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Oil Mixture


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I think that most people mix it at 80:1, which is 62.5 ml to every 5 litres of petrol. It does say in the manual for my Sherco to run it at 50:1 which is OK but when using a trials bike as its meant to be 80:1 is more suited as it wont oil up the plug as much. However if you are planning on using it more like a trail bike more oil can never be a bad thing.

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  • 2 weeks later...

#3 since handbook says 50:1 and yet you think 80:1 is OK I presume by the same reasoning you would recommend ignoring the other manufacturers instructions and only putting 2/3 required oil in gearbox or your car sump?

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#3 since handbook says 50:1 and yet you think 80:1 is OK I presume by the same reasoning you would recommend ignoring the other manufacturers instructions and only putting 2/3 required oil in gearbox or your car sump?

http://www.trialscentral.com/forums/topic/17883-the-great-how-much-oil-question/

80:1 is most popular for a reason :stupid: .

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Since I started mixing 80.1 using premium unleaded and expert oils in my Sherco, I found it easier to use the same mix in the ride on lawnmower, the push lawnmower and my chainsaw. All have worked well for years. I don't like the idea of using 50:1 with a muffler that cant be repacked......think Sherco.

I made my muffler repackable but will still stick to 80:1 whilst using good fuel and oils. Riding in 35deg heat is a good test, been doing it for a couple of years now, so when it comes to refreshing the top end [soon] I'll see the how things have gone.

Cheers Taff

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A poll is not only unscientific, lots of germans voted for Hitler but that turned out to be unwise. The words Lemmings and cliff spring to mind.

As I said previously if you think nearly halfing the manufacturers recomendations for the cylinder lube is a good idea, why not cut the gearbox oil by the same amount? A correctly carburated bike will not oil the plug at 20:1 fuel : oil, let alone 50:1

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I have quite a bit of respect for Jon Stoodley - but it does not mean he is always right nor do other tuners always agree with what he says.

The comment about gearbox makes as much sense as ignoring manufacturers advice. Why spend a lot og £££s on a bike then risk damaging it due to lack of oil?

Some recent research has shown that at 50:1 a good / top quality synthetic oil starts failing to protect piston rings at about 12,500 RPM so in theory at typical trials bike revs an 80:1 mix should be fine. But then add in some variables like water droplets, a bit of engine wear, poor carburation, variable petrol quality etc and 80:1 looks nowhere near a safe bet.

I stripped a 2010 gasgas recently (gearbox fault). Run on Motul at 75:1. Rings, piston, barrel all damp with oil, some wear but still within tolerance. Quite a bit of oil in the bottom end but little end far too dry for my liking. The piston, bottom end and even the reeds were covered in dark brown deposits caused by blowby. It would seem 75:1 was providing adequate lubrication but nowhere near enough piston cooling and ring sealing.

There is a serious drawback to advising 80:1 - You do't know what sort of use the bike is going to have, I have seen a beginner stuck in a peat bog rev the bike till the exhaust glowed dull red just outside the barrel. Try that at 80:1 and see how long the piston lasts.

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I have quite a bit of respect for Jon Stoodley - but it does not mean he is always right nor do other tuners always agree with what he says.

The comment about gearbox makes as much sense as ignoring manufacturers advice. Why spend a lot og £££s on a bike then risk damaging it due to lack of oil?

Some recent research has shown that at 50:1 a good / top quality synthetic oil starts failing to protect piston rings at about 12,500 RPM so in theory at typical trials bike revs an 80:1 mix should be fine. But then add in some variables like water droplets, a bit of engine wear, poor carburation, variable petrol quality etc and 80:1 looks nowhere near a safe bet.

I stripped a 2010 gasgas recently (gearbox fault). Run on Motul at 75:1. Rings, piston, barrel all damp with oil, some wear but still within tolerance. Quite a bit of oil in the bottom end but little end far too dry for my liking. The piston, bottom end and even the reeds were covered in dark brown deposits caused by blowby. It would seem 75:1 was providing adequate lubrication but nowhere near enough piston cooling and ring sealing.

There is a serious drawback to advising 80:1 - You do't know what sort of use the bike is going to have, I have seen a beginner stuck in a peat bog rev the bike till the exhaust glowed dull red just outside the barrel. Try that at 80:1 and see how long the piston lasts.

Although I do respect your opinion and what you are stating, this last example would not be average use by normal folke. I do believe the P.O.U. must be kept in mind.

For putting about and occasional revving, I feel safe with 80:1. For harder running or a road trial at higher(moderate) revs for long duration, I may go 50:1, and for extreme usage as in idiot use, well this may require a bit more such as 36:1 or so, thus I choose to stick with what works for my average use. And that is not extreme, thus the ratio.

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