Ducati.ms - The Ultimate Ducati Forum banner

1 - 20 of 23 Posts

·
Registered
Joined
·
72 Posts
Discussion Starter #1
I filtered through the FCR feeds here and didn't really get my questions answered.

1. I know it's an art form to get the air box onto the FCRs... and the posts on that drama have been helpful. But I think I'll be needing to have access to my FCRs on a regular basis as I tune them, so I think I'm going to go to the K&N clamp on filters. I don't want to go through the one hour process of removing and reinstalling the air box every time I want to tweak one little thing. Does anyone happen to know if the 3.5" is the correct one? See attached photo.

2. I've seen the links to the FCR tuning pages that have been posted here... but am shocked by what I see with the FCR synch process. What the absolute fuck? Can't use vacuum sync. Have to mechanically sync? Not even sure if mine are out of sync. I bought them brand new and bolted them on out of the box. If you've seen my ongoing rant, you'll note that they work good... but I know they could be much, much better. They're close enough now that I could live with them... but that's not why we buy old Ducatis. I want to clean this up and get it right. But I need to find out if they're in sync, and if not, sync them. I can't believe that the process has to be as noted here:

carbkie.html, Keihin FCR Carb Tuning Procedures

Good Lord. I did carb work on my last 900 SS with a Factory Jet kit, and it was a snap. This is a nightmare.

Anyway, thanks for the help.
 

Attachments

·
Premium Member
Joined
·
654 Posts
I filtered through the FCR feeds here and didn't really get my questions answered.


2. I've seen the links to the FCR tuning pages that have been posted here... but am shocked by what I see with the FCR synch process. What the absolute fuck? ... I can't believe that the process has to be as noted here:

carbkie.html, Keihin FCR Carb Tuning Procedures

Good Lord. I did carb work on my last 900 SS with a Factory Jet kit, and it was a snap. This is a nightmare.

Anyway, thanks for the help.
If you bought them new and haven't installed them yet, they'll be mechanically synched from the factory. That said, I see you're not going to take "it's fine" for an answer. Doing it off the bike is quite easy and once they are synched they don't go out of synch specifically because they are mechanically locked together. Follow the procedure to verify synch, fix what you don't like, then put them on; you'll likely never have to think about it again for the lifetime of the carbs.

I can't answer specifically about your filters. What you have shown are conical, I believe most people are using the round filters with a 20 degree offset though, the K&N RU-1750, but someone else should verify that.

Brad
 

·
Registered
Joined
·
72 Posts
Discussion Starter #3
If you bought them new and haven't installed them yet, they'll be mechanically synched from the factory. That said, I see you're not going to take "it's fine" for an answer. Doing it off the bike is quite easy and once they are synched they don't go out of synch specifically because they are mechanically locked together. Follow the procedure to verify synch, fix what you don't like, then put them on; you'll likely never have to think about it again for the lifetime of the carbs.

I can't answer specifically about your filters. What you have shown are conical, I believe most people are using the round filters with a 20 degree offset though, the K&N RU-1750, but someone else should verify that.

Brad
Thanks Brad. I bought them brand new, and carefully installed them immediately from the box. They should be good. The engine doesn't feel like they're running out of sync.... Here's my negative advertising for the N. Bay Area folks. I called Pasta Performance in Sacramento, and not only was the guy a real asshole to me on the phone, but he cut me off when I was asking him a simple question and insinuated that the carbs are probably all jacked up and will need to be gone through and synced before they can be run on a dyno. Anyway, Motowheels is who I got them from and they said essentially what you said, Brad... that they come from the factory locked in sync and set up with a base setting. I can highly recommend that anyone reading this steer clear of Pasta Performance IMHO. I'll look up the K&N you suggested. Thanks a million!
 

·
Registered
Joined
·
72 Posts
Discussion Starter #4
I think that's them... the ones you suggested Brad. I saw a Video on YouTube that showed the bent head.


Attached is the eBay photo of it... looks the same.

