Mikuni on an R80 help

Discussion in 'Airheads' started by hardwaregrrl, Sep 6, 2012.

  1. kpick

    kpick Free Range Human

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    For what its worth,
    I did a Mikuni swap on my R69s. Once all the jetting was dialed in, it was the best thing I could do for the rideability of the bike.

    Revs like no other airhead I've ever had.

    Do it!

    Good luck,
    KP
    #21
  2. hardwaregrrl

    hardwaregrrl ignore list

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    I did! no turning back now.:freaky
    #22
  3. Les_Garten

    Les_Garten Been here awhile

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    Sounds like you are getting it sorted out.

    Nice throttle response, ehhh?
    #23
  4. hardwaregrrl

    hardwaregrrl ignore list

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    Oh yes sir!!!! Looks like you're still trying to figure out a plan? Looking forward to hearing how it all shakes out!!!
    #24
  5. Beater

    Beater The Bavarian Butcher

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    I'm very happy that this worked for you! Looks like all those spares came in handy!!!

    GO JENNA!!!

    Jenna got the flat sides ... I have the VM's. The Jetting on mine is a 35 pilot, and a 160 main. I also have the needle clip at the top position of the needle.
    #25
  6. hardwaregrrl

    hardwaregrrl ignore list

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    Oh man I owe you. Going to keep the jets for a bit to make sure it's right. Then I'll add mine in for the next lucky contestant!!!!:freaky. Getting my wheels balanced at cycle gear right now then home to check fluids, valves, tools, spares a remount the wheels!!!
    #26
  7. hardwaregrrl

    hardwaregrrl ignore list

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    #27
  8. One Less Harley

    One Less Harley OH.THAT'S GONNA HURT

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    Jenna you'er one sick bitch...but I mean that in a good way!!!!! have fun and be relatively safe:freaky

    Saw BMW Blake at the LBL 200 this past weekend, it was a figgin mud fest for the 1st 27 miles, wore my ass out. Then picked up some single track fun for the DRZ....wow I tel you some of those guys can friggin fly!!! 210 miles for the weekend. Most was single track, and GREAT fun. I'm sore just abiut every where, from the pounding I took. Just muscles, not from crashes.
    #28
  9. Beater

    Beater The Bavarian Butcher

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    So ... how's she ride? Noticeable difference? More grunt?

    Like it? Worth it?
    #29
  10. hardwaregrrl

    hardwaregrrl ignore list

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    See post #18.....but in a word.......YES!!! But this weekend will really tell me a tale!!!
    #30
  11. ontic

    ontic

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    #31
  12. sithndman

    sithndman Been here awhile

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    Good luck and have a ton of fun!!!
    #32
  13. hardwaregrrl

    hardwaregrrl ignore list

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    So, these carbs are pissing me off. I'm returning 27mpg, not riding the bike much differently. I've been told mikuni doesn't list rich to lean on jet needles, and my needle jet is a Q2, theyre are 13 leaner needle jets. How many should I get? I cannot believe that I know people with VMs that are getting over 40mpg. Main jet is 155 now, pilot is 20 1 turn out, can't change the cutaway. What the fuck....yeah I spelled it out. I'm sick of this shit. I hate my Bings but they may be going back on. Any advice beside smart ass shit.....? I'm serious....don't poke the bear.
    #33
  14. RecycledRS

    RecycledRS Along for the ride

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    A couple of thoughts, if your running WFO while racing I doubt you'll see 40+mpg.

    Also a #20 pilot sounds a bit small ( 30 or 35 maybe) in my experience. Try going leaner by 2 needle sizes.
    #34
  15. Kai Ju

    Kai Ju Long timer

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    Here is Sudco's jetting page where you can find the info you're looking for:
    http://www.sudco.com/Carburetor02.html

    It does list leaner to richer for the individual components.

    How does it run with the needle in the leanest position ?
    How do the plugs look ?
    Where do you spend most of your time ? Get your mind out of the gutter, I mean in terms of throttle position.
    How much time do you actually spend at full throttle ?
    How do the plugs look ?

    Get a piece of tape, stick it on the throttle housing and mark where zero, half and full throttle are.
    Ride the bike and spend time at each throttle setting, evaluating how it runs. Does it feel rich at half throttle ? Full throttle ? etc.
    Have you done a plug chop ?
    I know, lots of questions but unless you have somebody else's known specs you'll have to find your own.

