nomad007
XS650 Addict
Hi Jan thanks yes I was going to try that first.
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No power to orange coil wire
- Thread starter nomad007
- Start date
Well, your problem may be related to that little o-ring on the mix screw going bad, and to replace it, the mix screws need to come out. Besides, they're usually set too lean from the factory so now you'll be able to set them right.
nomad007
XS650 Addict
Hi 5twins - so are you just suggesting just remove them and give them a good cleaning. Do they have to be seperated? The plugs did not look lean( they were tan) but those caps have been on for 45 years. I dont think this particular motorcycle with 9000 miles has been messed with or worked on at all. What is the best place to get rebuild kits and I assume like the hondas I work on all original brass is the best and should be used unless not possible.
nomad007
XS650 Addict
actually it seem like i could remove those brass caps with the carbs on the bike.
You probably don't need to separate the carbs from one another but I do recommend pulling the "bank" (carb assembly). As I mentioned earlier, the jets are probably really tight and would be very difficult to remove with stubby screwdrivers (if not impossible).
However, if you want to replace the butterfly shaft rubber seals, the carbs will need to be separated. To test if they're still good, you can spray some WD40 around where the shafts enter the carb bodies while the bike is idling. If the idle speed changes (dips) then the seals are leaking. When new, the seals are very soft and flexible, and they work by the vacuum in the carb sucking them in tight. When they get old, they harden up and no longer function as they should. This is an all rubber seal, with no metal band or spring in it like a normal seal. You can access the one seal on the outside of the left carb by removing the throttle cable bracket. They are a rather loose fit in the carb so you can pull the seal out and give it what I call the "pinch test". It should squeeze down into an oval shape pretty easily if it's still soft and good. Here's a new one .....
..... and here's an old bad hardened up one. It doesn't want to squeeze down, even with a lot of pressure ......
So, you be the judge on if the seals need replacing by how hard that one you can access is. Most of us buy Suzuki seals because they are much cheaper (exact same part). You'll need 4.
However, if you want to replace the butterfly shaft rubber seals, the carbs will need to be separated. To test if they're still good, you can spray some WD40 around where the shafts enter the carb bodies while the bike is idling. If the idle speed changes (dips) then the seals are leaking. When new, the seals are very soft and flexible, and they work by the vacuum in the carb sucking them in tight. When they get old, they harden up and no longer function as they should. This is an all rubber seal, with no metal band or spring in it like a normal seal. You can access the one seal on the outside of the left carb by removing the throttle cable bracket. They are a rather loose fit in the carb so you can pull the seal out and give it what I call the "pinch test". It should squeeze down into an oval shape pretty easily if it's still soft and good. Here's a new one .....
..... and here's an old bad hardened up one. It doesn't want to squeeze down, even with a lot of pressure ......
So, you be the judge on if the seals need replacing by how hard that one you can access is. Most of us buy Suzuki seals because they are much cheaper (exact same part). You'll need 4.
nomad007
XS650 Addict
Thanks!
Also, don't bother with carb rebuild kits. ALL of 'em out there are iffy... and have cheap Chinese crap in 'em. You can buy genuine Mikuni brass from these two places.
https://www.nichecycle.com/categories/carburetor.html
https://www.jetsrus.com/
They sell both the Chinese junk and genuine Mikuni bits. Make sure you order the real stuff.
https://www.nichecycle.com/categories/carburetor.html
https://www.jetsrus.com/
They sell both the Chinese junk and genuine Mikuni bits. Make sure you order the real stuff.
As 5twins pointed out, the o-rings for the mix screws are most likely shot. You can get a "kit" that has the screw, washer, spring and o-ring for about 12 bucks a side. Yeah, you can just replace the o-ring, I think it's better to just change out the lot. Ymmv
https://www.partzilla.com/product/yamaha/12R-14105-00-00
https://www.partzilla.com/product/yamaha/12R-14105-00-00
nomad007
XS650 Addict
Being that the mix screw is right below the plug, if you drill too far and go through the plug, you often then damage the mix screw screwdriver slot. Then a whole replacement screw is best. Yamaha doesn't list this screw on the XS650 BS34 parts diagram but it is listed on diagrams for other models with similar carbs. There are also aftermarket sellers on eBay that provide measurements of the screw. They seemed to match up so I took a chance and bought a couple, and they are, indeed, the same screw, a perfect match. But if you do successfully get yours out without damage and just need the o-ring, the size is 1mm x 3mm.
