Carb tuning advice

[memper]

Just did a nearly full teardown of my carbs to see what the PO had in there. Nearly bc I didnt have a small enough screwdriver to take one of the jets out.
It had 70 mains and the needle clip was at three which I moved one notch down toward the tip bc I assume I will be running lean with my soon to be installed pod filters and "gp-ish" exhaust.
What I dont understand is the pilot(?) needle. Its the small one that is pointy and has a spring on it. What is a baseline in terms of turns? Do I spin it all the way down til it gently seats then back it out?

[memper]

  Ha. I just realized that those are the A/F ratio screws. 2.5 turns from seated is probably a good start.

[motoxmann]

the 70 jet is the "starter" jet for the choke system, not the main jets. look again, the pilot jets should be 40, 42.5, or 45. and the main jets should be 132.5, 135, 137.5, or 140.

based on what your plans are, I would suggest looking into a jet kit, I recommend a factory pro kit.

the setting for the fuel enrichment screws will LARGELY depend on what size pilot jets are currently installed. could range anything from 2.0 turns out to 6.0 turns out

[memper]

Mains are 144's. Mikuni doesnt even make a 144 press in jet. Weird. Should I leave em? On Ducatisuite he goes up to a 142.5 with pod filters. Perhaps I should just buy one up and one down to be safe. Needles are double taper. Still havent seen what pilot jets are in there. Gotta get a tiny screwdriver...
Also, should I get needle jets or just worry about mains and pilots and floats for now?

[motoxmann]

ah, those are probably dynojet main jets, which means you might also have DJ needles and springs too. DJ uses different number ratings on their jets, and 144's are actually fairly small, similar to stock jetting iirc.
also the DJ springs are way to weak; the cause the slides to flutter too much and open to far which affects vacuum and intake velocity.
so yeah I would definitely recommend getting a factory pro jet kit, and yes I would definitely say replace the needle jets while you're in there. the stock needle jets typically only last around 5k miles. factory pro makes nickel plated needle jets now which last much longer, I strongly suggest getting those.
buy a couple sets of main jet o-rings too, they tear easily when they're aged.

so you have an idea: I have arrow high mount exhaust (no baffles/silencers), and cut airbox lid (not completely open, but much larger holes then stock), and my current carb setup is: FP springs, FP nickel plated needle jets, 45 pilots, screws 2.5 turns out, 137.5 mains, FP needles in middle position, floats at stock 14mm height. with pod filters you'll probably want everything the same as my setup with the exception of 140 mains.

[memper]

Interesting.
So I got my pilots out and they are 40's. stock is 42.5. Weird set up.
Instead of a whole kit I think I will just cherry pick what I need from jets r us.
Seems that a Dyno 144 is equal to a Mik 135. Gotta step up.
Thank you.

[memper]

Im getting 142.5 mains and 45 pilots and a few o-rings.
About the weak spring..anyone ever shim the spring so its got more compression behind it? Maybe with some washers that fit around the "spring post".

[motoxmann]

shims dont affect spring tension, only installed length and seat pressure. the tension throughout the movement of the slides is what needs to be proper.
it sounds like you have jets from a 600 installed in that bad boy.
you really would benefit from just buying a factory pro kit. it might cost a couple bucks extra, but then you'll know you're getting all the correct parts and then some for adjustability if needed, including new needles and springs.
you'll probably find a 142.5 is too rich. it might be ideal for 8k-9k, but it'll prob cause a power-robbing rich condition from 5k-8k. I'd say go 140 main, its rare to need anything larger than that unless you're running the 900 big cams and oversized valves along with pod filters. I'm actually a hair rich even with the 137.5 when it's warmer out, but its perfect for when it's cold out.

[memper]

ok. Thanks for the tip. Is 45 too rich for pilots?

[koko64]

If you have the stock springs you could try them.
Any buddies with 900s might have the 140 main jets.

I don't mind the Dynojet needles but have come to thinking like others that a stiffer spring is better. That piston flutter is domething to be seen. Also, using too soft springs will have the piston rising so quickly as to having you wanting an accelerator pump. Interestingly, I have seen late model Yamaha TRX 850s with the same carb but oem accelerator pump upgrade.

Don't assume that pods require more fuel than an open airbox, especially if they're small and dont have a nice velocity stack in them.

[koko64]

ok. Thanks for the tip. Is 45 too rich for pilots?

