5twins

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...

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...

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...

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...

Sorry, yes that's what I meant to say, the AP63. Look at it's specs. They say it has 4000 ohms of resistance.

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.

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...

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...

You're in luck, the price for stainless replacement pistons has dropped for some reason ..... https://www.ebay.com/itm/381857804424...

No, the 4 hole valve cover studs are M8, the exhaust studs are M10.

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...

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...

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...

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...

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...

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...

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...

Well, that's something I never even noticed, lol. I think common sense would dictate flat side towards flat side and the domed sides...

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...

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...

Sounds like you filled it twice.

I've never seen exact stainless replacements for the acorns. They're rather special, J.I.S. type.

Well, if the front guide needs replacing then the cylinders will have to come off so you can accurately center the new guide when...

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...

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...

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...

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...

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...

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...

The triple tree bolts on our 650 don't get torqued that tight, only something like 11 ft/lbs. I think.

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...

Yes, greasing or oiling the sump gasket should allow removal of the sump plate next time without it sticking or harming the gasket, and...

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...

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.

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...

The original left hand switch had a ground wire running into the headlight bucket and connecting to the ground wires in there that ran...

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...

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...

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...

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...

Yes, that looks like a standard original piston. The size new would have been 74.952mm.

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...

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...

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...

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...

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...

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.

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...

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...

So DE, how would you say it compares to our 650?