Ducati SS and Monster Mikuni Idle mixture adjustment on the gas analyser and rambling.

[@vvalekk]

Thanks so much for this! Very clear on the how, what and why. Seriously helpful 🙏🏻

[@kneiterleip]

Let me tell you quick story. Broke a monster 600, put a 900SS motor in it, with all the parts necessary to do so. I Couldn’t get it to run on 2 cylinders after many long long nights and ran out of motivation. And then It got parked for over 2 years. Yesterday pulled it out with the bare minimum of motivation. Went over everything AGAIN, And today was carb day. I took em off and noticed one throttle valve seemed closed compared to the other, but didn’t think the world of it yet, since i had to set them later anyway. Looked up some “base” settings for the carbs to just get it running. And i get to your video… The moment you start to mention it, it just falls in to place. You can fill in the rest i think… Thank you so much. If only this video was only back then. Maybe it was meant to be😂 Again, thank you so much. You have NO idea the stress and frustration I’ve had with this bike. I finally have a 2 cylinder 😂

[@bradthebikeboy]

it's quite surprising how much impact it has.

[@S3Moto]

I'm resurrecting a 98 CR, and I think I just found my fix!

[@SteveDuncan-ix7xk]

Brad is the man, brilliant info as always, thanks so much 👍

[@danielwoodhouse1870]

Brilliant thanks. I was always told if you have to adjust them more than 3 turns you should look at making the pilot jet bigger. Is it just these particular carbs that can have 4-5 turns out?

[@bradthebikeboy]

i choose the pilot jet based on low speed tuning requirements, then set the mixture as required. i wouldn't expect a dellorto or fcr to have a mixture screw out this far. just how they are ime.

[@danielwoodhouse1870]

@@bradthebikeboy ok cool. Thanks 👍

[@MrCornhole98]

Thank you for sharing this. I have a 94 900ss CR that has been plaguing me with carb issues.

[@henryhawk978]

Very nice, appreciate you taking the time to make the video. RIDE SAFE OUT THERE!

[@underarmbowler]

great and helpful vid, I just reconditioned and replaced all jets,orings and cleaned my BDST38 on 900SS FE after previous owner couldn't get going and idling correctly. My Q is; under butterfly plate when at closed position looking from engine side of carb, how many of the 3 pilot circuit holes should be visable under closed butterfly position (as a starting point) ? one (first hole) or idle screw turned in further until second hole seen or turned in more so all three can be seen under fly plate? or turned all way out (closed fully) no pilot circuit holes at all? .....thanks Brad. I have set fuel mix screws at 3 turns out and idle screw one turn from stop so far (one hole seen) both carsb in sync by the looks. cheers kindly, Carl

[@bradthebikeboy]

you wind the idle speed screw in until the idle speed is as desired. then adjust the idle mixture screws for the highest idle at that setting. then readjust the idle speed screw as required. it's that simple.

[@Rudeboycycles]

I recently acquired a 2001 m750 that had been neglected for quite sometime if not most of its life. I rode it home from acquisition 120 miles slowly as the tires were bald, fork seals were blown and it was running like poop. I had to refuel twice on the ride back riding a snails pace so I decided to remove the carbs in hopes to clean and rebuild them. Unfortunately 3 on one and 2 on the other side of the bowl bolts were stripped so I opted to chance it and only replaced the two large top diaphragms (one had a crack in it) one of the side little diaphragms and both fuel mix screws. I also eliminated the vacuum shutoff went to an inline petcock, all new lines, blocked the second intake and ran new vacuum line from the pump to the rider right side intake. Also eliminated the evap can (us bike) and plugged those inlets on the intakes as well. So the pump is definitely pumping (not sure if the volume is correct, ordered a rebuild kit anyway) I’ve also changed the plugs changed the oil. I have spark confirmed, I believe I have fuel and it’s fired up on ether but will not run off the fuel tank. Any suggestions? You seem to be by far the most knowledgeable of all the yt creators in regards to this carb configuration. Unfortunately I have a sync garage but it’s 1600miles away currently and I would really like to ride this bad boy thanks in advance Also I’ve confirmed it has spark.

[@bradthebikeboy]

remove the float bowls, clean all the passages, replace pilot, needle and main jets. look for anything wrong.

