Rebuilding Petcocks & Carbs

[sail4free]

Needles and emulsion tubes should be the same on the '79 SF. You can use the '79 F in place of it with no problems. Biggest thing is have all 4 carbs the same. Put the needles at the middle clip if they have been moved.

==========
But can we use the '78 (?S?) with no problem? Sounds like the Special had slightly shorter metering rods with a quicker taper -- seems like all four should be the same = either Standard *or* Special as long as they are the same? Some references show three clips -- others five -- I'm assuming (either way) the middle position is a good starting point?
==========
The latest from Tyler after I relayed all your comments to him:
"Sounds good. I am confident in our jetting as I ensured the the emulsion tubes, mains and pilots all matched. The only item that may have some variance is those needles. Which of course are the hardest part to access in the entire carb."
==========
Can I take this to mean we should have no issues with the slides or diaphragms being different (between the '78 Standard "donor carbs" and the '79 Special)?
JIM P.
==========

[sail4free]

Well, you just need to verify what bike you're borrowing carbs from. The 45 pilot jets may have been off a 1978 XS, where-as the 42.5's coulda been off a 1979. With the exception of the Mains, Pilots, and air jets, the '78/'79 carbs were the same. 1980+ were different.

==========
For now, we're assuming the rack of donor carbs was from a '78 XS and that the 42.5's were the original stuff from my '79 SF. It seems like we might be good on everything matching *except* the metering rods (different in the Special from the Standard). We'll be okay as long as all four are the same but I prefer putting the ones from the Special back in.
JIM P.
==========

[IanDMacDonald]

No, the diaphragms and needles are the same between the two I believe. And yes, the needles are hard to get to due to the circlip holding them in. Master cylinder snap ring pliers will get them out easily.

[sail4free]

42.5 pilots are stock for 80-81 carbs.....NOT the earlier carbs(79-79).
80-81Specials had same mains across all four(110's)
" " Standards had 115 mains outer cyls./120mains inner cyls. to better cool/'quench' inner two cyls. assuming the Standard in most cases would be packing a load over longer distances as opposed to the more sportier bar-hopper Special, lean'n'mean with the bit shorter, quicker taper metering rods for added attitude.
IF ALL jets used are not genuine Mikuni with their curly logo......all bets are off for any decent running ability if using K&L's or RD jets.

==========
I've read elsewhere that the 42.5 pilots were stock for the '79 Special as well. I wonder if the difference in metering rods applied to the Special before '80? Mine is a '79 and *if* there was a difference, that could explain what the mechanic is concerned about -- that all the metering rods might *not* be identical because some of them came from '78 XS carbs. The one jet I bought was billed as "genuine Mikuni" -- the other three 42.5 jets we used came from my OEM (as far as I know) '79 Special carbs. I do appreciate everybody's help on this.
JIM P.
==========

[motoman]

Why a cluster puck? He's using a combo of '78/79 carbs (hopefully). 42.5 pilot jets were stock from '79+. The '78 was the only year with the largest pilot and air jets, going along with their unique timing curve.

....just cause if using the early carbs, the jetting you've referred to is for one model of the later 80-81carbs(no cross-over tunnel).

[sail4free]

As long as ALL FOUR CARBS ARE SET THE SAME it does NOT MATTER!! I've swapped set's between '78, 80, '79, Etc. IF the bank is good, it will work well. The fine tune CAN be done once it runs.
ALL carbs mix air and fuel to a 14:1 ratio(or close to it!). Once close, with Mikuni jets, you can tune any year carb for any engine.

==========
As it turns out, we might have been better off to just go with the complete set of donor carbs from the '78 XS (assumption based on my best recollection) as three of my '79 Special carbs ended up not worth saving. Whether #2 is from the donor set or the OEM set, I am not knowing. If he can make sure that all four metering rods are the same, I'm thinking we're IN . . . but what about the slides and diaphragms? Are those the same -- between '78 XS and '79 SF? Thanks for all your help on this; it is great to not be shooting in the dark!
JIM P.
==========

[sail4free]

No, the diaphragms and needles are the same between the two I believe. And yes, the needles are hard to get to due to the circlip holding them in. Master cylinder snap ring pliers will get them out easily.

