jb1000rr wrote:Have any of you race and track day bikers run your NC30's with HRC carb set ups but with the airfilter still fitted instead of the drilled and modified carb bracket and HRC air scoop tray?

That's just not going to work well.

As Mark says, full hrc setup or standard (jetted).

It's an interesting subject.

So what is a standard jetted set of NC30 carbs? I'm not sure if Honda themselves had worked that out.
Jap R3K main jet front 110 & rear 110
Jap R3L + N front 115 & rear 118
UK R3L + M front 122 & rear 120

Then HRC produced main jets for the SS + SP that went from 140, 142, 145, 148 through to 150 and for the TT -F3 that went from145, 148, 150 through to 152.

I haven't even mentioned the numerous number of differing carb bodies, needles, slow jets etc!

So having got these HRC parts lying around it seems a shame not to be able to fit them. All I'm trying to workout is whether I can fit the vacuum pistons and low air funnels without changing the jetting or anything else. The bikes current standard carb setup runs brillantly. The bike is a show bike, not a track or race bike, but the more HRC parts that l can fit, makes it more interesting to those people that show interest. However, I still need it to get an MOT and to be able to ride it and that's why I don't want to lose the airfilter, hence my questions.

Just looking for honest help and advice from knowledgeable forum experts.

The person who gets a kit together that offers hrc carb sexiness but with filter should have no problem selling them.

In my opinion an infinitely large filter over the hrc setup would not affect it's working. As such it may be possible to shrink that size to something sensible and practical, but it's going to take more effort and resource than most can offer.

IMO filter technology has improved over the years to a point that it should never need limit performance anymore, just look at any f1 engine today, but for now I will stick to the standard setup.

jb1000rr wrote:All I'm trying to workout is whether I can fit the vacuum pistons and low air funnels without changing the jetting or anything else.

The hrc velocity stacks restrict the carb air jets. This has the effect of richening up pretty much the entire rev range. If you fit them and don't rejet the bike will run very rich. Try it and see if you're that keen on fitting them!

This is the bit that will give you troubles:




The main benefit of the hrc setup is not running a filter, allowing much more air into the cabs over the standard setup. Most of the other bits just fuel it correctly for this extra air, though the shorter stacks also might push peak power up a bit in the rev range.

Some hrc carb porn pics from my old racebike:

I have a set of the vacuum slides with the curved bottom from the NC24 that i will be using on my NC30 engine soon, it will still be running an air filter but has ported and skimmed heads, NC35 cams and a full exhaust system.

I figured removing the small restriction must have some benefit, regardless of how small it is.

The hrc velocity stacks restrict the carb air jets. This has the effect of richening up pretty much the entire rev range. If you fit them and don't rejet the bike will run very rich. Try it and see if you're that keen on fitting them.

The main benefit of the hrc setup is not running a filter, allowing much more air into the cabs over the standard setup. Most of the other bits just fuel it correctly for this extra air, though the shorter stacks also might push peak power up a bit in the rev range.

Some hrc carb porn pics from my old racebike:



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So from your pictures, you didn't run the HRC curved bottom slides in your Setup?

Yes I did eventually mate, the pics were from before I fitted the nc24 slides.