[@Rudeboycycles]

I’ve cleaned it really well, as well as i can without an ultrasonic cleaner. It now idle great but sure enough i got 1/2 mile down the road and it dies and wont start again. I am so confused

[@Rudeboycycles]

Oh didn’t realize I sent this one before all the pushing. So 4 attempts now it starts right up idles strong I get a helmet on and set off down the road and in my 4 trips I’ve gone 1 , 5 , 1/2 and 3/4 of a mile it dies then it will crank and crank not light or sputter light and put out then will not start again and i push it back. I’m in so Florida but it’s been night time so anywhere from 80-90 degree outside I don’t rebuilt fuel pump rebuilt carbs including diaphragms removed the Vacuum shut off for an inline Petcock blocked 2nd vac and is making vacuum to the fuel pump also installed a one way valve after the fuel pump as I read that i should in case I forget to turn off the Petcock. Was thinking maybe the floats are too high/low when I put them back in? Because it made it so much further the second night and it was cooler by a bit then I didn’t know if maybe its somehow heat related the fuel line is kink free but it does take a path closer to the motor now I’m so confused and sick of pushing lol

[@bradthebikeboy]

@@Rudeboycycles does it have spark when it stops? fuel in the float bowls?

[@Rudeboycycles]

@@bradthebikeboyso I’ve now replaced the ignition coils and just had it happen again. Checked for spark as you suggested and it has spark but again won’t start. I know the fuel pump is pumping (ive swapped out the vac shutoff for a manual pump the only thing I can think is and this may not be involved but is I did install a one way valve in case I forget the petcock as someone suggested) I’m completely at a loss as to why it starts and idles perfect and runs 15 min or so and dies.

[@peterbakker7039]

thanks Brad, much appreciated

[@maddietaylor2698]

Hi Brad are you using and exhaust sniffer in each pipe? We bought a SyncroKing wide and oxygen sensor but the sensor requires us to weld on the larger adaptor to each pipe. I presume getting the exhaust sniffer will be pointless in reading each cylinder for a 900ss twin system

[@bradthebikeboy]

i'm using a bosch co analyser and take offs from each cylinder. this video shows the bits - kzbin.info/www/bejne/nHi0ia2Na9Bne5I the wide band sensors tend to not be good for idle mixture setting - they respond too fast as a general rule. you could run it in to a damping chamber i guess, but the co meter is just a much better tool for the job.

[@flegolas3296]

Hi there ive got issues on my s2r 1000, it idles a little to low so sometimes when i let go of the gas it dies do you got any idia how to fix that? Best regards from germany✌🏻

[@bradthebikeboy]

if i was standing next to it and could touch it - i'd start going through the list of what could be wrong. over the internet - no. get someone who knows what they're doing to look at it. or learn. do everything - compression test, check tune, valve clearances, etc. sooner or later you'll find it.

[@flegolas3296]

​@@bradthebikeboyyeah i have to do the big desmo service in 3k km so then i have to take it all apart, i thought there might be a easier way to mabye set the idling a bit higher or something but i guess it aint that easy on an injecting bike

[@bradthebikeboy]

@@flegolas3296 it has an idle control valve, so should be taking care of the idle speed itself. you need a diagnostic tool to see what it thinks is happening, and go from there. give the idle control valve a spray with some cleaner - i like the three bond engine conditioner. clean the throttle bodies in case they're gunked up. all sorts of things could be the issue.

[@flegolas3296]

@@bradthebikeboy ill start by getting an Diagnostik tool thanks so far tho i didnt know about the idle valve thats a cool Thing

[@choompa]

Brad, I just want to confirm, how many turns from complete close? Was it 4 turns out?

[@bradthebikeboy]

the final setting? i don't know. do you want me to rewatch the video for you and tell you?

[@choompa]

@@bradthebikeboy Not really. The reason I ask is because I have a 91 Yamaha TDM 850 3VD. We have the same carburetors, Mikuni BDST38. From what I read, people who owns the same bike said that Fuel mixture screw should always be 2.5 to 3 turns out as per manual. Maybe it depends with what engine these carbs are put on?

[@bradthebikeboy]

@@choompa they were 5 to 5 1/2. have any of the people who say 2.5 to 3 had one on a gas analyser to see what that gives? if not, they're just parroting the manual. i'd suggest trying 2.5, 3, 3.5, 4, 4.5 and 5 turns out and see what happens. idle, low speed performance, fuel economy? i don't understand why people don't just try stuff. try, record result, try something else, repeat. it's called learning.

[@choompa]

@@bradthebikeboy Thanks, Brad. I have a rich mixture of what the plugs are showing with 2.5 turns.

[@bradthebikeboy]

@@choompa you're talking about idle mixture screws. they set the idle mixture. if you are fouling spark plugs it's unlikely to be an idle mixture issue. it is far more likely a needle jet issue with these carbs.