Pow Pow Pow... is what it sounds like.

Ok, for those who've been following along here > An Odd Rattle... I've got an update to the situation. Everything is back on and compression is at 150 in both cylinders. Huzzah! Next problem, she doesn't want to start. It turns, it pops, it kicks back and back fires (occasionally through the carb). Does this sound like maybe I've got the timing swapped about. Its a 360° Wasted Spark engine so Maybe off by 90°? I have a video of the behavior so you can check it out for yourself. Sorry its tilted I took the vid with my phone.

VIDEO HERE!

Thanks a bunch guys for all your help when the compression was shot!

Assuming we're talking about a twin, it's very possible (and common) to put the advancer back on 180 degrees out, and the results are just as you describe.

It is indeed a twin, however I did not remove the advancer. So unless it has twisted itself around I doubt this is the problem. I have advanced and retarded the timing on the plate, and found its way more finicky than it was before. It only pops consistently on every stroke when the timing is in one place. Previously it would run no matter how advanced or retarded I had the timing. I'm going to do a shake down tomorrow and make sure I get everything nice tight and sealed from the Air-box to the Exhaust. Also replacing the old B7ES with B6ES plugs. I had planned to do this before the whole engine trouble began. Could could I have put the cam chain back on just the slightest bit off (like a tooth or two) causing the timing to be off enough for this issue to arise?

First, I would assume you have checked for spark, and fuel and that both are present.

Second, I am not sure what all you did to the engine, and since I have not had a 400 apart I do not know if it is possible, but can the cam be installed backwards. I know that on some machines, this can happen. If the cam is installed correctly or you never removed it, are your sure the cam timing is correct?

I did remove the cam but it is facing the right direction. It might be hard to hear in the video but it is firing almost every cycle, so it has gas and spark. If I don't get it today I'm pulling the valve cover off and checking my cam chain position.

I have an '80 KZ440B1 that is now behaving in exactly the same way as your 400. I started out thinking that it was electrical (you'll find my thread under electrical as "timing advance"), but now my prime suspect is cam timing based on advice from this list. At least, I'm going to start there. I can't open it up in my unheated garage for a couple of weeks, so I'll be following this thread closely while it sits. Keep posting these updates, please.

Found that right now only the left cylinder is firing. Which is why its not running. Replaced spark plugs with very shiny B6ES ones, going to check to see if right side spark is igniting.

EDIT: Right plug is sparking, now my hand is tingly. Anything else I should check before opening her back up?

What are you using for air filtration? Ed

EDIT: Right plug is sparking, now my hand is tingly. Anything else I should check before opening her back up?[/quote]

You know, when they bite you it's good since it's a sign of life. Soon (with any luck) you'll be able to burn yourself, too. Always a joyous moment.

this sounds exactly like my kz1100 shaft im working on... the video at least, turns over hard, occasional backfire through the carbs but wont start for me, i just rebuilt the carbs and battery is fresh, extremely frustrating...

650ed wrote: What are you using for air filtration? Ed

Currently open, think may be too much air?

Robwolf wrote:

650ed wrote: What are you using for air filtration? Ed

Currently open, think may be too much air?

No doubt about it. If you still have it I would put the stock filter back on at least until you get the engine running. Then if you decide to switch to pods or a K&N cartridge you can tune accordingly. Ed