Bob, just checked my SG, which I believe was the final definitive version... and the single opening is 5.75mm dia. which is roughly 26mm in area.
So.... two holes at about 3.5 to 4 mm in diameter would give you the same.... about 26mm open area.
 
Yamaha originally used rubber plugs with small holes in them to sleeve the ports down. Maybe Gary could help you out with a couple? Or maybe you could find some rubber hose that would work, like maybe 3/16" fuel line? That way the "mod" wouldn't be permanent.
 
Thanks guys, I appreciate your thoughts on this. I’ll experiment a little more with it. I will definitely sleeve these down somehow. I was thinking about how the final version had just one, relatively small opening in it.
When I got this bike, you couldn’t believe how thick the gunk was on the bottom of the frame and swingarm. I had to scrape it off with a putty knife.
 
Yes, too much oil and oil vapor coming out of the breather was a problem many owners complained about on the early bikes. That's why Yamaha initiated several steps over the years to try and alleviate it. One of the first and maybe one of the biggest and most important changes was to lower the oil level in the crankcase by about 10mm. You might try this on yours .....

aW9xKs5.jpg
 
Yes, too much oil and oil vapor coming out of the breather was a problem many owners complained about on the early bikes. That's why Yamaha initiated several steps over the years to try and alleviate it. One of the first and maybe one of the biggest and most important changes was to lower the oil level in the crankcase by about 10mm. You might try this on yours .....

aW9xKs5.jpg

Yeah, I remembered something about that. I will definitely take a look at my dipstick ( NO WISE CRACKS) and take some measurements.
 
Look at your top crankcase too. The oil capacity was stamped into it. I'll bet yours says 3000cc, not 2500cc like your '77 (and all the later models).
 
Hey I’m looking for input here. I want to restrict the size of the openings in my breather to reduce the amount of oil fumes that collect under the bike. I’d like the bike to appear stock. I’m thinking about JB Welding some Machine nuts in there. It would take each opening from 10mm down to 3mm. Too much? Nothing has been done yet, just noodling.
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G'day Bobbbbb,

What I did was found a rubber grommet that fit in the hole, or punch one out to fit.

My grommet was a wiring one so had hole in the middle, I just filled the hole with Permatex gasket goop.

Works a treat.

GW

P.S. How is anybody going to look at your machine in the Arizona sunshine without wearing a welding Shield???
 
Look at your top crankcase too. The oil capacity was stamped into it. I'll bet yours says 3000cc, not 2500cc like your '77 (and all the later models).
Don't bet. I have 2 72s and 1 73 engine and all of them have 2500cc cast in them. I believe i read on here somewhere that the change from 3000cc to 2500cc was made when the starter was added.
 
Hey I’m looking for input here. I want to restrict the size of the openings in my breather to reduce the amount of oil fumes that collect under the bike. I’d like the bike to appear stock. I’m thinking about JB Welding some Machine nuts in there. It would take each opening from 10mm down to 3mm. Too much? Nothing has been done yet, just noodling.
View attachment 133607
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Hi Mailman,
the 2-hole breather in my parts stash had rubber bungs with ~1/8" diameter holes in 'em.
My '84's one-hole breather had a teensy restrictive ~1/8" hole through it's spigot.
I went t'other way on that one.
Drilled it out to leave a 1/8" wall thickness and ran a hose down to pant on the chain.
Eff the EPA, a bike's gotta breathe, eh?
 
When I got this bike, you couldn’t believe how thick the gunk was on the bottom of the frame and swingarm. I had to scrape it off with a putty knife.
Not sure what you are worried about.
I doubt if you ever let any gunk build up anywhere on that bike that will take more than a rag to wipe off. :geek:
 
Hey Superjet!
Yeah thanks for posting that. I had even thought about shopping for a cover like yours, but I think I’m just going to modify mine.
By the way guys, I took a few days off my project, but I got back to it today. Just not really enough progress to post yet. But I’m in a mood to get stuff done, so .......
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Mailman it is funny that you mentionned you took a few days off. Last spring after I got everything back together running I was surprised with problem after problem.....was a real let down once things started happening and would not let up. Seems it was so much of work and way little enjoyment. On some days, I just wanted to forget I ever purchased my XS but knew it was still special. I guess th6e needed days off are required sometimes owning a classic bike. They are far from maintenance free, but after having more than enough time off due to winter weather I sure do miss riding it! After seeing and reading up on build threads similar to yours, I see how patient one must be and to take the time to go thru it all....and I mean all parts. My 83 has taught me a few lessons. J-C
 