Thanks!
 

Attachments

·
Registered
Joined
·
1,701 Posts
you can get an adapter from k&n that is a plastic trumpet piece that screws on to the fcr to take a filter, that's an option.

vacuum syncing them is easy if you have the airbox out of the way, once you work out that you adjust the nut and lock the screw (is that right, backwards to what i expected anyway).
 

·
Registered
Joined
·
72 Posts
Discussion Starter #7
you can get an adapter from k&n that is a plastic trumpet piece that screws on to the fcr to take a filter, that's an option.

vacuum syncing them is easy if you have the airbox out of the way, once you work out that you adjust the nut and lock the screw (is that right, backwards to what i expected anyway).
At the FCR page I put up, and others, it says you can't vacuum sync. Was that wrong somehow? From the pictures in the FCR FAQ page, it looks like the mechanical link adjuster screw is under the covers... which cannot be removed while the bike is running...

... am I missing something?

See 4th photo down and read the description: http://www.ducatitech.com/2v/inside_fcr.html
 

·
Premium Member
Joined
·
850 Posts
Regarding the filters, I've attached photos of the K&Ns I used. Sorry I don't recall the part #. You'll also see the battery box I made to replace the airbox. I'm building a new battery box, as I've converted the bike to ie, so my old one is for sale if you want it.

Dumping the airbox and going to pod filters was the best thing I did after installing FCRs. Access to the engine is much, much easier. This is particularly important IMO when tuning the carbs. Throttle cable routing is better, as well.

The pics with the gold frame show the initial version of the batter box; the blue frame shows the later version.
 

Attachments

·
Registered
Joined
·
1,701 Posts
hook up vacuum measurement system to manifolds and check. no reason why you can't do that. adjusting is more effort. what's downstream of the carbs can also affect the manifold vacuum of a given cylinder, not just the throttle opening.
 

·
Premium Member
Joined
·
2,483 Posts
Why vacuum synch the FCR's at all?

Correct me if I'm wrong, but isn't the main idea of synching the carbs is to ensure the fuelling into each cylinder is the same from each carb?

I get that vacuum synching CV carbs is essential, given that their slides are opened by the applied vacuum from the cylinder - so if one cylinder is a bit off for some reason, then that slide will open more (or less) than it should do to be balanced with the other(s).

However, with mechanical opening slides - surely setting them by the static method achieves this? And any vacuum imbalances would then be due to engine peculiarities - and not particularly relevant?
 

·
Registered
Joined
·
72 Posts
Discussion Starter #11
Regarding the filters, I've attached photos of the K&Ns I used. Sorry I don't recall the part #. You'll also see the battery box I made to replace the airbox. I'm building a new battery box, as I've converted the bike to ie, so my old one is for sale if you want it.

Dumping the airbox and going to pod filters was the best thing I did after installing FCRs. Access to the engine is much, much easier. This is particularly important IMO when tuning the carbs. Throttle cable routing is better, as well.

The pics with the gold frame show the initial version of the batter box; the blue frame shows the later version.
If I understood you correctly, you're willing to part with the battery box you fabricated. Sold. I'll PM you to work out the details. Thanks for posting the pictures. I may have questions as I convert this to the pod filters... but right up front, was there anything substantial that needed to be done to the jetting when switching to the pods? When I first installed the FCRs, I used a billet ring to hold the filter on... no airbox lid. It ran poorly configured that way... like it was too lean. I put the airbox lid back on (with trumpets still installed), and it made a huge difference. By swapping to the pods, am I in for a roller coaster ride with the jetting to compensate? Did you have to do something specific to the base settings to make it work? Thanks!
 

·
Registered
Joined
·
72 Posts
Discussion Starter #12
Why vacuum synch the FCR's at all?

Correct me if I'm wrong, but isn't the main idea of synching the carbs is to ensure the fuelling into each cylinder is the same from each carb?

