Ducati Monster Forum

While you are saving up the big $$$ for FCR flatslide carbs, there are mods to deal with some problems associated with the oem Mikuni CV carbs and improve their performance. For those that like to tinker, tune and refine things, you may find this useful.
I will outline a few tricks the Harley guys have shown me over the years. Since for awhile Harleys had a CV carb (40mm Keihin), it was reasonably affordable for performance shops to do extensive mods to improve performance. Since us guys have two carbs to modify and a jet kit to buy, its probably cost prohibitive to go as far as the Harley guys. After all you need to save for those FCRs ;D.
There are some mods you can do yourself however that require few bucks and some careful time.
I'll go through all the mods and then the cheap DIY mods. I'll have a mate help me with pics in my next post.
Cheers.

Besides a jet kit the modifications that I know of, heard of, read about, attempted or have seen are as follows. You may have more info and if you do please share.

Unfortunately the BDST 38 CV carbs were built down to a price.

1. Boring the carbs and fitting a larger throttle butterfly. Basically making a bigger carb.
2. Radiusing or rounding the butterfly shaft if it is angular.
3. Knife edging or radiusing the edges of the butterfly itself.
4. Taper boring the carb.
5. Reorganizing the main fuel circuit to be more "linear". It looks like ducatigirl 100 did this.  Hey 100, you are welcome to share how this was done.
6. Radiusing the slide leading edge.
7. Radiusing/porting the transition ridge from the bellmouth casting to the bored throat area in front of the slide.
8. Polishing the bellmouth area.

Some of these mods require special equipment and would be costly to pay someone to do, or if you stuff them up DIY, destroy your carb.
I will focus on the last three modifications you can do at home. I will address these with relevant pics tomorrow.
Cheers.

But...What about riding to work everyday instead of driving ? 50mpg vs 18mpg will save me money faster for FCR's than anything.

I keeding you  ;D I thought about taking a dremel to the throats of my carbs last time I had them apart. Smoothing out the casting ridges might help but by how much ? Is it worth it with a 750 ?

in conjunction with other performance mods, it can help some.  there is a limit to what you can do with a street tuned 750 Ltwin though.

Think of polishing as lubricating the path that the air or air/fuel mixture takes.  It allows it to flow faster which can contribute to smoother running and some hp gains.

Most wouldn't bother, but if you're down on $$ but handy and like to tinker, then you may be interested. Its like Tiz said, incremental improvements.
I put my money into hi comp pistons as a priority on my old M900, so the FCRs had to wait. Years later, my wife bought me my FCRs, probably out of pity. ;D  I think the FCRs tie together the whole performance package when you have had your motor worked. Or another way of putting it, the oem carbs just hold it back.
The labour intensive nature of carb work makes it cost effective to just save up for the FCRs, unless you can do it yourself without wrecking them. I'm thinking put the gas money towards the FCRs. ;D

Some time ago Doug Lofgren  was doing some creative stuff with  BDST 38s, taper bore and other good stuff.  Rumor was they worked well plus you had chokes.

I have always been impressed with what he did with the CV carbs. I was going to send him a set to modify! He moved onto EFI.

The pics will show a job 90% done on a set of CV carbs.
#I have radiused the bellmouth to carb throat transition and removed the hard angle there. This helps improve flow by reducing turbulence. You have effectively ported the area. The cast angle of the bellmouth meets the straight bored angle of the throat with the edge restricting air flow and causing turbulance.
#As Tiz said the polishing of the bellmouth reduces friction and increases air speed. Zipper Performance and other tuning houses highly polish the carb parts that meet air, as distinct from air/fuel. S&S do this and Mikuni do this on their high end carbs. You pay extra for Mikuni Pro Series carbs that are hand finished.
The dremel is your friend. Use fine sand mops as you would for porting or equivalent tools. I finished with finer and finer polishing using very fine paint finishing material on a foam backing and then metal polish. Overdo it and you'll be calling SUDCO. [laugh] You've been warned. ;D
# With great care radius only the leading edge of the vacuum slides. Again to promote flow and reduce turbulence. Metal slides give more room for error. These Mikuni slides are plastic, so go slow and careful. The slide leading edge is a hard square angle and tuners deal with this. Dynojet are now selling nicely finished carb slides in their kits for Harley carbs. Again overdo this and you'll be calling Powerbarn or SUDCO. ;) The straight edge is gone and some say the straight edge contributes to slide flutter which gets worse with soft springs. Lofgren uses stock springs.

