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Altitude jetting for GS850.

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    #1

    Altitude jetting for GS850.

    Looking for some experienced counsel jetting my 1980 GS850G properly when I pull the carbs for a cleaning/rebuild. I'm in the Denver area, live at 5,400 feet, and frequently ride up into the Rockies over passes that average 11,000 feet. I know it would be difficult to jet for this large a range and would settle for what would be best at 5,400' as it is my daily commuter.
    The bike only has about 19,000 miles on it and is totally stock, no pods; has the original air filter set up. Many thanks in advance.
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    #2
    I brought my 83 850 down from Denver earlier this year and it had the stock 115 main jets still in the carbs. The PO ran them for 20+ years in that area and didn't see a need to chande them apparently. I am now running with 110's in Albuquerque which is similar altitude. Going up to 11000' I dont notice any change in power. Sea level on the other hand may be an issue, but haven't ventured that far yet.Are your carbs Mikuni VM or CV type? I'm not sure when Suzuki switched over.
    Roger

    Current rides
    1983 GS 850G
    2003 FJR 1300A
     Gone but not forgotten 1985 Rebel 250, 1991 XT225, 2004 KLR650, 1981 GS850G, 1982 GS1100GL, 2002 DL1000, 2005 KLR650, 2003 KLX400

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      #3
      Oh, and Welcome to the GSR! If you haven't already, look here

      http://members.dslextreme.com/users/bikecliff/
      Last edited by Burque73; 12-07-2016, 10:15 PM.
      Roger

      Current rides
      1983 GS 850G
      2003 FJR 1300A
       Gone but not forgotten 1985 Rebel 250, 1991 XT225, 2004 KLR650, 1981 GS850G, 1982 GS1100GL, 2002 DL1000, 2005 KLR650, 2003 KLX400

      Comment

        #4
        The 850G with it's CV carbs and with the stock airbox will compensate for elevation very well. No need to rejet anything.
        Last edited by tkent02; 12-08-2016, 10:24 AM.


        Life is too short to ride an L.

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          #5
          If you DO go leaner, as Burque has, you will have to re-jet if you ever go lower in altitude. The compensation only goes in one direction.

          .
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            #6
            Many thanks folks. I'll stick with what it has and just clean everything up. I especially appreciate real, applicable experience at altitude. I don't think I'll worry about dropping in altitude yet. I'm sure it can handle the occasional short trip at lower altitude to some of the motorcycle museums in Kansas. As I stated, it's my daily ride and around home is where it has to perform best.

            Comment

              #7
              Originally posted by MadEyeGuy View Post
              I especially appreciate real, applicable experience at altitude. I don't think I'll worry about dropping in altitude yet.
              I'm pretty sure Tkent has ridden through all of those mountains up there, and on more GS's than I will likely ever have.
              Roger

              Current rides
              1983 GS 850G
              2003 FJR 1300A
               Gone but not forgotten 1985 Rebel 250, 1991 XT225, 2004 KLR650, 1981 GS850G, 1982 GS1100GL, 2002 DL1000, 2005 KLR650, 2003 KLX400

              Comment

                #8
                As a winter project I'm going to do the carbs. I've already done all the boots, but those take little time. I'll check back and let everyone know how it does once I'm done and the weather breaks in the mountains; probably April.
                Again, many thanks for this and for all the handy info I've been reading since I joined.

                Comment

                  #9
                  Originally posted by MadEyeGuy View Post
                  As a winter project I'm going to do the carbs. I've already Sdone all the boots, but those take little time. I'll check back and let everyone know how it does once I'm done and the weather breaks in the mountains; probably April.
                  Again, many thanks for this and for all the handy info I've been reading since I joined.
                  Seriously? You should be able to ride nearly year round in Golden. Your season is a heck of a lot longer than it is 8 hrs. to the east of you. I have a daughter in the Longmont area and she constantly reminds me that when you guys get a foot of snow, it is gone within 2-3 days.
                  Larry

                  '79 GS 1000E
                  '93 Honda ST 1100 SOLD-- now residing in Arizona.
                  '18 Triumph Tiger 800 (gone too soon)
                  '19 Triumph Tiger 800 Christmas 2018 to me from me.
                  '01 BMW R1100RL project purchased from a friend, now for sale.

                  Comment

                    #10
                    Originally posted by tkent02 View Post
                    The 850G with it's CV carbs and with the stock airbox will compensate for elevation very well. No need to rejet anything.
                    Originally posted by Steve View Post
                    If you DO go leaner, as Burque has, you will have to re-jet if you ever go lower in altitude. The compensation only goes in one direction.

                    .
                    Yup. No need to change from stock.
                    1983 GS850G, Cosmos Blue.
                    2005 KLR685, Aztec Pink - Turd II.3, the ReReReTurdening
                    2015 Yamaha FJ-09, Magma Red Power Corrupts...
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                    Comment

                      #11
                      Originally posted by alke46 View Post
                      Seriously? You should be able to ride nearly year round in Golden. Your season is a heck of a lot longer than it is 8 hrs. to the east of you. I have a daughter in the Longmont area and she constantly reminds me that when you guys get a foot of snow, it is gone within 2-3 days.
                      Yeah, I ride all winter. Not every day, but certainly every week. Especially this winter:

                      Red Bull's Idaho Backcountry Snowbiking Video Latest edit with Ronnie Renner, Reagan Sieg, Brock Hoyer
                      http://www.snowbikeworld.com/2016/05/red-bulls-idaho-backcountry-snowbiking
                      Red Bull is all over the snowbike movement.


                      Life is too short to ride an L.

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                        #12
                        I would say you could run 117 main jets but you'd have to convert your exhaust like I did on my 750T while I was living in high elevation Alamogordo, NM. Plus, I did not change my stock air box and all was well in southern NM. MrBill can testify to that!


                        Ed

                        EDIT: I've ridden in cold weather here... low 30s was tough and I wouldn't ride for very long.
                        Last edited by GSXR7ED; 12-10-2016, 08:49 PM.
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                        my opinion shouldn't be taken as gospel or in any way that would lead you to believe otherwise (30Sep2021)
                        Originally posted by GSXR7ED
                        Forums are pretty much unrecognizable conversations; simply because it's a smorgasbord of feedback...from people we don't know. It's not too difficult to ignore the things that need to be bypassed.

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                          #13
                          Yes, we can ride all year around. I tend to use my DR in colder weather as I do not have grip heaters or a fairing on the GS yet. Either way, I'm only good to around 28 degrees and dry roads, then I whimp out. The DR has great grip heaters, brushguards, and a mediocre fairing that all help deal with the cold wind. It is only nine miles or so to work and not worth the investment in time and money for heated gear.
                          After the GS is equipped with a fairing, grip heaters and bags, it will then be the winter ride as well.

                          Comment

                            #14
                            Originally posted by MadEyeGuy View Post
                            I tend to use my DR in colder weather as I do not have grip heaters or a fairing on the GS yet. Either way, I'm only good to around 28 degrees and dry roads, then I whimp out. The DR has great grip heaters, brushguards, and a mediocre fairing that all help deal with the cold wind.
                            Tell me about this DR please?


                            Life is too short to ride an L.

                            Comment

                              #15
                              That would be my 1998 Suzuki DR650 dual sport. While for several years that was my only bike, it is now mostly relegated to when the GS is down for service, off road, and bad weather. Still a Suzuki though.

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