Ducati.ms - The Ultimate Ducati Forum banner

1 - 18 of 18 Posts

·
Registered
Joined
·
155 Posts
Discussion Starter #1 (Edited)
What air/fuel meter are people using? And in the same vein, what size are the plugs on the carbed bikes exhausts?

And lastly, what is the stock jetting on a 96 900SS? I want to know what the baseline is when I go through the carbs.

EDIT***Forgot to ask. Anyone here on the board do carb boring?
 

·
Registered
Joined
·
293 Posts
I am using Innovate MTX-L. I have no complaints about it. Heats up and starts working in about 30 sec, and displays the changes in afr fast.

The standard plug is with m18x1,5 thread. I have it welded at the rear exhaust about 20cm from the cylinder. You get the bung with the wideband unit.

Stock jetting is main 140, starting jet 70, needle 5c22-1 in US version, 5c19-4 in european version, pilot 37.5 in US, 42.5 in Europe.
 

·
Excel Addict
2001 900SSie
Joined
·
5,345 Posts
I have the Innovate LC-1 and when getting some dyno work done, the AFR was exactly the same as the dyno's meter.

Whatever you choose, order a stainless steel bung for your stainless pipes.
Then find someone who can TIG weld.
I am parrotting what I was told ... the bung is machine grade and without knowledgable welding, the weld can seep/weep/whatever into the pipe and hence reduce the internal diameter.

Look out for packages that include the meter as this is usually cheaper than buying bits separately.
 

·
Registered
Joined
·
7,083 Posts
I took a good look at mine when I rebuilt them and I doubt there is sufficient slide dia to bore them very much. Vacuum carbs open a bit slowly when stock, especially when compared to mechanical slides. Also flow less than slide carbs, but still I think fine for the street.
 

·
Registered
Joined
·
155 Posts
Discussion Starter #5
I ended up going with the Innovate MTX-L, so I'm looking forward to that.

As for the CV's getting bored out. It was a thought, and honestly don't know how much material there is to work with.

Harleys have benefitted from the CV44 for years when building up motors. And being that the flatsides are offered in the 41 flavor, I was hoping there was that possiblity of going larger on the stock carbs. Seeing as my bike is strickly for the street (ie going up and down hills and mountains) it would be a better way to go, for me.
 

·
Premium Member
Joined
·
2,496 Posts
Beardo - DONT waste your time with the CV's! I kept my 900 standard for years - other than fitting a K&N filter and a dynojet kit (and 39 tooth rear sprocket).
Then I finally went crazy (OK - I got some money), and gave it a birthday - Full spaghetti exhaust system, 41mm FCR's, and a alloy Barnett clutch basket. You wouldn't believe the difference! It now idles - from cold, doesn't surge at ~3000 rpm, uses less gas (about 1.5 litres less per 200 km), and the carbs don't ice up any more in cold weather (never had the heater kit fitted). And where I used to watch all the other bikes just pull away from me on even short straights, I'm now right behind them (even the 1000's)! At least up to 160 kph (100mph). It still doesn't really go any faster - but it gets there a LOT quicker, and it's really nice to ride.
Carbs were from CA-Cycleworks, as was (IIRC) the clutch. Exhaust was a Sil Moto Italia system - but they appear to have gone out of business... :(
Finished it all off with a Ohlins shock for the back (from local NZ distributor).
Carb jetting was about spot on out of the box - except for the main jets, which have gone up quite a few sizes...

BTW - all my riding is street as well. Not what I'd call mountains (but some would), and LOTS of very twisty roads.
 

·
Registered
Joined
·
7,083 Posts
The surge below 3000 can be tuned out. Harleys with vacuum carbs can fit a lighter spring to speed up the slide open rate. Cut a few coils off if you don't like to spend money. I was going to cut a few coils , and I might this winter. If you try this remember the needle is mounted in the slide, so it will tend to richen a bit as the slide opens quicker in relation to the butterfly. Make sure your breather hoses from the carb vacuum are not kinked. Make sure you filter these hoses if they are not connected as stock. They will suck in dirt. I use fuel filters that can be cleaned. If those vacuum diaphragm can't move air both ways freely, they will move slowly. This will slow throttle response. Don't clean the diaphragms with anything other than soapy water, they will absorb carb cleaner. My diaphragm caps were not flat. I used a pane of glass and some fine sandpaper to make sure the sealing surface was flat. And install new o rings. My carbs work well now, but it took some work.
 

