No power and comically large flames out the exhaust

With previous owners, there is no telling. Some people should have their toolbox welded shut.

wrote:

I picked up an 83 750 spectre 4 banger, non running. All stock as far as I know except for a very open exhaust. It wasn't running due to some electrical gremlins that have now been solved, but now I've got some... interesting issues. Bike is a little hard to start and when it does start it shoots up to about 2500 without the choke, eventually it'll bring itself back down to a perfectly decent idle, I already replaced the block to carb rubber boots. While it's running it is absolutely pluming smoke out of the headers and "muffler" and after warming up will shoot 4 foot flames after a rev and on some occasions will have a flame just sitting in the end of the exhaust while it's idling. Now as cool as that is, that's not normal. It's fuel fouling spark plugs pretty hard, bogs down when under load and doesn't seem to want to rev past 4k when in gear. Obviously it's running rich. What can I do to fix this? I'm going to try and back the mixture screw out to lean the mixture and see if that helps. I have no clue what the previous owner was doing with this so it's possible there's a horrible jet kit in these carbs, but I find that unlikely. 

Also one of the carbs is leaking out of the inlet when the bike is off. Not really sure what that's about either. Link is to what my bike is doing right now.  youtube.com/shorts/SWVqw57oAIk?feature=share


 

That candle (flame) is unburnt fuel (any fuel) hitting the air and reigniting when it get more oxygen (open air) Just look at any dragster with zoomies (open pipes) taking off, sometimes all the way down the quarter mile.

NO its not normal, especially on a street ridden machine. Your better off with some back pressure built in (muffler/restrictor) it will idle better, accelerate better. People think if they take out the restriction (run straight pipe/no muffler/baffle etc) it will run better = FALSE.

This is my 650 so I know all about straight pipes :

 

This runs methanol and some nitro
 

On another bike, not KZ, that I had, I went to start it and a giant flame/shotgun blast came roaring out of the muffler. I pulled the oil filler plug and gave it a sniff, yup, the crankcase was filled with gas. (I really didn’t have to sniff because the fuel/oil mix came out of the hole). I rebuilt the leaky petcock, added oil into the cylinders and did two quick oil changes with a short run in between. Then all was good.