5twins
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    • 5twins
      5twins replied to the thread 750 Tripple carb tuning help.
      No, they're BS34's, a smaller version of the '76-'77 BS38's mounting their needles the same way. XS360 carbs were very similar, BS34's...
    • 5twins
      5twins replied to the thread 750 Tripple carb tuning help.
      Something else you should check is if the needle is assembled correctly. The thick plastic spacer ring should go on top of the e-clip...
      • '78-'79 Slide.jpg
      • 5O2 Needle Washers.jpg
    • 5twins
      5twins replied to the thread 750 Tripple carb tuning help.
      I agree with JP, your plugs are black from starting and running with the choke on. But also, if your carbs are original '79 ones, your...
    • 5twins
      The "kill" switch doesn't ground out the R/W wires, it simply disconnects them from one another. You have one R/W wire running into the...
    • 5twins
      5twins replied to the thread Mikeys new to him 81.
      Sorry, yes that's what I meant to say, the AP63. Look at it's specs. They say it has 4000 ohms of resistance.
    • 5twins
      5twins replied to the thread Mikeys new to him 81.
      I just Googled the SP63 and it says it's a resistor type that has 4K ohms of resistance. You better check those plugs closer.
    • 5twins
      5twins replied to the thread Mikeys new to him 81.
      You only want one instance of resistance in the line. That can be plug or plug cap (not both). On bikes, you generally don't use...
      • NGK LZFH.jpg
    • 5twins
      If you haven't pulled that caliper apart and cleaned it out, you really should. I haven't needed to replace many rubber parts in them...
    • 5twins
      You're in luck, the price for stainless replacement pistons has dropped for some reason ..... https://www.ebay.com/itm/381857804424...
    • 5twins
      No, the 4 hole valve cover studs are M8, the exhaust studs are M10.
    • 5twins
      5twins replied to the thread Uncapped hose under carbs.
      No, that's the breather hose alright. I recognize it from having to deal with it on my '83 before I yanked it and the airboxes in favor...
    • 5twins
      5twins replied to the thread Template for drilling disc.
      Yes, you want the swirl to go "backwards" so to speak, starting at the inside and moving to the outside opposite to the direction of...
    • 5twins
      Pretty much all the acorns are still available from Yamaha but at $5 to $6 each, they're not cheap, lol. And the ones for the exhaust...
    • 5twins
      5twins replied to the thread Template for drilling disc.
      Yes, the stock disc is a real porker, lol, at almost 7 pounds. The SR500 5mm thick version is about 1.5 pounds lighter but honestly, I...
    • 5twins
      5twins replied to the thread Template for drilling disc.
      They're pretty easy to drill. I do all the holes first with the smaller 3/16" bit, that goes through pretty easy. Then I go back and...
    • 5twins
      5twins replied to the thread Template for drilling disc.
      Now let me talk about hole sizes for a minute. Being that I'm dealing with used discs that may be worn a bit thinner, I decided to use a...
      • DiscHoleSize.jpg
    • 5twins
      5twins replied to the thread Template for drilling disc.
      I started out years back on my 1st disc with a 7 hole swirl and 6 swirls ..... This worked OK but I wanted more holes. I also didn't...
      • NewWheelMounted6.jpg
      • NewWheel.jpg
      • normal_650-500_disc_drill_pattern_jpeg.jpg
      • SR Disc.jpg
      • Old Disc.jpg
    • 5twins
      5twins replied to the thread I am back with a Yamaha.
      Well, that's something I never even noticed, lol. I think common sense would dictate flat side towards flat side and the domed sides...
    • 5twins
      5twins replied to the thread I am back with a Yamaha.
      You should check the head bolt torques while you've got access to them. I see you still have the original rubber/metal sealing washers...
      • ButtonHeads.jpg
    • 5twins
      5twins replied to the thread Warped intake valves.
      Your main jets may be too small as well. 135 is the stock size for the '78-'79 carb set. I would go 140 or 142.5 if it will take it...
    • 5twins
      5twins replied to the thread 79 XS750 breather puking oil?.
      Sounds like you filled it twice.
    • 5twins
      I've never seen exact stainless replacements for the acorns. They're rather special, J.I.S. type.
    • 5twins
      5twins replied to the thread Cam chain adjuster querie.
      Well, if the front guide needs replacing then the cylinders will have to come off so you can accurately center the new guide when...
      • OldFrontGuides4.jpg
      • OldFrontGuides7.jpg
      • GuideMount.JPG
    • 5twins
      5twins replied to the thread Cam chain adjuster querie.
      Well, if the chain gets loose enough to jump teeth when the tensioner is backed off, it's definitely stretched out and in need of...
    • 5twins
      5twins replied to the thread Cam chain adjuster querie.
