Maybe I was in a cave for the past 18 months since I've been reading about Samurais. Until last week I had not heard about the TSB on the Samurai for the vent tube fix. I ordered one from GB Auto Parts for $13.58 and slipped that puppy into the carb today. It is literally less that 3 minutes from start to finish to install.

Before I put in the tube the best 0-60 time I ever got on my Sammy was 20.9 seconds. After putting in the vent tube I got 16.8 seconds.   The software I was running calculated my wheel HP at 37HP before the mod. Afterwards it was showing 49HP. So I have to say that little vent tube made a significant improvement on the little 1.3L engine. Not bad for less than $20 bucks!

I later saw the Same part at Petroworks for $9.50 but they charge $12.34 for shipping. Shipping at GB Auto was about $3.
I almost didn't buy it because the first couple places I found wanted $35 and $50 for that little piece of aluminum pipe. If you don't have the vent tube installed in your original Samurai with the Hitachi carburetor, you really should put one in.

Could you post a link to their website so that I can check this out? Thanks, Tux...

Here is the PDF of the Suzuki TSB:

http://www.petroworks.com/pdf/IN-02%20Vent%20tube.pdf

Here is a link to the part at GB Auto Parts:

http://www.gbcarparts.com/proddetail.asp?prod=SUZ-13211-831Z0

Basically it is a dealer part so perhaps a local Suzuki dealer may also have them for less or same without having to pay for shipping. Suzuki part # 13211-831Z0.

Looks like the fix is for 1985 through 1988 Samurais with the Hitachi carb.

If you Google "Samurai vent tube" quite a few links come up. Don't know how I missed this for so long. Apparently the original carb design is flawed because a vacuum is created by the vent hole that messes up performance. The vent tube extends the vent hole higher up and eliminates the vacuum that creates the problem in the carb.

16.8 seconds is still on the slow side but much better than 20.9! Now it feels more normal driving it rather than it feeling like it is struggling to keep up with normal acceleration of other cars.

Here are a couple pics I found online with and w/out vent tube installed. Look at 7 o'clock position. Bottom pic has vent tube installed.

You can read the Technical Service Bulletin on Acks Faq as well. 

http://www.acksfaq.com/TS_4-06_03109.htm

also if you remove this one way vacuum modulator it will allow the secondary's to open faster.... big bang... small buck. just remove it and replace with a tube or one piece vacuum hose

Love the avatar! LOL. Tried your suggestion. Can feel an extra kick when accelerating. My Sammy drives much better now after the vent tube and this. Not fast but also no longer a slow turd leaving the light.

I order a tube when I placed the order for my rebuild kit. When the motor goes back intothe truck this will be on it!!

In the bulletin/instructions there is a installation tool. Does that come with the part?
Where do you get the tool?

Just used a thin wall socket to install one...  made a big diff too

Good to know!  Thanks for sharing

petroworks is great, i get alot of my sammy parts there.. yeah shipping a little pricy but when u got to have it its worth it.. coming from a guy that lives 20mins away from petrowoks..  and yes the vent tube does help..alot

also if you remove this one way vacuum modulator it will allow the secondary's to open faster.... big bang... small buck. just remove it and replace with a tube or one piece vacuum hose

I tried this and it did seem to make a difference.  Have to admit that I kept the modulator in the glovebox during the test drive, just in case it became inexplicably undrivable, which it didn't.  It seems to run MUCH better when cold.  It used to be a little balky until up to temp, but not anymore.

I had a hard time sourcing the vent tube for as cheap as you guys found it, but I just dropped the CC number on Spidertax.  $28 and some change to my door.  Still seems like a good deal if it really does what you all say it does. 

Waiting by the mailbox with fingers crossed.

Maybe this would explain why my rig was always getting past by loaded log trucks Hell that was on 31's and when it hits the street again it will be on a 33 so this is something I will be doing before that. I wonder what other tubes I can pull off the carb to clean it up a bit under there and maybe get a little more power.

I had the vent tube fix, but my Sam still had a little bit of hesitation when the secondary opened.  I just removed the modulator and now that hesitation is gone.  Thanks for sharing.