Xj750 Keeps dying out

Hello, my 1982 xj750 seca keeps dying, this bike is a project and hasn’t been ridden more than up the street since I bought it not running. I rebuilt the carbs for the 3rd time and it started up and sounded great ran great, however it did backfire plenty upon acceleration. Eventually it died out as it had upon the few other previous attempts at riding it(it didn’t run as nice this times however or make it as far(0.5 the first few attempts almost a mile on the most recent.) When the bike dies out it will still crank but won’t start. This most recent run I took it home after it died and and it started right up with starting fluid but wouldn’t run great, when I had the choke open it would rev up and then slowly rev down, it also backfired plenty it also won’t rev sometimes while I was playing with the choke. I’ll try to attach the video I have of me playing with it.

video link(Google drive): https://drive.google.com/drive/folders/19CENOojTCqYuBTX5zWdiUxM2jLZa8GZG

 

2 things.
Take a spark plug socket and ratchet with you when you test ride it.
When it dies or starts going to shite, pull over and pull the plugs and see if they are dry or wet or super black and wet.
I had a rich idle circuit and too large main jets way back.
Ran great then flopped about at high speeds then died.
I was carrying a few tools to unfoul the plugs and get going again.
Could be your issue... Or lack of fuel, crimped hose, bad filter, clogged air filter it's goes on and on!

 

Yeah, so went it was first dying out I checked the spark plugs and they were black one wasn’t wet but I believe it was just fuel as it evaporated, I adjusted the jets from where the previous owner had them(main fuel 136-120, pilot fuel from 112-40) and I checked the spark plugs and they all looked good this time so maybe now it’s running lean? It does have pod filters and rn the jetting is completely stock. I used an aftermarket fueling/filter because of the condition of the tank, but I unscrewed the one bowls drain and it had fuel in it the others were all stripped long before me.

 

One thing I noticed plenty of is back firing and a weird rev hang with the choke engaged. There’s a video in the original post, if that helps.

 

Choke engaged is a weird thing on these carbs.
It really means flooding the cylinder with fuel from the bowl. Not choking air. Fuel enrichment circuit is the term.
If you look at it that way, sans pods issues, it may help also.
Backfiring means unburnt fuel heading out the exhaust valve or just remaining on the input valve cycle depending on your backfire experience.
So super rich or a timing issue or a valve issue.
I will recite the cv carbs mantra.
Carb sync, carb float levels, carb main and pilot jets, idle mix screw and... Valves and... Compression.
All magical stuff.
Start at valves then carbs. Be strong! It'll work out.

 

You may have seen the YouTube video for cleaning plugs that are rich. It's basically cooking the hell out of the plug with a torch, hard to do on the road but essentially what a clean running system does.
Map gas torch and a bit of patience before you melt the plug and it burns away the carbon on the insulator which is the main issue when super rich.
A new set of plugs is easier but doesn't help when trying to dial it in.

 

I appreciate the advice, I think my valves probably need adjusting, I checked my spark plugs this morning and they look fine except for cylinder #3 is still super dark, this morning it ran a little bit and the tried to ride it and it died coming out of the driveway.

 

Are you saying three bowls have stripped drain screws? What does that mean? Can you not do a fuel level sync with a sighting tube connected to each carb?

 

What did the gas tank look like inside. If the carbs are clean and you feed them fuel that has rust or bits in it, that clean job is done. Watched the vid, there is a lot of popping going on. I don't know if you did a bench synch or not, but guessing there is another issue. Are you running PODS or have a air box? I could tell from the vid that bike is very custom, so not sure how far from factory the rest of the bike is. My first XJ project took me six carb cleaning jobs to get it right. If you have not gone to the "house of clean" on this sight and seen just how to clean these carbs, you might want to.

Good luck, keep working at it and keep updating us.

 

Hey, thanks for the help everyone. I was very lose so I ended up talking to a guy who’s been working on carbs for longer than I’ve been alive, he helped me out a bunch. As it turns out the intake boots for the engine to carb were loose and the clamps weren’t all the way on. My diaphragm/piston assembly was missing a washer and a few other things, I’m not 100% sure on what all he did but those are a few things. Bike runs great now, I’m pretty sure the main issue was the gas tank but all the other little things helped. It is on pod filters currently.