Carburateur (Mikuni BS30)adjustments for Seca 650 Turbo

Hi, I just bought a 650 Seca Turbo that has been sitting, in a heated garage, since 1988. I have taken the carbs apart, and the slides were stuck, all the jets were also stuck! Everything was gummed up, had to use a small impact wrench to get jets out. The carbs have been cleaned up nicely in an ultrasound tank, now I would like to know the adjustments for all the jets?
TIA, Charlie

 

Ultrasonic bath or no - youll have to check each and every passiageway by squirting something through there - including the ones in the float bowls - did you?
There is no adjustment needed for the jets, you need to set the fuel levels by tweeking the float heights, set the butterflies all the same (bench synch), set mixture screws 2 and three quarter turns out from soft bottom.
See "the church of clean" behind the gif at the top RH of this page, all the info you'll ever need.

 

Thank you very much! I am new at this, and want to be sure I do things properly. The carbs were blown out very well after the ultrasound.
Thanks again, Charles.

 

You're not listening are you?
You squirt fluid through all the carbs and if one is blocked or semi blocked you can see the difference...

 

Yes, I am listening! The carbs were blown out with air, and carb cleaner to make sure there is nothing blocked.
Thank you.

 

Devil's in the detail, well done.

 

Thanks again!

 

Exactly where are the mixture screws on these carbs?

 

Ah, so you haven't squirted carb cleaner through all the passages, otherwise you would have removed the (possibly hidden) mixture screws.
In the US the emmissions people made Yamaha cover the screws over with some plastic plugs. They sit at the end nearest the head, at the top. I believe you stick something sharp in the plug and lift it out. Then you unscrew the mixture screw and squirt carb cleaner along the passagway from the idle jet, making sure it comes out both from the screw hole and idle orifice.

 

Be careful of the spring, small washer and small o-ring at the bottom of the well.

 

A pretty good write-up on Mikuni carb.

https://www.xj4ever.com/mikuni carb cleaning.pdf

 

All the turbo carbs I've rebuilt have brass caps over the pilot mixture screws. I drilled a small hole in the cap and then used something like a small slide hammer to extract the caps.

They sell small rubber plugs to insert after you have rebuilt the carbs.

Be sure to clean the small hole in the bottom of the float bowl used by the enrichment circuit. Makes the bike MUCH easier to start...

 

The OP is in Canada so there will be no blanking plugs.
I've never actually encountered these on an XJ up here.

 

Cool That certainly makes it easier to remove them for cleaning!

 

The OP might have been Canadian, but the poster looking for the screws is USA...

 

I removed and cleaned them up well. The bowls were also very well cleaned out.

 

Hi again, I am at a loss right now! I got the fuel pump (OEM) working really good after a good soak and ultrasound bath. I had tried another pump I got from Amazon that pumped good when I tested it before installing everything. It started right up, but only for a couple of seconds, then stalled, and wouldn’t restart. I left it overnight, and tried again, and sand thing, starts stalls! Replace the pump with OEM, and same results! It won’t start after initial start up, and stall no matter what!

 

In the float bowls, right at the bottom, is a tiny jet that allows fuel to fill the chamber the enrichment tube sits in. If this is blocked, or semi blocked, the well will fill over time, but not remain full when the enrichment is used during starting.
I believe this is what you're seeing...
Earlier reply, from someone:-
ltrasonic bath or no - youll have to check each and every passiageway by squirting something through there - including the ones in the float bowls.

 

See @Roast644 s post above..