Both carbs have the choke . The only thing different was the H/L screws threads .
my buddy told me the reason they took the carbs off was the jetski would bog when riding it ( they also replaced some of the fuel lines .) which i blew air through and all seem right. but thats it i assume dirty jets since its a 04 and had never been had the carbs cleaned that and coming from 2 stoke motorcross bikes/atvs since the plugs are brand new ( but would still run start and idle ). he tried to even take the ski to our local yamaha dealer but they dont work on stuff earlier that 2008 .. so they took the carbs off to clean them but did not have the mechanical know how to get that done. so i put both carbs in my ultrasonic cleaner completely torn apart then rebuilt both of them . also like i mentioned ordered all new gaskets and rebuild kits .
im thinking likely im going to try and break down the oem carb what happen was a common issue i know ( choke plate stuck). so i may try and get that out today and see if i cant swap it off the ebay carb which moves as should and or just go ahead and swap to a primer that way i know both carbs having the same settings and see if that helps .
So the OEM Carb has a Choke and the A/M Carb does not? Air Flow will be DIFFERENT...
-they both have chokes.
Since you got the SJ with the Carb Set removed, must wonder what problems the SJ was having...Not sure why a SJ Engine used "20 times" would have a bad Carb?
- i personally know the guy i bought it from 1 owner some rich kid.. that hardly used the thing sat in a barn at his lake house only fresh water as well.
Post some Pics of the Engine and Carbs.
-ill do that later today after work .
1st thing would be to do an Air Leak-Down Test to ensure that Engine has NO AIR LEAKS. If it does, Tuning will be a waste of time.
2nd Do Pop-Off Tests on each Carbs to make sure the Needle Valves are popping nicely and have the SAME Pop-Off Pressure.
- did this and pulled all the parts out the oem carb so the pop off springs and all that are the same in both . will do a test today
2nd, the Dual OEM Carbs have a Master/Slave Arrangement. Master has the Pump and feeds the "Leftover Fuel" to the Slave Carb via its Return Line. And both Carbs have a #60 or 0.6 mm Restriction Orifice in the Return Outlet. What size is the Return Orifice in the A/M Carb? If it's too big, most of the Fuel will go to the Tank and not feed or bypass the Carb giving a Lean response or runaway.
-ill check this today ,this maybe the issue . i plan on trying to get the oem in useable shape and steal the parts off the a/m carb .
3rd, are both Throttle Butterflies SYNCHRONIZED , meaning do the have identical positions at all Throttle openings?
-yes on this
4th, install T-Handle Carb Adjustment Screws for ease of Tuning. Otherwise, it will be very difficult to turn the Adjustment Screws once installed in the Hull.
You have some work to do before you can start tuning...