You'll need to give the carbs a bloody good clean and blow air through them.

See below more like how they should come from the factory compared to stockers which show the bored ridge, sharp edged slide and unfinished bellmouth casting.

(http://i1024.photobucket.com/albums/y304/tonykokonis/20160506_221305_zpszdpyyxol.jpg)

Any before pics?

As you can see, still more polishing to go. I put them together for pics and to not lose anything. I will do some more polishing of the bellmouths to promote air velocity.

The pics of the slides show the radiused leading edge. Despite the discolouration they are smooth as a baby's bum. I did not touch the actual cutaway size itself,  just the bottom leading edge. Dont be fooled by the phone pics, each cutaway is symmetrical.

They need a little more work but there is a gentle radius to the throat from the bellmouth with the angled edge eliminated. It gives a nice taper which will help airflow.

All this should help reduce turbulence and improve airflow in volume and velocity.

Actually...my stock carbs were gifted to another member that had a set on his SS that were acting up.

I'll never have to look at the inside of them again. ;D

I was surprised how bad the transition to the throat was and how "grippy" the bellmouth casting was to the touch. With the square edged slide and throttle butterfly, and bad transition from bellmouth to carb throat, it's no wonder the carbs have slide fluttering turbulence.

Surface finish alone is a complicated enough subject when discussing flow and turbulence, never mind shape. It can all get very counter intuitive.

Hurts my brain. ;)

I hear you.
Mikuni use coatings on some TM carbs,  polish RS slide carb bellmouths and hand finish the bellmouths on TM Pro carbs. WASP use golf ball like dimples on their velocity stacks and CD/TPO have smooth anodized velocity stacks. S&S leave a mirror finish on their bellmouths.
 :P
I went with polished on the air side and textured on the air/fuel side (ports and manifolds).
When I fit these carbs Im curious how soft a slide spring I can use without slide flutter.

I think I'd have done the same knowing what little I do about the subject.

The laminar flow thing on the downstream side is what really gets tricky.

Yeah, I know a bloke in the 80's who polished the ports of his race motor only later having to tear it down to scuff up the heads. ;D
I hadnt my licence long and this guy was a racer who started explaining this stuff to me. He found out the hard way. It was like another language, I was pretty green and just learning  about, well, everything!

I wonder if there would be any advantage with a vortex shaped surface leading into the bell mouth?  Something to direct the incoming air in a pattern..

I really dunno. Modifying evidence of cost cutting is easier. What do you mean?

You got a pic of unmolested carbs?

Nibor has a set of stockers. I'll ask him to take a pic to show the hard edges on the slide and in the throat.

I'll pass it on to Nibor and let you know when he gets back to me! :P

When he tells you, let me know ;D

PM sent.

Nibor came by last night with a set of stock carbs off Nugget and took some pics.

Examining the stockers, not only does the bellmouth to throat area transition have an angle from the front of the carb, but drops over into a lip or ridge because the carb is bored from the rear and the boring stops short of the bellmouth casting. You cant see it, but its quite pronounced when feeling it with your finger. That wouldnt help smooth airflow. I'm guessing that if the bore went through, they would have had to clean up the angle by hand, which costs. Like I said, built down to a price. You dont see that on Keihin or Mikuni performance carbs.

