you check voltage on the 4 wires coming out of the magneto and they show voltage when you crank you shouldnt have an issue. I saw .2-.6 volts coming out so they seem to be working I guess? But upon following where the wires go they all go to my ignition switch that doesnt seem to get continuity through most of the wires so is there anything I can jump to take the switch out of the equation?

 

[BSWIFT]

I'll give this a shot. Check each wire on the switch for continuity to ground(frame). I do not remember if you need a ground to run or to remove the ground. Two wires from the magneto are for the ignition and two are for the lights. .2-.6 volts seems weak. Check with the switch off (and NO battery) if you have continuity to ground on any of the four wires from the magneto. If any on those has a ground, turn the switch and see if the ground goes away. If the ground goes away, you should not need to "jumper" any wires. I'll suspect that you are not getting anything through the "points".
Should you need to clean the "points", use some 320 grit sand paper or a emory board finger nail file. Open the "points" and gently clean the contact surfaces. Blow out any debris and try again.

 

[inteva6184]

It runs!!!!!!!!!!!!!!!! Not well but it runs. So I ripped the wiring harness apart and removed all of the hacked wires from its days of an enduro. Then picked up a manual from my dads 76 dt175 hoping to get a clue. Well it helped to prove I shouldnt be an issue. So I took your advice bswift even thought it was getting voltage when I cranked. Filed the points and what do you know it has spark!!!!!! So I try to start it and it barely runs turns out the plugs bad. So I didnt have the right plug so I found a plug that was shorter and installed it just to see if it would run. It runs and idles great. I took it for a spin and it bogs a bit at high rpm and smokes like a beast. Im sure having the wrong plug may cause that. The other issue im having is the oil injection is unhooked and gas poors out of that nipple on the carb and out of the hose on the bottom of my bowl. I dont know if it does it while running or just right after I shut it off. So thats that I have work to do but atleast it runs.

 

[inteva6184]

Thanks bswift. Onto my next post of questions haha.

 

[BSWIFT]

Call a Yamaha dealer and find out the correct plug. Good idea to block off the oil injection and mix your fuel. If you can find a hose that fits the nipple on the carb for the oil injection, plug up the hose and then put the house on the nipple. Clean the carb and blow out all of the passages with compressed air. Be careful with the gaskets because they may be hard to get or find! Those little 80's were a blast when I was 10.