Help on carb setup

[DanR]

Whats the recommendations regarding carb setups (been a while since having carbs) standard settings on carbs link pipe and scorpian can and is a bit flat in places depending on what gear was thinking either
1: Dynojet kit + K&N filter setup on rolling road (luckily friend runs a shop with rolling road)
2: Upping the jets (not sure what sizes are best)
3: HRC carb setup on Akhara.com (but mine is not a racebike)
Any help would be good
thanks

[Spike16]

similar question on my part

got a scorpion can on a standard system, dual density filter foam (shouldnt make much difference) and planning the HRC 2.5mm slides modd , there is a flat spot at around 5k which iv heard is because of the standard jetting with the race can

gona rebuild tha carbs this week and was just wondering what jetting should i change to? as ifd like to get it running a bit better (not that its that bad at the moment)

[royster81]

planning the HRC 2.5mm slides modd , there is a flat spot at around 5k which iv heard is because of the standard jetting with the race can

the slide mod has nothing to do with HRC,it's there to help increase bottom end pick up and the flat spot, i'd have a good guess has nothing to do with the can either

[Cammo]

Whats the recommendations regarding carb setups (been a while since having carbs) standard settings on carbs link pipe and scorpian can and is a bit flat in places depending on what gear was thinking either
1: Dynojet kit + K&N filter setup on rolling road (luckily friend runs a shop with rolling road)
2: Upping the jets (not sure what sizes are best)
3: HRC carb setup on Akhara.com (but mine is not a racebike)

Assuming yours is an nc30:

The std filter is regarded as performing very well, k&n isn't available. Dynojet kits have a poor reputation for the nc30.

Best recommendation for the road is to stick with a standard air filter, any other sort of filter will throw the jetting out significantly. 118 front and 120 rear main jets will generally suit your setup. Sticking an extra 0.5mm washer under the needles (1 x 0.5mm is standard) helps with the midrange flatspot. Aftermarket exhaust half or full systems or also help with the flatspots.

You can drill the holes in the slides to 2.5mm for better throttle response, I've never generally bothered on my bikes.

I have the hrc carb setup on my racebike, it wouldn't be very rideable on the road.

[Jon]

Nc30 or NC35 carbies?

The NC30 carbies are quite sensitive to modifications of the Airbox and hard to get the HRC bits for.
I think Graham France had a set of HRC inlet trumpets for sale on here recently.

The NC35 carbies have more flexibilty with airbox mods and better midrange control.
Rick Oliver is in the process of putting together another batch of replice HRC carbie Kits.

Your midrange is mainly influenced by the needle size and clip position (shims if you don't have clipped needles).


Drilling the slides will increase the speed that the air slides react.

A CLEAN paper air filter will run as much air as any of the aftermarket options but is less flexible in its maintenance.

If you access to a dyno I would give it a run on that and see what you need rather than buy a kit first unless you are going to HRC the carbies.

Quick road test is to pull on a bit of choke then accelerate through the flat spot, better = too lean, worse = too rich.

regards
jon

[DanR]

Hi Jon sorry for not saying it is a nc30. Thanks for the info bigger jets sounds the way to go (cheaper too).

[Cammo]

got a scorpion can on a standard system, dual density filter foam (shouldnt make much difference)

gona rebuild tha carbs this week and was just wondering what jetting should i change to?

Spike, I think you'll find that the foam filter will throw your jetting out quite a bit. Dyno is the only way you can be sure it's right.

At a guess it will need 125-132 mains, wide difference due to the different flow rates of various foam filters.

[Spike16]

really? Rick O said it wouldnt make too much difference as long as you use both parts of the dual density filter

on the HRC naming front thats just how i was described the modd by another forum member

so what should i do? drill slides to 2.5mm, 0.5mm washer under needles and play about with the jetting?

how much are we talking about setup on a rolling road?

[Neosophist]

Spike i'm with stickshift on this one.. get a std filter in there..

[Morespeedvicar]

Hiya, ive got a foam filter(well a couple a layers of HRC foam to stop the bricks) but its not bothered me nc30 at all, and the airbox lid is drilled, i think the jets are 120 allround.
Try it if youve got it.
Cheers
Ian