FAO people who run nc35 carbs on nc30's set-up help needed !

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G-MAN
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Re: FAO people who run nc35 carbs on nc30's set-up help needed !

Post by G-MAN » Thu Sep 24, 2009 8:01 pm

Hi Rory,

like I said my carbs has 110f/112.5R set-up on the dyno and that works fine but it could be that the floats could be a little out in your carbs and also that you are to rich on the mains. I do think that you should put an extra 0.5mm shim at the rear carbs only after you set/checked the floats just to see what it does.

1. Clean carbs
2. Check floats
3. right main jet holders in front and rear carbs. Front - holes far apart, Rear - holes close
4. Set main jets
5. Set needles to standard shims then add 1 x 0.5mm shim on rear first and check ( test ride ) then on front if needed

Let me know how you get on as I want to fool around on my carbs some more cause I think I can get it better :grin:

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Re: FAO people who run nc35 carbs on nc30's set-up help needed !

Post by G-MAN » Thu Sep 24, 2009 8:20 pm

Here is a copy and paste jobby as I dont have the link anymore :oops: :spank:

1. Top end (full throttle / 7.5k to redline -
Best Main Jet must be selected before starting step 2 (needle height)!
Select Best Main Jet
To get the best, most even top end power (full throttle/after 7500 rpm), select the main jet that produces the hardest pull at high rpm.
If the bike pulls harder at high rpm when cold and less hard when fully warmed up, the main jet is too large. Install a smaller main jet and retest until you find the main jet that pulls the hardest at high rpm when fully warmed up. This must be done first - before moving on to the other tuning ranges.
If the bike doesn't pull well at high rpm when cold and gets only slightly better when fully warmed up, the main jet is too small.
In order to properly tune the midrange and low rpm carburetion, THE MAIN JET MUST FIRST BE PROPERLY SELECTED after 10 to 15 minutes of hard use!
Do not pay too much attention to the low-end richness when you are changing main jets - you still need to be using the main jets that produce the best power at high rpm. You will deal with the low-end / cruise later - after step 2.

2. Midrange (full throttle /5k-7k)
Step 1 (Best Main Jet) must be selected before starting step 2!
Select best needle clip position
To get the best power at full throttle / 5k-7k rpm, adjust the needle height, after you have already selected the best main jet.
If the engine pulls better or is smoother at full throttle/5k-7k in a full throttle roll-on starting at <3k when cool but soft and/or rough when at full operating temperature, it is too rich in the midrange and the needle should be lowered.
If the engine pulls better when fully warmed up but still not great between 5k-7k, try raising the needle to richen 5k-7k.
If the engine pulls equally well between 5k-7k when cooler as compared to fully warmed up, the needle height is probably properly set.
Do not pay too much attention to the low-end richness when you are changing needle clip positions - you still need to be using the clip position that produces the best full throttle / 5k-7k power in conjunction with the main jets (Step 1) that produce the best power at high rpm. You will deal with the low-end / cruise next.
3. Low end (full throttle / 2k-3k)
Step 1 (Best Main Jet) and Step 2 (needle height) must be selected before starting step 3!
Float height (AKA fuel level & how to..)
To get best low-end power, set float height (fuel level) so that the engine will accept full throttle, without missing or stumbling, in 2nd gear from 2.5k to 3k rpm at minimum.
Float heights, unless otherwise specified in the installation guide, are measured from the "gasket surface" of the carb body to the highest part of the top of the float - with the float tang touching but not compressing the float valve spring.
If the engine has a "wet" rhythmic, soggy area at full throttle / 3k-4k rpm, that gets worse as the engine heats up, lower the fuel level by resetting the float height 1mm greater (if the original was 13mm - go to 14mm). This will lower the fuel level, making full throttle / 2k-3k rpm leaner.
If the engine is "dry" and flat between 2k to 3k rpm, raise the fuel level.
Example: change float height from 15mm to 14mm to richen up that area.
REMEMBER, since the main jet WILL affect low speed operation, the MAIN JET has to be within 1 or 2 sizes of correct before final float setting.
Warning: If the engine is left with the fuel level too high,, the engine may foul plugs on the street and will be "soft" and boggy at part throttle operation. Adjust Floats to raise/ lower the Fuel Level.
Base settings are usually given if a particular application has a history of fuel level criticalness. The Fuel level height in the float bowl affects full throttle/low rpm and, also, richness or leanness at cruise/low rpm.
Reference: a bike that runs cleanly at small throttle openings when cold, but starts to show signs of richness as it heats up to full operating temperature, will usually be leaned out enough to be correct if the fuel level is LOWERED 1mm. Check out and RESET all: Suzuki (all), Yamaha (all) and Kawasaki (if low speed problems occur). Needless to say, FUEL LEVEL IS EXTREMELY IMPORTANT!!!
If there are low-end richness problems, even after lowering the fuel level much more than 1.5mm from our initial settings, check for needle wear and needle jet (part of the emulsion tube). See Worn Needle and Worn Needle Jet diagram. It is VERY common for the brass needle jets (in the top of the "emulsion tube") in 36mm, 38mm and 40mm Mikuni CV carbs to wear out in as little as 5,000 miles. Check them for "oblong" wear - the needle jet orifice starts out round! Factory Pro produces stock replacement needle jets / emulsion tubes for 36mm and 38mm Mikuni carbs. Click here
4. Idle and low rpm cruise
Fuel Screw setting (AKA mixture screws)
There is usually a machined brass or aluminum cap over the fuel screws on all but newer Honda. It's about the diameter of a pencil. Cap removal details. Newer Honda carbs have no caps, but use a special "D" shaped driver, usually supplied in the carb recal kit. We do have them available separately, too. 800 869-0497 to order -
Set for smoothest idle and 2nd gear, 4k rpm, steady state cruise operation. Set mixture screws at recommended settings, as a starting point. For smoothest idle, 2nd gear 4000 rpm steady state cruise , and 1/8 throttle high rpm operation. (pj tuning information)
Pilot fuel mixture screw settings, float level (but, you've "fixed" the fuel level in Step 3 - which you have already done!) AND pilot jet size are the primary sources of mixture delivery during 4000 rpm steady state cruise operation.
If lean surging is encountered, richen mixture screws (turn out) in 1/2 turn increments. Alternative pilot jets are supplied when normally required.
Pilot fuel mixture screw settings, float level and pilot jet size also affect high-rpm, 0 to 1/8 throttle maneuvers. Too lean, will cause surging problems when the engine is operated at high rpm at small throttle openings! Opening the mixture screws and/or increasing pilot jet size will usually cure the problem.
NOTE: A rich problem gets worse as the engine heats up.
If the throttle is lightly "blipped" at idle, and the rpm drops below the set idle speed, then rises up to the set idle speed, the low speed mixture screws are probably set too rich: try 1/2 turn in, to lean the idle mixture.
NOTE: A lean problem gets better as the engine heats up.
If the throttle is lightly "blipped" at idle, and the rpm "hangs up" before dropping to the set idle speed, and there are no intake leaks and the idle speed is set at less than 1000 rpm, the mixture screws are probably too lean: try 1/2 turn out, to richen mixture. Be sure there are no intake leaks and the idle speed is set at less than 1000 rpm!