==========
So the difference in metering rods (between the Standard and the Special) may be something which began in '80? If this is true, there should be no difference in the rods between '78 XS and '79 Special? Can we assume the slides are interchangeable as well?
JIM P.
==========

[DiverRay]

The needles/metering rods ARE different between the '78-79 Standard and the '79 Special. The slides, and the rest of the carbs, WILL interchange. Just get all 4 metering rods the same, and you are good to go.

[sail4free]

The needles/metering rods ARE different between the '78-79 Standard and the '79 Special. The slides, and the rest of the carbs, WILL interchange. Just get all 4 metering rods the same, and you are good to go.

==========
Well -- I *think* this is good news as it explains the 'minor difference' that Tyler was concerned about. He emailed this morning:
"I got the needles all swapped out last night and will do another bench sync before putting the carbs back on."
==========
Tyler may be moving out-of-state within the next two weeks or so (will find out for sure next week), so one way or another, this chapter may be closing soon If we can get the ol' girl to fire up, I'm happy to bring her home and finish loving her back to speed.
JIM P.
==========

[sail4free]

The needles/metering rods ARE different between the '78-79 Standard and the '79 Special. The slides, and the rest of the carbs, WILL interchange. Just get all 4 metering rods the same, and you are good to go.

==========
Got a little more info from Tyler:
" . . . it was a good thing I pulled the needles. There was some variation. I found 4 needles that all looked brand new and matched. Not sure WHICH set would have had 4 brand new needles in it, but I used those and put them on all in the 4th clip up because they are 6 clip needles, which makes me think they are aftermarket. According to the book stock needles only have 5 clip locations."
==========
Like you say, as long as all four needles are the same, we should be able to get some kind of tune. It may run more like a 'Standard' and less like a 'Special' but, after not riding it for 12 years, I doubt I would know the difference. At this point, it's tough to know if the "new" needles came from my Special *or* the donor carbs. Thanks for your help!
JIM P.
==========

[sail4free]

Mo' Questions?

==========
After reading through crazy steve's easy bench sync method:
http://www.xs11.com/forum/showthread.php?t=36021
I forwarded the link to Tyler and asked him to check the orientation of the vent holes.
==========
His response:
"That is interesting. That the first time I've seen carbs with two notches for the diaphragms to line up. You carbs only have one notch, so there shouldn't be any room for error on the vent hole. But I'll double check just to be sure."
==========
And then this:
"I double checked last night and they are appropriately aligned."
==========
He says there's only one positioning tab on my carbs, so pretty tough to goof that up I guess. And because we didn't replace any diaphragms, I'm assuming the little hole in the bottom of the slide should be oriented in the right direction (towards the engine) . . . as long as it was before, eh? So the vacuum which raises the slide (and therefore the metering rod) is created by air rushing past that little hole in the bottom of the slide? Once tuned with the air filter pods, I should be able to remove the pods and SEE if all four are moving up together under throttle? The new kit for rebuilding both petcocks should be here tomorrow -- getting close to that moment of jubilation (I hope!). All work (aside from the petcocks) to get the ol' girl running again is done. I can hardly wait!
==========
sail4free
==========

[IanDMacDonald]

Just curious- Is Tyler a real mechanic, or somebody off Craiglist tinkering on bikes?

[sail4free]

Bad News!

Just curious- Is Tyler a real mechanic, or somebody off Craiglist tinkering on bikes?

==========
Ummm -- jury still out on that one -- likely closer to the latter, eh? He has five bikes in his garage that he's working on but I'm fairly sure his day job is doing something else. It's not the perfect scenario but at least we're making *some* progress
==========
The latest from Tyler:
First go at the carbs was not successful. Fuel pooring from the air jets and breather hose. I checked the float height, so my guess is that the float needles aren't seating and may need replaced. I know these carbs are notorious for this issue because the needles are all metal, no rubber tip like a lot of carbs.


Maybe run it by your group? Attached image shows where the gas was escaping circled in red.
[I'll upload the image later but looks like fuel coming up out of filtered vent between #3 and #4 -- also coming out of port on left side of carb throat (looking in from where the filter will be).] NOTE: The bike *is* on the center stand.
JIM P.
==========

[IanDMacDonald]

Lol, that was funny. You know what? As-long as it's getting done right, it may not matter.

[sail4free]

Lol, that was funny. You know what? As-long as it's getting done right, it may not matter.

==========
I guess it'll either get done right now . . . or later ) Is there a good source for float needles/seats for this '79 XS Special?
JIM P.
==========