I get that vacuum synching CV carbs is essential, given that their slides are opened by the applied vacuum from the cylinder - so if one cylinder is a bit off for some reason, then that slide will open more (or less) than it should do to be balanced with the other(s).

However, with mechanical opening slides - surely setting them by the static method achieves this? And any vacuum imbalances would then be due to engine peculiarities - and not particularly relevant?
I agree with your analysis.
 

·
Registered
Joined
·
72 Posts
Discussion Starter #13
Regarding the filters, I've attached photos of the K&Ns I used. Sorry I don't recall the part #. You'll also see the battery box I made to replace the airbox. I'm building a new battery box, as I've converted the bike to ie, so my old one is for sale if you want it.

Dumping the airbox and going to pod filters was the best thing I did after installing FCRs. Access to the engine is much, much easier. This is particularly important IMO when tuning the carbs. Throttle cable routing is better, as well.

The pics with the gold frame show the initial version of the batter box; the blue frame shows the later version.
Ok... have the pods ordered. Also picked up the CA Cycleworks Ignition kit that you have bolted to the new version of the battery box. Ready to get rid of the dead weight air box. I think I bled plenty reinstalling the box last time. I'm good. Haha. I don't mind digging into the carbs to tune them... it's literally been just the prospect of taking the airbox out and putting in back in repeatedly that's given me pause. I was on the cusp of actually paying someone to do it for me. And here in CA, the entry fee on that is around $675. For that kind of money, I can make my carbs glow in the dark on my own. :yeah:
 

·
Registered
Joined
·
800 Posts
When I first installed the FCRs, I used a billet ring to hold the filter on... no airbox lid. It ran poorly configured that way... like it was too lean. I put the airbox lid back on (with trumpets still installed), and it made a huge difference.
When I installed FCRs I was also using a ring to hold the filter down and no lid. The bike wouldn't start hardly at all, and ran like crap. Though they were jetted as part of the CA Cycleworks kit, it was still way off for my application. I finally had to trailer the bike to a knowledgeable mechanic. He had a lot of trouble with it too and finally found that the ring wasn't holding the filter on tightly enough and the filter would bounce around. This really messed up the mixture and caused the bike to run lean at times. He rejetted the carbs and installed an airbox lid without trumpets and it improved dramatically. Still doesn't really like to start, and I live in a warm climate.
 

·
Registered
Joined
·
552 Posts
Why vacuum synch the FCR's at all?

Correct me if I'm wrong, but isn't the main idea of synching the carbs is to ensure the fuelling into each cylinder is the same from each carb?

I get that vacuum synching CV carbs is essential, given that their slides are opened by the applied vacuum from the cylinder - so if one cylinder is a bit off for some reason, then that slide will open more (or less) than it should do to be balanced with the other(s).

However, with mechanical opening slides - surely setting them by the static method achieves this? And any vacuum imbalances would then be due to engine peculiarities - and not particularly relevant?

My understanding is that on a CV vacuum is the only method you can balance the carbs, on a mechanical slide carb like the FCR they're (as has already been said) synchronised from the factory and pretty much "ready to go". But cylinders are different, there's sometimes differences in them that will effect a CV vacuum balance, a slight difference in condition or build tolerances can change compression which will change the set up if you're willing to get that fussy. It's not a major process with the airbox off and if one spends that kind of cash on a carb upgrade then why not fine tune it, the closer the balance the easier it starts, idles smoother has a crisper throttle response off the bottom......
My SL had them years ago, cold blooded fuckers they were too, never had it on a dyno, i had the jetting as supplied from CA Cycleworks when i bought them and they were great, just not as user friendly to get going on cold mornings as the Mikuni CV's....

I could be wrong though, often am, it's YEARS since i've owned a carbed air cooled 2 valve bike....
 