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royster81
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Re: FAO people who run nc35 carbs on nc30's set-up help needed !

Post by royster81 » Fri Sep 25, 2009 11:42 am

so in reading that G it could be a mixture of my needle height being to high which in turn coupled with a slightly rich main jet could cause my poor running around 5-7 grand, carbs where cleaned and balanced before fitting so off they come and i'll check the float heights while they are off, whip out the shims and try again.

anyone got 4 x 112 main jets i could borrow/have :grin: i'll swap you some 122.5 :grin:
It's not having what you want but wanting what you've got....Loud ,Proud and Modified ....

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Re: FAO people who run nc35 carbs on nc30's set-up help needed !

Post by G-MAN » Fri Sep 25, 2009 1:19 pm

Yes, have a go at that and see how she pulls, trail and error is the only way ;). I had 112.5 all round with a standard system + race can but wen I got the JHA system they dropped to 110 in the front so I was like " If she blows up I'm going to feed you a tyre wrench :fight: " he just laughed and said ok :wanker:

I did the clearances myself so I was confident in the motor
I murdered her on the TT course ( had to stay with an R1 and SP2 ;) ) went around that course more than 20 times in practice week and she never skipped a beat :up:

Anyway my setup works well and everyone's not always in the same boat but like I said, I know she can be setup better so I shall tip away until we get FI or members like G-Force and MR Carbon gives us some clarity on his top secret Carbon Flat Slide rattling RVF :grin:

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Re: FAO people who run nc35 carbs on nc30's set-up help needed !

Post by G-MAN » Fri Sep 25, 2009 1:34 pm

Rory , wen your bike heats up it gets worse so I would say you have to raise the needles not drop it as it seems the fuel is evaporating so you need to richen it in the mid-range

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Re: FAO people who run nc35 carbs on nc30's set-up help needed !

Post by Cammo » Fri Sep 25, 2009 1:49 pm

G-MAN wrote:Rory , wen your bike heats up it gets worse so I would say you have to raise the needles not drop it
I agree. Try an extra 0.5mm washer under the needles.

If this isn't the answer then try changing the main jets (although in reality they won't be coming to the party at the revs you're having problems).

The float heights should be set at the factory rvf carb specs, no need ever to deviate from this.
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Re: FAO people who run nc35 carbs on nc30's set-up help needed !

Post by royster81 » Fri Sep 25, 2009 11:13 pm

well i got 30 mins free today to give the carbs another look, i decided to try it with NO shims under the needles and had another look at the floats.

the floats looked to be fine and as to what the haynes say so out with the shims and a quick road test.

the result....

the bike still has a little wobble around the 5-6 mark but clears quicker ,if anything i'd say it's helped but not cured the problem, and to be honest i didn't think it would as i think i need to down size the mains first but until i'm far happier with the bike as it is..

cheers for the help guys
It's not having what you want but wanting what you've got....Loud ,Proud and Modified ....

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