50CC Dirt Bike Auto Clutch Oil

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Aug 19, 2021
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Hello!
I was recommended to start here in trying to find some additional information on my project. I had a company in Cary, NC (WearCheck) conduct a fluid analysis on a clutch fluid for an automatic clutch in a 50cc motocross race bike. I had a few requests, one is still on going.

1. Determine the longevity of the recommended clutch fluid as it is change every 1 hour or every ride.
2. To determine what the fluid really is. Several people use alternates however gathering information on their specific performance changes is tough to get.

Cobra Clutch Milk - this is the recommended fluid and what I had testing. Sample 1 was new oil. Sample 2 has 1 hour run time.
Maxima MLT 75wt - is an alternate that several people use.

Some properties of the Cobra Clutch Milk from the report. I can also post the full report if needed. What is this stuff??

66ppm Magnesium
28ppm Calcium
498ppm Phosphorus
293ppm Zinc
2881ppm Sulfur
0.847 Acid Number (AN) mg KOH/g
40.1cSt Visc @40C
7.11cSt Visc @100C
Viscosity Index (VI) 140

Thank you!
 

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  • OA-RPT-B-D08192021WUSCAR-078-162882 (004).pdf
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Joined
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It is a transmission fluid. In general it's easiest to think of it as a relatively light duty gear oil (less heavy duty than GL-5) that doesn't hurt the clutch friction performance but protects gearing. That Maxima product is fairly well liked for those minis as I'm sure you know.
 

saathoff05

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It is a transmission fluid. In general it's easiest to think of it as a relatively light duty gear oil (less heavy duty than GL-5) that doesn't hurt the clutch friction performance but protects gearing. That Maxima product is fairly well liked for those minis as I'm sure you know.
It has the weight of a transmission fluid but more color of a gear oil. I started this project more for fun. The cobra clutch milk is like $16 a quart but in the overall scheme of things its not that expensive. The marketing of the cobra clutch milk has the majority thinking it is magic potion and should be changed every 15min moto haha.
 

MolaKule

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Interesting that they did not report the 100C viscosity of the new oil.

As far as color, no additional dye has been added.
 
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Joined
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Messages
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It has the weight of a transmission fluid but more color of a gear oil. I started this project more for fun. The cobra clutch milk is like $16 a quart but in the overall scheme of things its not that expensive. The marketing of the cobra clutch milk has the majority thinking it is magic potion and should be changed every 15min moto haha.
Yeah, unless the clutch is being abused and burning up, (which shouldn't happen with the auto anyway) those fluids should last a good long time. The motorcycle trans fluid I made had a much larger lifespan than most of our customers were comfortable running it for. As long as the trans and clutch are working properly and there's no contamination from the crank, that fluid doesn't really have any reason to go bad in a short time.
 

saathoff05

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Interesting that they did not report the 100C viscosity of the new oil.

As far as color, no additional dye has been added.
I did receive a few different reports. This attachment has 7.11 Visc @100C.

I really have no idea what I am looking at on the report. I also have no baseline to judge it from. I was hoping to find out what the fluid really is as the motorcycle manufacture does not make the oil I am sure.
 

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  • OA-RPT-B-D08192021WUSCAR-078-162882.2.pdf
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saathoff05

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Yeah, unless the clutch is being abused and burning up, (which shouldn't happen with the auto anyway) those fluids should last a good long time. The motorcycle trans fluid I made had a much larger lifespan than most of our customers were comfortable running it for. As long as the trans and clutch are working properly and there's no contamination from the crank, that fluid doesn't really have any reason to go bad in a short time.
These clutches do not last to long. Guys replace them at like 20-60 hours depending on how fast the kid rides. The little 50cc motors make like 9HP and clutch engages at 9500ish RPM.
 
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20-60 hours is far from short for a race bike though, and not a lot of people are pleasure riding on a Cobra. Like you said, some people change the fluid every heat/race, which is just crazy talk in my opinion.
 
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