Pre mix ratio and brand of oil y'all use

[Cory Heidler]

Hey guys new member here... I've got a millennium edition rx that I just burnt the rear piston on it Sunday afternoon... I know this is probably unrelated to that since that is most likely cause by a lean condition..... but I digress. I have an oil block off and premix using 93 octane fuel. I've been mixing at about 40:1.... I've been told that is to rich and to back down to 50:1... I don't know but that sound pretty lean to me. Also I'm currently using royal purple HP 2c 2cycle oil... Good or bad???? I was also told this was the worst oil I could be using... Just curious and thanks for y'all's input!!

 

[ashr8]

I mix 40:1 with seadoo xps two stroke it's more expensive than your average oil, but it's good stuff and worth the money!! What ever the oil you choose to use it needs to be low ash fully synthetic oil (clean burning)


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[LouDoo]

Hi and welcome to the SeaDoo forum.

Personally I don't recommend using premix, with proper maintenance the oil injection system is very reliable. However since you have already done it, 40:1 is the correct ratio, and at stated above you need to use a full synthetic, API-TC rated oil, I also use BRP XPS-2. I'm not familiar with royal purple HP2C but if its full synthetic, and has a API-TC rating its O.K to use.

You didn't state what year RX you have, but if it's a DI (direct injection) you shouldn't use premix at all, if it's a carburetor ski premix is O.K.

Lou

 

[Spimothy Leary]

I always did 40-1.

not to split hairs, but I was corrected on this a while back during a discussion, but aren't the lean/rich terms reversed ?

ie: 40-1 is lean and 50-1 is rich ?

I've always, for years, described it the same way as the OP (40-1= rich and 50-1=lean) but had someone tell me I had it reversed because your describing the fuel, not the oil when you describing it...

 

[AdamXP800]

Yea I've always described it as 50:1 lean 40:1 rich. But I believe you are correct 50:1 is richer on fuel and 40:1 would be a leaner fuel

 

[Spimothy Leary]

oh, and to backtrack and answer the other question, I always used Amsoil, (and you can get it discounted by paying $20 a year to become a preferred member $10 for a trial 6 month membership) I used quicksilver for the longest time, but got tired of wallyworld not always having it in stock, so I switched to Amsoil and had a case shipped right to the door, much easier that way.

 

[brianmcb]

32:1 amsoil interceptor on my fresh 951 for the first tank and 40:1 afterwards.
I saved about 40$ by becoming an amsoil prefered customer buying four jugs of interceptor rather than buying xps my local dealer.


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[Cory Heidler]

Awesome... Thanks for the input... I thought that quicksilver oil was junk... But apparently not... A lot of people use it huh... Ok so now new question. I'm rebuilding the top end... I'm already .25mm oversized as it is... What pistons should I use and also have you heard of using 100 octane race gas to eliminate detonation and piston melting like I had an issue with... It was NOT oil starvation


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[brianmcb]

That sounds extreme..I run 87 in mine and have never had an issue. .5mm oversize sbt pistons. How hot are the plugs your using? Stick with stock br8es if your not already


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[Rosie2514]

Whoa whoa. Not to change subjects but I do beleive you reversed the correct way the oil to gas mixtures work .
40:1 is richer than 50:1.


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[Rosie2514]

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[mikidymac]

The ratio is 40 parts fuel to 1 part oil or 50 parts fuel to 1 part oil. So the more oil you have the richer the ratio is. As long as you are running stock compression the bore size does not change your requirement for race fuel. If you burned the rear cylinder you have something else going on.

 

[Rosie2514]

You sir are correct ^


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[cyaman37]

Not to split hairs here but I always believed that the terms rich and lean had to do with the amount of said mixture you are injecting into your cylinders through the carb not the ratio of oil to gas. Even if you run a 32-1 ratio of oil to gas you can still have a lean condition by not getting enough of that mixture through your carb. Correct?


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[Rosie2514]

You are correct again sir


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[Cory Heidler]

Wow y'all are freaking me out in the ratio thing ... I got it 40:1... Thanks everyone... Ok so I am using stock NGK plugs like brianmcb said... I am currently running 93 in mine... I've also learned that I can bump up my main jet to resolve the issue on the suspect cylinder carb


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[Cory Heidler]

Oh yeah and can I use OEM wrist pin bearings with the aftermarket piston and pin??


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[68ragtop]

The aftermarket & oem pins are the same diameter. however, I am not a fan of the caged aftermarket bearings, especially on the 951's. Loose needles are going to be more reliable. new oem loose bearings even come with an integrated disposable install tool.

 

[Cory Heidler]

Yup... I've heard a lot of bad things about the caged bearings


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