·
Registered
Joined
·
616 Posts
Now my 2 cents worth--I have NEVER installed or serviced a set of racked flat slide carbs--again I work mainly on BMW twins so there is no such thing as racked carbs. I have dealt with CV, Flat slide & Dellorto's on BMW twins. They all have to sync'd so they both pull the same --Now call me crazy but in the 35+ years of working on these things I never assume that anything is done correctly (@ the factory or at the carb mfg.) I have seen too many times that it was done wrong before the item was shipped--I would ALWAYS check the settings prior to turning it over to a customer or even before I test ride the bike -I want to make sure everything is correct. jetting is a different thing all together-once sync'd then the jetting changes should not-but can change everything. So I would check and adjust the synch since it is easy to do--then check jetting and adjust as needed--then check the synch again just for peace of mind. ---just an example of not trusting the factory--I have uncrated 100's of BMW's New in the crate from BMW--supposed to be set up from the factory--many of these the timing was not even close ( but it should be)--rebuilding gearboxes that require shimming to set correctly--I have seen very few that were shimmed correctly from the factory and I have rebuilt and continue to rebuild these on average of 6 a month. Again I am not a Ducati expert but I have even seen a few things with Ducati's --( from the factory) that would leave you scratching your head and saying --W.T.F.---I trust what I see---not what someone else says they did--remember C.Y.A.
 

·
Registered
Joined
·
72 Posts
Discussion Starter #19
Now my 2 cents worth--I have NEVER installed or serviced a set of racked flat slide carbs--again I work mainly on BMW twins so there is no such thing as racked carbs. I have dealt with CV, Flat slide & Dellorto's on BMW twins. They all have to sync'd so they both pull the same --Now call me crazy but in the 35+ years of working on these things I never assume that anything is done correctly (@ the factory or at the carb mfg.) I have seen too many times that it was done wrong before the item was shipped--I would ALWAYS check the settings prior to turning it over to a customer or even before I test ride the bike -I want to make sure everything is correct. jetting is a different thing all together-once sync'd then the jetting changes should not-but can change everything. So I would check and adjust the synch since it is easy to do--then check jetting and adjust as needed--then check the synch again just for peace of mind. ---just an example of not trusting the factory--I have uncrated 100's of BMW's New in the crate from BMW--supposed to be set up from the factory--many of these the timing was not even close ( but it should be)--rebuilding gearboxes that require shimming to set correctly--I have seen very few that were shimmed correctly from the factory and I have rebuilt and continue to rebuild these on average of 6 a month. Again I am not a Ducati expert but I have even seen a few things with Ducati's --( from the factory) that would leave you scratching your head and saying --W.T.F.---I trust what I see---not what someone else says they did--remember C.Y.A.
I'm with you! This is why I'm swapping to the pods... so I can access the carbs easily and check the sync and adjust the jetting or anything else I need to adjust.... not to mention access to the top of the horizontal cylinder and front of the vertical cylinder for valve jobs. Right now, with the airbox installed and connected to the FCRs at the cost of about a pint of my blood, I'm done with that. I'm dumping all of that, and first thing I'll be doing is verifying the sync.... then go from there. It runs good now... but I know it can run great. Just needs a little work. Oh, and my primary ride is a 17' tripple black BMW GS. My Duk is a labor of love as an aging Ducati enthusiast that fell in love with the 2V normally aspirated bikes of the 80s and 90s. I have it in part because of that old "zen and the art of motorcycle maintenance' adage. I love to actually work on my bikes. With my GS, I hook up the GS911 and my laptop does most of the maintenance. How boring. HAHAHAHAHA. Cheers.
 

·
Registered
Joined
·
616 Posts
lol well the newer BMW's with the canbus system I personally hate but I work on them every day, My primary bike is a 1977 R100SRS she now has 1 million 10K something on the clock, I am leaving Sunday morning early going to PA. to a BMW rally --Hans Muth the designer of the R90S, R100RS, GS80, R65 -& Suzuki Katana will be there again, He has said this will be his last trip to the U.S. --I am taking my all original unrestored 1977 R100RS to this event,
 
1 - 20 of 23 Posts
Top