HRC carb tray and velocity stack - NC30

[lukemillar]

HRC stacks are tiny - barely even a "stack'! But thanks for the info Cammo

Some pics here comparing stock NC30 -> HRC NC30 -> NC35

http://www.akhara.com/nc30/nc30hrccarb/index.html

[Cammo]

Cammo, I didn't know that about the air jet no filter setup, nice one. What's the difference in size between the hrc stacks and the rvf stock stacks?

Yeah it catches many people out trying to replicate the hrc setup - me included until a 400GB guru offered up this info many years ago!



The nc30 hrc stack is below (poor pic sorry), you can see how it shrouds the air jet, restricting the amount of air that will enter.




Simply, the more restricted the air jet is, the smaller main jet size is needed. Having a smaller main jet (e.g. 140+) is beneficial for the fuelling transition form the needle to the main jet (much smoother, no big hole in the power delievry.

With a standard air jet (e.g. cut down standard velocity stacks taht won't shroud it) big main jets are needed (e.g. 160+), however the bike will struggle to rev through the massive midrange hole when the transition from needle to main jet occurs.

You can restrcit the air jet in many different ways if you don't have the hrc stacks. You can tap it to take pilot jets and then drill them out to the required size. I know that more than one tuner blocks them completely instead of making them smaller.


Pic of my whole carb setup (because I like it! ):

[superlite]

You can tap it to take pilot jets and then drill them out to the required size.

If you cut off the skinny part of a pilot jet, you can press fit the large bit straight into the air jet (a snug fit). Just drill the pilot out to the required size. 3 mm seems to be about the going diameter if I remember correctly. I tried tapping them to take grub screws, but it's a bit of an effort to drill a tiny grub screw well.

Then I gave up and got some HRC stacks

[montsta56]

luke why dont you get hold of dynopro and go for ram air???

[lukemillar]

You can tap it to take pilot jets and then drill them out to the required size.

If you cut off the skinny part of a pilot jet, you can press fit the large bit straight into the air jet (a snug fit). Just drill the pilot out to the required size. 3 mm seems to be about the going diameter if I remember correctly. I tried tapping them to take grub screws, but it's a bit of an effort to drill a tiny grub screw well.

Then I gave up and got some HRC stacks

Got any spare you wish to part with?

Ram air- Just checked online but information is patchy and no kits are listed on the dynopro website. I assume it is pretty much what it says on tin i.e retrofitted ram air ducting? Or is there more to it?

[Cammo]

Ram air- Just checked online but information is patchy and no kits are listed on the dynopro website. I assume it is pretty much what it says on tin i.e retrofitted ram air ducting? Or is there more to it?

BMC (uk) also offer the ducting kits.

You also need to do some plumbing mods to the carbs so that the pressure in the float bowls is equalised with the intake air, and fit a fuel pump.

Oh, and restrict the air jets!

Royster had a good thread showing what was done to his carbs, I can't find it now. There's a bit of information around if you try a search in the workshop section for 'ramair'.

[montsta56]

mate I'd just ring Chris at dyno pro he'll have you sorted quick smart an for not alot of money. An trust me it's way better than an air tray imho.

[amaechizzle]

I swear that rick has done more for this site than many others combined.

and if you knew him you'd know he's not like that

RO doesn't make a living out of it, he's a cool guy and helps many of us.
(right can get my discount now )

Wow... you really took what I said the wrong way.

I just ordered some parts off him, I appreciate what he does, as I couldn't of got the parts cheaper over here.
Let alone get some of his parts at all.

[Variablevalves suck]

@ cammo, what are the NC30 stacks made from? and how do they fit/connect onto the body. I am making parts from carbon for my bike and have a load of small offcuts, could the stack be made from carbon (ridgid) or are they flexy in the way they have to fit. Same withe NC35 i read there are differnt lenghts for the NC35.

[Drunkn Munky]

Chris, 30 and 35 stacks are completely different. Standard 30 stacks are long and rubber, 30 HRC stacks are basically just little rubber boots that sit flush to the base plate.
Standard 35 stacks are made from ally and have 2 long ones and 2 short ones, HRC stacks are all short although not the same length as the standard short stacks.