Sigma vs. Dynojet carb kits

[8541Hawk]

Very good Tony. That pretty much hits the nail on the head, oh hold on...you might hammer me down for that.

Your right though, there's not much between various kits and they all take slightly different approach to things. It's all down to getting to know what does what and finding an even balance where the bike runs as you like it. Jet kits might juts be a waste of money and one could take Hawks route http://www.vtr1000.org/phpBB3/viewtopic ... 31&t=28922 which works well for a lot of folk. Maybe use the money that would have been spent on the jet kit on a flow commander instead.

(:-})

You beat me to it.....lol but yeah that set up does give you most of the benefits of the HRC kit with the least amount of expense.
Which also means if you don't like how it works, you are really not out much.

The only thing you don't get is adjustable needles but it is not very hard to just shim the needles up a touch.
While the HRC needles do help the stock needles are some of the best stock units I have ever worked with.

So don't be afraid to run the stock needles as about all you get with the available aftermarket needles, IMHO, is the ability to adjust them with the clips.
As far as needle profile, I haven't seen much improvement over the stock units except for the HRC (or Moriwaki) needles and they are radically different than the stock.

[Bleh]

Thanks once again Cybercarl and I will say that you have a vast amount of experience with VTR's in comparison to myself and take on-board what you say.

[how the hell is a kit bought over the counter or on the internet meant to be tailored to suit your particular engine, mileage, rev range ridden in or riding style?

^ Fair point but kind of why I'm trying to paint a picture of other peoples experiences with what they have found for themselves.

I can calculate many aspects of a motorcycle and its (potential) performance but I can't calculate experience, especially that of people with vast amounts more than me.

As for which colour is fastest, the answer is obviously black... As common knowledge teaches us, black absorbs light (where as white reflects it) and as light is made up of particles (and waves as our lecturer who's phd is in particle physics fried our brains with recently) it has momentum when it travels. When the moving particles make contact with the black of your bike, energy is stored (Newtons law which says (in short) energy cannot be created nor destroyed but transferred from one state to another) in the form of heat which in turn helps the air around it heat up and therefore the air being drawn into your air box, through the carbs and into the engine via the inlet valves which are also producing heat through friction which in turn heats your air up even more assists with the combustion ensuring there is no unburnt fuel and so producing higher pressure within the cylinder, and as we should all know, the greater the pressure upon combustion, the greater the force pushing the piston down which eventually transfers through the gear box and to the back wheel, so yeah, black is the fastest colour.... I best get down to Halfords tomorrow for some rattle cans

But wait, what good is all that extra power on a black motorcycle if your tyre is bald? So, shouldn't the real question be which tyre is fastest? No point having a black, faster bike with a bald tyre if my blue, slower bike with a full tread can put it down better.... AAAARGGHHHHH

[VTRDark]

You beat me to it.....lo

I aim to please.

The only thing you don't get is adjustable needles but it is not very hard to just shim the needles up a touch.

Which works great with your set up as the mains stay as they are and the 48 pilot is pretty much standard anyway. I have found when one goes with bigger mains and/or the pilot is increased having the adjustability the other way may be required.

(:-})

[VTRDark]

As for which colour is fastest, the answer is obviously black... As common knowledge teaches us, black absorbs light (where as white reflects it) and as light is made up of particles (and waves as our lecturer who's phd is in particle physics fried our brains with recently) it has momentum when it travels. When the moving particles make contact with the black of your bike, energy is stored (Newtons law which says (in short) energy cannot be created nor destroyed but transferred from one state to another) in the form of heat which in turn helps the air around it heat up and therefore the air being drawn into your air box, through the carbs and into the engine via the inlet valves which are also producing heat through friction which in turn heats your air up even more assists with the combustion ensuring there is no unburnt fuel and so producing higher pressure within the cylinder, and as we should all know, the greater the pressure upon combustion, the greater the force pushing the piston down which eventually transfers through the gear box and to the back wheel, so yeah, black is the fastest colour.... I best get down to Halfords tomorrow for some rattle cans

Now that's the best I have heard in a long time.

