Help with a vacuum leak

[eekster]

I just recently acquired a 94 with 28K on the clock. I knew there would be some issues to deal with for a bike with low miles at this age.
When I drove it home, I noticed the fuel gauge had dropped noticeably on a 45 mile drive, I didn't drive it after that due to the front tire being extremely wore out/bad.

Things I noticed. Idle was off/amiss...couldn't quite place any real solution just yet. Also, when checking bike out originally, bike was outside in a pole frame tent with tarp. Exhaust pipes where pointing out "door" one side of tent was partly rolled up. On cold start to fully warm it took many minutes..let's say 5-7 minutes...the exhaust gas fumes where pretty bad...and this is outside and there is a breeze!

So, after getting home and letting it idle in garage, I noticed there was some engine oil/grimey/goo I could wash off with brake cleaner at the back of right bank of cylinders, just behind last spark plug. So I shot brake cleaner on it in that general area and the rpms went up, idle smoothed out! This was at best...a 2 second blast of cleaner.

Now, my question is, what vacuum hoses are in the lowest part of engine bay? I have removed the carbs, the black rubber mat, the infamous 90 degree bend hose is not compromised ( but is to be replaced). I can't seem to find anything that might give me a clue as to what lies between and under the intake manifolds as far as vacuum hoses go.

Any ideas on what I am looking for?

[newday777]

Sorry I haven't been into the vacuum hoses, but a 2 second blast is too long to pinpoint a leak.
Very short, intentional shots are the only way to find specific vacuum leaks.

[newday777]

The 1st thing that came to mind as I read your post is your petcock is the cause of how rich it was running and lots of gas used.
Be sure to rebuild your vacuum petcock as the rubber in them crack. I've read of guys going through 3/4 of a tank in 75 miles, basically dumping unspent fuel on the road as you ride. It also will give a hunting idle when it leaks.

[newday777]

https://cyclemax.com/products/gl1500-fu ... ebuild-kit

[eekster]

Thanks for replies. I did see a petcock rebuild kit in box that manual and a few. other assorted items that came with bike, easy enough to do.

Yea, a 2 second blast ( at best- maybe it was a second) however I wasn't even thinking a vacuum leak would be discovered, just cleaning some goo off engine and that was a secondary discovery!

I'll spend more time today looking around the lower engine bay area and see what I can discover. Bike definitely perked up when that brake cleaner entered the engine bay area.

[eekster]

Did the easy petcock rebuild. Looked way down in the engine bay...I can see 6 rubber hoses coming off intake and 4 (?) chrome looking pipes ( I'll just say at the 4 corners of engine bay). These chrome pipes have o-rings under them ( from what I can see on parts diagrams I look at ) and then there are those 6 hoses...anyone have any experience doing those?

[newday777]

Again, no I don't. But seeing you are in the high heat desert, change the rubber hoses while you are in there.

[eekster]

Ordered some parts, now I wait...

[Snowmoer]

The chrome tubes are coolant tubes. There are also rubber hoses that are a little bigger than the vacuum hoses that are also coolant. I replaced just about all the vacuum hoses on my 88. They are metric and you will not find them at the local auto parts store. I got the sizes off the parts fiche when I replaced mine. I bought bulk metric hose off Amazon. I just cut new hose to fit the length of the old one. From what I remember, there were only one vacuum hose on the middle of the intake manifold on each side. All the rest went to different control parts of the bike away from the motor. There are also a bunch of them on the carbs. If you don't have a shop manual, get one so you have the vacuum hose diagram.

[newday777]

The chrome tubes are coolant tubes.

PAR tubes not coolant tubes.