Air hissing out front of motor, help!

[schaeffer32]

Ok , my name is Matt n I'm fairly new to the xs world but madly in love! I'm building a chopper out of a mess of a 72 xs that I saved from the scrapyard! The bike ran when bought but this winter I did all the frame. Custom work to get it where I wanted it!? That being said yesterday I took off the exhaust to weld some slash cut tips on I made n when I installed them I ran the bike till warm sounded normal until I shut it down! It was hissing out I the front of motor like something boult pressure n it was bleeding off!, it lasted a minute or so then stopped!? I used some good old smoke from my cig at the time to try to see where it was comin from but no such luck! Anyone experience this kinda thing it's the first time it's done it n I've been running it a decent amount lately! Any advice woul be greatly appreciated thanks

 

[schaeffer32]

Here r some pics

 

[Downeaster]

On the rear of the cylinder head, above and between the carbs, there should be a box-shaped fixture with one or two hoses coming out of it.

This is the crankcase breather. Check to see that it's there and that the hose(s) are free of obstructions. You may want to take it off the head and check inside and clean as necessary.

 

[rusty rocket]

Im thinking the problem was the cig!!!!!!!

 

[schaeffer32]

I actually thought of that n the hoses where already off the breather but I am pretty sure it was from up front! But I'm goin to run it now n see what it does! Is there anything inside I have to worry about falling out on etc. when I pull the cover off!???

 

[Downeaster]

There is a baffle in there, but it's pretty obvious how it goes in if it happens to fall out.

The leak in the front is (most likely) because pressure is building up in the crankcase. The most likely reason for that is a blocked breather.

If it was a pulsing leak in time with the pistons going up and down I'd more suspect a head gasket issue, but if it's leaking after the bike is shut down, pressure in the crankcase is the only thing that make sense to me.

Of course, I'm wrong a lot too...

 

[schaeffer32]

Ok I will check that I'm running it rite now to see wha happens!!? Ty

 

[schaeffer32]

Well jut rode it around till good n hot n it didn't do it so maybe it was just that one time but I will take ur advice n clean that breather good ty!! Any suggestions on takin out advance weight to grease them they r sticking n I'm afraid to mess with! I ordered a manual but want to get it fixed any help would appreciated!!

 

[lakeview]

If you were welding on the double wall exhaust you may have closed off the end where the slash tips went and the air was just leaking out of the exhaust pipe breather hole up front when you shut down.

 

[schaeffer32]

Ok makes sense now!? Is that anything to worry about should I change anything!? It hasn't done it after that time!