A DISORGANIZED UPDATE,

Well it seems like I’m working on a lot of fronts simultaneously and progress is kinda slow....:shrug:

I’ll just run through what I’ve been up to and not all of it is completed, some things just pointed to the need for more parts.
The first thing I started, and I’ve been messing around with this for a stupid amount of time, is my front brake assembly. It 99% new parts, which would make you believe it would just go together in a jiffy. If I had it to do all over again, I would just put a stainless braided one piece brake line on it and call it done. But I was really trying to keep it original looking and the whole front brake line is pretty distinctive , but I gotta say.....I DONT LIKE IT.
It’s too many pieces, too many connections for potential leaks, too fiddly to assemble, and it has these special rubber bushings that go around the fittings and are then held by brackets, and the rubber I have is rotted and they are obsolete and this whole setup is getting on my nerves! Here you can see all the connections and the arrows point to the rubber bushings.
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The last part (#16) that screws into the caliper is a specially bent steel line, that is obsolete and Gawd awfully expensive if you can find one on eBay and the threads were buggered on one end and it kept wanting to cross thread. I worked on it forever to carefully make it fit.
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I tried and tried to improvise something to substitute for those bushings, but no joy. I’m throwing in the towel and ordering replacements, either NOS I found on eBay or some universal substitutes I found at HVCycles.
So for now, the whole front brake assembly is just loosely assembled until I get new bushings. I will be using a pressure activated front brake light switch. It will be covered by a rubber boot when I’m done and I’ve already replaced the black wiring loom with silver to match the rest of my bike. I’ll tie that wire into the handlebar control wiring and I don’t think it’ll be that noticeable when I’m done.
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Pay no attention to that wiring hanging down by the brake line. That will be up on the handlebar later.
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I also worked on torquing down my head bolts and motor mounts. I never fully torqued down my head bolts after my rebuild, so today I backed them all off and began from the beginning, working my way up following the torque recommendations set forth in Jim’s rebuild guide.
E8E7727A-3656-4E5A-AC9E-7E7424F9883A.jpeg


After that I installed new spark plugs and worked on the head stays. I did not paint these, they are a central ground connection and I wanted these clean, in fact I sanded the mounting points on the frame to bare metal and anywhere the brackets touched together I shined them up too.
50EFC7C7-0219-4462-B04C-FDDE860D8D4B.jpeg
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I then worked on removing the original grip off of my throttle tube and cleaned that up, then just kinda loosely assembled my new switchgear and throttle and master cylinder onto the handlebar. ( I know I’m telling this out of order, as I said I was jumping around from job to job). I was surprised to find that throttle tube is VERY thin walled aluminum. I’m sure glad I was gentle in removing that old grip which was glued on with something really hard to remove. I have some Grand Tourismo knock offs I’ll install later.
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I also went ahead and JB Welded a couple of machine nuts in my breather and re installed that.
D801B753-22EA-44EA-9FF8-BFA2AAD14835.jpeg


Then I worked on my rear brake linkage, and this only created more questions in my mind.
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I greased up all the pivot points and got it installed, but here is what is baffling me. It’s the pedal return spring.
Here you can see the spring and the post it is supposed to hook to when the brake pedal is all the way up.
25B87C1C-64D9-4447-823A-44F273FD02BB.jpeg


It is completely off of the post. Here it is when the brake pedal is fully applied downward, still no contact.
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At first I thought I must’ve installed it wrong, so I went to my reference photos and sure shit, that’s exactly the way it was before, the spring doesn’t contact the post and there is no return tension to pull the brake pedal up in the deactivated position.
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The way it is now, the rear drum would continually drag. I think I’m going to look for a shorter spring.
Here’s everything installed, for now.....it’ll all have to come back off to put a new spring on it.
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So it’s this kind of stuff that makes the going slow now, I’m getting into the details and realizing what’s working and what will have to be replaced, then order, then wait, then take things back apart and on and on......
This is what was bogging me down and made me walk away for a while. But I’ll get there, I’m nothing if not persistent. :cautious:
Later,
Bob
 
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