nomad007
XS650 Addict
Hi 5 twins - I had to work a lot that last 2 weeks but I am back on it- I managed to remove the brass plugs and the pilot and main jets but these mixture screws are tough - did the factory loctite them in as well as brass plug cap them? What is the exact screw driver you like on these ? I clicked the wiha link but it did not seem clear. I don't think these carbs have ever been apart although they seemed clean - the pilot jet did need to be cleaned. Thanks for any help- the carb guide made the removal very easy - thanks. I read the tool guide but wondered if there was a magic one for this and if I need heat? I am afraid I am going to strip them and if that happens- yikes is it drill and extractor - hopefully it does not come to that.
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They're probably just stuck in there with old gas varnish so heat (hair dryer) and penetrating oil. As far as a recommended screwdriver, no, I don't have one. Just find one that fits well, even if you have to grind the tip to make that happen.
nomad007
XS650 Addict
thanks
It may take an overnight soaking with penetrating oil and several heatings and coolings with the hair dryer to break these free so be patient. Try turning the screw both ways (in and out) when trying to break it free. Then once it breaks free, you may need to "work" it in and out a little as you remove it to distribute the penetrating oil and get it turning freely.
nomad007
XS650 Addict
Hi 5 twins and all members,
Well I have soaked those mixture screws for days applied heat- ground screw drivers and then some.
I even took it over to my mechanic mentors shop for help. We got them both turning but I can not get them out. When I say turning - I mean like a 1/4 to 1/2 turn each way. You can feel the point on the bottom. and the left side seemed to be 1 to 2 mm lower on left side from factory. Not sure what to do now was contemplating buying and trying the attached extractor. I have seen it used on carb jets online. It is a shame because if we believe the odometer these carbs have 9000 mies. They looked pretty clean to me when I opened the bowls. I really don't think anyone has opened them before. So I guess I could leave the pilot mixture screws how they are and clean everything else. ( the pilot jets do look like they could use a cleaning but mains are very clean) try the extractor which if done wrong ruins carbs) - buy another set of carbs. - Anyway this is not the first bike I have worked on so I get this is how it goes sometimes - I just have never worked on Yamahas until now. Maybe I am missing something. All other jets removed no problem and brass plugs were not bad to remove. Carb removal was kind of easy compared to a 78 cb550 knuckle ripper I had. Any advice would be appreciated - Thanks as always. Damon
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nomad007
XS650 Addict
Also I have a feeling my problem might still be electrical - although I am glad I took these carbs off because I do believe the pilot jets or (the small jets under black caps )did need cleaning I just hope I can get the screws under brass caps that I removed ( I think the term is mixture screw) removed without ruining carb bodies.
I'd suggest you keep up the lube and turning. Eventually the gunk on the threads will give up... just keep rocking it back and forth.
Also, if you have a small (1/8") punch, give it a few light taps from time to time... that helps break up the gunk too.
Since you got them both turning, I don't see the need for that extractor, and like you said, there's more of a chance of damaging (and maybe even ruining) the carb body with that. Just keep at it with the penetrating oil and heat. What penetrating oil are you using? PB Blaster is pretty good but Kroil is even better. I'd say they need to come out so you can replace the o-ring at the bottom. That's what seals the screw in the hole and if it's bad, the mix screw won't function correctly.
Yes, when screwed in all the way and lightly "seated", the tip of the mix screw will hang out into the main bore a little bit, like so .....
But, a stock bike with stock size pilots runs best with the screws set between 3 and 3.5 turns out, so you wouldn't see the screw's tip then. Even a modded bike with larger pilots still likes 2 to 2.5 turns out.
Yes, when screwed in all the way and lightly "seated", the tip of the mix screw will hang out into the main bore a little bit, like so .....
But, a stock bike with stock size pilots runs best with the screws set between 3 and 3.5 turns out, so you wouldn't see the screw's tip then. Even a modded bike with larger pilots still likes 2 to 2.5 turns out.
