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Discussion in 'Dakar champion (950/990)' started by Billroy, Jan 11, 2006.
Just for the thread...which way is leaner?
Lower height floats is richer.
Ben, mine did that as well with a facet pump. I ended up at 1 psi, and it's been fine since.
Thanks! I'll bump it down some.
Mine came fitted with a facet and fuel regulator fitted, P.O. informed me that 1 was the correct setting for it, on a few occasions after working/washing I've managed to move it to either .5 or up to 1.5-2, .5 meant the old girl dying around the 85 mph Mark,( not enough fuel) 1.5 seems to not make a difference although mpg went down a tad, 2 on the other hand ran rough with sh-ite mpg.
Ran into this while searching our forum (and Google) about running different main jets.
Richer fueling lowers temperatures. If it weren't for the fact that 2/3 of our intake charge converts to H2O, combustion chamber metals (especially the exhaust valve) would not last long. Since the days of air-cooled twins & multi-cylinder bikes, aircraft radial engines with up to three rows of cylinders, the cylinder(s) with the last air flow had jets at least a size larger, even more on racing bikes (70's Ducati 900ss etc). The water content of combusted methanol cools the 11,000+ horsepower of an NHRA top fuel dragracing car's heads & pistons, certainly not the radiator...
... which they don't have...
It's a common misconception found all over the forums, don't want to flame you Keener
There is some other reason, I'm running the same sizes this go-round (148's from my KLR spares, SDR cams, de-cat'd stock muffler CJ 2- Y pipe, stock box/K&N/Headwind prefilter snorkel) and will report back
Sounds very interesting, what is your fuel pump (type and pressure) and float settings? Running the same mains front and back did you adjust the vent hose lengths, assuming you have the individual lines?
Did you use the same needle position?
I use the stock fuel pump, and vent hose lenght doesn't matter if you use an ITG filter.
Since no one has responded on this thread Ill re-post with an update. I put 42 pilot jets and Front main 162 and rear 165 main jets with clip on the needle second slot from the top. Sound right for 5,000 feet? seems to run ok
With the needle on the 2 position I think 168F AND 172R will be better
I have found out by now that best main jet for itg configuration for 15-30oC ambient temperature is with 178s on both cylinders. There are a lot of main jet correction charts and i attached one above. Assuming that your ambient temperature is approximatelly the same, you could use 168s or 170s on both cylinders. You could also try needle clip @2nd w/o the washer (1.5 needle clip pos.)
Thanks for both of those posts
Hey guys! I've read through this pretty thoroughly and I'm at a loss as to why my bike isn't running quite right. 2004 950 Adventure, ITG intake, carb vents routed using the wrong size line so they don't seal on the fittings. One of the SAS valves was partially open to atmosphere, I've got some blockoff plates on the way but for the time being I sealed it with RTV and this seemed to help a little but not as much as I expected.
A lot of the time it's very close but just isn't dialed and I think it's generally running lean, particularly above 5000RPM. Some symptoms I don't like:
- Starts easy with some choke, idles cold at 1400RPM but when it warms up it idles at 2000RPM. Makes me think it's lean on idle.
- 4000RPM feels good and cruises great. Once I'm at about 5,000RPM and up it gives a vibration I can feel pretty well, it will run ok but it feels like the engine is unhappy.
- Bottom end is smooth but still has good power. Mid-range up to the top doesn't feel as strong as I expect 100hp to be. I can get the front end to come up in 1st gear only, and that's with 16/42 sprockets!
- Popping on decel isn't terrible but I want to get rid of it. I made it better with a little more IAMS but it's not fixed.
- Mains @ 170/172
- Pilots @ 45
- Starter Jets @ 68
- Needles @ 2nd clip with small washer underneath (look to be Factory Pro needles. Were at 3rd clip with small washer underneath).
- Floats @ 3.5mm (were at 4mm front and 3mm rear)
- IAMS at 2.75 turns out
- Main Air Jet, ACV Jet and Idle Air Jet sizes unknown, assuming factory
- I do not have the tool to sync carbs
- Have not checked TPS
- 500ft above sea level but will be using it from 4-10,000ft on Continental Divide
- old school FMF 2-2 popes with spark arrestees
- ITG intake
I'm really not getting what's going on here. The jetting in the carbs seems like it would be very rich on idle and good on the mains, yet it seems lean through the whole band. I am not used to these bikes, CVR carvs, or dual carbs!
IAMS set at how many turns? Flex jets make easy work of fine tuning IAMS
Needles: Factory Pro or KTM? Clip in #2 position is leaner than #3 position- depending on altitude and ambient temps I'd move it to #3 position.
Recheck float height- ITG filter set up likes 4mm
Ive found the 45's to be fat and thirsty; not necessary on the ADV versions unless you run upper rpm and WOT a lot. I prefer the 42's as they work well at high & low altitude and deliver better economy.
Anytime the carbs come off the engine- synch is called for; not always necessary but its FSM protocol. Check TPS values closed and full open record voltage.
@ABuck99 thanks for the reply! I updated my post. Elevation is 500’ but I’m prepping for the continental divide at 4-12,000’. IAMS at 2.75 turns. I stated I think the needles are FP, here’s a pic
I believe I need bigger main jets and want smaller pilots so I leaned the needle and floats a little from what they were. I understand that if I don’t go bigger mains that would be going the wrong direction. I have heard overs echo your thought that a 42 pilot isn’t best and that’s what I’d like.
I’m surprised the 42 pilot and FP needle on clip 3 weren’t way rich on the bottom end though!
I’ll double check my jetting notes for high country- generally recall my set up for 6000-12000 ft was mains in the low 160’s and 42pilots and clip #3- and 1.5 turns om IAMS. FWIW 45 pilots are way to rich for CDR elevations. I’ll dig out my notes and post back up.
Well maybe I've found one source of my misery! My Idle Air Jets are 70's instead of the 50's I believe came stock. So the previous owner had 70 air jets, 45 pilot jets, and a FP needle at 3rd clip (or 3.5 with the small washer under it?). Just throwing a bunch of fuel and air into the mix on the bottom, think that made the rest of the jetting difficult?
Or does this all sound like the perfect higher altitude jetting? Previous post has all specs.
FWIW- I checked my notes on my high altitude set up; good starting, running, econ performance results from 4500-13,000 ft.
ITG Air filter-
Clip #3 position ( FP needles)
IAMS: 2 Turns
For reference: other jets stock
Main air jet: 40
Idle Air Jet: 50
Thank you for the help! I’m usually lower than that, do you think just upping the mains would balance that setup out for lower altitude?
Yeah- maybe. if you look back a page or two there is a jetting/altitude reference that might help.
I re-jet for the trips I take West so I feel like I dialed in a good performing set up for my bike and riding prefermces and I swap back to my Georgia jetting when I get home. For riding Colorado- Utah- Ive experimented with a few jetting variations with different pilots, mains and clip positions- the set up I posted worked well for the wide range of altitiude between NM-UT-CO-WY-MT.