gas, gas, and more gas

[dipstick]

Guys, thanks for the info. Still waiting for my manual to come in although Im rethinking the 100.00 factory manual for the forty dollar Clymers. Just wondering if the clymers is a clone of the factory manual or is the origional worth the money in spec and re build detail. The bike did not come with an owners manual but I found some factory spec in an old cycle encyclopedia, they rated this bike at 95bhp stock. Sounds good, but is it close? Also, wonderin if anyone attempted bown draft carbs. Dont know much about them, but my stock ones are quite weathered, so Im thinkin new carbs an KN filters. Can this be the way to better bhp and eleviate the freakin gas everywhere problem? Still, Im workin on the the rack as we speak, got parts soakin in zylene, cleans like new and sparkly too. Ive picked up some good info from the maintenance and repair dept, two thumbs way way up. Have agreat long weekend. Dipstick

[TopCatGr58]

Hey there Dipstick,

I feel like I'm "insulting" you with that nickname!! That BHP rating is accurate. BTW, if you would like a 'close' owner's manual, go to the links section, second page, and D/L the PDF for the 81H/SH, it's about the same. As for the carbs, unless the rubber diaphragms or butterfly seals are damaged, then you don't really need to get new ones, just a good and thorough cleaning. I'm working on a rack of 79SF carbs, and they are coming along nicely. And you probably don't need to spend the $$$ for actual K&N's, you can get generic Indy filters from several places. As for boosting horsepower with Indy's, there are mixed opinions about that. It'll breath better, and you'll be able to hear the engine/intake sounds better, so it'll SOUND more powerful! Watch your plugs, may need rejetting if too lean!! Can't say anything about down draft carbs!?
T.C.

[Czekus21]

The horse power was rated useing calculations of the bore and stroke, as well as the size of the carbs and their jetting. and the valves. Basically, it was figured out on paper. Back when these bikes were being tested. There was no way to hook up a dyno to the driveshaft or crank. The best way to check horse power is to put it on a dyno and check for yourself. You'll then know the actuall power at the back wheal. That's the important part. What's being delivered to the ground. The Clymers manuel vs shop manuel. The shop manuel was ment for people who have a knowledge of motorcycles. The Clymers was developed after the fact. They took a bike and totaly disassembled it and put it back together in laymans terms so the everyday shadetree guy could work on there stuff. There are a few discrepencies in both manuels. This is where common sence is supposed to kick in.

[MAXIMAN]

A friend of mine that is an genious mechanic indicated that these BHP figures are actual measurements...but not from the rear wheel. They were taken from the clutch at the factory.

I think I've seen RWHP figures on a stock XS11 and it's on the order of 72 or 75 rwhp. Don't ask where I saw these figures because I can't recall.

[MartyA]

That 75 RWHP was estimated from some preliminary cycle magazine road test articles, because as Czekus21 mentions, they didn't have the ability to hook up a shaftie to the regular dyno equipment. 95 hp was the Yamaha claim in 1978, with 66 lb-ft torque.

Somebody posted their dyno chart last year, I think it hit 75 HP? Torque curve was flatter than I expected.

[Deni]

Dipstick,
I got an XS100F last fall without any manuals. Since then, I've bought a used owner's manual on ebay as well as a New Clymer manual. The owner's manual has some things about operation that the Clymer doesn't have. The Clymer manual is pretty good, and it always amazes me when people say they are working on their bikes without a service manual, since they are so plentiful and so cheap (relative to a mistake). I just bought a nice Yamaha service manual off ebay, too. Some things I like better than the Clymer, like it has some pictures of parts or assemblies that the Clymer doesn't have. The Clymer has some pictures that the factory manual doesn't have. I like pictures, so I'm very glad I have both and wouldn't touch my bike without one of them. Torques are easier to find in the factory manual because they are boxed in. You also have bigger pages in the factory manual, so you don't have to turn as many pages (which is nice). If I had to pick one, it would probably be the Clymer, but it would be close.

Mine had gas all inside the airbox when I got it. I second T.C.'s thoughts on the carbs. I bought a set of 79SF carbs off ebay because they were in excellent cosmetic shape (better than the ones on the bike). I've rebuilt them with new gaskets and float pins/seats (<$50) and they work great. I don't expect any problems for years. Also cleaned vacuum petcocks, too, (no new parts) and don't have leaks and don't expect problems for awhile. Maybe I'll have to buy petcock rebuild kits in the next 5 years (?), but what an easy and cheap fix! I wouldn't alter this setup at all to anything aftermarket. These problems arise because they sit for decades. Even if I have to redo this every 5-10 years, it's cheap and easy with a little patience and care.