NC30 battle rearsets

[Cammo]

mmm, it's a mixed bag really, had a lot of people telling me that pilots will only effect bottom end, and a lot telling me it will shift the whole curve up a smidge.

Pilot jets flow fuel through the entire rev/load range, pilot screws affect off-idle performance only.

I suspect 59HP out of an unopened engine is probably about as good as it is going to get for now.

My racebike was putting out about 65 hp (dynojet dyno) - fresh built rvf engine by a V4 specialist, hrc carbs, full hrc exhaust and quietening gears removed. Having a fresh engine with the right tolerances is a good starting point when trying to extract every last hp from these engines. Getting over 70 hp out of them is big $$!

To be honest, i don't know why more people don't try this, the full HRC carb set up took me about an hour, including griding the ridges/dividers off the carb plate, and drilling it out. then it was just the fine tuning at the dyno

Yeah I agree, one of the easiest ways and cheapest ways to extract more power from a track bike.

Still need to figure out how to get rid of the small dive at the top end... right after peak power it leans out and falls away by about 3-4HP (at about 15000rpm). going to try a different needle, maybe the profile of the HRC unit will help... but I also suspect one of the slides is a bit lazier than the others too..

I don't think you'll ever get rid of the drop off at high revs, the engine (stock cams etc) becomes inefficient after a point. I rarely revved mine over 14k, just wasn't necessary with the torque curve. The needles won't be affecting the fuelling at over about 12k revs, it's main jets mostly from there.

Just a thought - some people (me included) used the nc24 carb slides (same as nc30 hrc slides) with the hrc carb setup. Are you running these?

[poomba2hd]

nah, just running standard nc30 slides with the dampener hole drilled out .5mm bigger.. i have heard a mixed bag regarding the one bigger hole versus 2 smaller ones. don't have spares to test the theory though...My problem is not with the power curve (so i think anyway), the slides are working well from what i can tell (very/steady curve).

I did entertain the idea of going different Pilots, however as the engine stands at te moment, it is a perfect mixture, perhaps slightly lean up top. very slightly... so i think the engine as it sits (i.e. stocker with current bolt ons) is probably making about as much as it will make with out giving it a freshen up.

I will have a look at valve tolerances soon though, perhaps i can squeeze something out there but i suspect they are good..

Me and a mate also have a spare motor. so once i am done building this bike, that will get the treatment, so will hopefully be a bit of fun.

[Cammo]

nah, just running standard nc30 slides with the dampener hole drilled out .5mm bigger.. i have heard a mixed bag regarding the one bigger hole versus 2 smaller ones. don't have spares to test the theory though...My problem is not with the power curve (so i think anyway), the slides are working well from what i can tell (very/steady curve).

The benefit of the hrc (or nc24) slides is the different cutout profile, not the holes. It affects fuelling at low and midrange, and might even assist with your power drop at high revs since it doesn't leave dead space like the nc30 slides do when fully retracted. The hrc/24 slides smooth out the inlet tract.

They're probably not essential to the setup, but the whole kit was made to work together, lots of people run into issues when they decide to use only part of the carb kit parts. Check out the slide comparo pics on Mike's site:

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

Sounds like you're getting pretty decent results already, but might be something to look at in the future.

[porndoguk]

The benefit of the hrc (or nc24) slides is the different cutout profile, not the holes. It affects fuelling at low and midrange, and might even assist with your power drop at high revs since it doesn't leave dead space like the nc30 slides do when fully retracted. The hrc/24 slides smooth out the inlet tract.

Cam'

when i fitted my NC24 slides last month, i left a NC30 slide in carb cylinder 1 and a NC24 slide in carb cylinder 3 when i blew on the vacuum hose both pulled back and fully retracted there is no obstruction on either, the NC24 slides are longer (unless mine was a NC21 it only has one hole which i drilled to 2.5mm Dia) so therefore the only difference it can make is idle and mid range and then into the final full WOT untill it fully retracts into the houseing.

it has ironed out my rich flat spot and its now perfect right the way through. Dyno time soon :D

i do hope this will have the job jobed for the Road carbs the next task is then the HRC carbs :D

[poomba2hd]

yeah, i can see what you both are saying...

the NC30 slides do slide all the way into the housing, and leave an unobstructed path, the NC24 slides are slightly longer, however are shapped to match the body/throat of the carb.

The downisde of the NC30 slide, is that once all the way in, the flat profile and cavity caused around the extremes of the slide in the throat of the carby, causes turbulent air. more turbulent the air, the slower the velocity through the carb, the worse the emulsion and hence you have a less efficient the carb.

I can see the benifit of the nc24 slide, but have not been lucky enough to find any!! that, and i suspect my exhaust can be a 'twin' system for longer, and provide better flow right up top.

My power drop is at 14700 rpm, right before the limiter, so it is not like i need that extra 500rpm of peak power, that is about where i am shifting anyway. I am also making pretty good power (more than most anyway) with a stock motor, and i know the mixture is spot on.
Until I build a better motor, which will have extensive tuning and a properly flowed exhaust, i am happy to let it go, unless playing with the needle profile helps, but cant really justify the dyno time for 500rpm!

