Yamaha Waverunner 1.1L (or MR1) overfilled with oil, How to prevent, How to fix issues it caused.

These Waverunners are known for being easily overfilled with oil due to how you need to check the oil.
Correcting the oil level is easy enough, but oftentimes there is a noticable lack of power after the oil has been overfilled. Typically the top speed drops to 40-45 mph, when before it was 50-55 mph.
This is caused by the design of the crankcase breather system flooding the air filter housing with oil if the engine is overfilled, which saturates the air filter media, restricting air flow and reducing performance.
Many PWCs and boats do not run any kind of air filter, as it is not super common to use these machines in a dusty environment like you would see on an ATV, SxS or Motorcycle.
So a common practice is to simply remove the air filter, and enjoy the machine. Or, you could choose to replace the air filter with a new one and avoid overfilling the oil in the future.
➡ Here is a link to the OEM air filter: amzn.to/3REdXn2 (6D3-14451-00-00)
0:00 Intro
1:50 Starting process
2:30 Oil check
3:25 Correcting oil level
4:15 The MR-1 weakness
4:58 Removing air filter
6:15 Oil saturated filter
7:25 Happy MR-1
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[@trythistv]

➡ Here is a link to the OEM air filter: amzn.to/3REdXn2 (6D3-14451-00-00)
Links here are most likely affiliate links, should you choose to purchase from one of them, I may earn a small commission for referring you to the seller. And, this is done at no extra cost to you!

[@AchikSarih]

Merci beaucoup ❤❤❤❤❤❤❤❤❤❤❤

[@daniels.904]

Thanks mate!

[@trythistv]

Happy to help!

[@vojtechchaloupsky7270]

Thanks for these useful watercraft videos and your insights. I have been working on quite a bit of these waverunners and also the high output MR1s where the intake is sitting on the top of the engine and have seen so many air filters soaked with oil and was wondering what is causing this fenomenon.

[@trythistv]

Glad to help!
I had a customer who complained his mr1 machine went through a quart of oil every weekend and only went 40mph. Pulled the completely saturated air filter out, back to 55mph, no more oil consumption.
Yamaha had a very specific way to check the oil in mind when they made them, and it wasn't super clearly communicated that it had to be done just so.

[@AMZHomeImprovementLLC]

Yesterday I was out on the water and my 08 VR Deluxe wanted to start but wouldn't crank over a few times (finally did). I noticed the oil was slightly over the mark and I constantly (every year) end up changing plugs. Any idea if the oil being slightly over would cause these issues?

[@trythistv]

A slight bit overfull probably wouldn't cause issues that quickly, if it was high and flooded the air filter to get down to the level its at now then it could cause some weird issues.
Plugs seem to be a fairly common thing, My Honda tends to foul one or two the first time I start it for the season, but then is good until the next year. My Sea-Don't fouls them at the first start and sometimes once more during the season.

[@AMZHomeImprovementLLC]

I have a 2008 VR Deluxe with 135 hrs and can barely reach 50 mph. I changed the oil filter once around 40 hrs ago but even then, only got to maybe 51 mph. so if I pull the air filter completely this won't harm the engine in your opinion?

[@trythistv]

My opinion is that boats haven't had air filters for decades, PWCs didn't for a long time (no 2 stroke had an air filter that I'm aware of), New Sea-Doos don't have an air filter from the factory, and never have. Kawasaki hasn't put them on that I'm aware of either. Its just Yamaha and Honda that used air filters on their PWCs.
The lake/ocean is not really a dusty environment for a jetski to be in, so how much is an air filter going to catch?
I've personally seen and serviced rental PWCs with over 2000 hours that did not have an air filter, and they did not consume oil, have low compression or any other issues that could be attributed to the air filter being removed.
I say take it out and see how she performs.