XS650F carb removal.

Mannyroad

Mannyroad

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Hi,
I've just acquired a 'barn find' imported XS650f that I need to get prepped for an MOT to get the bike UK registered. The bike hasn't run for a good while, so the battery is toast and the carbs will need a good clean, so my job at the mo is the carbs. The bike has the OEM airboxes on it and they look pretty closed in by all the other bike equipment packed in around them. So my problem is, how do I remove the carbs, which seem trapped by the rubbers each end? I've squirted som WD40 on the rubbers to try to ease them from sticking to the carb bodies, but unless I can somehow move those airboxes I fail to see how I can get the carbs out. I just have no idea how to deal with the airboxes. Any guidance on carb removal procedure would be very much appreciated. appreciated
 
Hi Mannyroad, I can't be sure of the differences with a F but with my 1978 SX650SE, the air boxes have to come out to get the carbs off. So it's seat off, tank off, side panels off, remove the cross-head screws securing the airboxes, up near the seat rails. Loosen the clamp at the carb end and the air box pulls out to the sides in two halves. There's a tube joining the two halves, will come out with either, remember to put it back when refitting the boxes.

Now you can get at the carbs themselves. Loosen the clamp on the engine side, remove throttle cable, pull/wiggle the carbs back. Once they are free of the inlets, its still needs a bit more wiggling to remove them from the bike. The problem is not much room in front of the vertical frame tube. Removing the cap on the chain tensioner gives a little extra space but I usually end up taking the r/h inlet rubber off the cylinder head. Then you take the carbs and gently turn and move them about until you find a way out. Calls for patience.

As Haynes might say, reassembly is the reverse of dismantling . . .

Not relevant right now, but when doing an engine swap, it's worth remembering to fit the carbs when you have the long central bolt under the engine in place, but before fitting the other bolts, because you can tip the engine a few degrees forward giving ample room for the carbs to go in.
 
Hi Raymond,
Thanks ever so much for this info, and so quick too. I hadn't realised that the airboxes split into two. Only had bike a couple of days.. And that tip on the engine swap is also noted. Time to get out in the shed and have a go.
 
Well, after much heaving to and fro, and scraped and cut hands, I still can't get these airbox halves off the bike. I've removed the two bolts that retain them, to the back of the boxes, and now the boxes sort of wiggle a little but not much. It just feels like there is something else going on because they simply won't pull back at all, certainly not enough to clear the carb bodies.
 

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Haha!! Found it! Tricky to spot. All out now, and carbs off, thanks.

Going to have to pull the carbs to bits and sonic clean them. The 'choke' levers won't move, so clearly pretty jammed up. And the throttle slides won't descend any further than in the pic, so that can't be good.
 

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Just a note on your carb top screws. The two outside ones in your pic are in the wrong places. They should be in some of the inner holes where the butterfly shaped bracket mounts. You need the longer length there to reach through all the threads provided. But this is an area that Yamaha cheaped out in, lol. You need a longer screw anywhere a bracket mounts. That would mean four in the butterfly shaped bracket and one in the throttle cable holder, for a total of five. Yamaha only used four. You'll want to get one more long screw. If you use the shorter screw, it only grabs a couple threads and it is easy to strip the hole in the carb body.
 
Cheers 5twins, didn't spot that. Thanks for the advice. Will make a point of getting some longer ones for the rebuild.
 
Carbs are ready for the sonic cleaner. One of the air enrichment mechanisms is well stuck in the carb body, but expect this will free up by sonic cleaning. Measured the ventures and was surprised to find they were 38's. My other '80 xs650, rephased 750 big bore motor uses VM34's. Was expecting 34/36 carbs on this.
 

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Yes, those are BS38's, a '78-'79 set to be exact. An XS650F model would be a '79. The '80 model was a G.

You are aware that there are little rubber seals on both ends of the butterfly shafts? Sonic cleaning probably won't hurt them but there's a good chance they need to be replaced anyway. They are very soft and flexible when new, and just the vacuum draw through the carb is enough to suck them in and seal them. They harden up with age and then that doesn't happen, lol.
 
