New to me 2008 Zuma 50cc 2 cycle final drive fluid question

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XB_Fan

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Apr 5, 2022
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Bought a cheap Yamaha Zuma 50cc 2 stroke moped with 5000 miles on it. Wanting to get fluids all changed, etc.

The manual says regarding transmission oil:

Final Drive Oil is 10w30SE or Gear Oil

Researching over at moped forums, I read conflicting posts.

Some say 80w90 gear oil, 10w30 engine oil, or 85w140

For longevity, would you go with 10w30 or one of the gear oil choices above.

Thanks!
 
The thing only holds 3.2 ounces so it isn't a huge sump and likely isn't carrying any true load. If they say that a SE rated 10W-30 works then you'd likely have to get that from a motorcycle shop.

If you want to use a gear lube then the closest viscosity grade you'd find to a 10W-30 motor oil would be a 75W-85 oil. You could use a 75W-85 GL4 which can be found quite easily. I wouldn't put any 85W-140 in that tiny thing.
 
l had one of those for quite some time. Since the 50cc engine was a bit down on power, I purchased a big bore kit, maybe 72cc. I also added the final drive gearing change for higher top speed. I did not change the exhaust or carb. Don't recall if I re-jetted it or not.

In any case, the little beast was every bit as quiet and smooth as stock, but top speed was way, way higher.

After the mods, I could ride it to the airport, about 26 miles away, on the local 'bee line', not quite a highway, but a 55mph road.
 
These seem to have quite a following due to the Minarelli 2 cycle on them. If I could mod this to even get up to 45, that would unlock nearly the entire community I live in (220,000 people 85 sq miles) for me to explore on this. I am currently working on getting my weight down to under 200, so that should help considerably.

Watching YouTube videos on modding this, it looks fairly simple for a novice.

I've never owned a moped before, but am excited to start working on this thing. As long as parts remain available. Looks like they sold enough of these since the early mid 90's for parts to be around.
 
Because the viscosity of gearbox and engine oils are measured on
different scales, an 75W85 gear oil viscosity range is about the same
viscosity as a 30 grade motor oil...

SAE 80 gear oil is roughly equivalent to an SAE 20 grade engine oil...

SAE 85 gear oil is roughly equivalent to SAE 30 grade engine oil...

SAE 90 gear oil is roughly equivalent to SAE 40 grade engine oil...

gearoil-3a-jpg.223167

In the name of longevity I would pick SAE 80 gear oil or SAE 30 grade motor oil and not the SAE 90 or SAE 40 that would only serve to cost your poor little 50cc engine more HP in unnecessary oil drag...
 
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I didn't even think to compare gear oil viscosity to a corresponding engine oil. I seldom have ever dealt with anything that has gear oil in it. Never owned motorcycles, four wheel drive vehicles, etc. Thanks for that visual. Makes sense!
 
3.2 ounces (1/10 of a quart) will not add any undue drag on the engine in power output to the rear wheel of that small engine unless you go to an extreme of thicker viscosity. Simply choose the one that's easiest for you to deal with and go with it.
 
45mph is easy and cheap with the big bore kit. Trying to get more HP from a stock cylinder engine is not so easy. Requires porting, tuning, carb, noisy exhaust and still falls short of having smooth usable power.
 
Used 10w-40 on two different Zumas for years, 4 stroke 125cc variant but basically the same. Never any issues. I was using 10w-40 since that's what the engine used. Its not picky.
 
Thanks for finding that Yamahalube stuff. Didn't even know it existed. Grok never mentioned it either. lol
 
We're Metals said:
Used 10w-40 on two different Zumas for years, 4 stroke 125cc variant but basically the same. Never any issues. I was using 10w-40 since that's what the engine used. Its not picky.
Click to expand...

I was thinking of a 40wt as well as the primary usage of this is going to be heat of summer. In my locale, June, July and August are pretty brutal for temps. 90-95F becomes pretty standard with a half dozen over 100F days.
 
Cujet said:
45mph is easy and cheap with the big bore kit. Trying to get more HP from a stock cylinder engine is not so easy. Requires porting, tuning, carb, noisy exhaust and still falls short of having smooth usable power.
Click to expand...

I watched a really good video on a guy replacing the piston, head and gaskets on a Zuma and it looked pretty approachable for a newb. Taking my time, I'd like to get that kit installed. I'd have to budget for a replacement carb and exhaust. Probably 4-500 for the nice Malossi kit with everything.
 
XB_Fan said:
I was thinking of a 40wt as well as the primary usage of this is going to be heat of summer. In my locale, June, July and August are pretty brutal for temps. 90-95F becomes pretty standard with a half dozen over 100F days.
Click to expand...

Those gears really take next to no abuse. They are constant mesh and aren't affected by much heat since they are far from the engine. But I hear you.
 
XB_Fan said:
Probably 4-500 for the nice Malossi kit with everything.
Click to expand...
$40-50 for the big bore kit on Ebay. Just make sure to chamfer (round off the edges) of the ports before installing.

The gears are $107.

That's what I did, and it worked really well. You will need a hydraulic press to change the gears. It's not difficult, but can't be done without a press.
 
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