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KOSO Performance 34mm Throttle Body (DY623013)
Fits '13-'15 Honda Grom
• Control the amount of air flowing to the engine's combustion chamber
• Combining throttle body with OPTIONAL intake manifold will allow a better air/fuel mixture for quicker throttle response
• Recommended used Only with Big Bore Kits or Modified Cylinders and Heads.

This is a great combo for the Finbro 125 ported head and Flat Top Piston setup.

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KOSO THROTTLE <<

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best upgrade I ever done for both my groms, I did have to port match the inlet tube to the grom head for even better performance and if you are using the stock air box the Koso matched rear rubber hose is a plus also.
 

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Just wondering: Your ported head has an intake port dia of 25.5mm and the 34mm TB is 30.5mm at the flange. How is that a great combo?
It works ok that way, but if you want better performance you port match the head to the inlet pipe I/D via your local machine shop or your handy dandy dremel tool and the right size grinding wheel.
 

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Steady has a intake just for the larger TB no need to use the smaller tube
 

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silicone reducer, got it
I don't love the idea of a reducer - it seems to reduce the effectiveness of the larger throttle body.

Here's what I used:

Pegasus E90.48-Black silicone hose, 1-7/8" ID, 90-degree, 4" legs
K&N RU-2450 universal rubber filter
HPS AJ300-187 6061 aluminum joiner tubing with bead roll, 13 gauge, 3" length

I used the 90-degree hose to avoid my oil cooler which I installed where the air box used to be and I vented the plastics to make sure it gets enough air. I'd use a U-shaped piece if you don't have an oil cooler or mounted it lower.

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While i do not have the Chimera intake to check its size, per fox85,
To keep velocity up in the runner. The chimera ID is within a mm or two to the 34mm throttle body ID, so no real gain to be had by making it bigger, plus the Chimera has an inlet that approximates the shape of a velocity stack.
Either way, this coupler is for those who have the chimera and upgrade to the 34mm Tbody.
 

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Has anyone got pics of how the Koso intake manifold fits to the stock airbox. I have a brock velocity stack.. will the Koso intake just delete the little bit of hose still inside the air box with the stack on it?
If you get the posted head and flat piston how many hp are people getting from it? Im getting the brock promise of 10.6 with velocity stack,pcv,exhaust and hurricane filter hoping to crack 11 with Koso intake and throttle body.. Maybe 12 with headport and flat top piston.. Too ambitious?
 

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Koso 34mm throttle body with matching inlet tube and rear rubber hose on a stock airbox

Koso rear rubber hose on stock OEM airbox


Koso 34 throttle body to stock throttle body


Koso 30mm inlet tube to stock or Finbro inlet tube


Koso 34 installed on BrianS 170 grom


Koso 30mm inlet tube installed with finbro 6 hole F/I




DIY airbox mod with Koso rear rubber hose ready for install
 

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Discussion Starter #13
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Thanks for the great photos.


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Koso 34mm throttle body with matching inlet tube and rear rubber hose on a stock airbox

Koso rear rubber hose on stock OEM airbox


Koso 34 throttle body to stock throttle body


Koso 30mm inlet tube to stock or Finbro inlet tube


Koso 34 installed on BrianS 170 grom


Koso 30mm inlet tube installed with finbro 6 hole F/I




DIY airbox mod with Koso rear rubber hose ready for install
 
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