(:-})

[Bleh]

Soooo, reading Hawks post, getting standard jets and needles and ensuring the primary are #48's then blocking one of the holes in the front slider as well as replacing the front shim with a 0.5mm one and ADDING 0.5mm to the rear gives significant improvements?

I just wonder if blocking one hole up completely puts more pressure on the diaphragm (although probably an insignificant amount!). Would it not possibly be worth increasing the remaining hole size by 20% (for example) with a burred edge either side to reduce any (again probably insignificant) impact turbulence may have?

Doing a degree doesn't mean I know it, just means I know how to over-complicate it

[mik_str]

The last off the shelf HRC jet kit was sold not so long ago. You wont find one

(:-})

Yessir, and I'm staring at it as I type this.......

sorry, couldn't pass it up.......

[mik_str]

The size and number of the lift holes have virtually no effect (as in 99.9% no effect) on the slide's equilibrium height; what it does is alter how fast or slow it lifts and falls when accelerating and/or decelerating. Been there, done that......

[8541Hawk]

The size and number of the lift holes have virtually no effect (as in 99.9% no effect) on the slide's equilibrium height; what it does is alter how fast or slow it lifts and falls when accelerating and/or decelerating. Been there, done that......

Exactly

The slide gets or "sees" vacuum (or negative pressure) from 2 sources.

There is a port in the carb throat and the lift holes in the slide.

The port in the throat is the "coarse" setting and gets the slide speed in the ball park.

The lift holes fine tune the speed.

So going 20% larger on one of the hole will increase the slide speed.

HRC found one standard lift hole to be optimal for the short stack (and depending on which aftermarket stack you have both slides)
You can try going larger but I didn't find anything there.

I have also played around with the cut out and also didn't find anything worth bothering with.

[tony.mon]

As for which colour is fastest, the answer is obviously black... As common knowledge teaches us, black absorbs light (where as white reflects it) and as light is made up of particles (and waves as our lecturer who's phd is in particle physics fried our brains with recently) it has momentum when it travels. When the moving particles make contact with the black of your bike, energy is stored (Newtons law which says (in short) energy cannot be created nor destroyed but transferred from one state to another) in the form of heat which in turn helps the air around it heat up and therefore the air being drawn into your air box, through the carbs and into the engine via the inlet valves which are also producing heat through friction which in turn heats your air up even more assists with the combustion ensuring there is no unburnt fuel and so producing higher pressure within the cylinder, and as we should all know, the greater the pressure upon combustion, the greater the force pushing the piston down which eventually transfers through the gear box and to the back wheel, so yeah, black is the fastest colour.... I best get down to Halfords tomorrow for some rattle cans

Now that's the best I have heard in a long time.

(:-})

Is it? So hot air going into the inlet helps, does it?

That rather blows the "cold intake being denser, therefore having more potential molecules of oxygen to produce better combustion" theory out of the window.
(sigh) I'll put the intercooler back on Ebay......

[Bleh]

Is it? So hot air going into the inlet helps, does it?

That rather blows the "cold intake being denser, therefore having more potential molecules of oxygen to produce better combustion" theory out of the window.
(sigh) I'll put the intercooler back on Ebay......

It was meant to be a bit of humor at the end of the day but as you mention it, yes, colder air is denser resulting in molecules being less stimulated therefore being able to fit more into the combustion chamber to help with stoichiometric ratios, but the result of such means there is more unspent fuel and in turn the engine has to work harder to produce that extra power... However, warmer air does aid in the combustion of ALL fuel within the chamber and results in a bigger bang producing more power at a lower rev range (despite how minute the relevance is, it still helps).

Just consider F1 and GP traveling the world to all these hot exotic countries (warm air) where they don't really care about their fuel ratio as such... the only things they try to cool is the engine to prevent over heating.

My car certainly shows better MPG in the colder months but certainly feels a lot more responsive in the warmer months. It's all about the compromise!

[tony.mon]

Interesting thoughts.....
Probably the difference either way is barely measurably.

I always think my bike runs best in the rain, annoying really as I need most power when it isn't.

(I was also joking about the intercooler, too, before anyone else asks.) I'm definitely keeping it.