When cleaning up that area don't venture too deep and damage the bore and CV slide recess. Stay short of that area unless you are Jerry Branch. Im only suggesting the mods that shops have been doing since carbs were invented but are DIY. Just want to clean things up a bit and get a nice radius on transitions.

Thanks for your help Nibor.

(http://i1024.photobucket.com/albums/y304/tonykokonis/1024x768_bestfit%203_zps1vihhjhr.jpg)

You can see how unfinished the stock carbs are to meet the price point.
The modified carbs aren't quite finished, but you get the idea.

(http://i1024.photobucket.com/albums/y304/tonykokonis/1024x768_bestfit%202_zpszifpzduw.jpg)

I Googled Vortex to get the Fluid Dynamics perspective rather than the Star Trek perspective. ;D

You guys are spelling it wrong.

http://www.vorteccyclone.com/what-is-it.html (http://www.vorteccyclone.com/what-is-it.html)

that's interesting.

my thought was that it would enable a better mixture and "aim" the air flow.. no idea something like that existed.

Vortex generator testing:
http://www.popularmechanics.com/cars/a310/1802932/ (http://www.popularmechanics.com/cars/a310/1802932/)

That is not what I had in mind -- that adds an obstruction to the air intake.

I'm saying to shape the intake bell mouth sids in such a way as to have a vortex shape -- not add vanes to the center.

You probably don't believe in these either
http://www.jcwhitney.com/airaid-econoaid-throttle-body-spacers/p3089913.jcwx?filterid=j5 (http://www.jcwhitney.com/airaid-econoaid-throttle-body-spacers/p3089913.jcwx?filterid=j5)

I was just wanting to refine and finish the part to bring it up a bit in an attempt to follow the established practices of people smarter than me. Well, the easier ones anyway. ;D

There are mods I just don't have the theoretical knowledge or equipment to attempt. It no longer surprises me that so many theories when put into practice, often don't work as expected. I have access to two dynos, one is very free access, but someone's gotta pay for it and I don't want to anymore. ;)   

"Jc" means "just crap"

OK, how about this?
http://www.kjmagnetics.com/proddetail.asp?prod=FuelMag1&gclid=CJ2Xhvzci8YCFcMSHwod1kAAsA (http://www.kjmagnetics.com/proddetail.asp?prod=FuelMag1&gclid=CJ2Xhvzci8YCFcMSHwod1kAAsA)

Also good for lumbago. ;D

 ;D

Just an update.

Things were quiet, so out of interest, I thought I would try out my finished "ported" OEM carbs and road test them. I have no idea if they make more peak power as I have not taken the bike to a dyno, but they definitely give more response. The small throttle transitions are more responsive as is roll on response. Nowhere as good as FCRs, but better than the dyno tuned jetted stock carbs that I was running as a comparison.The carbs could be better tuned as my synch tool is at a mate's place at present, so response should improve even more with the carbs synched.

I tested different slide springs and needles, OEM, Factory Pro and Dynojet. I did not encounter any slide flutter even with the DJ springs (maybe a smidge, maybe). Normally the slides quiver at larger throttle openings with soft springs (iirc from a while ago). Mind you my test was looking down the carbs on a revving, stationary bike, and not at "speed" on a dyno. I'm guessing the carbs flow more air due to less turbulence with air being better guided down the throat of the carb. Any thoughts on that?

I got good response with the DJ springs and ended up using them with DJ needles. The richer DJ needles on the richest notch gave the best response as the bike wanted more fuel than with the stock carbs. The lean spitting/missing was eliminated only on the richest notch.The plug colours were milk chocolate brown. I suspect 1/4 and 1/2 throttle are good, but that it may be too rich at 3/4, or vice versa, but we'll see. Maybe the FP needles might work on a high setting there. I may go back a notch for economy at cruise after more testing, not sure.

