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Discussion Starter #1
Ok... if you've been following my rants about setting up the FCRs, here's the next chapter. I got the EMR needles in the mail a couple days ago. I pulled the stock EMT needles and held them next to one another... you'd probably need a microscope and an engineering degree to tell the difference.. but I used a magnifying glass, and sure enough, they're both stamped appropriately... EMT and EMR. Anyway, I swapped them out. I had the EMT needles on the 6th rung from the bottom (richer setting - lifting the needles out). I put the clips on the EMR needles on the 4th spot as a starting point... and though they look identical to the EMTs, the bike runs noticeably different. Better. I almost wonder if I should have gotten EMQ needles. But, still having the same very small problem in the same range (1/2 to 3/4th throttle). Feels ok at 1/8th to 1/4th throttle. When I'm wide open and the RPMs exceed 6k, the bike takes off and almost feels like it's floating it's charging so hard. I moved the clip to the 5th spot as an experiment. About the same... Looking at the plugs, the color is better than with the EMT needles, but still could be interpreted as lean(ish). Very light brown on the electrode... leading to almost a white tip. And the top of the threads are pretty white. I'm wondering if I should go to the 6th spot, or just move to a larger main jet. Looking at the FCR table that shows where the effects are greatest, it's not the main jet area that needs to be better. It's where the needles are... And everything I've read says it's more about throttle position than about RPM (hence why I'm describing this in terms of throttle position instead of strictly RPM). The spot that needs to be cleaned up is with the throttle at 1/2 to 3/4ths. Again, needle territory. But it was evident that with the EMTs, I was running out of adjustability. I don't want the same problem with the EMR needles. Should I buy EMQ? Should I try a larger main jet? Not sure where to go from here.

Tossing in a photo at great risk. I'm sure everyone will start fighting over the color of the plug. Sorry if that happens.
Plug.jpg
 

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What plug gap was that? I forgot, do you have the stock coil packs? I seem to remember you did just replace the spark plug wires?

At any rate, new plugs for the new needles and or adjustment tests.
 

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the emr has a smaller root diameter, and the only impact it will have is before the needle taper section comes out of the top of the needle jet. ie, up to 1/4 throttle or so at a guess. it's an attempt to make a smaller pilot jet (and realistic idle mixture) work with the resultant low throttle change you get.

** i think this bit is wrong now > well it'll also be a bit richer all the way down due to starting at a smaller diameter. but i don't think that'll make that much difference. i might modifiy my dellorto spreadsheet. off to excel land. what a happy place.

maybe you need a needle with a steeper taper, one one that starters the taper earlier hence giving a smaller diameter at higher lifts. see the attached chart - maybe an fmr or ehr for instance.

 

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found some cool charts here, this is #1 for the fcr needle comparison, go next to go through the series. https://pbase.com/jdjetting1/image/61896683

not sure about graph 2, from how i read the needle charts the measurement is from the top, however this graph would indicate that the measurement is constant at / taken from the bottom and the smaller root diameter would make the taper start later. i assumed the taper would start from the smaller diameter at the same point, which would give a graph with 4 parallel lines, not a single line with 4 starting points. but if this how it is, that's easier to interpret and compare.
 

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Discussion Starter #5
What plug gap was that? I forgot, do you have the stock coil packs? I seem to remember you did just replace the spark plug wires?

At any rate, new plugs for the new needles and or adjustment tests.
For RockAZ, I put in the CA Cycleworks coil pack with new wires. The kit came with new plugs, but I just installed new plugs a couple weeks before the kit arrived (exact same plugs came in the kit that I just installed - brand/nomenclature). I don't recall what gap I used.. .032" sounds familiar ... but I pulled it from the service manual for the 900 SS and used the plugs recommended by the same manual in the NGK brand.

maybe you need a needle with a steeper taper, one one that starters the taper earlier hence giving a smaller diameter at higher lifts. see the attached chart - maybe an fmr or ehr for instance.
Thanks for the information, Belter! I'll look over the link you sent and see if I can't figure out what needles to go to next. They're cheap and easy to get hold of. I paid mid $20s with free shipping for my EMR needles. No biggie to buy more.

