Vacuum Lines?

[pshaw]

I recently bought a 81 MNS that I took apart and am now putting it back together. I decided to not put the original air cleaner on because I don't think I have all f the parts (the bike came with a box of parts) so I'm using the air cleaner pods. My problem is that now I have hoses with no destination and ports that had hoses but I don't know how to hook them up. The carbs have been cleaned and it is getting spark, and will turn over and run as long as I keep spraying with starter fluid. My guess is that the fuel is not getting to the carbs because the vacuum lines aren't hooked up correctly. Does anyone have a diagram of how it should look? Thanks, Phill

[TopCatGr58]

Gettin' Hosed!

Hey Pshaw,

Here's the Octopus routing diagram, since yours is a Special:


The carbs have only 1 vacuum port that should be used, #2, goes to the vacuum advance module. The other vacuum line should go to the #3 carb intake BOOT, it goes to the vacuum side of the Octopus valve. The Petcocks are gravity flow, both outlets are fuel, for regular running, and reserve, and Prime mode which bypasses the Octopus, and sends fuel directly to the carbs without the need for engine vacuum!

There is a hose that comes up off of the tranny case, but it just vents to air under the gas tank!

Hope this helps, write back if you still have hoses or ports leftover, but aside from what I mentioned, the rest are usually capped off.

[pshaw]

Thanks for the diagram. The vacuum lines were hooked up incorrectly, but I still can't get her started. I have it on prime to bypass the vacuum. I will probably have to remove all of the lines and check for blockages. I'm running out of ideas.

[mro]

no flow?

Did you pull the fuel line off the carb and turn the pet cock to prime to see if gas flows? If it does prob is in the carbs, if not pull hose off pet cock and see if it comes out. Isolate the problem.

[pshaw]

Well I took all of the hoses apart, replacing the leaky ones and am finally getting gas to the carbs. It even started long enough to watch the gas pour out of #1 carb...what a mess, but it runs. Now I need to find out what is clogged. Thanks for your help.

[trbig]

My octopus is working fine, but with all the carb on and offs, I am thinking of just "Y"ing the lines. I guess the line that goes from the intake boot to the octo just gets capped? I am having alot of trouble with kinking from the one fuel line on the left side that goes from the petcock to the octo. I hate to "fix things that aint broke", but it seems like it would be easier.


Tod

[John]

Tod, The vacuum line that controls the octopus can just be capped at the intake boot nipple with a 3/16 vacuum cap from any auto parts store. I eliminated my octopus many years ago. I have both petcocks connected by a hose on the nipple that has the fuel flow when the petcock is in the On position, that should be the nipple that is to the rear of the petcock. The front nipple is for prime only, and you will not need that nipple for anything, cap it off with a 1/4 inch cap The carbs will prime in the on position. I just inserted T fittings in the hose where I needed to attach a hose to feed the carbs. This way I can use just one petcock to supply the carbs, and I have never had any fuel starvation issues running at high (80-85mph)freeway speeds. When my fuel light comes on I open the other petcock also to tap into the available fuel on that side of the tank, before hitting reserve. Once you get used to manually opening the petcocks, it will become like second nature.

[trbig]

Not trying to hijack this thread... sorry. I already turn both my petcocks on and off for every ride, so I figured this would be no big deal. I thought of later adding an in-line shutoff in case my petcocks leak, but may worry about that later. It may cost me a tank of fuel at some point.
That brings another question. If you turn your petcocks off and they leak... say it sits for a while and leaks out... will you still have a reserve amount of fuel, or will it leak it all out?? You should have at least one side of the tanks reserve... couldn't see both petcocks springing a leak at once, but would they leak out from the main petcock inlet for the fuel.. or the reserve inlet? Sorry... I have never had one apart to know. I can see TC's post now titled... "Taking a leak!" lol..