I wont understand all the ramifications of the carb mods until I do more road testing, plug chops and dyno test with an EGA. 
There was a better connection between the throttle and the back wheel. Quite noticable. I will try adding an airbox mod when I can get a fresh airbox lid to molest.

When you say taper bore, does that mean tapered from inlet toward engine?  I have heard of doing an oval bore, that is actual boring the same size as carb bore but moved up so as not to disturb holes on floor of bore.
Sterling

Expert tuners/builders like Doug Lofgren have used taper bore modifications as you describe. I mentioned such modifications among the more expensive options requiring specialized equipment in skilled hands. I can understand not wanting to bugger anything up!

I think the Mikuni CV38s have a good taper in the bellmouth but the transition to the carb throat is poor imho. It starts well then ends poorly. Im just porting the transition area by hand to finish things. As I've said you can see how they are built down to a price. In the past, going from CV carbs to FCRs was a no brainer, but FCRs are becoming very expensive down here with the falling Aussie dollar, new import taxes and increased shipping costs, so I've had a rethink on that. Just playing with jetting and slide springs, while giving some improvement was still very frustrating, but this has been a step in the right direction. Its all about acheiving that linear response.

I have been encouraged by some recent testing of hand finished carbs akin to "porting". There is evidence so far of increased midrange air flow and increased air velocity at lower revs/throttle positions. There is improved throttle response and a more direct feel. More testing is needed with airbox and jetting mods however to determine and adjust fuel requirements. At least test riding is fun! [Dolph]

The idea of this thread is to show what so many very capable hands on members here can do themselves. It's pretty much the Ducati story of polishing up these pearls.

Mikuni have "Pro" series flatslide carbs which are hand finished. Mikuni claim flow improvements applying the principles of hand porting to these carbs and you pay a premium accordingly.

I have seen oval and "badge" or "heart" shaped inlet bellmouths in the Dellorto catalogue. The smaller diameter lower section promotes air velocity over the slow fuel circuits and the large top section gives the air volume for top end power. Some of Dellorto's premium flatslide carbs have this feature. Pretty cool looking carbs.

Here is some interesting tuning information from Factory Pro.
http://www.factorypro.com/tech/carbtun.html (http://www.factorypro.com/tech/carbtun.html)
There are two sections, up to 7000 rpm and  7000 rpm and above.

Cold weather will be here soon.  I have a big list of projects for my M750.  These carb mods will be another.
Sterling

I got that one, it's a good guide. [thumbsup]

Feel free to ask for help tuning the carbs if you modify them. Im testing jetting at present. If Im not around, there are other more knowledgable people who can help. Cheers.

Just a tuning update for anyone considering this. Some things that stand out so far:
1. Idle mixtures may or may not be affected depending on what type of airbox mods you are considering.
2. The mid range requires more fuel. With no or only simple airbox mods hopefully not more than one or two notches on the needle.
3. Running a stock airbox or open but otherwise stock airbox will be easier to tune.
4. The extended or expanded open airboxes I have been testing appear to make greater demands on the tuner to change jetting in a sometimes counter intuitive way. This is a subject for a seperate thread.
5. Consider normal jetting for stock or open airboxes with an extra notch richer on the needle to start with.
Edit:
6. Further testing has indicated that the fuel may be atomized more efficiently at low rpm as I have needed smaller pilot jets and/or idle mixture settings. This may mean you have to play with the needles to compensate for the area that overlaps the two circuits in the lower mid range. Just thought I'd add this as you will need to be prepared to play with the jetting if you do these mods.

CCW has 37.5 pilot jets if you find the bike will run with the idle mixture screws closed like I did. I even tried 35s but would need even more lower midrange fuel again.

If you try these mods, let me know and we can discuss jetting options.
Cheers.

I have sold my Monster, so my testing has ceased until I  work on another carbed bike with this mod.
First time in my life that I dont own a carbed vehicle. ;)

 :'(

Yep :'(

On the bright side, it has gone to a customer who has desperately wanted one and who will cherish it like I did. It stays in the family and I will still take care of it. :D


I'll pick up this thread if there are any questions or when I next work on a set of modified carbs.