Here's where I currently sit just as an update. I have the EMR needle now on the 6th position (started at the 4th). I swapped out the 155 standard main jets with 165. Bike runs noticeably smoother across all rev ranges and takes off like a scalded cat at wide open throttle. Pulled the plugs... both are now a nice even golden brown across the whole of the electrode. No dark or white/gray spots anywhere.

The interesting thing is that when I had the EMRs at the #4 and #5 spot, with the 155 main jets, the power was good at wide open throttle and linear up to redline. With the 165, it's VERY noticeably stronger over 6k, but poops just over 7k (you can feel it start to drop off). If I keep the RPMs between 5.5k and 7k, it's amazing!

The 1/4th through 3/4th's throttle still seems a bit lackluster unless I keep the RPMs pretty high (engine doesn't really come alive until about 5.5k RPM as noted above). I don't need this to be a torque monster down low necessarily... but I'd like for it to go when I turn the throttle instead of just make a bunch of noise. As it sits, I have to downshift to get moving if I'm below 5.5k.

Idles great now that I know the secret with the mechanical idle adjuster... turn it up to get it to start and idle... turn it down as it warms. No hanging idle for the most part. From zero to 1/4th throttle, nice and clean.

I'd say at this point, the bike is livable as is. I may ride it this way for awhile and see if there are any changes over time to the spark plugs.

Any thoughts?
 

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ime the 900 with 41 will get rich at the top end. like quite a lot. the 165 would i expect be quite too rich 8k up, and that may be influencing what you're feeling. they have a leaner lump in the air/fuel curve 6 - 7k.

if it's not coming good until 5,500 maybe it needs the cam timing done. what mufflers are on it?
 

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Always hard to say without seeing what you are looking at. I had a 944ss with split 41's and the mains needed to be larger than normal simply because he was running a exhaust that was too large for the motor. Jetting is about fitting the needs of the motor with what you have assembled, good and bad parts. in my experience if you are throwing fuel at it , the bike is telling you that something likely is not as good as it should be.

You mention that it runs great at about the area where belter mentions a lean spot so that sounds like the bike might prefer you to lean out the main jet and then work on richening the lean area to get you to the same place it is now and runs well.

For the cost of a few sets of needles why not find a dyno in your area and get air fuel mapped out so you have a better idea what you are looking at?
 

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Discussion Starter #8 (Edited)
ime the 900 with 41 will get rich at the top end. like quite a lot. the 165 would i expect be quite too rich 8k up, and that may be influencing what you're feeling. they have a leaner lump in the air/fuel curve 6 - 7k.

if it's not coming good until 5,500 maybe it needs the cam timing done. what mufflers are on it?
belter,

I'm running the stock headers with Fast by Ferracci slipons. I have pod filters with the FCRs (racked 41s). No cam work done ever. Fully stock.

You mention that it runs great at about the area where belter mentions a lean spot so that sounds like the bike might prefer you to lean out the main jet and then work on richening the lean area to get you to the same place it is now and runs well.

For the cost of a few sets of needles why not find a dyno in your area and get air fuel mapped out so you have a better idea what you are looking at?
ducvet,

Here in CA, it's over $600 for a dyno run, and they're typically booked a couple months in advance. Riding season is from January to December, so they have plenty of business. HAHAHAHA. I can buy every conceivable needle and jet for less than that. I don't need it perfect... just having fun trying to get it close.

Also, that's not the first time I've heard what you and belter said about the size of the mains.... I had to go digging around once I read yours and belters words... Bikeboy.org says the same thing.... See: http://www.bikeboy.org/900SSwithkeihinfcr39and41mmcarbs.html

Perhaps I should go with .... ummm..... 150 mains? I have the two kits (one for each carb), but in 5 size increments... 150, 155, 160, etc... Bikeboy said he went with the 152... the 150 will have to suffice.

