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Vacuum Leak at Petcock?

Started by Lrndthehardway, Wed 10, Mar 2021, 19:48:08

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Lrndthehardway

I have a 99 standard, been chasing what is either a vacuum leak, weak spark, or gummed slow jets. Its desmogged and have propaned every spot there could be a leak, the ONLY area that my engine revs up is when I put the hose at the forward, right side of the petcock, when standing on the right side. Ive checked my airbox and the crankcase breather hoses, fuel hose to petcock, hose to #6, every single hose or connection there is and cant for the life of me find where this leak is. Ive checked the screws on the petcock to. I can see someone was in there at some point tho because the nipple for vacuum is pointed down not to the side.

Any ideas where this leak might be around there that I havent seen? is it possible someone caught something in between the parts of the petcock when they reassembled it or something?

Its bike week here and Im stressing about riding it lol. Anyone at bike week wanna take it for a spin and tell me what the hells wrong lol. It sat for a month while I took care of a rear end service, bearing and brakes, and now its running like crap, so Im really assuming its gummed jets. Threw a can of seafoam in it and need to ride it I guess so I can get the Berrymans I just got in there next. Just hate riding it like it is. Anyway, about the vacuum, that would just be nice to figure out and fix anyway

gordonv

Quote from: Lrndthehardway on Wed 10, Mar 2021, 19:48:08
Ive checked the screws on the petcock to. I can see someone was in there at some point tho because the nipple for vacuum is pointed down not to the side.

Sorry, not much help. but what do you mean "the nipple for vacuum is pointed down not to the side"?

The petcock has a drain pointing down on the bottom. The vacuum line is behind, and you can't see it from the front. I like going onto ebay and search for a part and inspect it.

1999 Black with custom paint IS


Lrndthehardway

What I mean is, its supposed to point in the same direction as the fuel hose, out the side, my vacuum line points down

The emperor has no clothes

Quote from: Lrndthehardway on Thu 11, Mar 2021, 12:48:02
What I mean is, its supposed to point in the same direction as the fuel hose, out the side, my vacuum line points down
I don't remember if the bolt holes will line up, but maybe someone put it together incorrectly.


Lrndthehardway

It does, its been like this the whole time Ive owned it, going on 2 years now. Someone told me it doesnt matter what the orientation is, my concern is why my bikes surging when I propane that area, and have looked over all the hoses..  :???:

The emperor has no clothes

Quote from: Lrndthehardway on Thu 11, Mar 2021, 17:55:41
It does, its been like this the whole time Ive owned it, going on 2 years now. Someone told me it doesnt matter what the orientation is, my concern is why my bikes surging when I propane that area, and have looked over all the hoses..  :???:
Maybe the propane is getting sucked into the air cleaner ?

Lrndthehardway

Nope, thats why Im perplexed. Its desmogged and everything is tight. Even put the hose around the 6 tubes from carbs into air box. I dont get it either

The emperor has no clothes

Quote from: Lrndthehardway on Thu 11, Mar 2021, 19:54:03
Nope, thats why Im perplexed. Its desmogged and everything is tight. Even put the hose around the 6 tubes from carbs into air box. I dont get it either
What I meant was getting sucked in with the air. The air inlet is right above that.

Lrndthehardway

You mean the opening on top of the airbox? I didnt think of that. Think it could get sucked in from that far with the propane being heavier than air? Have to think of a way to test that I guess

The emperor has no clothes

Quote from: Lrndthehardway on Thu 11, Mar 2021, 20:14:16
You mean the opening on top of the airbox? I didnt think of that. Think it could get sucked in from that far with the propane being heavier than air? Have to think of a way to test that I guess
I ain't no engineer or nothing. But these engines suck a lot of air. But, I've never used propane to check for leaks before.

gordonv

Quote from: Lrndthehardway on Thu 11, Mar 2021, 12:48:02
What I mean is, its supposed to point in the same direction as the fuel hose, out the side, my vacuum line points down

Makes sense now, looking at the pic posted, most likely someone messed with the petcock, either rebuilt it or changed it to manual operation.
1999 Black with custom paint IS


Lrndthehardway

Right on, its still vacuum thats for sure, forgot to put the hose back on when I first took it apart and it wouldnt start at all. Was super pissed then lol, cussing up a storm and all kinds of crap like "WTF NOW!" lol