01 M750 BDST-38
What is the correct float height number?  I read 14mm somewhere, the carbs are now on my workbench.  The number I'm getting is 10mm. 
Pilot jets are 37.5, mains are 140.  Manual call for 40 pilot and 132.5 mains.
K&N air filter and exhausts are now straight thru with perforated tube.
Any suggestions?
Sterling

Most use the 14mm height, but that is with stock pilot jets. It might be that the PO raised the float height to counter the effect of the smaller jets.

The ;larger mains make sense with the exhaust mod,

How did it run?

Or they used the FCR float level by accident (9mm)? A 4mm difference is a fair step..
Stock airbox?

When I got the bike it had foam pods.  One of them caught fire.  I went back to the stock airbox with a K&N filter.
The bike ran pretty good but before putting it away for winter the idle needed to be turned up.
I have since shortened the silencers and removed everything inside.  I used a perforated tube with fiberglass packing.
I did ride it once after the silencer mods, bike ran well but would not idle without help from the enrichener.
Now I have the carbs off, I'm going to install #40 pilots.  Now I don't know if I should reset the floats to 14mm or what.  Its going to be 70 here tomorrow, 72 on Wednesday. So what do I do?  I can change jets easy with the carbs on but setting the floats for me is next to impossible.  Replacing the cables took me a couple of days last time.
Sterling
Thanks for responding

14 mm.

Don't disconnect the cables from the carbs, disconnect them from the throttle tube.

Check your needle jets for being worn oval by the needles sawing at them. If they are silver looking in colour and not bronze, then leave them as they are more likely to be ok.

With straight through pipes consider a larger main jet again if it feels hesitant and weak at higher revs and greater throttle opening. You may need a jet kit. Maybe give Dynojet or Factory Pro a call and discuss your open pipes.

Also, you will need to adjust your idle mixture to get a nice even idle. Once you have put the 40 slow jets in you could start at three to three and a half turns out from gently seated as a base line. Set your warm idle speed at around 1250 rpm if it has a tacho. If you have a manometer  giving the carbs a good synch works wonders for smoothness and response.

My plan as of this morning is:
Adjust floats to 14mm
Install the #40 pilot jets
Put everything back together and see what happens.

Hopefully I'll have some results this afternoon.

Thanks, Sterling

How did it go?

The #40 pilots are to small, I have 42.5s and 45s coming tomorrow. 
It will idle but screws are out almost 4 turns.  Will not take throttle and will not cruise at low rpm's.
It rips if the rpm's are up.  When I get the pilots right, maybe at low rpm cruise will get better.
I knew that lowering the floats 4mm would create new problems. 
Appreciate your interest. 
Rain is predicted for a few days, so I'll do the jets tomorrow.  When the rains stops I'll do some more testing.
Sterling

What method did you use to adjust the float level?

Will be interested to see if 42.5s or 45s work best.

Would you describe your exhausts again, or maybe a pic?

That might be your issue there. Don't be surprised if foam pods don't flow as well as an airbox with K&N filter.

I took some pictures.  Can someone direct me to a tutorial to upload.
Jets should be at the mc shop today. 

http://www.ducatimonsterforum.org/index.php?topic=109.0 (http://www.ducatimonsterforum.org/index.php?topic=109.0)
http://www.ducatimonsterforum.org/index.php?topic=72635.0 (http://www.ducatimonsterforum.org/index.php?topic=72635.0)

In Flickr, click on the image and then click on the curved arrow and it will give you a choice of what type of link. Choose bbcode in an appropriate size and paste inbetween the [img] tags.

Not yet...