·
Premium Member
Joined
·
2,496 Posts
The surge below 3000 can be tuned out. Harleys with vacuum carbs can fit a lighter spring to speed up the slide open rate. Cut a few coils off if you don't like to spend money. I was going to cut a few coils , and I might this winter. If you try this remember the needle is mounted in the slide, so it will tend to richen a bit as the slide opens quicker in relation to the butterfly. Make sure your breather hoses from the carb vacuum are not kinked. Make sure you filter these hoses if they are not connected as stock. They will suck in dirt. I use fuel filters that can be cleaned. If those vacuum diaphragm can't move air both ways freely, they will move slowly. This will slow throttle response. Don't clean the diaphragms with anything other than soapy water, they will absorb carb cleaner. My diaphragm caps were not flat. I used a pane of glass and some fine sandpaper to make sure the sealing surface was flat. And install new o rings. My carbs work well now, but it took some work.
I had the Dynojet kit in mine - which has lighter (quite a lot) diaphragm springs. It still surged. Mainly it was too lean at that rev range. It was only a bit annoying, so I never bothered to spend the time sorting it. On the other hand, it was noticeable by it's absence once I fitted the FCR's.

A note on cutting coils off springs - that usually increases the spring rate (makes it harder), due to the length of the spring reducing. I.e. the shorter the spring, the more force needed to bend it - the longer, the easier it is to bend. Something I picked up from car suspension mods...
 

·
Registered
Joined
·
155 Posts
Discussion Starter #9
Just to clarify, I have no problems with the stock CVs. I am eyeing performance mods for the future, thus the reason I inquired about carb boring services.

I have been through more CVs than I care to remember. I would rather work on a flatside, but the CV does have it's place, and when properly dialed in, a CV is a wonderful carburetor.

At any rate, I'll keep looking. Thanks for the replies!
 

·
Registered
Joined
·
920 Posts
If you need new diaphrams then Yam FZ1000 and TDM fit. Check the float settings - 14mm in mine, the Factory Pro site has good info on setting up. They also sell chrome plated needle jets to replace worn originals. I've found the plastic slide guides in mine distorted but managed to file them to straightening things up and stop sharp edges protruding into the carb bore. I doubt there is enough metal to bore them out to anything worthwhile.

I fitted ignitech ignition to mine and then fitted a TPS to the carbs and enabled the 3d map. After a little experimenting the bike is less of a pain in town and has better pick-up. Another thing that helps (A tip from from Askim MC in Norway -thanks) was to use 2 of the threaded brass tubes from a Scotoiler and some vacuum tube to create a balance pipe. We used to do this trick on jap 4s in the 80's but I didn't think it would work on a V. It does.

I would like to try a pressurized intake like the 851. This would need all the carb vents routed into the airbox. This won't happen though as I have a complete injection engine on the bench......
 

·
Registered
Joined
·
155 Posts
Discussion Starter #11
WOW, you guys aren't quite getting what I'm saying.

The carburetors on my bike's engine, are fine.

I was simply asking if there was anyone, within the Ducati community, that offered carb boring services.

That is all. Now, I'm kinda sorry I asked.
 

·
Registered
Joined
·
18 Posts
I'm glad you asked. That was some good info.
Thanks guys.
 

·
Premium Member
Joined
·
2,496 Posts

·
Registered
Joined
·
7,083 Posts
I had the Dynojet kit in mine - which has lighter (quite a lot) diaphragm springs. It still surged. Mainly it was too lean at that rev range. It was only a bit annoying, so I never bothered to spend the time sorting it. On the other hand, it was noticeable by it's absence once I fitted the FCR's.

A note on cutting coils off springs - that usually increases the spring rate (makes it harder), due to the length of the spring reducing. I.e. the shorter the spring, the more force needed to bend it - the longer, the easier it is to bend. Something I picked up from car suspension mods...
Spring rate isn't the question here. The spring is considerably longer before installation. This is called preload. By reducing preload the initial tension against the slide is reduced and it will be able to move with less vacuum applied. The replacement slide springs were probably smaller dia. Wire, and more coils per inch. Both these things reduce rate, which is expressed as the amount of force needed to move the spring a specified distance. But less preload i.e. cutting off coils, shortening the spring, works. It's not as good as a specifically designed spring but it gets the job done. You only change the preload when you cut off a suspension spring unless you cut off the part with closer coils, as the rate in this area is lower . It does feel stiffer, but you didn't change the actual rate.
 

·
Registered
Joined
·
154 Posts
Look up noted Ducati guru Doug Lofgren . He used to have a taper bore /jet kid mod that he performed to make the stock carbs work quite well . I know he used to be in the Minneapolis area . His website was called motorcycle performance services I think , and he used to work at Fred Snyder's shop Silverback Performance.

Ron
 

·
Registered
Joined
·
7,083 Posts
See, we're going to help you wether you like it or not, and if that includes answering questions you didn't ask, so be it. If you do find someone to bore the carbs, let us know. Remember you'll need larger diameter throttle plates and these must be precise. If you have a machine shop make them, make extras and sell them. The cost will be in the machine setup. Several sets shouldn't cost much more than the first set.
 
1 - 18 of 18 Posts
Top