1998 KDX200 fuel/ oil mix

Discussion in 'Canadian Daves JustKDX' started by Jason Larabie, Apr 30, 2017.

  1. Jason Larabie

    Jason Larabie Rookie
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    Just got a 98 Kdx 220 and ran it all weekend on open hydro roads and technical climbing. I ran it at 40:1. Question is, can I run it at 50:1? I realize I will probably have to do something with the jetting maybe. Just want to make sure it will be ok for an older bike. Any help is appreciated!


     
  2. Rich Rohrich

    Rich Rohrich BioHazard
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    Oil volume should be in direct proportion to load, time under load and rpm. For example trials riders can run their engines at 80:1 because they spend a lot of time at very low loads and low rpm. When they run higher loads and rpm rpm it's usually just for short bursts, so the 80:1 is adequate. Motocross riders and trails riders tend to run higher rpm, higher loads and longer time under load. So more oil is required.

    Most OEMs recommend 32:1 for a good reason, more oil is usually better than less. If you take the time to learn to jet, which is something only a tiny percentage of riders ever do, you can run as much as 16:1 in an MX bike without spooge running from the pipe or fouling plugs. I ran my MX bikes at 16:1 - 24:1 based on the course. I run my Montesa trials bike at 40 - 50:1 without issues. More oil tends to make better power and tends to make parts last longer, IF you take the time to jet the bike properly.

    Most guys are lazy and rather than bother with tuning, they keep putting less and less oil in trying to keep the plugs clean.

    Don't be one of those guys.
     
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  3. Jason Larabie

    Jason Larabie Rookie
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    I ran 40:1 all three days that I was out and had no spooge and it seemed to run pretty good.
    Iran 40:1 all three days that I was out with really fast open road stuff and tight gnarly slow stuff without any spooge.
     
  4. Rich Rohrich

    Rich Rohrich BioHazard
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    If you ran at 40:1 and it was working well, why would you want to switch to 50:1.
     
  5. truespode

    truespode Wheelie King
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    I have the same question.

    I ran 32:1 back in my smoker days and had spooge but not too bad. My last smoker was 3 years ago. GG 250 and I believe I ran 40:1 with that with no issues.

    I really don't see a need to go leaner and risk a failure. It's not like there is a big savings in cost for using less oil to get from 32:1 to 50:1 and not a power advantage for most dirtbike applications.

    Ivan
     
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  6. Jason Larabie

    Jason Larabie Rookie
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    Was just wondering what effect it would have. I almost ran out of fuel and my buddies gas was mixed 50:1 for his KTM.
     
  7. Rich Rohrich

    Rich Rohrich BioHazard
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    Putting in fuel from your buddy's KTM isn't a problem in a pinch. It's unlikely you will notice a difference.
     
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  8. ridejunky

    ridejunky Pro Class
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    manual for a 98 calls for 32:1. I have a 98 and run 32:1, I cant remember last time I fouled a plug and I ride gnarly tight wooded singletrack so I'm not exactly wringing it out. The only thing I notice is that when its hot out and I'm bogging in heavy mud it has a tendency to run a little hot and can start to boil the coolant. I think running 40:1 is probably OK but 50:1 is a little light, as Rich said though, once in a while is not going to hurt anything.
     
  9. jaguar

    jaguar Subscriber

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    It's all relative but what is missing in this conversation is the oil viscosity. Everything pivots on that. 40:1 for a heavy viscosity oil can equal 30:1 for a light viscosity oil.
     

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