(https://farm2.staticflickr.com/1511/24508554272_9f764ea6bc_b.jpg) (https://flic.kr/p/DkJKjy)ratinbooth (https://flic.kr/p/DkJKjy) by nh_painter (https://www.flickr.com/photos/26408631@N02/), on Flickr

Quote my post and you'll see what you're looking for

I have to give this up for now.  Be back later.

(http://i1168.photobucket.com/albums/r490/swcaudill1/ducgagexh%20098_zpsowtjrswb.jpg?t=1458073970)
(http://i1168.photobucket.com/albums/r490/swcaudill1/ducgagexh%20092_zpsni6cxk6w.jpg?t=1458073977)
(http://i1168.photobucket.com/albums/r490/swcaudill1/ducgagexh%20092_zpsni6cxk6w.jpg?t=1458073977)
Looks like it works.  Pictures are too big.
I'm getting too old for this type of tech.

This is the third pic.
(http://i1168.photobucket.com/albums/r490/swcaudill1/ducgagexh%20096_zpshkuso24f.jpg?t=1458073977)
First picture previous post.         Float level gage
Second picture previous post.     Silencers cut to 10" oal
Picture this post                        Silencer exit end, 1 1/4" perforated tube

Floats set to 14 mm
Changed to 42.5 pilots

With 40 pilots very lean, popping on decel
With 42.5 pilots transition from idle to midrange seems rich.

I may have a fuel delivery problem. 

Sterling

Thanks Speeddog and Ducpainter for posting help.

This is a great forum.  Thanks to all for the help.
 

Often the way. Sorting one rpm range and having an issue on the overlap to the next fuel circuit. You fitting a jet kit? Needle postion, taper and root diameter via a Factory Pro or Dynojet kit may give you options. A smaller root diameter might let you get away with a smaller pilot. The oem needles are on the lean side with a large root diameter and very little taper if thats any help.

If the 42.5 pilots are to rich in the middle.... try to move the clip on the needle  up a notch    ex: if you where 3th notch from the top put it a the 2th notch from the the top .....

This will lean out the mix between 1/4 to 3/4 of the trottle.

If it dosent work well

Go back to 40 pilots ( assuming they don't pop at idle)   and move the clip position on the needle as needed .

Clip closer to the top = more lean
Clip closer to the bottom = richer

 [shot]thanks Ducatigirl
My needles have only one notch.  My bike is '01 M750.  My copy of the Ducati parts book (750 Dark) show notches. 
I can remove the washer on the needle, but going to think about this until tomorrow.
Sterling
 

What needle is it?  Manufacturer and number.

Mikuni symbol then 5C22.  The needle looks like polished aluminum.
Sterling

Some carb porn for you, Koko  :P

http://www.yoshimura-jp.com/en/products/engine/yd-mjn.php (http://www.yoshimura-jp.com/en/products/engine/yd-mjn.php)

(http://www.yoshimura-jp.com/special/yd-mjn_black_absolute/images/yd-mjn_ba_main.jpg)

Hot! Looks like a magnesium bodied race carb. Pops Yoshi.

Sounds like the needles are stock, so a good Dynojet or Factory Pro jet kit might give you the adjustability you need to play around with the settings and dial out the transitional issues. It can take some time without a dyno and EGA.

I'm a fan of Dynojet needles and Factory Pro needle jets.

I guess I could share the "black magic" of this mood ..   ;D

 ;)

I am interested in the process and may try it on a spare set of carbs.

Any progress?