So that brings me to richening up the middle where the problem is.... I've been looking over the the FCR needle selection stuff....

belter mentioned, "maybe an fmr or ehr for instance."

If I'm reading the chart right (see attached), then the current EMR would read:
(E): 1degree00
(M): 79.15 = L1
(R): 2.755 Diameter

Looking at the Pat Burns tuning guide (http://900ss.proboards.com/thread/162/fcr-tuning-proceedure), it says in part,

"Needle selection:

1st letter: This portion of the needle controls mixture between approximately 1/3 and full throttle. If the engine fails to respond to main jet changes, you may be too lean on this, causing the tip of the needle to be very large. This would tend to artificially limit fuel flow at full throttle, taking control of WOT fuel delivery away from the main jet. Selecting this is much easier than many believe. If you find that mixture is good at 1/4 throttle, but too rich at 3/4, you probably have a needle with too great a taper angle. If the mixture is good at 1/4 throttle, but too lean at 3/4, you probably have a needle with too small a taper angle.

2nd letter: This generally doesn't need to be played with much. If, when adjusting the clip, you find that you are at the 1st groove and still need to start the taper later, you may need to select a needle with a longer L1 dimension. If you find yourself at the 7th groove and needing to start the taper earlier, you may need to select a needle with a shorter L1 dimension.

3rd letter: This portion of the needle has the greatest effect on mixture between closed and 1/4 throttle. If the engine is too rich while gradually accelerating through 1/8 throttle, select a needle with a larger root diameter. If the engine is too lean when gradually accelerating through 1/8 throttle, select a needle with a smaller root diameter."

So if I'm understanding that stuff, since I'm now on position 6 of 7, I may need something with a shorter L1 dimension. So maybe go EHR? That'll give me a 77.35 on the L1 as opposed to the 79.15 for the EMR I currently have. Going with a smaller main jet will probably cure the cut off at the top with Wide Open as you both mentioned... so maybe no change necessary in the taper (first letter to say... an F as belter recommended)?

To sum up the possible changes:
150 main
EHR needle 4th clip position.

I could go with a FHR as suggested, but if it's rich up high, then wouldn't that make the taper angle steeper? In the 1st letter above, it seems that the angle need to be less steep. Maybe I'm reading the chart wrong?

Or I could just go 7th clip position on the EMR with the 150 main.... ???

Thoughts?
 

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Here in CA, it's over $600 for a dyno run
I think i need to move to california........... not really.
Yeah so I should charge more than $50?

Really you should check I would be shocked if it is that much ( I assume you kid) that price is more jetting on the dyno than just a set of three runs to get you air fuel readings printed on a graph.

As I mentioned before it is all bike dependent and the parts bolted on add to the confusion. I have used mains possibly larger than a 160 but again I believe it was to bandaid a bad pairing of parts. If you are not outside of the normal mods with custom stuff and you have a "typical" motor then you should be darn close with the needles supplied by sudco in the carbs straight from japan. If you are not then you may have something else contributing to the need for odd jetting.

The original needles are close most of the time on most bikes. There is absolutely nothing wrong with playing like you are so keep at it. you might look into one of the weld in O2 sensors to data log Check with Punch to see if he has any recommendations on a wideband O2 setup for you. Either way you are learning and that is just good, be sure after you get it you swap back to original setup to make sure you made a real improvement instead of just improving on the last mess.
 

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It's been a while since I checked but 3 runs and some needle swapping was quoted to me at about $600 as well. $150 for a single run no service. I've not kept up with any special promos in the area, probably should, there are three bike dynos in town that I know of.
 

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Yes if they are making changes to the bike it would add up fast . basic runs should not be much time to make so I would check around it should be only a half hour labor to run a supersport so if they are charging $150 that is above shop time I would think. Well prevailing rates apply so I guess that's what it is. Time to re-adjust my rates I guess, at those rates a dyno should be paid off shortly .
 

