What is that hissing sound!?

[Valk_ca]

Got the Valk all back together. Did the brakes, fluids, timing belts, tires, new exhaust pipes, Pingel, final drive and shaft maintenance. Brought it down off the lift, put the key in it, gave it a bit of choke, crossed the fingers and hit the starter. Purred to life. Man, she runs sweet! But....
I'm getting a hissing sound on the left side somewhere around the front carb that is quite audible on start up but slowly lessens in level but not completely goes away. As you pull away it comes back and keeps hissing all the way thru the gears and is still slightly audible even at 70 mph. Thought it might be a vacuum leak but from what I've read on the other threads it should be running like crap if its got that significant a leak. And it sure doesn't run like crap! I know it can't be normal for this engine as I have a '97 'Wing with the same motor and it doesn't make this sound.

Any thoughts or suggestions? I'm planning to try the starter fluid/WD40 spray trick to see if does anything to the idle speed. Right now it idles right at 1000 and shows no sign of faltering under load.

[R J]

Did ya have the air box off or the carb bank?

If so look for a rubber boot not on properly or a bad 'O' ring on the carb bank to the head.

[F6BANGER]

I think youre right with the vacuum leak. Right again with the starting fluid spray around the carbs. If the Rpm's go up, you just gotta find that little crack in the hose or where ever it is. 

[Valk_ca]

But if its a vacuum leak shouldn't it run rough? And is there harm in riding it with a leak?

[Ricky-D]

But if its a vacuum leak shouldn't it run rough? And is there harm in riding it with a leak?

No, with 5 good cylinders you may not realize any difference with a vacuum leak on the sixth cylinder.

Possible problems, worst could be a hole burnt into the piston top, least maybe could be bluing of the exhaust header pipe.

Easy to find so there's no need to hold off finding the leak.

***

[Challenger]

All good suggestions to be checked, also I see you have new pipes, double check the torq on the header nuts, especially If you used the old crush washers, if you used new ones, you might have to retighten a couple of times.

[Thunderbolt]

If you have a large diameter hose or piece of pvc pipe, you can use it kinda like a stethescope to search for the noise.

[Valk_ca]

Found it. The vac line coming off of cylinder #4 reacts to a spritz of WD40. How the heck am I suppose to get in there to replace it? What's it going to? I see it ties into a T but can't see where the T comes from or where it goes to. How much do I have to disassemble to get at it? The vacuum line that I took off of cylinder #6 when I changed to a Pingel has a #10 stamped on it while the one coming out of #4 has a 4 stamped on it. Are they different sizes? Can I just replace with the one I took off of #6 cylinder?



Found another cracked line coming off the bottom of the carb for cylinder #4. Seems to be a drain line of some sort. Take a look:



Am I off to NAPA to find replacement hoses?

[YoungPUP]

The second pic is a bowl drain hose for the carb.  The first pic shows that its time to do a de-smog. Look  in shop talk for the instructions, and then head to NAPA with the grocery list.  cost me about $5 a year ago.

[sugerbear]

and while your out pick up a coupla these.
http://www.harborfreight.com/2-piece-11-inch-straight-90-angle-long-reach-pliers-33203.html

your fingers will thank you

[chrise2469]

Head to napa and buy some hose.  You don't want to replace only one hose.  If that one split it's time for them all to be swapped.

Here's a link to shoptalk article
http://www.valkyrieriders.com/shoptalk/AirBox%20VentHose/venthose.htm

Personally, I would just pull off the tank and do the string method above.  I'm also in Winnipeg, not the worlds greatest wrench but I've done a few mods to the bike (you can always search by user name and posts) so if you need help or some advice let me know.  You seem to be pretty much checked out so far.

Ride safe.
Chris

[X Ring]

The first pic shows that its time to do a de-smog. Look  in shop talk for the instructions, and then head to NAPA with the grocery list.  cost me about $5 a year ago.

Here's your answer.  Why replace the vacuum lines and wonder when it's going to happen again.  Desmog now!

Marty

[Bobbo]

Head to napa and buy some hose.  You don't want to replace only one hose.  If that one split it's time for them all to be swapped.

Here's a link to shoptalk article
http://www.valkyrieriders.com/shoptalk/AirBox%20VentHose/venthose.htm.

Personally, I would just pull off the tank and do the string method above.  I'm also in Winnipeg, not the worlds greatest wrench but I've done a few mods to the bike (you can always search by user name and posts) so if you need help or some advice let me know.  You seem to be pretty much checked out so far.

Ride safe.
Chris

Whoops!  You added a period to the URL.

http://www.valkyrieriders.com/shoptalk/AirBox%20VentHose/venthose.htm

[JC]

The first pic shows that its time to do a de-smog. Look  in shop talk for the instructions, and then head to NAPA with the grocery list.  cost me about $5 a year ago.

Here's your answer.  Why replace the vacuum lines and wonder when it's going to happen again.  Desmog now!

+1 for the desmog  You've got to get under the airbox to do the job right, so go ahead and remove the rest of it while you're in there. Much less to worry about later.

[Valk_ca]

Yeah, after looking at the links I think I'm going to go ahead and do the de-smog. Fewer parts to play with and a cleaner look. Thanks for all the advice. And, Chris, if I ever get this thing on the road we'll have to get together and compare stories. I sure like your blue. Would've been my first choice but beggars can't be choosers. Maybe my next Valk.