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R1 airbox and trumpets.... quick question
Major Stare - 24/8/10 at 09:03 PM

Fitted an air box to my 5PW R1 after a brief spell with a sausage filter.

Checking a few things tonight and noticed the airbox trumpets are all the same height, but the trumpets that came with the engine, the inner 2 trumpets were longer than the outer? ? ?

Why?

jimgiblett - 24/8/10 at 09:17 PM

Graves velocity stacks fitted? I had them on my Phoenix.

- Jim

Major Stare - 24/8/10 at 09:31 PM

What are they?

They look like they have been glued in, about the same length as the shorter stock trumpets but not really "trumpet" shaped

RazMan - 24/8/10 at 10:24 PM

Graves Velocity Stacks are designed to smooth out the power curve, increase horsepower and improve fuel efficiency. They are said to give power gains of 4 HP in the mid range and 2 HP at the top end. The longer trumpets give more low down torque and the shorter ones, more top end - basically sharing the extra power between the cylinders.

Major Stare - 24/8/10 at 10:32 PM

I still have the longer trumpets, so its worth putting these in the air box (inner two trumpets).

jimgiblett - 24/8/10 at 10:34 PM

Here they are

linky

[img]www.yamaha-motor.com/sport/accessories/acscitemdetail/5/6/183/2025/all/all/8782/0/detail.aspx[/img]

jimgiblett - 24/8/10 at 10:54 PM

quote:
Originally posted by Major Stare
I still have the longer trumpets, so its worth putting these in the air box (inner two trumpets).


If you are changing from the foam filter you will need to have it remapped so why not get every bit out of the motor you can.

Major Stare - 26/8/10 at 07:35 AM

The bike engine came with everything except air box, so i ran it with a TTS for about a month before fitting the airbox...... so its pretty stock.

But, i couldnt work out why the engine came with 2 different lenght trumpets, yet the air box had same length trumpets?