New (old) 79 1100 SF, vacuum problem?

[ron2830]

Owned a 78 1100E many years ago, decided to get back into bikes, bought a 79 1100 special, 22K miles, Vetter fairing, great bike. Has a 4 into 2 aftermarket exhaust with turnouts and a K & N air filter in airbox. Everything works well, but appears to be running rich. #1, 2 and 4 cylinder plugs are black, #3 looks correct, kind of tan. very strong but stumbles from about 4900 to 5200 rpm then just screams. Read thread below about "cutting out" and think the vacuum hoses might have been misrouted after previous owner cleaned carbs. Vacuum ports on intake manifolds (boots) on #1 ,3 and 4 are plugged. #2 cylinder has hose running from port on boot to carb body, short u shaped hose, this does not seem right?

Vacuum advance hose connected from advance mech. under left engine cover plate to what appears to be a vacuum manifold above carbs, same manifold appears to have vacuum to petcocks ( need to remove tank to get a better look. )

Any comments appreciated, just does not seem right that vacuum hose goes from #2 intake to #2 body.

Liking this bike more every day, who says you can't relive your youth!

I have a Clymer manual but can't find good pics or drawings to show correct vacuum line routing.

[mro]

Any comments appreciated, just does not seem right that vacuum hose goes from #2 inta

Not familiar w/78, but vac advance hose goes to #2 carb body.

On the 80G 1 & 4 intake are "capped"
2 & 3 go to petcock

Think there is a post w/hose diagram, you need to do a search.
Special different than standard and has the "octopus".
Also something about a few ports being vents and need to be left open?!.

Plenty of Guys w/specials here to get you straight.


mro

[DiverRay]

ron2830,
The short hose on the carb boot should be connected to the "vacum manifold". The hose from the engine connects to the carb body.
That should help some of the problems. I would plan on pulling carbs, verify the float levels are to spec and all the jets match, then resync the carbs one you have them back on. I've learned to trust myself, and not some other "mechanic" over the years.
If you read the "Tech Tips" on the left side of the page, they will help a LOT.
Ray

[ron2830]

Thanks Ray, switched the hoses around but it still stumbles through the midrange when I mash the throttle, then I have to hang on up to 8000 rpm, boy the memories are back about my 1100e this is a fast bike. Probably better start taking it easy though for both my safety and wallet. I almost bought a V twin Yamaha 1100 Silverado for over four times the money but this is a lot more fun.

I am going to check the timing and sync the carbs to see if that helps. As posted in another thread, if I apply the throttle smoothly it does not stumble much.

Any other comments or help appreciated. Glad to find an active XS 11 forum, I am hooked.

Ron

[ron2830]

Forgot to say thanks also to mro, love this forum.