RVF needles and fueling.

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RVF needles and fueling.

Post by CRM » Sun Apr 24, 2011 8:29 pm

Guys, got some questions and struggling to find the definative answers.

RVF carbs, what needle options are there - and what difference / setup are they suited too ?
RVF pilot screws, 1+5/8ths - is screwing in leaning the mixture low down or richening ?
Fuel heights - setting a couple of mm either way, does that have the effect to weaken or richen in any area ?
RVF needles - are there any washers as standard ? if so am assuming the .5mm (ish) ones.

How to remove a fluffy 5k - 7k area ?
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Re: RVF needles and fueling.

Post by Neosophist » Sun Apr 24, 2011 10:22 pm

Screwing the pilot jets in richens up the mixture.

Float heights are 12mm stock, adjusting these will make the bike leaner or richer marginally throughout the rev-range, you will feel this effect mainly on your 'gas the throttle from cruise'. I don't think you would need to change this by more than 1mm either way.

There is one 0.5mm washer.

You can get FI and HRC needles (I think there are 3 types of the HRC neeldes). Rick-O used to sell copies of the HRC kits (needles / stacks / emulsion tubes / springs), he might still do...

These are designed for air-tray or ram-air style setup like the HRC bike and bigger mains (think 140-160ish)

If its just a small flat-spot your trying to sort out, you could try raising the needles slightly as this will affect your 6-8k range

also worth checking your emulsion tubes are in the right carbs, all 4 should have 3 holes in them but the front two carbs should have the first hole near the top of the emulsion tube and then two at the bottom, the rear carbs have the first hole much lower down and then the other two in the same place as the front carbs.

Oh and if your still on the stock 108 jets put 112s in there if your planning on sticking with the factory airbox setup and not going the full HRC setup and itll go much better
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Re: RVF needles and fueling.

Post by CRM » Sun Apr 24, 2011 10:28 pm

good man,
its currently running a 3/4 yammy and is not on 112's all round with an extra .5mm washer.
it was running 115f 117 rear, and pulled like the clappers up top.

i think its slightly worse funnily enough since its been in 112's in the midrange, however its the same after 7k to the redline, so i guess 112's are working ok up there. they are running 2 x .5mm washers at the moment

my issue is the fluffy 5 - 7k area, crack the throttle from cruise and it stutters and feels a bit flat but still makes progress and takes off well at 7 - 8k

air screws are standard, float heights on each side of the float are between 12 - 13mm
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Re: RVF needles and fueling.

Post by Neosophist » Mon Apr 25, 2011 2:51 am

Hmm..

No doubt cammo will be along soon to add something to the mix.. hopefully he can help more than i can! :)

Granted my bikes been in project hell for 18 months but when I was sorting the carbs i tried 114s but it was too rich so went with 112s.

Float heights are stock and i think (would have to check) air-screw are 2 turns out.

With two washers under there though it shouldnt be running lean if there stock needles.. have you tried ditching the washers all together and seeing how that makes it run (its just a rough idea and its easy to remove the washers, plus youll find out if leaning it off in the mid-range imroves things or makes it worse)

I have the stock 0.5 if memory serves right..
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vic-vtrvfr wrote:Ask xivlia for help, he's tackled just about every problem u could think of...

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Re: RVF needles and fueling.

Post by CRM » Mon Apr 25, 2011 5:43 pm

well i can confirm the following

112's all round and 2 washers = good low down and up top but fluffy midrange bit stuttery around 6k

112's all round and 1 washer = good low down and ok up top but midrange worse and quite stuttery 5 - 7k

112's front and 115 rear and 2 washers = good low down and good up top and slight fade around 5k but no stutters, as such this is the best combi i have found so far.

devils advocate and extra washer again lol ?
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Re: RVF needles and fueling.

Post by Martin » Mon Apr 25, 2011 7:01 pm

You've got nothing to lose mate. At least if it makes it worse you 'll know you've gone too far the wrong way. At that point i'd put it back to 2x .5mm washers and richen the pilot screws by 1/8th of a turn to see if that improves the crossover.
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Re: RVF needles and fueling.

Post by hardnutdvd » Mon Apr 25, 2011 8:37 pm

i know its difficault.. but when you say stuttery, how do you mean? .. i am gettin this prob in any gear at anything below 5k...

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Re: RVF needles and fueling.

Post by CRM » Mon Apr 25, 2011 8:49 pm

Mine pulls perfectly upto 4k then it feels a bit lacking upto 7k then the power kicks in smooth and strong. it feels like its just a bit empty in the midrange, almost as if the brakes are binding (they are not)
Strip the carbs down, and one by one check each one out (so you dont mix up and muddle up needles in wrong carbs)

get an old plastic credit card and cut this out making sure the 12.5mm height is spot on
carb_float.gif
Now after cleaning all your jets out, and blowing through all the air tubes and passages, use this card over the easy to work with carb ( the one on the right ) making sure the float is just touching the springy needle tip and not compressing it, also make sure the floats are not twisted and are equal on both sides, some slight gentle bending with a small flat head screw driver may be required, then thats one float height set.
Repeat for all the other floats and return to the correct carb body and check again using the paired needle it came with.

If it feels strong when cold between 3 - 5k and sluggish when warm, then set the float heights to 13.5mm
If it feels worse when cold and slightly better when warm, then set the floats to around 11.5mm
Don't go any more than 1mm either way.

once you have all this set and it still feels weak between 4 - 7k then try another .5mm washer under each needle.
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Re: RVF needles and fueling.

Post by Cammo » Wed Apr 27, 2011 12:30 am

Neosophist wrote:No doubt cammo will be along soon to add something to the mix.. hopefully he can help more than i can! :)
I've stayed away from this one Neo, sounds like Paul has done all the right stuff!

Paul: I would suggest that the problem is to do with induction air rather than any fuelling combo in the carbs, it sounds like the classic symptoms of the bike getting a little too much air in for the stock type setup. I think running extra washers on the needles is just covering up the issue a bit rather than correcting it. Does your bike use a standard honda filter? Standard airbox, snorkel, sealed properly etc? Rubber flap in place? I'm not sure of the rvf rubber flap setup, but they do have something in there (or 2?).

I'm sure you've checked this stuff but worth another thought.

FWIW my road bike (with rvf carbs) runs 112's, standard 0.5mm washer on the needles, and Rick's hrc slide springs. No flat spot to speak of. I think the hrc springs are a better option than extra washers, perhaps worth trying as they're quite cheap.

This thread may shed some light on your issue:

viewtopic.php?f=24&t=25572


Let us know how you go.
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Re: RVF needles and fueling.

Post by CRM » Wed Apr 27, 2011 9:12 am

nice one Cam, sounds like a plan
The RVF air setup is as follows (well on mine anyway)
rubber flab present over the front rocker cover to keep the water / crap out.
air box base plate - all standard, but they are not the same as the NC30, and dont have a long flat piece than goes into the headstock recess (or correct me if i am wrong and mines been hacked)
standard air filter.
standard RVF airbox lid

good call on the springs, will speak to rick tonight and see if i can source some.
cheers for the input chaps.
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