Needle and jet help

[Bike_Nut]

Yea im getting scared now with what I have read and started looking for another airbox. Mind you, faint heart never win fat tart so I have bought some dyno jets in 126, 128 and 130 and will try them out as I am expecting the top end to go quite lean. Still running standard filter and airbox top so dont expect to need any bigger jets than these.

Hopefully will be able to give some feedback by the weekend. At least the slides are now drilled so even if I go back to the standard airbox arrangement I might have had a worthwhile improvement.

[CMSMJ1]

I use 135 jets in RVF carbs on my NC30 - no airbox lid and a std filter.

The mid is a touch messy but it rips up top. It has taken a years worht of fettling to get it so I am happy so beware..it is a ballache!!

If you are going to run a filter and a lid then you might be too rich with the high 120's

do you have a free flowing exhaust or ay other pertinent mods?

[Bike_Nut]

I suspect my bike has a half system exhaust on it (not really sure) and a through flow exhaust. Looking at the plugs it might have been a bit rich in the midrange with the bakudan needles on the 4th groove, so I am leaving that as is and just going for the bigger mains hoping the extra air will lean out the midrange. 135 seems quite common on RVF's with airbox mods hence the reason I thought I would try the 128F/130R combination - rather be too rich than too lean.

I sold my 600RR and kept the NC30 so guess I like it enough to spend some time and effort improving it. It just could to with a bit more top end to minimise the speed differential with the bigger bikes on a track day.

[CMSMJ1]

It just could to with a bit more top end to minimise the speed differential with the bigger bikes on a track day.

They are still going to be blown away by anything 600cc or bigger. I have that issue too and it just makes it more fun to be able to put the same laptimes in as someone on a rocket ship.

Getting serious power out of a 400 takes some good cash outlay and some time spent too.

Mine is noting special but have seen a 10% improvement on power measureed when I fitted a Yamamoto system, open airbox and RVF carbs to it. NOwadays I have an ethos system and the pipeline sees a programmable CDI being set up, ported heads and a lighter flywheel.

I have also lost 2 stones this past 3 months and I reckon that will have made me faster than anything else I did with it!!

[Bike_Nut]

I am limiting myself to good value mods - The pipe was in a state when I got the bike but got a new perforated pipe and some packing and repaired it for about £20. Now £20 on jetting is not doing too badly if I can get it up to about 64hp

The only other mods I am concidering are race seat and alloy subframe, with the tail lights and indicators being a clip off arrangement for the track, and the jack-up kit to get the handling a bit better. Oh and have to do something about those horrid rearsets that keep touching down around the track lol

[fastdruid]

It just could to with a bit more top end to minimise the speed differential with the bigger bikes on a track day.

They are still going to be blown away by anything 600cc or bigger. I have that issue too and it just makes it more fun to be able to put the same laptimes in as someone on a rocket ship.

+1

The only time I notice it being an issue is if you are faster than someone but cannot make a pass on the way into a corner then you lose out on the exit due to the double blow of loss of momentum and lack of power.

Nothing like harassing dedicated trackbikes/racebikes round a track on a road going 400 though. :D

Druid

[Bike_Nut]

The RR was great for blasting down the straights, but I want to learn to brake late, corner hard and get on the gas early - and still ride it home at the end of the day. VFR is sweet for this.

Swapped the needles round and was fitting the new jets when I checked the Jet holders (emulsion tubes?) Turn out they are different too! One lot has 4 holes, the other 5. Which way round should they be?

[Cammo]

the needles round and was fitting the new jets when I checked the Jet holders (emulsion tubes?) Turn out they are different too! One lot has 4 holes, the other 5. Which way round should they be?

That's standard, 4 holes in the front carbs, 5 holes in the rear.

[Bike_Nut]

You guessed it, 126/128 jets are too rich. Mind you, with the filter out it was getting close.

Went back to the 115/117 jets as I do not have anything around the 120 mark and it seems a tiny bit lean, but nothing as bad as what I expected. I would say the airbox mod has taken it from being a touch rich to a touch lean.

Lessons learned:
-The bike was running well because it already had a jet/needle kit in
-I believe the kit was fitted back to front so now that is corrected.
-Midrange seems a bit more responsive with the drilled slides and airbox mod, hopefully the top end will also improve with 118/120 jets
-Listen to advice about jet sizes lol

Thanks for the help guys

[CMSMJ1]

Sounds good dude. SO what mods have you done to the airbox?

Jets are cheap so get your mitts on some more