MAIN -jet and needle - rebuild kit

[226dark]

If any gurus can help please (Hough, etc.), i got the rebuild kit from Sirius and the Main needle has 5 notches at top for a circlip; old needle the placement was in the middle of the 5. When I pull down from the diaphragm assy the mainneedle doesn't seem to travel much at all. I was expecting it to 'move' considerablly more than what seems like a couple mm (but I wouldn't know). Is there a way to know the best location for the circlip exactly?

Other ?uestion: In Clymer, for example, it shows thge main jet being SIMPLY removed. Not the case for either carb for me. Even tryed a gentle tap or two from opposite end without doing anything extreme or forceful which i might regret. So I just left them at that.
The Carbs are thouroughly cleaned; checked all ports; special attention to the transition port and 3 pin holes -- with thumb on pilot jet port and spraying from air intake side there is a nice stream spraying throught the "transitioning pin holes" (?), ,and so on. All good EXCEPT can't be absolutely certain of the main jet since they both seem SET and wedged where they want to be.

That reminds me, a THIRD question: the rebuild Pilot Jet comes with no holes in the sides of them, as the ones removed, and in diagrams, and as pictured below???
Any and all help big THX!

 

[xschris]

Look like you got a bad pilot jet there should be holes in it. As for the needle there should be a little movement it it but not much. If you are running a stock bike set the needle to your models stock setting(should be in the manual). If you are running pods of aftermarket exhaust than I would start in middle and move it up to lean it or drop it down to make it richer. The needle adjusts the carbs fuel for 1/4-3/4 throttle. As for the needle jets or emulsion tubes I would try to get them out it is the only way to get them clean.

 

[drewpy]

pilot jets have either the bleed holes or are solid. if yours had the bleed holes, then you need to keep them that way. Mikes xs has them.

the rest I'd agree with chris

 

[lhaolpa]

Always helps to mention what year model of bike you have,as there are a lot of differences between them.The emulsion tubes above the main jets will come out toward the inside of the carb with a wooden dowel,and the main jet keeps it in place. lha

 

[HoughMade]

Sounds like many above have hit the high points, but I'll toss my 2 cents in:

1) When the needle is installed, a millimeter or two is all it will move in the slide. It's the slide itself that moves the needle in and out of the emulsion tube.

2) I am a big fan at starting with stock settings, so I would put the new needle in at the same notch as the old and see how it performs.

3) The main jet should unscrew from the bottom end of the emulsion tube, then the emulsion tube should push up through the carb throat from below with a blunt rod of some sort. If the main jet will not unscrew, try heating the carb body.

4) I've only seen pilot jets with the holes, so I personally can't say whether some may not have the holes or not.

Good luck!

 

[lhaolpa]

The pilots without holes are from '82 and up bikes,which don't have plugs covering them. lha

 

[226dark]

Did I say Main jet when I meant Needle Jet (emulsion tube?)?

Thanks for all help here!!!

Pilot Jets with no bleed holes - to MikesXS I go

The center notch setting of that circlip on main needle - sounds great, will go with it to start with

BTW, bike is as OEM as possible. Also, sorry, it is a 78 XS4002E. Occasionally I will refer to it as a 77 to avoid confusion since that's essentially (or exactly) what it is sans electric start. Kick only. (offered as a 78 "Special Value Edition", not the NEW for 78 XS).

Concerning the Needle Jet Main Nozzles (emulsion tubes?), I haven't gotten to it yet but will apply heat if needed and get a wooden dowel or find something.

Was wondering though: "should push up through the carb throat from below" (Houghmade) seems as if diff. info and either direction is ok????
Haynes says "displace the needle jet from the body towards the venturi side of the carb." Great!
Clymer only says "Remove the needle jet" and a picture of removing from float bowl side.
Generic download manual (?) p. 1284 "12. Pry out the washer beneath the needle jet, and remove this jet by tapping it out with a wooden dowel or the like from the top of the carburetor." IOW tap from top/venturi and out the float/bottom side.

BTW, I'm not online at home, sorry for the slow or no response
Your' help is all valuable and appreciated

 

[xschris]

You should push down this hole and it should come out this way

 

[HoughMade]

You should push down this hole and it should come out this way

Beat me to it- yep, that's right.

