Loud pop sound and smoke from under engine

[bryand46]

I bought a 78 xs650 a few months ago and recently ran in to some issues.

First, after trying to kickstart it several times with a battery that was a bit low in charge, I hooked up a charger and it started right up. Problem identified there... So, today I was kickstarting it while the battery charger was hooked up and could not get her to start. Actually I did get her to start, just not keep running. I probably should have stopped, but I couldn't let it go and upon my last kick a loup pop came from the left side of the engine and I noticed quite a bit of white smoke coming from under the left side or the engine. Basically right where the left foot controls are but behind.

I stopped after this and jumped on these forums and did see something posted that seemed very close to what happened here. But I just wanted to be sure that this is just from the carbs needing to be cleaned and that it was a detenation from the intake valve? And if this is the case, did this do any damage to my motor, and can anyone offer a little more insight in to this whole issue? I have had quite a bit of popping on the left side since I've owned the bike. Because I haven't riden it much, I haven't looked in to fixing yet. Besides I'd rather do it myself if I can.

Thanks!

 

[pamcopete]

bryand46,

Well, could the smoke be coming from under the battery box? White smoke is associated with an electrical part, so is it possible that you had the charger hooked up backwards and fried the rectifier under the battery box?

 

[5twins]

It may have been a simple backfire out through the carbs. Inspect them to make sure it hasn't popped them out of the mounts. Your ignition timing being off a little is a common cause for this. Since it doesn't seem like you've done anything to the bike but ride it since you got it, I can pretty much guarantee you it's not in a proper state of tune.

 

[bryand46]

Thanks for the feedback guys. Yeah I'm thinking it's probably a backfire through the carbs. I know I definitely had the battery charger on correctly and the smoke didn't come from near the battery. I was just quite worried since the smoke and pop sound came from the lower left side of the engine. Probably going to have some one a little more experienced than myself take a look at it.