Backfiring and maybe fried coil advice

[Chrispy]

Hello again great knowledgable ones.

I come to you once again seeking council.

quick stats recap: 78 stock. points, original rotor, seems like original coils, pretty much everything but the exhaust is stock. bought it used and brought her back from the grave.

Here is the situation: the bike has been absolutely tearing since I rejetted. I mean, holy hell does it scoot. Ive got 2 into 1 pipes and stock airboxes, so I went up 2 on the mains and 1 on the pilot and that seemed to do the trick. However, since making that change I've had some mean backfiring, the first of which blew my carb out of the boot. So after riding for a couple days I decided it was time to deal with the backfire. so I pulled the carbs, checked the boots (seem good), fixed the tangs that got bent from that blowout, cleaned them and put them back. Then I did cam chain, valves, and timing. I should mention the top points connection was sparking and the bottom was not.

heres the kicker, I went to start her up for a test ride and like an absolute dumb*ss forgot that the left spark plug wire was not hooked on. only noticed after I kicked it five or six times. So probably fried the coil but I couldn't figure out how to test it so I thought "well I already beefed this might as well see what happens". So I plugged in the spark wire and kicked her and she REALLY reluctantly came on but was backfiring like a banshee. both exhausts got hot evenly so I thought okay maybe I didn't burn it out, lets see how she rides. so I took a lap around the neighborhood and boy, she is not okay. Super jolty and weird, backfiring at all rpm. so im assuming that coil is bustered, and the cylinder was only firing intermittently. also after riding I noticed gas on the gearbox which seemed to leak out of the bottom gasket.

so with all that in mind im a little lost and frustrated. I am open to any procedural advice, and probably need some new coil suggestions. I have read everything I can find but I have so many symptoms that im not sure where to start.

thank you for anyone who had the time to read that.

 

[xjwmx]

If you have two coils and wonder if one is buggered, switch the coils around and see what happens. You should be able to tell which side is running okay by disconnecting one side -- if you disconnected the bad running side there won't be much change.

 

[gggGary]

Big sparks on a set of points usually points to a knackered condenser. cheap and easy fix.
Then file and set the points, check timing idle AND full advance again.
Torch both plugs dry cuz once fouled it can be hard to recover a clean running plug.

 

[Jim]

Coils don't usually cook themselves from open HT leads (not on the plug). It's possible, but not likely. As Gary says, sparking points usually means a bad condensor. Since the problem started after you adjusted the timing, you might want to revisit that.

 

[gggGary]

Coils don't usually cook themselves from open HT leads (not on the plug). It's possible, but not likely. As Gary says, sparking points usually means a bad condensor. Since the problem started after you adjusted the timing, you might want to revisit that.

or an unplugged condenser....

 

[gggGary]

It also started after you were messing with a plug wire.

 

[5twins]

It's very easy to contaminate the faces of the points if there's any oil at all on the feeler gauge. Then they misfire or possibly not fire at all.

 

[Chrispy]

Thanks guys!
So I filed and cleaned the faces of the points and replaced the condenser that was making the left one spark so much. It’s still backfiring the loud pinging backfire, and my advance unit it giving me problems. I just cleaned and greased it because it had been sticking, but that did not solve it. It appears the the contact elements of the points are preventing it from coming back from full advance. Is it normal for them to press that hard? Can I tighten the springs without totally ruining the advance timing? Forum searches are almost all lubrication solved but that doesn’t seem to be the problem here

 

[5twins]

Besides the advance unit itself, did you lube the advance rod that runs through the head? That's the usual culprit.

 

[XSLeo]

Yes, springs can be adjusted. Not hard to do. Take one off, clip off the loop that it hooks on with. Turn the next turn of the spring up for a loop. Just do one spring. Color the one you clipped with a sharpie so you can tell which is which. Often that's enough. If not you can do the other spring.
As 5twins mentioned, lube of the rod and the bushings in the cam is needed. If you use the wrong lube that might cause it to be stiff. Wheel bearing grease may be to heavy. Chassis grease is closer. Chassis grease with moly is better.
If you read the right thread on lubing the advance rod it tells how to check for proper advance action.If you manually open the advance weights and release them they should snap closed.
Leo

 

[Chrispy]

morning everyone,

So after a weekend of tinkering here are the results. Advance was still sticking to I pulled it out and cleaned like I had never cleaned before. Took off the weights, scrubbed every contact point and added a touch of grease anywhere it rubs. Clipped a half coil off one of the springs to give it some more mmph and it now appears to be working well. I fixed my backfiring problem by fixing my timing because like an absolute novice I hadnt checked both sides, and while my left side was dead on my right side was way behind. fixed that and the backfire went away. still chuffs a little in the left carb sometimes but its way better than that loud a** backfire. Currently tracking an issue where my right side is running rich, but she runs like a banshee now so for any other newbs who come across this, check the timing on both sides.

thanks for the help guys

 

[Jim]