help with jetter

Is it safe to go through an inch and a quarter pipe with the big jetter? our company has them electric mini jetters but they suck to work with. trying to clear a vent stack through the roof,cabled it a few times pulled back black muddy stuff. My main concern is getting the big jetter hose stuck down the vent pipe..kind of new to drain jetting been plumbing 6 yrs have used the big jetter only on 3 inch main lines to this point...thnx for help D:smile::devil3:

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