Carb not creating vacuum

[Suzukidave]

This may be a reach but is it possible in the rebuild the piston was put in backwards ?

[Suzukidave]

I just saw your other post that the vacuum port barb had fallen out .

[Vintageman]

With the additional info Whit just gave, my gut says either some JB Weld is where it shouldn't be, blocking the vacuum, or there is a big air leak, leaning the mixture and reducing the vacuum available at the vacuum barb.

My worst seal was on the left and I never had a problem getting vacuum enough to open petcock even when it was weak due to wasted crank seal

How about filling carbs, start it, pull the vacuum line off petock and see it's pulsing.

If I recall it does run well on prime position.

[Whit]

The vacuum line was and is totally blocked. 60 psi won't do anything but blow the rubber tube off of the air gun. I gave up on it and used the hole close to the intake (the one I previously JB welded). Now the vacuum outlet is in the same position that Suzuki used on the 69 Titan. Looks original and has a strong vacuum. Also went down one on the needle valve and now I have cleared up the left cylinder running lean. Bike runs great in the neighborhood but I have not gotten out on the streets yet as the roads are wet and I still have to put the master cylinder, calibers and my new brake hoses on to declare end of rebuild. Thanks for all the help. Will post pictures once brakes and front fender are on. //Pat

[tz375]

Pat,
That all makes sense.

Just as a point of references, I went out to the shop and dug out sets of 72/3 carbs and the JB holes are NOT DRILLED as they come from Suzuki. I suspect that a PO drilled the holes with the intention of fitting vacuum connections or because he had already plugged up the vacuum port.

I also looked at the slide locating pin and they are a press fit from the outside of the carb. I would suggest that you locate yours with loctite or JB weld to make sure that it does not come loose.

[Whit]

Thanks. Yes I put a spot of JB weld on the slide pins. I guess I was just lucky to find them loose before they fell out. //Pat