1982 Yamaha Seca 650 (Project)

What do you do when your carbs are so changed and different that you need to start fresh? You find a virgin set of carbs for $100 CAD

Now I can do some comparisons and checks for things like slide changes, jets and needle.

Even the drain screws look like they have never been touched

 

you might find that turns out to be a

 

I have good coaxing skills... good penetration lubricant and some heat and even the most stubborn holes become easy to work with.

 

Matti, don't

 

Are there any other models of carbs that will work with a 81 xj 650 I just picked up another project and the float bowl drain screws are so stuck i cannot crack them open, P.S. Next time i buy a project i might just test these float bowl drain screws and if they are stuck, Its a great reason not to buy the bike, This is the most difficult and expensive part of these old yami`s is the carbs in my opinion, I guess it could be that im not very good at it, last project i had to redo the carbs 2x the project before that was 2x on the carbs then gave up and paid a guy 400.00 to do them. I Guess you could say not my strong suit.And now facing this all over again breaks my spirit dont know what to do about these drain screws even. and offers of help or advice strongly appreciated.

 

you soak them in pb blaster then put in a vise drill a hole in the screw and use an easy out. I use the square screw extractors no need to buy a second set of carbs just for the bowls.. someone here has extra bowls if you needed them
.
soak them heat them chill them and soak them then extract

i use the square extractors and give them a rap with a hammer to set them

i put kroil in the drain side and the card bowl hole as well as the screw head

https://www.amazon.com/CTA-Tools-90...t=&hvlocphy=9002383&hvtargid=pla-434809604614

 

650 and 750 carbs are the same except for the jets and slide needles

you could bring the bowls to a machine shop and have them extract the screws

use T handle not a spanner

 

UpDate : I Ended up taking the carbs apart to have closer look, I Could tell by the smell after taking the first Float Bowl off I was in for some disappointing fun .Yes they were very bad Geez what do they put in our fuel these days that turns into such a foul substance after a few short months. Any way these carbs were way bad. So I Was able to find a set of 4 carbs a few hundred miles north near Seattle and i bought them had them shipped already. And these are clean im much happier now with those stinking dirty carbs behind me. But I realize the battle is far from over, Now i got to get them to work,Actually they look pretty darn good and 80.00 bucks plus 14.00 shipping was not too bad.

 

Well an update to this thread.. I got the jets all changed out and it runs much better now. The bike isn't perfect and still needs some tuning so I think a carb sync will be in short order.

Feels so good now that it will want to actually rev like it wants although there seems to be a bit of a "gurgle" if you wish at idle and a bit of a stumble from off idle.

I'm not sure where I am with the mixture screws but I think I'll set them to 3.5 out and see what happens.

 

If everything else is as it should be, you'll run rich at idle.

 

I'm just concerned about the "gurgle" at idle. Starting high I can easily adjust down to where it sounds good.

It's just fine tweaking from here now. Having it run like it does feels good.

 

what da hells a gurgle

 

Lol it's a sound you usually hear I'm a old muscle car when idling. The loping sound.

 

these technical terms confuse me

 

my sink makes a gurgling noise when the dashwasher runs.

 

Quick question in regards to the pilot air jet size for the XJ650RJC.
Specs show it should be #195, however I just opened carb and found all 4 to be #205.
Will the bike still run properly with the higher pilot air jet?

 

sounds like you have maxim carb air jet
Years & Models: 1982-4 XJ650 Maxim Canadian models
Carb Manufacturer: Hitachi
Carb Series: HSC32
Carb Model ID: 5N900 or 5U900
Main FUEL Jet Size: #112
Pilot FUEL Jet Size: #43
Main AIR Jet Size: #50
Pilot AIR Jet Size: #205
AIR COMPENSATOR Jet Size: #36
Starter FUEL Jet Size: #40 (non-replaceable, in float bowl)
Main jet NEEDLE ID: #Y-10
Main needle JET Size: #3.2mm (the main needle JET is also known as the "power valve" or "emulsion tube").
Fuel Level in float bowls: 3mm +/- 1mm (.118" +/- .039")
Idle RPM's: 1,050 rpms

 

Many spec you see on line are for US bikes
Those jet sizes are the same as my xj650rjc and she still pulls hard all the way to 9000 in any gear