Question about engine venting

[kwats]

On my project bike, a '79 SF, there are two vent hoses on the back of the engine. The large one is obviously a crankcase vent, but my question is concerning the smaller one with a metal clip attached. Does this one just vent to atmosphere, or back to the airbox? The PO had partially disassembled the bike and I'm working on the puzzle.

[petejw]

hi kwats,

there should be 2 rubber hoses coming from the top
of the carbs, these go to the airbox, on either side of
the crankcase vent which goes in the middle of the air box.

[rpgoerlich]

Smaller one should be the middle drive vent. The clip mounts on top of the airbox bracket that mounts just forward of the fuel tank rear mount. The clip doubles as the vent line holder and holds down the wiring harness.

[strom]

The other vent hose from the crankcase (smaller one) comes from the middle drive. I had it routed a bit upwards, then down... along with the battery and gas tank vent hoses.

[petejw]

sorry, i didnt read the question properly,
lucky the others had.

[natemoen]

sorry, i didnt read the question properly,
lucky the others had.

It happens Pete, don't worry about it.

[kwats]

Thanks guys...

While I have worked on bikes since the 60's, these XS11's are quite unique.

[DGXSER]

Ain' they though!! And mostly in a good way! Pretty darn simple in general and so far I find them enjoyable and relaxing to work on.

Used to love to work on cars and trucks, but the new ones have everythign so packed into small little holes and nothing is easy to get on or off without buying that special factory only $1,000 tool. When it takes a book, two techs, and experience to figure out how to get access to the spark plugs in a Ford Truck...when I sat on the wheel well of my 70 F250 and pulled the head, something seems REALLY wrong here!! Thats why I like working on this bike, if I can't reach something, just walk around the bike and its right there!!

[natemoen]

when I sat on the wheel well of my 70 F250 and pulled the head, something seems REALLY wrong here!!

Aint it great when you can sit inside the engine compartment and work on the engine! I love that type of vehicle!!

[kwats]

After fiddling with this '79SF for a while, I have come to the conclusion that the design engineers of the time were dreaming up $hit to add to these bikes. Three things that will be removed from this bike will be the vacuum petcock system, the tip over switch, and the reserve lighting device. In my opinion, these just over complicate everything.

This bike was stored in a fellows outbuilding for many years with probably a couple of gallons of fuel in the tank. It took a while to clean out the fuel system, but all is well now. Since the bike only has 5600 miles on it, I felt it was worth the effort.

Somebody had apparently tried to get it running sometime during the years, they broke a float post off, rounded all the idle jets, and cracked one of the vacuum chambers. I found a good set of carbs that didn't even need rebuilding, so the kits I bought will be hanging on the wall. Just waiting on a fuel sending unit and new petcocks now. I expect to start the bike next weekend.

I appreciate all the information I have gathered from this site.

[natemoen]

After fiddling with this '79SF for a while, I have come to the conclusion that the design engineers of the time were dreaming up $hit to add to these bikes. Three things that will be removed from this bike will be the vacuum petcock system, the tip over switch, and the reserve lighting device. In my opinion, these just over complicate everything.

This bike was stored in a fellows outbuilding for many years with probably a couple of gallons of fuel in the tank. It took a while to clean out the fuel system, but all is well now. Since the bike only has 5600 miles on it, I felt it was worth the effort.

Somebody had apparently tried to get it running sometime during the years, they broke a float post off, rounded all the idle jets, and cracked one of the vacuum chambers. I found a good set of carbs that didn't even need rebuilding, so the kits I bought will be hanging on the wall. Just waiting on a fuel sending unit and new petcocks now. I expect to start the bike next weekend.

I appreciate all the information I have gathered from this site.

I agree with the vac petcocks and the RLU but I dont agree with the tipover, its nice if you go down when your on the road. But to each their own.

Do you still have the old carbs? I could take them off your hands if your just ditchen them!

Also you dont need to buy new petcocks to git rid of the vac operation from them.

[CatatonicBug]

That RLU has saved my butt a couple times aready. The tipover switch too. Definitely not "extras" IMO.

[kwats]

I still have the old carbs in my parts pile for spares if needed. The fuel strainers were trash, so I hunted down new petcocks with strainers. I was ready to weld in bungs for aftermarket petcocks, but I found original ones in pristine condition.

The bike was only ridden for 2 years, still had a 1981 plate on it, and I told my son that the PO was probably scared of it. Turned out I was right, the bike was too much for the fellow. Having been an MSF instructor for many years taught me that there are certain people that shouldn't try to ride large motorcycles.

Back in 1980, a friend and I rode in the Iron Butt (Canada to Mexico). I was riding an Electra Glide and he was riding an XS11 Standard. We traded bikes for a while, and I was certainly impressed with the big Yamaha. Told myself I would buy one someday, and I did. I am restoring it with a twist, adding a full tour package and updating the rear fender and lighting system to something that doesn't just look like some added do dads on a stock bike.

Trying to decide on a color...got all winter to play with it. I'll ride it for a while next year and then turn it over to my son.

[petejw]

thanks nate.

i agree with the rlu and vac petcocks,
but that tip over switch is really handy,
i removed it for a little while but when i accidently knocked
the bike over while working on it,
petrol started pissing out of the back of the carbs
and the engine kept running,
i put that switch back on straight away.

kwats,
glad ur getting it all sorted.

[Cobia]

Hey Don,
Ain't that the truth, it took me half a day to change the plugs on my Explorer. I even had to take off the right side tire and use double universal socket extensions to get at those buggers. No need to ask me what i was saying about those design engineers...