Installing HRC carb kit

[Cammo]

and I'll check my plugs too after going up n down the street a few times.

There's no point unless you do a plug chop (engine off, clutch in) from wide open throttle at high revs in 4th or 5th gear (e.g. high engine load). Not great to do on the street. If you just pull in as normal, turn it off and check the plugs all you'll be seeing on the plugs is idle mixture. Plug chops are useful on a 2-stroke where jetting is far more critical.

Best thing to do would be to get it to a dyno, your setup sounds near enough that there won't be drastic changes needed.

[doodleface]

Heya cammo, well I went for a quick blast and i think i'm really close, it pulls hard up to 5ish, kinda bogged to 8k, then it pulled like a SOB. Sounded fantastic...

So just to check I took the airbox off (Cause it was fast) and had another quick blast, and the problem got worse, but still pulled really hard above 8.

So this tells me my mid range was a bit lean, (I did raise the needles 1mm, so i'll drop em back to 0.5)
I think i've pretty much nailed it once thats done!
Appears to be pulling really hard though, sounds good, can't wait to dyno it.

[Cammo]

Sounds good mate, probably close enough to fine tune it on a dyno.

So this tells me my mid range was a bit lean, (I did raise the needles 1mm, so i'll drop em back to 0.5)

Raising needles (or lower clip position) = richer
Lowering needles (or higher clip position) = leaner

[doodleface]

Yeah sorry just realised how awfully that reads...
So yes appears to be lean in the midrange based on when I removed the airbox (thus leaned it up) it got much worse, leading me to believe the midrange is still too lean after I lowered the needle height by 1mm. I've since rather then putting in more shims, gone to the A needles which allow a tiny bit more flow.
Hopefully it will richen it up and be sweet as if no dice by tomorrow I'll dyno it Friday

[doodleface]

So i just wanna point out here that anything I type or say is not my opinion but simply information gathered from another source with many years experience in racing/fixing/building 400's competitively...

So, I just couldn't get those needles to work, less to say I've tried them all...
Dismayed, on good advice I called a group in Australia that have a good reputation as ex-importers and racers of 400 bikes, plus run a shop etc.

I rang and spoke to a guy there and explained that i couldn't fix my boggy ass midrange with the HRC kit... he laughed and said if only he had a dollar for every time he heard that...

He proceeded to tell me that the problem is the needles are manufactured (Both A/B/C) with shitty flow curves, if they are ok in the midrange they are too lean up top, and if fine up top too lean in the mid range. He said it was a common problem he hears all the time.

He proceeded to tell me to : (and i did all of this)
1: Keep the short stacks
2: Go back to original emulsion tubes (in the right config)
3: Go back to original springs.
4: Original Needles with 1mm shim (total).
5: Drill slides to 2.5 mm (I did this carefully)
6: Throw away airbox, consider purchasing one of their custom air trays with a built in air vent that helps draw air up from below (Haven't seen but will probably buy one.)
7: Use 150's all round as i had them but play with those first later.
7: Throw pretty much most of the kit other then the short stacks over my shoulder. (I put them in a box :) )
8: I also noticed i had HEAPS of wiring down there, I unplugged it all and moved it to the side of the bike near the right radiator. Heaps more air flow can get through now.

I did all of these...

Once done, I all of a sudden got a super smooth mid range, really excellent acceleration and a smooth transition to maximum torque which pulled really really hard. Bike appears to be wonderful.

I can only assume that I couldn't make the needles work with my setup, or the HRC kit requires heaps of other mods (like engine mods) to be practical. (Though i'm not sure.)

At least for racing, my current setup is bad ass. Just a shame I could only make some of the HRC guff work for me, mind you I did honestly try every needle at every clip position with the airbox on and off, and it took up all of my days off, so wasn't through lack of trying, so you can't say I didn't give it a damn good go. Sorry cammo I feel like I let you down in a way not being able to make it work.

Can I ask though what is the function of the HRC springs... what are they supposed to do?

Cheers all for your help, Race 2 is on the 7th and 8th and i'm glad to finally be ready to roll!

[mo haggs]

interesting results. let us know how it feels in a race

[doodleface]

Well was planning to go for a track day today but it was cancelled due to weather, next up is my race on the 7th and 8th of july, will give some feedback then.

[doodleface]

Hey all, back from racing on the weekend, and did fantastically well, really good PB's, qualified 11 and 13th in the F3 and 4 on new tires I wasn't familiar with and next to no suspension setup!

Overall after 8 races I think I did very well, not sure but i'm guessing after the weekend i'm running 10 to 12th?
Crashed in the very last race on lap 3 coming into turn 1 off the straight, fucking high speed, sucked a fat one. Only minor damage but i'm ok.

Anyway, I still seem to be lacking a bit in the midrange, going to have to go to a test n tune, i have at speed next to nothing under 10, not sure if the JHA pipes are effecting things... gonna need a good dyno, maybe a compression test.

[J.B.]

FWIW I couldn't get satisfactory results with the HRC copy needles or emulsion tubes on my track NC35 either. I kept Rick's springs but reverted to stock needles shimmed 1 mm, short velocity stacks all 'round with the stock emulsion tubes for the rear cylinder carbs in the front cylinder carbs also. I use the carb tray but no air box lid (will experiment with the Tyga HRC copy lid, just haven't had time). Mains are 145 all 'round with standard plugs, 142 all 'round with cool plugs but it's hot here in Thailand, no doubt where you are there are more reasonable temperatures and some oxygen too.

[doodleface]

It's interesting you mention the emulsion tubes, I left the HRC ones in there perhaps thats part of my problem, or maybe its becuase we don't have our timing advanced from the help of one of the ignition boxes? Though looking at the supplied dyno graphs on other threads they seem to have nil effect till the very top end. I've pretty much concluded any airbox lid is pretty much void as the part is played by the fuel tank anyway... What we really need is someone who produces 60 + hp to provide their setups. A "Do this and you'll get a definite 65hp" etc. As you can see on the racing video I have no where near the mid range of the vfr. Maybe we are missing something in the float bowl height or something?

I've considered perhaps running a much smaller top radiator and smashing more air in there, or perhaps no top one at all, I never seem to get over 1/4 heat even on the racetrack anyway...

I'm at the point of taking it to a good dyno tuner, and seeing if I can extract that bit more after I look at rings and valves... maybe I'm loosing some compression or something.