'82 XJ650 with Seca 750 swap cutting out above 3/4 ish throttle

Hey guys, just picked up a '82 XJ650 and been having some fuelling issues I think. Full disclosure I don't know nearly as much as I would like so I'm just taking a shot in the dark here. Bike sometimes stutters going past 3k rpm but as soon as I break 4k rpm and have more than 2/3's ish throttle it breaks up. To me at least it sounds like it's not getting enough fuel but I'd love to hear any suggestions you guys might have to help diagnose.

Sorry if that's not enough info, I'll try and add anything else I discover.

Thanks!

 

650 frame 750 motor?
are you running the 750 carbs?

could be wet fuel setting is low
Setting the fuel levels

vacuum hose could be leaking and not opening petcock fully replace hose 4mm ID vacuum hose .
take a ride set to prime.

stock set up or pods?

 

Yep, I'm 99% sure its the 750 carbs. Its the stock setup. I'll take a ride tonight or tomorrow on prime.

I did notice during idle it sounds like a puff of air coming from the carbs consistent with the rpm. Not sure if that's a vacuum leak or just a sound the bike is making to scare me haha.

Thanks for the info, I'll take a look at that pdf tonight.

 

Could also be rust or crap in the tank clogging the pickup a bit, but that would be a bit more likely to cause it to die intermittently as well.

Any idea whether you have the correct TCI for a 750?

 

Not a clue about the TCI unfortunately. I'll see if I can dig up some information. Did a good 30 minute ride on prime, didn't make a difference. Could it just need to be cleaned?

 

Post the part number from the TCI box (the module further to the rear under the left side cover).

The safe assumption for any carbureted bike bought from someone who didn't recently clean/overhaul the carbs would be that they need to be cleaned/overhauled. It's probably even a good assumption in cases where the PO did "recently" "clean/overhaul" them.

 

is there a air cleaner on this?

 

Yep gave the carbs a quick clean and its idling and putting down power much better. Check the plugs and cylinders 1-3 (from left to right) were lean and 4 was rich. Checked the fuel screws and 1-3 was 4 turns out, 4 was 5 turns out. Put them all at 4 1/2 out and going to check the plugs again in a few days.

As of right now only issues I'm seeing is some slight hesitation at about 3k-4k rpm but its a massive improvement over what it was.

Going to order some gaskets, build/find a yics stick and do a valve adjustment and full carb clean sometime. Anything major I should be checking that the previous owner may have neglected?

Thanks for the help guys!

 

you can oil up an old sock or tee shirt and stuff the yics chamber. old thread on that too

 

That's an awesome solution haha. I'll have to take a look at that, thanks for the info.