Sorry about my delay posting. 
Set the floats back to the original setting.  Dropped back to #40 pilot jets.  Todays ride was good, not perfect, bike is fun to ride.
I'm going to ride this set up a few days. May need to go back to #37.5 pilot and drop needles a little.
There is so much info about float setting.  The right side float measures about 2.5 mm higher than the left because of the shape.
I set the left side at 11 mm, right side float was 13.5 mm.  I'm talking about one carb float, left side and right side.
Maybe this is common knowledge, but I've learned a lot more about these carbs.
My friend that lives in NW PA reminded me we have a ride in Lewistown, PA in May.  He rides a 900SS bevel that he bought new it is a beautiful bike.
thanks,  Sterling

Yeah the two float halves in each bowl are not symmetrical. You measure off the squarish one rather than the romboidish shaped one in each bowl. Its 14mm off the squarish float half. One of the float halves is trickier to measure on the inside position. Going off the wrong float half throws out your setting big time. The float has to be only half bottomed out because the needle has an internal spring. A 45 or less degree angle of the carbs not quite upside down gets you the correct drop of the float. Its easy to stuff it up if you dont know the little nuances of these carbs.

Just got off the phone with Eric. Flatslides have risen in price significantly for this year. Sudco is saying the price will be $1400 with no availability until July.

Start saving nickles and dimes along with those pennies. :-\

Ok everyone, and just so you know I'm not getting anything outa saying this, but snap up the FCR carb kits from Motowheels and California Cycleworks while they have stock. Prices are under a grand USD for the 41s and under $900 for the 39s, so you save yourself 500-600 bucks. If I had the cash I'd buy a dozen sets, but nearly all of my few Ducati customers already have them.
They are sponsors so I'm happy to plug these guys and give you the heads up. I think the oem carbs were a real bad choice for these motors bar the enrich/"choke" circuit.

Upon investigation the FCRs are getting scarce, so I guess I better start modifying Mikuni CV carbs and putting them aside.  :P
The lack of response of the oem carbs is really apparent after you have tried FCRs. Some of the mods in this thread help noticeably, but you just cant emulate the immediacy of response you get with well set up flatslides.

BSST 38 question.
  I've been having trouble with the idle.  Seems like the throttle stop screw is much further in than I remember. How far open should the throttle plates be?  These are open 2 to 3mm. 
Sterling

What kind of trouble?

Doesn't want to idle, I continue turning the idle screw in but after a ride its too low again.  I'm going out for a short ride now.  Report back later.  

The ride didn't happen.  Wind came up with some rain.  I'm thinking the idle circuit must be plugged or something.

Hows it going?

After a bit of playing with components, here's a thought; you can add a quick turn throttle to carb mods for the soft acting BDST38s. Unlike flatslide carbs, the carbs are forgiving to the point of being boring.

Motion Pro, Domino and Mikuni all have single cable, quick turn throttles and some come with different cams to tune the action. While FCRs can be abrupt and nowdays come with a gentler initial throttle action, the BDST 38s require a long pull and have a slow action. Being butterfly carbs, a single cable throttle will work fine if correctly set up in contrast to slide carbs which need a push/pull throttle or heavy return springs for safety. I consider a single cable for ease of installation and a clean action. The irony of push pull throttles is that if set up incorrectly they can cause your throttle to jam open! Otherwise they can return poorly and be unsafe with very high idle speeds from not returning correctly. Caveat: Any carb can jam open if set up and adjusted incorrectly.
A quick turn throttle will therefore help the impression of throttle response on the softly responding CV carbs.
I am going to test a Mikuni Quick Turn CR Pro Comp throttle I have ordered from our Mikuni importer. It appears to be made by Motion Pro for Mikuni. Will let you know how it goes.

Last few days I been riding not tuning the carbs.  One of my problems was the small spring that goes between the sync lever and throttle lever was missing.  I think it fell out while reinstalling the throttle cables
Now I have the mixture screws out 4 1/2 turns.  Idle is good and bike pulls strong.  The problem I'm having now is at low rpms (2000-3500) there is some surging.  Really not bad.  The warmer weather helps.
I now have 40 pilots installed, since the mixture screws are so far maybe I should go up to 42.5. 
The needles (one notch only) has the stock washer under the clip.
Sterling

Needles stock or aftermarket? Do they taper to a point? One notch from top or bottom?

I read it as the needles only have one notch. That would make them stock....no?