 

[226dark]

Awesome bitchin sweet! Pics always good -- a bic plastic pen, that's it! And a second opinion!! ALL GOOD AND THANKS

 

[xschris]

I did not use the pen it was just there but if it works for you

 

[226dark]

can see from the second pic, that is the only way it seems it would want to come out. When I get back to carbs i will see if the pen is mighty enough (and if it fits), nice

 

[lhaolpa]

Download the free manual from this site,then print out any page you need to use in the garage or shop.It's found in the tech section or links.This will help you work on your bike,and fix the carbs.I have the original Yamaha manual that I got from ebay for about $10.00 shipped.It's the same,but english only,so shorter.There's a wealth of info in there.So you got your emulsion tubes out.Clean them as well as possible,as they must move the gas to the needle orifice,and to the motor.Good luck,and the secrete to cleaning these carbs is clean,clean,clean again.They really have to be clean,then get a good gas filter.Good luck. lha

 

[226dark]

pilot jets have either the bleed holes or are solid. if yours had the bleed holes, then you need to keep them that way. Mikes xs has them.

the rest I'd agree with chris

The pilots without holes are from '82 and up bikes,which don't have plugs covering them. lha

So I haven't yet ordered Pilot Jets with bleed holes that i need; have been corresponding with SCI. They are awful at answering the phone yet they will return your call in same day at least.
I plan to put motor back in this weekend and want carbs ready but not crucial since I still have to get new pipes anyway before I start it.
Here are a couple email replys from them:

On my own personal XS400 I ran both types of jets in various sizes… the holes made zero difference. Running the stock 42.5 with the bleed holes in them or ours with no holes didn’t matter. One of our dealers who specialize in carb rebuilding told me the same thing as well. You’ll be fine with the ones in the kit (we sell a lot with no issues), thanks!


Chris Martin
Parts Manager

Sirius Consolidated Inc.
44 Saltsman Dr, Unit 8
Cambridge Business Park
Cambridge, Ontario N3H 4R7
Canada

Dealer Phone Line: 716-304-9745
FAX: 888 894-2755
Mon - Thurs 9-6
Fri 9-2

I wrote:
I had been informed that Pilots without the bleed holes are from '82 and up bikes. Was curious what year your XS is?
Thanks for the quick reply and correspondence!

His reply:
Mine was an 1982 XS400SJ SOHC model, same as yours. They called it a Heritage Special which basically meant “we make bike from leftover parts”. So it has the same Mikuni BS carbs as yours (although they blocked off the pilot screws so you can’t mess with them… unless you pull the caps… J ), the same motor frame, etc, with cast wheels and front disk from the 400E model.


Starting in 1982 they also made an XS400 Seca/Maxim model with a DOHC engine and a completely different carb setup. Those bikes are crap and tended to explode, not many left out there… J


So why the holes? Well, when the jet is installed it seats in the hole and the only way for fuel to flow through to the carb is through the tiny hole in the top. Nobody really knows why they thought holes in the side were a good idea on the sides other then maybe it was thought that if dirt got in the carbs instead of blocking the jet it would go to the side or something. They don’t have any effect on vacuum or flow or anything… what it can have an effect on is if they are old and seized in there they can snap around the holes when you try to take them out.


So, run the no holes pilots and get a good inline fuel filter like this: http://www.siriusconinc.com/pro-detail.php?pid=&product_id=1032 to keep the crap out and you’ll be just fine!

Chris Martin
Parts Manager

INTERESTING! SORRY TO ANYONE WITH " XS400 Seca/Maxim model with a DOHC engine"

ANYWAY. . . . . . here is the real deal anyway. It appears that they do not specifically sell carb kit for XS400-2E and I actually ordered the item KY-0482 for the XS400D. I didn't mention that to them but after looking at free download manual from you guys i found some good specs which lead to more questions

Page 1285 of download manual:
400D Main Jet = 142.5 and 4002E = 137.5
400D and 4002E Pilot Jet both 45 (Great!)
400D Main Needle = 5Z1-4 and 4002E = 5Z1-3 (whatever that means for size?)

Thanks for help!!!

 

[drewpy]

I originally installed the new non bleed hole pilots and the bike hunted on trailing throttle, replaced with the bleed holes and equilibrium was restored!

 

[226dark]

I originally installed the new non bleed hole pilots and the bike hunted on trailing throttle, replaced with the bleed holes and equilibrium was restored!

I believe it! Not convinced by SCI saying to just use it and be happy. They have good products, too bad about the subpar, even misleading customer service.

 

[lhaolpa]

I never heard about the DOHC models being"crap".The DOHC motors have been in use by Yamaha and other companies for years,and about the only thing different about them is the valve train. Oh well,opinions are like as@#$%^&les,everyone has one! lha

 

[xschris]

I think he meant the xs400 dohc all I know is that they where made for only two years

 

[lhaolpa]

That's what I was talking about also,xs400rj seca,DOHC.They only made the xs400 for two more years,like all other models,they make them for a few years with changes made throughout the run and then move on to other models.They stopped making all the models that are no longer made,but that doesn't mean that they were"crap". lha

 

[DogfaceYT]

I'm looking for a rebuild kit for my '51 400xs carbs, any idea who has them?