You got it. That's a sweet bike ... I worked on quite a few of them when I was working at a Yamaha/Honda motorcycle shop back in the late 70s, early 80s.
Yamaha Seca 750, 1982 model
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This was a sweet bike. In 85 was riding a 79-CB750F Honda super sport, and got to ride one of these that was for sale used at the dealer when I went in for parts.
It was sitting at the edge of at the parking lot and the key was in it I walked up to and was checking it out- " Take it for a spin" the GM told me.
I dropped my tank bag in the office and took him up on it.
I liked it better than my bike instantly - it was smoother, didnt have to mess with a chain, and perhaps that time most importantly after WOT 1-3rd on a nearby onramp It was faster than my bike, I could feel it. It was also more comfy as a freeway cruiser - something I thought I was immune to at that age, but yet I noticed instantly.
The only downside (I needed to find something) was the shafts bit of lift and drop under hard acceleration and engine braking might, It COULD bite you if you are already hot in a corner - a situation I endeavored never to get in to begin with. At least I told myself this was a compromise - needing something to ride away with that didn't make me feel totally inferior.
I rode away wishing I had the money for this baby.
Enjoy it. It's a great machine.
( I was wearing a helmet, jacket and gloves, they were just on the ground in the highly embarrassing shot sometime in the summer of 85)
I've accidently done the non-JASO MA energy conserving oil experiment in my '01 Kingquad 300 in ~2005, and it made the clutch slip when cold, in like 20 hrs of that OCI. Its a utility ATV so we just used a lower gear that didn't slip until it warmed up.
Switched to unofficial JASO MA rotella and it took a couple changes before the clutch gripped in the cold again, but it did and its been 1000+hrs on it, and a couple decades before the clutch is now slipping again, but anytime under heavy load in higher gears. But I'm quite sure its wearing thin, or the clutch springs have overheated a bit from the kids beating on it and slipping the clutch in the higher gears...
Yeah, I'm not advocating for using energy conserving oils. I bet you would not have any problems with a 15w40 HDEO or a 10w40 gas engine oil.
What was the viscosity of that oil?
I've had a couple XS1100s, first bike to get in the 11's in the quarter mile. The engine ran backwards relative to every other bike. With that, it helped the bike to squat down under acceleration as opposed to lift up with the shaft drive. Seca does not rotate backwards, you can tell by the position of the cam chain tensioner. If it's on the back it's the traditional rotation, if it's on the front it rotates counterclockwise.
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That's interesting. Which side of the bike is the drive shaft on the XS11?
BTW, you didn't comment on my post #55.
Shaft is on left side, XS1100 and Seca 750. All of the late 70s early 80s Yamaha we're left side. A modification many of us did to the XS 1100 was graft the final drive housing from a 750/850 Yamaha Special onto the XS 1100. Lowered engine speed at 60 MPH in 5th gear by 400 rpm. That's a main reason the XS11 was so "fast", it was geared short. 4,000 rpm stock at 60 mph vs 3,600 with the final drive mod. Gained 2-3 mpg out on the open road. Also made first gear useful, pretty much need to shift out of first before you got across an intersection with the stock gearing. It was a strong engine, made no real world riding difference despite the taller overall gearing with the final drive swap.
Sorry I missed your post, the front brakes have poor feel. Rebuilding the master cylinder and getting it back in there was ridiculously time-consuming. Definitely top 10 worst motorcycle designs ever with respect to the front brake. It wasn't hard to bleed however with a cable between the lever and the master cylinder under the headlight, my first bike with a handbrake as a kid had better feel.
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So on the XS11, is there a secondary shaft or gear to change the rotation direction?
The 83 650 Nighthawk also spun backwards if I remember. Has to be another gear to change direction.
That cable brake is the only one in existence that I know of ever made.
Agree, only brake cable going to a master cylinder I'm aware of.
XS1100 had a hy vo chain that transferred power to the clutch via a cush drive damper, then transmission had bevel gears and a pinion gear transmitted it out the back via an automotive U-joint through the drive shaft to the rear wheels. Automotive U joint was chosen for the strength because it was the most powerful engine at the time. Apologies if I didn't get that exactly right or in the right order but I never spent a lot of time with the middle drive. Only did the main modification of the rear final drive housing when I swapped on an XS750 unit to lower the RPM like I said earlier.
XS1100 had a hy vo chain that transferred power to the clutch via a cush drive damper, then transmission had bevel gears and a pinion gear transmitted it out the back via an automotive U-joint through the drive shaft to the rear wheels. Automotive U joint was chosen for the strength because it was the most powerful engine at the time. Apologies if I didn't get that exactly right or in the right order but I never spent a lot of time with the middle drive. Only did the main modification of the rear final drive housing when I swapped on an XS750 unit to lower the RPM like I said earlier.
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It's my understanding by spinning the engine backwards, and the Nighthawk 650 was the same thing, it eliminated an extra shaft during the process.
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Bought a used Nighthawk 550 15 years ago, paid very little. Bike was mechanically sound, cosmetically it was rough. That bike was a runner. Spent some time cleaning it up and resold it. If I found another one I'd pick it up.
In reading back when I had the bike, literature indicated the 550 used most of the same engine components from the 650, such as the head, clutch, transmission, main engine casings. The head included the same cams as the 650. Which made it darn near as quick as the 650. Main difference in performance was the displacement from what I understood.
In reading back when I had the bike, literature indicated the 550 used most of the same engine components from the 650, such as the head, clutch, transmission, main engine casings. The head included the same cams as the 650. Which made it darn near as quick as the 650. Main difference in performance was the displacement from what I understood.
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Good Postings and Explanation, ZeeOSix! 
Looks great and brings back memories! Mine had the quarter fairing and I put about 77,000 trouble free miles on that bike. One of my all-time favorites!
