I had my first opportunity to install one of the new HPI modified FBW 54mm TB's this weekend. I saw them at the HPI booth in Cincinnati in February, but this is the first one I've installed.

The bike was an 08 SG with a TMan Stage 2 107 that had 1.800 intake ports (by request), with TR625 cams. The original TB used on the build was an HPI modified S/E 58 MM unit. We used it because we had to have a piece with 1.800" intake ports rather than the stock 1.670's. While it worked well and made good "numbers", and the owner was quirt happy, I felt the TB was too big and was making it a little more "lazy" than I thought it should have been. Like I said the owner was happy and unsure I could make it better.

We sent his stock FBW TB in to HPI for their 54mm rework and requested they fit it with the required 1.800" intake.

The unit came back looking KICKAZZ! Notice the new intake has a "Y" shape compared to the stock units "T". THis is much better as and helps control & keep separate the charge for each respective cylinder…

HPI 54mm Modified stock TB on left, HPI modified S/E 58mm on right


another angle…


and a 3rd….


Notice how you can see through the S/E on the right, but not nearly so much on the new unit on the left


Here's a look at the throats. Bigger is NOT ALWAYS BETTER!


one final look…


So, with the new unit on (same injectors), the bike fired right up. It will have to be retuned, but even as it sits, the throttle response is much quicker & crisper. I rode it in the parking lot & showed my buddy that his bike DOES do wheelies on demand! Now, it has the feel I was looking for. It's CRISP & snappy. Can't wait to try it after it's retuned!!!!

 

Is is only useful on built motors?

 

While it's certainly "more" value for a built up motor, the "Y" shaped intake would be of value to any FBW motor.

 

Very interesting information. What would the best use be for the old TB?

 

If you mean the HPI S/E unit we pulled, it would be better suited for something like a 117 or 124...

 

that's good stuff right there...definitely a great bang for the buck. as always, phil is on top of things ;-)

 

Hey Phil, what's a setup like that running cost wise?

 

It's actually quite reasonable! It lists for $399.

 

Phil,
What is the deal?
I remove my TB, mail it in, they mod it, mail it back?
Or, is that price for a new TB?

I recall you telling me the stock TB was fine for my HQ 107" build.
Do you see any benefit of this mod for the HQ motors?

 

Also, does this mod change the spacing on the air cleaner?
It looks to be a bit longer in the pics.