    I am getting 40mpg on my R100 with VM38s and a 210 mainjet in mixed riding. That means I spent most of my time between 1/4 and 3/4 throttle.
    Start by dropping your needles, evaluate what happens, look at the Mikuni charts and let us know what happens.
    #35
  16. supershaft

    supershaft because I can

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    Poke the bear? I always want to snuggle with the bear. :D I have the cutest wild cat I sure wish I could snuggle with! A friend of mine has dyno tuned a bunch of airheads with round slides but he can't remember the numbers. I can't either. Sorry. I usually try my best but I am out of the loop on Mikuni's right now.
    #36
  17. Les_Garten

    Les_Garten Been here awhile

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    I feel your pain...

    I am in the process of redoing my bike.

    I put Mikuni 40mm Flatslides on mine back in '92.

    My carbs have accelerator pumps. I turned them off because they could throw a stream of fuel about 10' literally.

    I also went to bings for a while because of gas mileage.

    I am however redoing mine with the 40mm Flatslides again.

    I won't get into the weeds on all the details till it's done and I post a thread. But the gist of it is that IMO, you need to tune the bike with an Air Fuel Mixture gauge.

    If I were you, and I know you're pretty serious about this, I would have an O2 bung welded into one of the headers. Doesn't cost much. Buy an Innovate LC-1 or something like that. I has to be a wideband O2 sensor. Need to really get a good one.

    Mark your throttle grip with whiteout or something temporary at 1/4 -- 1/2 -- 3/4 -- Full throttle marks.

    Then you can tune that baby perfectly. All other means will be guesses and approximations. You'll have it too lean at some points and too rich at others. IMO, you'll never get it right without doing it this way.

    Then you'll be done and you'll KNOW it's right. The bike will be at it's best, and your MPG will be at it's best.

    Then you can reference your thread you'll write up and sell the LC-1 at 3/4 what you paid for it and smile!

    Some Forums have tool loaner programs were someone donates a tool to the round and the tool travels. This would be a good candidate for a tool loaner program.

    p.s. That Sudco tuning manual is worth what they are asking for it.
    #37
  18. hardwaregrrl

    hardwaregrrl ignore list

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    Thanks guys!!! I'd like to stress this is my only bike. I do not race it every day:D Most of my time is spent....on the highway. Around 4800-5200 rpm, 3/4 throttle. I just(for the hell of it) took the main from 175 to 155 and It had a flat spot and ran rough. I put the 165 main in and it felt better. I agree that the pilot is too small, but that will not effect my fuel mileage. I turned in a half of turn and the bike starts fine on full choke cold. I talked to Sudco (guy wasn't that helpful) and he told me that the jet needle in the TM32 isn't listed from Mikuni rich to lean....and looking at the catalog, he's right. The only thing I can do at this time is needle jet. It came with 389-Q2 which are toward the rich end. O0 being the leanest.....and they climb in increments of 2. Plug looks good, a bit dry fouled. Needle is at the leanest position and the bike runs fine. I spend very little to no time at WFO. I am the only person that I know of that is running 32mm flatsides on an R80.

    I'm heading to the swap meet at Barber Vintage tomorrow and I know I'll be able to pick up some jets, and would like to know is where to start as far as what needle jets to look for. Start in the mid P's, or all the way to O's. Here's the chart I was thinking a P2 and O2....

    I cannot change the jet needle according to the guy at Sudco as they cannot tell what is lean and what is rich. The needle is obviously my problem as I do not live on my bike at WFO.......but that would be fun.:lol3
    #38
  19. Kai Ju

    Kai Ju Long timer

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    I cannot change the jet needle according to the guy at Sudco as they cannot tell what is lean and what is rich. The needle is obviously my problem as I do not live on my bike at WFO.......but that would be fun.
    __________________

    You may not be able to tell rich or lean but the larger the diameter the smaller the annular ring will be between the needle and the needle jet.
    Look up your needle jet and get a fatter one. That will make it run leaner.
    I'd still suggest what I'm running in my VM38s because I'd think that the smaller flatslides aren't far off in airflow to the larger VMs.
    I'm jealous about Barber, I've never been there.......
    #39
  20. robtg

    robtg Been here awhile

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    ..... " I am the only person that I know of that is running 32mm flatsides on an R80".......There may be a good reason for that. VM36's or maybe even 34's would be better. Nothing wrong with flatslides, but 32's are a bit small.
    #40