[Arschloch]

From the first pic it looks like they've made a new injector body to go with this. I assume the throttle body is stock.

[ace.cafe]

I was informed that the port measures 45mm x 26mm. So if my brain is still working, the port area is comprised of 2 x 13mm radius semicircles, effectively a single 13mm radius circle, plus a rectangular area which is 26mm x (45-26) = 25 x 19mm. My calculations came to a cross-sectional area of 1030sq mm, roughly halfway between that of a 36mm carburettor and a 37mm (Keihin FCR) carburettor, though most CGT owners are probably thinking in terms of FI throttle bodies, I would suspect.

Any help?

A.

Yes, helpful.
Thanks!
In other words it needs a bigger than stock throttle body, or velocity takes a big dump at the transition.

It's a tough call to make as a designer.
Do I port it big for maximum power and rpm, or do I make it work best with the stock throttle body on the street?
Interesting choice.

In the interests of full disclosure, I ported our Ace billet 2-valve heads to work best with the stock TB on the street, and left the bigger porting to the purchaser if he wants it bigger. I figured most owners would use the stock ancillaries.
Derottone ported his up to 36mm at my last hearing.

[Arschloch]

You would probably want to go with the 36-37 mm carb with this arrangement, which may direct you towards to the 6.5 - 7.5 k revs if that valve train is capable of it.

[Adrian II]

Using a carb will need a custom manifold for a smooth transition, of course. Could be an interesting morning's work with a block of alloy.

A.

[Arschloch]

Using a carb will need a custom manifold for a smooth transition, of course. Could be an interesting morning's work with a block of alloy.

A.

Should be a good rehab work for the covid patients. 

[KD5ITM]

Staying within the same topic but throwing out a bit of a different question...

All I've done to my 2014 GT is the stage 1 performance kit, the Power Commander 5, free flow header pipe and Muffler along with the K&N Filter. The RPM range that my bike spins nearly 100% of its time is between 3:00 and 4,000 RPMs. And when I'm on the highway, I'm very comfortable keeping it right around 62 to 64 mph which keeps it a bit under 4,000 RPMs.

I would love to boost the performance of my bike but not necessarily looking for maximum top-end speed. Where I would benefit from more power and torque would be on the freeway at 62 mph riding into a block 15 to 20 mph headwind where you have the throttle cracked 80% and the bike is struggling to keep speed or at the same time, trying to pass a semi truck without the bike struggling.

What would be the most beneficial modification to boost the mid-range torque and Power?

[Adrian II]

612 kit?

A.

[gizzo]

Supercharger

[KD5ITM]

612 kit?

A.

I've heard more than once on here that the 612 Big Bore Kit causes the bike to run out of breath at higher rpm. Good for low-end torque in hilly terrain or if using a sidecar.

[KD5ITM]

612 kit?

A.

I've heard more than once on here that the 612 Big Bore Kit causes the bike to run out of breath at higher rpm. Good for low-end torque in hilly terrain or if using a sidecar.

[ace.cafe]

Staying within the same topic but throwing out a bit of a different question...

All I've done to my 2014 GT is the stage 1 performance kit, the Power Commander 5, free flow header pipe and Muffler along with the K&N Filter. The RPM range that my bike spins nearly 100% of its time is between 3:00 and 4,000 RPMs. And when I'm on the highway, I'm very comfortable keeping it right around 62 to 64 mph which keeps it a bit under 4,000 RPMs.

I would love to boost the performance of my bike but not necessarily looking for maximum top-end speed. Where I would benefit from more power and torque would be on the freeway at 62 mph riding into a block 15 to 20 mph headwind where you have the throttle cracked 80% and the bike is struggling to keep speed or at the same time, trying to pass a semi truck without the bike struggling.

What would be the most beneficial modification to boost the mid-range torque and Power?

Increased compression with squish mod, as I mentioned on the other thread.
It will help at any/all rpms.


As for the 612, I have never been a fan. Just my opinion.

[gizzo]

I've heard more than once on here that the 612 Big Bore Kit causes the bike to run out of breath at higher rpm. Good for low-end torque in hilly terrain or if using a sidecar.

You've said yourself that you're not operating in the higher rev range so what's the problem?

[KD5ITM]

As for the 612, I have never been a fan. Just my opinion.

I believe it was you Ace that said a couple of years ago that you felt that the 612 kit caused the bike to “run out of breath at higher RPM’s”, but did allow for more torque at lower RPM’s “for side car use or in hilly terrain”. 

Whats your thoughts on the reason for it “running out of breath” at higher RPM’s. 

[ace.cafe]

I believe it was you Ace that said a couple of years ago that you felt that the 612 kit caused the bike to “run out of breath at higher RPM’s”, but did allow for more torque at lower RPM’s “for side car use or in hilly terrain”. 

Whats your thoughts on the reason for it “running out of breath” at higher RPM’s.

Because the head isn't ported to handle the extra displacement, and the piston speeds from the longer stroke cause it to choke the intake earlier.
It's not insurmountable, but it needs somebody who knows what he's doing.

In addition, the bottom end parts are not the strongest, and the longer stroke will limit the reliability in higher rpm ranges.