will too much 2 stroke oil cause lean running?

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Just rebuilt our jetski engine and the dealer double mixed the fuel. So the fuel/oil mixture is probably around 25 or maybe even a 20:1 ratio at the moment. I have to give it about 1/4 choke to get it to to run otherwise it just stalls out or boggs if you try to go past 4000rpm and can't even get on plane. Now if I give it a little choke it will run good and it pulls real hard with lots of power all the way to redline. My question is should I have the dealer adjust the carbs or do you think I should run this tank through and see if it still needs choke with the next tank. Would running twice the oil cause it to lean out enough for me to have to use a little choke? Also just as long as it's not bogging down/leaning out the engine should be ok especially since it already has plenty of lubrication right?
 
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Yes the mix will lean out about 0.3 parts of air per part of gasoline. So if your carburetor was set for a stoichiometric mix of 14.7:1 it will run at 15.0:1 and you will have the problems you describe. If it was set richer like 13.5:1 then it will run at 13.8:1 and you probably wouldn't notice any change.

Put the right mix on it to see if it improves before readjusting your carb.
 
The difference between a 32:1 ratio and a 20:1 ratio is a whopping 2.4 ounces of oil dispersed into a gallon of 128 ounces of fuel. If your tune is such that 2 ounces of oil causes the running condition that you mention then you definitely should have the carburetors looked at. You're on the verge of seizure due to a lean air/fuel ratio.

I'd suspect that you have an induction air leak.
 
FowVay said:
The difference between a 32:1 ratio and a 20:1 ratio is a whopping 2.4 ounces of oil dispersed into a gallon of 128 ounces of fuel. If your tune is such that 2 ounces of oil causes the running condition that you mention then you definitely should have the carburetors looked at. You're on the verge of seizure due to a lean air/fuel ratio.

I'd suspect that you have an induction air leak. [/quote

That's great. Hopefully I haven't messed up the engine already. I didn't let it lean out where it would bogg down so hopefully it's still ok. I'll just bring it back and have them check it out.
 
If it runs good and doesn't feel like it's starving for fuel then It's not running lean right? One guy says the fuel is the problem, the other says it's not and it's the carb. I only have to give it just a little bit of choke, like a third of the way so I figured once we run this tank through and get back to regular gas it would run richer.
 
Why was it rebuilt? Running lean piston damage?
I wouldn't run it needing the choke on, I doubt your motor is supposed to be tuned that lean that 20:1 mix would make a difference vs 40:1.
 
Originally Posted By: IndyIan
Why was it rebuilt? Running lean piston damage?
I wouldn't run it needing the choke on, I doubt your motor is supposed to be tuned that lean that 20:1 mix would make a difference vs 40:1.


It dropped a power valve and destroyed one cylinder. I called the dealer and they said to just run that one tank through and see if it still does it. I hate this dealer. Bunch of idiots. Unfortunately nobody works on waverunners in my area.
 
Sounds to me like you need to have your carbs rebuilt.... not that you want to hear that but it's my guess. Although running heavy on oil can cause issues I highly doubt your ski is having that problem. How long did the engine sit before being rebuilt?
 
Ha, sounds like the pwc mechanics in my area. Are you sure they put in twice the amount of 2 stroke oil? I would never use them again based on that alone. How full is the tank right now? I would do a quick calculation and see if putting in just gas would bring it near the correct ratio. If so then do that and see if she runs right. If not then take it back and demand your "fixed" motor is fixed.
 
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