Must be stock, only one notch. There is a small amount of taper.

Yep sound like stockers. They will be way too lean for an open airbox.

I have a stock airbox with a K&N filter.
If I can sort out the surging, it will be fine for me.
My local MC shop has the washers for raising the needles, I'll try that.

A good tune by synching the carbs after getting the spring replaced and resetting idle mixture should work. No wonder its surging. Maybe get the shop to go over the carbs and give them a tune.

Koko,
The spring is replaced and carbs synced.  Idle is good.  Plugs look perfect.  I'm hoping 42.5 pilots will allow me to screw in the mixture screws some.  Then I'll try the raising the needles a touch.
Bike is a blast to ride.  Eric at Clubhouse Motorsports did my forks, I'm really happy with the suspension.
So I need to put some miles on and see what's next.

Cool [thumbsup].
Enjoy your machine. There's nothing like a Ducati.

He's a magician when it comes to modifying and setting up forks. I recommend him to everyone with no hesitation.

Did Eric end up fixing your carbs?

No, but he did give me some advice.
What sucks is removing everything for access.  But, once you've done it a few times its not so bad.
This is a great forum, kept me going when I wanted to give up.

Thanks 

 [thumbsup]
I seperate the battery box from the airbox into two parts to make it easier. Then a light Lithium battery is good to reduce stress on the battery box bolts and you lose 4-5kilos.

I'm old school when it comes to batteries.

Give me a flooded lead acid battery every time. I'll lose 4 kilos off my lard ass if weight is an issue. ;D

My bikes get lighter, but I get heavier. :P

need more mods for the Mikuni's Koko, so we have more time to save. need much more time to save now!!

cant believe that price hike...

Yep, shipped with Paypal they come in at over two grand of our Pacific Pesos.

(http://i1024.photobucket.com/albums/y304/tonykokonis/20160506_221305_zpsu1vindj1.jpg)


Just a recent pic of two Mikuni carbs showing the before and after work. Someone handy or with experience can do this with a dremel. The carb bore is bored from the engine side and stops just short of breaking through to the bellmouth. This creates a double lip which can be smoothed out. Maybe some batches were better than others.
It gives the impression in the pic that you have made the bore larger but all that is done is unite the throat diameter with the bellmouth diameter. This gets rid of the turbulence causing step and creates a smooth radius and transition to the carb throat for better flow.
Next you radius the front edge of the lower slide to reduce slide flutter and improve flow.
Polish the bellmouth to reduce friction to the surfaces that face incoming air to increase air velocity and you get another 0.5 hp [laugh].
Maybe it's worth it now FCRs cost a bajillion.
If you want to go nuts notice that the butterfly shaft is square and not round like many other butterfly carbs [bang]. Then you can go really nuts and knife edge or "airplane wing" radius the butterfly itself.

Yep, Mikuni BDST38s, built down to a price.

However, I think the BDST 38 bellmouth has a better taper bore to it than the FCR, and a choke.

(http://i1024.photobucket.com/albums/y304/tonykokonis/1024x768_bestfit%2021_zps5wcnfprn.jpg)

Without the slides to show the porting.

 [clap] [clap] [clap] [clap] [clap] [clap] [thumbsup]

(http://i1024.photobucket.com/albums/y304/tonykokonis/20150617_104652_zps0p2ilasy.jpg)
(http://i1024.photobucket.com/albums/y304/tonykokonis/20150617_104540_zpsqddxnarc.jpg)
The down side of these carbs is carb freezing but as discussed in another thread there are some things which helped a lot. Finally got some pics up on this. Worked quite well at temps you could endure while riding.

The 42.5 pilots are in, 2 turns out.. No other changes.  Bike is running great.   
Sterling

 [thumbsup]

(http://i1024.photobucket.com/albums/y304/tonykokonis/1024x768_bestfit%2015_zpsr7uscdpv.jpg)