Triumphrat

Forchetto · 10-20-2012, 02:03 PM

Quote:

Originally Posted by Lasermax

Ultimately, and I've already seen it done here, is to have a set of velocity stacks going from the carbs right into the airbox, or to pods if you prefer.

I remember, a long time ago, peering inside a then new Honda CB750's airbox minus paper element filter, and seeing that it had four velocity stacks or bellmouths, made of rubber, that lived out of sight to the casual observer.

There's a new idea, for KTM's at the moment, with a combined stack and pod-type filter that's rather clever, on this post today. There's a dyno chart as well:

http://www.triumphrat.net/twins-tech...ml#post2401447

Lasermax · 10-20-2012, 02:50 PM

That's awesome.

Would certainly be the ticket. Thanks so much for your posts. Sakurama, what am awesome thread on ADV rider. If I don't have to take half my bike apart again, I'll be putting in stacks, with the results you've gotten, wow.

georider · 10-22-2012, 12:02 PM

Quote:

Originally Posted by PieMan

GeoRider, the theories would most probably be correct if the factory snorkel was designed for performance, but it was designed to muffle the induction noise which adds something else in to the equation.

The dyno below shows the effect the Breathe has on engine performance by directly replacing the factory airbox cover/snorkel with the Breathe, with corrected fuelling. It shows a significant increase in torque in the mid range and if you remove the airbox baffle, that increase carries on to the rev limiter.

It very interesting reading this these graphs.
At high revs, 6.5 k-8.0 k, when the motor needs more air, the power and torque are the same.
What conclusion can one take from this?

grzegorz · 10-22-2012, 12:42 PM

My conclusion is that you getting more HP and torque where you need and using it most of the time

similar situation you can see here stock CDI (blue)against TTP reprogrammed one(red)

I gained there where is more usefull 3-5k

georider · 10-22-2012, 01:53 PM

yes, you're right.
But there's not a clear relationship air port size/power.
At high revs the result is the same with a much larger hole.

grzegorz, what was your air box set up when you had the bike "dynoed" ?

grzegorz · 10-22-2012, 02:45 PM

on this graph internal snorkels romoved,K&N filter,Polaris belmouth run was made back to back ; run 29 CDI reprogrammed by TTP followed by run 30 with stock CDI with only rised REVs to match new unit

in the past this happened;

when I changed top snorkel(cut at the bottom) for rubber velocity stack

diffrence -----68.4hp was 67.12hp
--------------57.46ft/lbs was 54.37ft/lbs

118 main jet (four sizes up)
needle rised clip 3rd position from top

CRS carbs

georider · 10-22-2012, 03:28 PM

Helpful post.
I'm trying to get a pattern here.
In the K&N site I got this answer:

An engine can only draw in a certain volume of air depending on the engine's size (measured by such things as bore, stroke and number of cylinders). Vehicles are designed to accommodate large changes in air pressure so they can operate at sea level or at an altitude of 14,000 feet.
Engine computers adjust the amount of fuel required as a result of changes in air pressure (density).
Air filter restriction when the filter is new and especially as the filter loads with dust will result in lower air pressure and availability similar to being at a high elevation. High-flow air filters that were invented by K&N were designed to reduce the work necessary to pull air through the filter and to increase air pressure. Increased air pressure is one of the key elements in producing more power.

This is a graphic from one of Forchetto's great posts

What I'm getting from the graphs is that at high rpm the power and torque remains the same regardless air port size.
Performance does not increase in proportion to Air flow provided from bigger air port.
Hummm... need to go deeper...

Lasermax · 11-03-2012, 08:26 PM

So if I have TWO Polaris bellmouths, having dual openings now, I get to double the length of the line on that chart. That's my math and that's what I'm going with.

PieMan · 11-04-2012, 06:05 AM

Quote:

Originally Posted by georider

It very interesting reading this these graphs.
At high revs, 6.5 k-8.0 k, when the motor needs more air, the power and torque are the same.
What conclusion can one take from this?

The airbox baffle limits airflow in to the engine at high revs. As I said, if you remove the airbox baffle the engine makes more power to the rev limiter.

Here is a dyno graph showing with the airbox baffle and without.

GySchmit · 11-04-2012, 11:28 AM

OK.... having read this entire thread (and associated linked threads) and trying to figure out a starting point for my carbs my brain hurts! Need this info for my mechanic.

Bike is a 2005 Thruxton (Carb)

Historical info. Bought bike with EMGO Reverse Cones & AI Removed. Over the past two years have removed snorkel and fitted K&N Air Filter.

Bike is being rebuilt from a crash so with it off the road in the shop I'm having/doing the following modifications.

Airbox Restrictor Plate being removed.
Header Crossover pipe being removed and welded up.
Headers being cut just after second bend (when it heads back) and Lossa mini reverse cone mufflers being mounted (ala "TT Style")

Could someone that understands all this data please give me a starting point on carb settings.... Please Please.