I saw at RCR's website that Rick will bore out your stock carb. Has anyone done this? I like this idea, as it is $60 compared to a couple hundred for a larger carb. Plus you keep the fit and finish of the stock carb. I assume you only get a few extra millimeters out of it?

P.S. I have a trailblazer with the stock 30mm Mikuni.

 

I was told 1.5mm. I sent mine off last week. Hopeing for it any day. Also sent my flywheel to have it lighted. For my Xplorer 400. Ill let you know how it works.

 

Pllease do let me know. Are you having RCR do the boring?

 

Lurch77,

Why have it bored when you could go to a larger round slide? They are about half the cost of the flatslides and, with the addition of a UFO, can be made to perform as well as the flat slides. The minimum size that a UFO will fit in is a 34mm. If you do go to a 34mm carb with a UFO, send me an e-mail, I'll give you the correct jetting for it.

 

What is a UFO in carb terms Not that Alien SHI$ thanks .

 

Jaime,

Oops, sometimes I forget myself. The UFO (Ultimate Flow Optimizer) are a series of round plastic discs that fit into the bottom of a round slide carb's slide. Basically it smooths out the airflow at lower throttle settings to the point of exceeding a flatslides airflow.

If you look at the bottom of a round slide, you will see it is hollowed out on the bottom. This hinders air flow at lower throttle settings and doesn't allow for the complete atomization of fuel. The UFO fills in this hollowed out space, and smoothes out the airflow.

The airflow is SO much greater that you will have to REDUCE the pilot jet size by half! Yes, I had the same thought, melt down on a global scale, right. WRONG! The carb now flows so well that a 15 pilot jet is almost too rich. I also had to increase the main jet by one (200 to 210) to acomodate the leaner pilot jet but that was about all the changes I've made.

You will need to drill out the slide to install the UFO (they give you a drilling jig) and grind away part of the back of the slide, but installation is fairly straight forward and simple.

Well Mike, how well does it work? The Trailblazer I installed it on already had the old 34mm from my Sport. The throttle response was about the same as stock. With the UFO added the response became much snappier. I won't say that it worked as well as a good set of reeds, as there is only so much you can do with piston port motors, but it was about the same as my Sport when it was stock. Needless to say it was a BIG improvement.

You do have to play around on the sizes of the UFOs. They give you four from 2.0 (richest) to 3.5 (leanest). I've found that my TB is happiest on the 2.0 UFO.

Most importantly, the UFOs are made for 34mm carbs and up. They won't fit the smaller 30mm carbs. But for $30 and the price of a larger roundslide you can have big $$$$ carb performance.