Bad Backfiring after Valve Cover Gasket Replaced

Hey all, so I just replaced the valve cover gasket on my '83 KZ750 F1 as I suspected it was bad. I made the gasket myself out of a roll of rubberized gasket material and everything seemed to fit back together well. It started right up choked but didn't Rev up to ~4000rpms like it normally did before, it got to maybe ~2000 and then it backfired a couple times before it died. Attempting to start it again it immediately backfired a couple more times. It's always backfired a little when I had it choked and it was a hot day but these sounded significantly louder than normal and it didn't start up like it normally does afterwards.
The only thing I messed with on the engine was the valve cover and the spark plugs wires since they were in the way. Did I reconnect the wires wrong or somehow flood the engine? It's carborated so I don't understand how it could have flooded but that seemed to be the most likely reason for Backfiring. Any ideas here because in relatively new to bikes and am not sure what's going on.

A couple plug leads on the wrong plugs?
Steve

Before you put the valve cover back on, did you release tension on the cam chain? When the cover was bolted back on did you then reset the tension? It sounds like the valve timing is wonky, almost as if the cam chain has jumped a tooth.

It was the wires - someone before me flipped the coils so when I was looking in the manual I messed it up.

And I didn't to anything with the cam chain, I just left it alone as best because I didn't want to mess with it. Should I have adjusted the chain or anything else while I was in there?

You should use a real gasket not a home made one made out of rubber. If the rubber stuff you used is not the same thickness as the original gasket you may have changed the position of the upper cam chain guide, and that may affect the cam timing. Ed

I was thinking about the injector ports possibly sucking in air.

It has almost exactly the same thickness, and it is actual gasket material I got in a roll that they carried at AutoZone. I would have preferred to just order one made for it but I couldn't afford to wait the one to two weeks for it to arrive as this is my only vehicle and it was in pretty desperate need of replacing. The whole engine basically needs rebuilding so when Im able to do that I'll put the proper gasket in unless the one I made starts failing prior to that.

In my good guys thread is a list of vendors I get my gaskets from. 2-3 days, $12 free shipping.
Steve

The factory auto cam chain tensioner has to be locked in position or removed before the valve cover can be removed. If not, then the cam chain tensioner will over-tension the cam chain to the point of breaking the guides (or other stuff) when the valve cover is put back on. When the valve cover is put back on, the cam tensioner needs to be unlocked or reset for it to work properly, otherwise all sorts of hell will break loose.
Where those steps taken?
Or do you have an aftermarket tensioner?

Those steps were not taken and I do not believe I have an aftermarket tensioner. I'm looking in my Clymer now for the steps to properly reset it.

I have a Clymer for 80-81 750 fours. The valve cover installation instructions are on page 75. Step one details that the tensioner must be disabled or locked back so it is released while installing the valve cover.

You have a later bike (and probably later manual), but I would expect the instructions to be similar.

If you have a ball-lock tensioner, you have to remove the short bolt and use a longer bolt to lock the tensioner from tensioning.
If you have a cross-wedge type, you remove the cap (big 17mm hex) and crosswedge. There is a spring that will pop out as well.
Then install the cover and re-enable the tensioner.

Since you already have the cover on, you only need to release the tension, and re-enable the tension. It will automatically re-tension. Maybe turn the motor forward slowly by hand for the first revolution after re-enabling the tensioner.

The gasket thickness won't affect the timing by any significant amount.

I had the cross wedge type, got it reset and everything is running well. Took it out for about 3 hours last night and so far no fresh oil on the engine which is better than I could say before.

One question I do have is could replacing that gasket affect performance? I've noticed a huge difference in how the engine feels when accelerating and I have a lot more pull in 4th and 5th than I did before. I don't understand how just messing with the valve cover could have affected performance that much though. I just did it because I suspected it was leaking oil. Any ideas?