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Discussion Starter #12
It's been a while since I checked but 3 runs and some needle swapping was quoted to me at about $600 as well. $150 for a single run no service. I've not kept up with any special promos in the area, probably should, there are three bike dynos in town that I know of.
Thanks jumping in RockAZ. I swear I'm not insane. The thing is, there are so many people getting stuff done here in CA that the folks that run the dynos see a single run to get a printout a waste of time when they're already booked a month to two months ahead for people that want the full menu. I may keep shopping around to see if I can find something palatable cost-wise to get a single run in.
Yes if they are making changes to the bike it would add up fast . basic runs should not be much time to make so I would check around it should be only a half hour labor to run a supersport so if they are charging $150 that is above shop time I would think. Well prevailing rates apply so I guess that's what it is. Time to re-adjust my rates I guess, at those rates a dyno should be paid off shortly .
Thanks for the vote of confidence, ducvet. I honestly think that if you hopped on my bike, you'd probably tell me to stop whining. It runs pretty good. With the inclusion of pods, changing the needles made a very noticeable difference across the full rev range. I mean, even the core diameter moving from 2.775 to 2.755 made a difference in how it starts/idles/warms up. So I'm happy with that. I've been told a few times that the sudco setup should be fine. I can honestly say that after installing and running this thing with the pods, the plugs were almost iridescent white. Super lean. I'm glad I didn't damage anything. I almost wonder if it has anything to do with the fact that this is an FE? On one of the history pages it says that for the FE, the engine was redone and tuned. See: https://www.motorcyclespecs.co.za/model/ducati/ducati_900ss 97.htm

It says in part, "Based around the 900 SS Superlight, the FE had special cosmetics, a tuned engine, and elegant chassis changes. The special silver single seat bodywork was wrapped around a modified engine...." I'm not sure what they did to tune the engine, but I had a 95' 900 SS/SP for years and years about 20 years ago, and it was like a completely different bike. Even when I bought the FE a few months back (it came fully 100% stock), it was like a different bike than I had before. So it may need a few different things when converting to the FCRs. I don't know.

Again, I may experiment with going to 150 mains tonight just for fun.... or should I even bother? It takes longer to take off the fairings and put them back on then to swap out the mains. I can run that and see if the power stays up past 7k RPMs. If it's worse, I can go back to the 165s. I considered doing with wideband O2 setup... and may still... but that's beyond my skillset. I'd have to find someone that would be able to do that for me. Until then, seat of the pants it is. Even if I find a dyno that's cost effective, it'll be mid to late December before my turn comes up.
 

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fe is no different engine wise, apart from usa spec models have the later 3 phase alternator..
If those quotes were not just marketing hype, the "tuned engine and modified engine" would refer to being "computer-controlled" electronic fuel injection instead of carbs which was a big deal in those days and unique for motorcycles. IMO, calling last years motor "modified" by adding fuel injection is not what I think of modifying but I suppose the statement is true. And fuel injection does "tune" on the fly based on a few simple input sensors,...
 

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If those quotes were not just marketing hype, the "tuned engine and modified engine" would refer to being "computer-controlled" electronic fuel injection instead of carbs which was a big deal in those days and unique for motorcycles. IMO, calling last years motor "modified" by adding fuel injection is not what I think of modifying but I suppose the statement is true. And fuel injection does "tune" on the fly based on a few simple input sensors,...
the fe engine was carby. are you referring to the ssie? that's a different model.
 

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Discussion Starter #18
Went with the 150 mains.
Linear to redline... slightly less pull than the 165s
Pulled the plugs, and they're white again. Way too lean.
Maybe I'll try a happy medium. 160? I liked how the 165 felt, but like I said, it kinda' stumbled after 7k rpm.
I'm bummed that the 150s made it way lean again. I don't mind the slight decrease in pull in exchange for the nice linear feel along the rev range.
Back to the drawing board.
 
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