XJ or XS carbs

[tinman905]

I picked up these carbs thought they were for 80/81 XS but the choke is a bit different. Is the choke on the XJ carbs the same as the XS ? Here's a pic , there is no choke lever on these that's why I think they are for the XJ.

[trbig]

Yup.. XJ.

They are junk. Might as well send them to me!

You can change out that choke bar carefully and replace it with the XS bar and attach the lever onto those carbs. Also, the jetting is a lot different than the XS... 112.5 mains and 47.5 pilots. Neoprene floats though.. much better than brass in my opinion.

Tod

[blue giant]

XJ carbs for sure James.
I'm not sure how you could add a choke lever and cable to the handle bars. If you can find a choke lever and rod from a set of XS carbs I think you could make them work quite well!

Paul

[Ivan]

You might look into some old school venture controls for the left side. They had a choke lever on them and on my 84, looks like it wouldn't be too hard to do the wiring swap. You won't have a 4 way switch though, since that is on the dash of the venture.

[trbig]

John borrowed the choke assembly off of my parts bike and tried to see if he could adapt it somehow to work with the XS's. It attaches to the bottom of the left control. He didn't use it and don't exactly know why. You could just get a left control from an XJ and make it work, but you would lose the 4-way flasher since it is mounted on the XJ's RIGHT control handle.

If you have a fairing, or some way to mount one, you could just attach an aftermarket choke cable that you can pick up at any auto parts store. It looks like you're missing the little hold down arm that fits under that screw on the little bracket between the #3 and 4 carb. That holds the cable down. The hardest part would be to figure out a way to attach that aftermarket cable to the end of that choke bar.

OR.. just swap out that choke bar like I mentioned and use the choke (Enrichener) lever from the XS.

Tod

[Jerry]

You may also note that the intake side bells are slightly larger, 54 mm instead of 52 mm IIRC. If you are going to use the stock '80 airbox you may have to use the XJ (larger) boots to make the hook-up.

[TopCatGr58]

Hey Jerry,

He we go again! Jessie/XS81Project/Moderator has been working on lots of sets of carbs, and has measured all of the years, and they are all 54mm. I checked the fiche on the Yamaha site for the air filter intake to carb boots, and they are ALL the same part #, and the ones I've measured are also 54mm.

I'm not sure exactly where the 52mm size info first came from, but it's not correct. Sites that sell the pod filters offer 54 and 52mm, I think some of the XS650's have 52mm intakes, but the XS11's and XJ's are all 54mm.

Tinman,
Yeah, they are jetted a bit richer in the pilots, but about right in the middle for the mains vs. the book values of 110 - 120's for the later 80-81 series carbs. They will probably be close to plug and play with perhaps a bit of tweaking of the pilot screws for a good idle and low rpm roll on and transition to the mains.

It shouldn't be too difficult to take the choke lever and rod from your existing carbs and put them on the XJ's. On those carbs, the Xj cable actually PUSHES the rod towards the left of the bike to open the enrichener. Depending on the design of the cable clamp on the end of the rod, I've seen someone tap some threads on the end of the rod, and just screw a knurled knob on the end instead of a fancy hinged mechanism. You might be able to cut off the cable attachment, flip the rod around so that it's coming out the left side of the bank, and attach a pull knob to it. Just would need to check the alignment detents/notches in the rod....if there are any, come to think of it, I think it's a smooth action lever for the XJ's enrichener, and you can adjust the amount of enrichener by where you push the lever on the handlebar. I don't remember feeling any clicks/detents when working on BNE's Maxim!? If there aren't any detents, then it wouldn't be a problem to swap the position of the rod so that it would pull from the left side!
T.C.

[trbig]

The XJ's enrichener is smooth with no notches. BUT.. where that screw is on that bracket that's holding the cable hook.. as I said, there is a missing piece there that holds the end of the enrichener cable sleeve tight. When you engage the "Choke", it PULLS the rod to the left, not pushes.

Up on the left control switch, you pull the lever to the left and it engages the choke/enrichener by pulling it to the left. Pushing the lever to the right pushes that rod back to the right. It's much more adjustable and fine tunable than the XS system if you let it warm up at idle.

Tod

[trbig]

Sorry.. looking closer.. that piece I thought was missing is in fact there, but it is just spun around the wrong way. If you spin it 180 degrees, that arm pins the cable sleeve against that bracket to keep it from moving.

Tod

[tinman905]

Thanks guys ,way more infor than I was expecting. I will see what I can do to make them fit my XS.