5twins said:
Yes, those are BS38's, a '78-'79 set to be exact. An XS650F model would be a '79. The '80 model was a G.

You are aware that there are little rubber seals on both ends of the butterfly shafts? Sonic cleaning probably won't hurt them but there's a good chance they need to be replaced anyway. They are very soft and flexible when new, and just the vacuum draw through the carb is enough to suck them in and seal them. They harden up with age and then that doesn't happen, lol.
Click to expand...
Great info 5twins, thanks a lot. Will swap these out too. I presume they come with the rebuild kit. My bike's headstock OEM sticker actually seems to suggest a date of manufacture of 5/78. Presume this is correct for an F model too.
 
My '78 has a rear brake switch.

EDIT Meant of course to say front . . . doh!
 
Last edited:
5twins said:
You should have a front brake light switch as well. It's usually attached to the perch by the end of the lever so the lever can activate it when pulled .....

View attachment 247364

As far as the butterfly shaft seals go, I've never seen a rebuild kit that includes them. Most of us use Suzuki seals here, same part but much cheaper. You'll need 4 .....

https://www.partshark.com/oemparts/p/yamaha/256-14997-00-00/-seal

https://www.partshark.com/oemparts/p/suzuki/13651-51011/seal
Click to expand...
Thanks for your inputs here. Very much appreciated. Sorry im going off topic here, given the thread is about carb removal but, well, I have a bit of a dilemma going on with this bike. Now I'm confused over the model, as in, is it an xs650 F, SF, 2F (US 1979) or XS650 E, SE (US 1978).

I'm somewhat confused because the bike was imported from the US, by an importer and sold as an F model. However, the original manufacturers sticker on the headstock stated its manufacture date as 5/78, suggesting an E, SE model. Yet the matching engine and frame numbers start 2FO, suggesting it is a '79 2F model. So I'm confused.

The Haynes owners manual shows different wiring diagrams for US models SE, SF, 2F. All have a fuse box, all have both front/rear brake switches and all have a Lights on/off switch on the RH switch cluster (my bike doesn't have the Lights switch - seems to have the XS650 G/ SG cluster). My bike appears to have had a fuse box previous to me buying it, but the wires that once went to it seem to have been 'looped out' by Mr. Molester (read bike importer). He has also very crudely bridged certain wiring in the loom, I think but am not sure, to circumvent the safety relay/ flasher cancelling unit / Reserve Lighting / Light Checker equipment.

Currently there are issues with the headlight (not working) and indicators ( LH works intermittently, RH doesn't appear to work). Haven't checked if kill switch works or other stuff because I need first to establish what model I have. I believe it is a 2F model but the year of manufacture suggests otherwise.

Can anyone give me some certainty?
 
From XSLeo.....
"In 79 they had 3 models. The standard, a special and a special II.
The standard had spoke wheels, drum brakes on the rear, side hinge seat.
The Special had mags with disc brake rear, seat tipped up from the rear and lifted off.
The Special II was a combonation of parts from the standard and special.
They did this for a couple years. This phenomenum confuses lots of people.
Kinda like they had extra parts left over after making the standards and Specials, put the parts together and called it a Special II"
 
650Skull said:
Without pics no way to help.

This thread has what you need to identify your bike.
https://www.xs650.com/pages/tech/
Click to expand...

OK, cheers for that. Seems to nail it, as my frame VIN (2F0-152377) corresponds to it being an XF. Attached is a pic, though the seat isn't correct for the bike -and so won't fit obviously. Think.i might need to start a new thread to talk over my electrical issues.
 

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Serial numbers on U.S. '78 models also start with 2F0. The 5/78 build date would suggest a '78 model but your 152377 number would be a '79. I didn't think they started production on next year's model that early but apparently they did. It's definitely a Special, not an SPII or Standard.

Looks like you have extended forks, not much, maybe 2 inches, but longer than stock ones for sure.
 

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