[Cammo]

The downisde of the NC30 slide, is that once all the way in, the flat profile and cavity caused around the extremes of the slide in the throat of the carby, causes turbulent air. more turbulent the air, the slower the velocity through the carb, the worse the emulsion and hence you have a less efficient the carb.

That's right, they both retract fully but the '24 slide provides a much smoother inlet tract for incoming air.

[999Gomerz]

Nice to see another 400 out in VIC, Is this a track bike or are you planning to race it? We have a few days coming up a Broadford wiht low numbers and plenty of time available on track, especially for another 400. If your keen, let me know.

What did do you do to the GSXR shock? what length is it? I feel I may have to shorten mine little as it is feeling a little nervous on entry and at steady lean angle with trail throttle, currently at 314mm. What weight spring are you using?

I have 14/45 at the moment and it is not too bad, almost at max revs on back straight and doing 173 kph. With 14/41 I wasn't getting out of 5th.

Who did the shock and fork mods?

Cheers,

[poomba2hd]

g'day 999gomerz.

I have been doing the bike up for race. I am super keen to get into the race scene, I have my MA license and just need to get my number. The bike is now finished, so it is ready to race, however i am due to have a knee reconstruction on monday, so will be off the bike for at least the next 2 months.

I would like to come along to a race day anyway and check it out. so any info you can give would be great.. What club are you a member of??

Re: gearing, I have just got in a 13T front and a 43 rear, so that should almost be about the same as your 14/45. I have a very light weight chain (it is a moto2 520 GP chain) so can risk going smaller front sprockets.

Re: Shock/twitchy setup: how far do you have your forks through the tripples?? Are you using the standard link under your rear shock?? I had my setup done at kroozetune suspension - bloke named Dave, he is fantastic with setup. My bike FIRST TIME out on the track was set up pretty much perfectly!! (for me anyway). all i had to do was wind the preload down a smidge to have the front end spot on.. not bad for a bench set up...

The shock was revalved, sprung, and lengthened - only prob is it was so long ago i cannot remember what the spring rate and shock length is... i am using the standard link.
the forks have CBR1000rr cartirdiges in them.

[999Gomerz]

Dave does know waht he is doing. Good choice.

The standard link is very very progressive which is fine for toteling around but I believe that to push harder you need soething else, something flatter. I believe the ratio increase so much that the bike squats and then slides at lean angle. I am getting a HRC link for the VFR and will wait to see if it changes as I suspect it will.

If you look at the markings on the spring you should be able to tell the rate.

How far the tubes are through the clamps is irrelevant if you have different length forks as I do and you do too probably given you are using 1000 internals, you can probably put them through by as much as 40-50mm. But is always best to pull the springs out and just check clearance before riding. I mentioned in another post that your back seems too low, maybe the front is also too high if you only have a little bit showing at the forks with the CBR internals as is indicated in your earlier photos?

I found that a 13T front sprocket caused the chain to hit the frame, The Moto 2 teams that I know use DID ERV3 Chains which are similar dimensions to a VT2 I cant see how this will prevent frame rub.

[poomba2hd]

The standard link is very very progressive which is fine for toteling around but I believe that to push harder you need soething else, something flatter. I believe the ratio increase so much that the bike squats and then slides at lean angle. I am getting a HRC link for the VFR and will wait to see if it changes as I suspect it will.

True however some work can be done to counter this with the right valving i suppose. At this point i have not felt any sliding, but in saying that, i don't considder myself fast. getting there...

How far the tubes are through the clamps is irrelevant if you have different length forks as I do and you do too probably given you are using 1000 internals, you can probably put them through by as much as 40-50mm. But is always best to pull the springs out and just check clearance before riding. I mentioned in another post that your back seems too low, maybe the front is also too high if you only have a little bit showing at the forks with the CBR internals as is indicated in your earlier photos?

No I have about 30mm through the clamps, Given i have only tracked this once, i am not conviced my setup is a problem at all as yet. I only mention this as you had said your setup feels twithcy, Which can commonly be caused from too steeper front end.

regarding the rear setup on mine, It feels good, it is a couple inches higher than it was, considdering the shock was extended, this makes sense. I wanna get a few more laps on it before i make any decisions to change it. Only just dropped a bundle on it getting it setup this way!

I found that a 13T front sprocket caused the chain to hit the frame, The Moto 2 teams that I know use DID ERV3 Chains which are similar dimensions to a VT2 I cant see how this will prevent frame rub.

what rear sprocket where you running with it? where does it rub on the frame?? (i.e. the front of the swing arm??) the chain i am using is a DIDERV, so i gues i'll find out how the 13T goes when i install.
I have a mate with the same bike and a 13T front, with no problems to report, then again, i wasn't looking for it either.

What club do you race with? Are you racing interclub or hartwell/ other?? Assume it is not heartwell, or you would not be a broady so much) I am looking to join another club so i can race interclub...

What kind of times are normal for formula400 at broadford?