.

On the rich side is good for cold weather riding, but can be a bit lumpy on low speed throttle transitions when the bike is hot. I have tried a little lean on my 900, smooth low throttle but a pregnant dog in the cold and bad carb freezing. Try each and keep an eye on plug color if you like.
MM has the experience with the 750, so he has useful data.

[motoxmann]

ok. Thanks for the tip. Is 45 too rich for pilots?

I run 45 pilots with the screws 2.5 turns out, I live in new england and it's perfect right now. when it was warmer out I tried 42.5's and I was able to dial in the idle but it was surgy off throttle (too lean), so the 45's went back in even when it was warm out but had the screws at 2.0 turns out.

by the way, I've tried the stock springs, dynojet springs, and factory pro springs. stock springs (quite stiff) the bike is a bit sluggish and choked, but very smooth everywhere. DJ springs were way too soft, and throttle was extremely touchy, and as mentioned above leaves you wanting an accelerator pump because it would get lean spikes whenever increasing throttle and would cause some surgyness. top end was great, but part throttle and midrange was a pain in the arse and ran fairly crappy. the FP springs are about in between those two, and provide amazing results everywhere all things considered, with the exception of a bit of chunky inconsistent running conditions at higher throttle in the 2k-2500rpm range, but you should never really give heavy throttle in that area because it lugs the motor which is not good for it, so that shouldnt even be a concern. the FP springs definitely make the throttle much crisper and they did give me a noticeable increase in midrange power, and the higher rpm powerband seems to come on much earlier/smoother and hangs in there right til the end.

overall, each spring set is good for specific types of riding:
stock springs seemed best for just cruising around, but are annoying if you do any type of "spirited" driving.
FP springs are great all around for pretty much any type of riding
DJ springs honestly pissed me off, but seemed awesome for a track day type of thing where you're racing it and keeping rpms high pretty much the entire time you're on the bike.

also, both DJ and FP needles are much better than stock needles, but I did find that the DJ needles actually wore down against the new nickel plated needle jets. I tried the DJ needles first because several people said the profile of them was a bit better than the FP needles, and I do agree with that. but considering the DJ needles wore, that will destroy the profile of them in short time anyway, and I had only about 500 miles on them when they started showing signs of wear. so they went in the garbage, and the FP needles got installed. very difficult to notice the difference in running conditions between the two needles, but 3k miles later and there is zero wear on the FP needles, so they are staying in there.

aaaand, both the FP and DJ needles are thinner at all points than the stock needles, so the concept of determining what main jet to use actually gets thrown out the window because the needles do even affect that area. IE: a 140 main jet with stock needles will perform similarly to a 137.5 main jet with FP needles.

hope this helps a bit more
also a big reason why I'm suggesting a full jet kit is because you dont know how old the springs are, or even what springs are in there, and same for the needles, you don't know which ones they are. so best bet is to just refresh everything simply so it's all new but also so you know what it actually has

[memper]

 Wow. What a response fellas. Thanks. I truly want the FP kit its just a matter of telling the wife at the right time.

[motoxmann]

lol, well considering the jets you have in there right now, it has to be running awefully lean. lean means stupid hot, potentially piston-melting valve-burning hot. so it wouldnt be a lie to tell the wifey you need the FP kit because continuing to ride the bike with the currently installed jets could become extremely hazardous to the bikes health. and $100-$150ish for a jet kit and needle jets right now is MUCH cheaper than an engine overhaul in the near future. and parking the bike isnt an option because riding stabilizes your sanity, and without it she may not like you very much :p
just offer to do an atypical chore or two, like dishes or laundry, and she'll most likely jump at it. and a tip: if you do a crappy job at whatever chore(s) you do, act proud that you did them and act like you did a great job and enjoyed putting in the effort to get extra bonus points, so she actually sees how "well" you did, and if she sees how crappy of a job you did she may (crossing fingers) ban you from ever being allowed to do that chore again, so it's a win win )

[memper]

  all good points except my wife is the breadwinner and I'm what I call a "professional father". I cook (wife is inept) and I clean and take care of the kids. I work on illustration at night. Lol.
Bike is very lean. Did a throttle drop test and they are bone white. Hopefullly the valves are ok.
I work hard, she'll likely be ok with the purchase. But on another hand I read here that its easier to apologise than to ask permission...