      Andy, if you do have the 59mm long screw and longer type E plunger then you need the 3mm thick rubber/metal damper washer. With it, you...
      • CamChainTensioners.jpg
      • D-EPlungers.jpg
    • 5twins
      5twins replied to the thread Cam chain adjuster querie.
      Wow Gary, how come that tensioner rod is so far in? Does it just need adjusting because it hasn't been yet or is this the way those big...
    • 5twins
      5twins replied to the thread Cam chain adjuster querie.
      Maybe the chain is worn and stretched out? On a stock machine with the bolt-on adjuster plate, having to turn the adjuster that far in...
    • 5twins
      5twins replied to the thread 22's 1980 xs650 build thread.
      Well, your BS34s don't have an overflow pipe in them so it would come out where the air filter attaches. There's a possiblity it can run...
    • 5twins
      5twins replied to the thread Timing chain link connecting.
      I have the cheaper MikesXS tool (well, it was cheap when I bought it, lol) but have Motion Pro replacement rivet tips for it. They work...
      • X Cut.jpg
      • Cam Chain Link.jpg
      • Pins After Tool.jpg
    • 5twins
      5twins replied to the thread Triple Tree Bolts.
      The triple tree bolts on our 650 don't get torqued that tight, only something like 11 ft/lbs. I think.
    • 5twins
      5twins replied to the thread 22's 1980 xs650 build thread.
      Yes, when a gasket starts leaking, it usually just seeps some, it doesn't pour out like you experienced. Your issue sounds more like a...
    • 5twins
      5twins replied to the thread I am back with a Yamaha.
      Yes, greasing or oiling the sump gasket should allow removal of the sump plate next time without it sticking or harming the gasket, and...
    • 5twins
      5twins replied to the thread 79 XS750 breather puking oil?.
      Looking at the parts diagram, it seems this is a "closed" system. It looks like there should be a hose running from the breather up to...
    • 5twins
      5twins replied to the thread 79 XS750 breather puking oil?.
      Three cylinders? Is this the 750 triple? If so, I'm not familiar with it's breather set-up. The info I provided applies to our 650 twins.
    • 5twins
      5twins replied to the thread compatible motor for my 1981..
      Yes, you would simply swap the alternator and rotor from your current motor on to the "new" motor if it had the older points set-up. You...
      • Tensioner I.D..jpg
    • 5twins
      The original left hand switch had a ground wire running into the headlight bucket and connecting to the ground wires in there that ran...
    • 5twins
      5twins replied to the thread Headlight lamp gasket.
      The later bikes don't use part #8 on the front signals, only the rears. Maybe you don't need it either. On the later bikes, parts 6 and...
    • 5twins
      5twins replied to the thread Headlight lamp gasket.
      Yes, I think they are all the same from '74 on. They were also used on several other Yamaha models (XS500, XS750 & 850, some XS1100s) so...
    • 5twins
      5twins replied to the thread Piston indentification.
      Not that I'm aware of. There should also be a 3 digit number stenciled on the sides of the cylinder sleeves where they hang out the...
      • CylinderSize3.jpg
    • 5twins
      5twins replied to the thread 79 XS750 breather puking oil?.
      I'd take the breather off and make sure it hasn't been "gutted". There's supposed to be a baffle plate in there. Other than that, if...
      • BreatherPlugs.jpg
      • Late Breather.jpg
    • 5twins
      5twins replied to the thread Piston indentification.
      Yes, that looks like a standard original piston. The size new would have been 74.952mm.
    • 5twins
      5twins replied to the thread Headlight lamp gasket.
      Mine don't have them either. It may be something Yamaha eliminated as the years went on. But I have changed my headlights to H4 units...
    • 5twins
      Yes, I think the bike will still crank over with the starter if the kill switch is "Off", it just won't start because power to the coil...
    • 5twins
      Don't try grounding the right switch to the triple tree, or anywhere else on the forks for that matter. They are not a suitable...
      • 83GroundWire.jpg
    • 5twins
      5twins replied to the thread No start Mystery.
      Are you trying to electric start it or kick start it? If the battery is a bit low, many times the bike will crank but not start. The...
    • 5twins
      5twins replied to the thread Headlight trouble shooting.
      You're missing the point - on your early model, the bike doesn't need to be running for the headlight to be turned on. It doesn't have...
    • 5twins
      5twins replied to the thread I am back with a Yamaha.
      You also have to have the gasket surfaces really clean, eat-off-it clean. There can't be any remnants of old gasket left on them.
    • 5twins
      Yes, one of the first things I do on an old "new-to-me" bike is replace all the cables. Some of those look well past their "Best by...
    • 5twins
      5twins replied to the thread New here!.
      I prefer the simplicity of a drum rear brake, and if you're going to be dirt riding, you may like it too because it doesn't lock the...
    • 5twins
      So DE, how would you say it compares to our 650?
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