2 Stroke Engine Oil Contest

[mlatour]

Myself on a YZ125, recreational MX, not raced but certainly 'ridden like a 125 should' (hitting max rpms / overrev a few times per lap)

 

Engine has approximately 100 hours of use, currently on it's 5th piston & ring (cast OEM pistons is all I use)

Of course the old pistons barely showed any wear but during the off-season I like to freshen things up preventatively for peace of mind.

The cylinder's plating is only just starting to show some light wear near the exhaust bridge but is still quite serviceable,

the bottom end has never been touched, no up/down play anywhere, no discoloration, rust or any other sign of concern.

 

91 octane pump premium + 25% race fuel for a total of about 96 octane, 

stock engine & pipe, the only 'mod' is the compression squish height which was reduced from 1.37mm to 1.05mm (182psi).

Liking a very crisp running engine I tend to jet quite on the lean side and don't even bother with plug checks,

I can certainly feel when I've reached the limit of lean (engine 'wails' more) or, the settings are too rich for best power/throttle response.

 

No spooge whatsover at any pipe joints or at the silencer's tip, even the power valve's vent hose barely drips.

The oil ring pattern inside the expansion chamber is about 1-1/4" (30mm) deep past the exhaust flange, from that point on the pipe is dry.

 

Been using Amsoil Interceptor at 32:1 since day one.

 

With these results, anyone would be hard pressed to change my mind on the choice of oil, premix ratio or jetting it richer 'just to be safe'.

Edited October 3, 2018 by mlatour

[pcnsd]

8100 rpm, water cooled, Maxima K2 @ 32:1

[2strokenut]

When I raced moto I used Benol at 28:1 with no spooge in a modded 300SX. Not sure how anything can top pure castor and the smell is awesome. Stuff is too dirty for the hard enduro stuff I do now. I run Legend oil which is a snowmobile oil in my TPI.

 

What was the contest again?

[jaguar57]

yes I have data on Honda HP2 (54:1 water cooled 12,000 RPM,62:1 water cooled 9500 RPM)

pcnsd, K2 should be used at 56:1 in your situation. everyone says that too much oil does no harm but it causes spooge, shortened plug life, and viscous friction at lower RPM (you lose horsepower due to the rings having to push heavy oil. oil is more viscous the lower the cylinder temp. low RPM=low cylinder temp)

mlatour, why in the world are you using an oil specifically made just for snowmobiles? 125cc mx bikes need an oil with ash depositing additive for extra protection during high stress moments.

[mlatour]

2 hours ago, jaguar57 said:

mlatour, why in the world are you using an oil specifically made just for snowmobiles?

 

I understand it's formulation likely promotes better cold flow and pumpability in injection systems but it doesn't mean it is limited to that,

just because it has a picture of a snowmobile on the label doesn't mean it will fail in a dirt bike applications. 

Interceptor is actually marketed at anything recreational, not only snowmobiles:

https://www.amsoil.com/shop/by-product/motor-oil/2-stroke/interceptor-synthetic-2-stroke-oil/

The key word is recreational applications, not constant WOT racing where Amsoil markets it's Dominator premix for that.

 

From the usage described in my earlier post, any weakness of this oil in my

particular application would have no doubt been very apparent by now which is not the case.

 

If ever availability or higher costs becomes an issue, Shell's Advance Snow Ultra would likely be my 2nd choice.

In Canada many dirt bikers who also own 2T snowmobiles use it in all their applications without issue.

If you are not familiar with snowmobiling, the constant resistance of plowing thru deep snow is likely

equal or higher stress on an engine than what a dirt bike (non racing) experiences.

 

Edited October 3, 2018 by mlatour

[jaguar57]

my calculator says 27:1 for Interceptor op to 12,000 RPM water cooled

[mlatour]

Jaguar57, perhaps you can answer me

by memory I had read an article mentioning how to gauge the jetting and/or premix ratio by the depth of the oil 'ring' visible in the expansion chamber.

Mine is showing a 'moist' oil ring about 25-30mm deep into the pipe past the port's mounting flange.

 

What is your take or, would you have any more infos about this theory?  Thanks!

Edited October 3, 2018 by mlatour

[jaguar57]

I wouldn't pay any attention to that theory unless it was proposed back in the day when everyone used mineral oil. If so then it only applies to those oils.

Synthetic oils leave very little carbon deposits if any at all.

Your fuel/oil ratio exists to make sure you have enough oil to protect metal parts.

Too little oil and rings wear fast. Too much oil and your engine wastes power fighting viscous friction.

[chrispick]

BelRay H1R , singletrack, and desert YZ250 w/bigbore kit

[jaguar57]

Bel-Ray H1R 42:1 water cooled 9500 RPM

[chrispick]

Nice, I have always mixed at 40:1, splitting the difference from what the factory recommends and what I grew up doing (70's)

Thanks again

[shrubitup]

9 hours ago, 2strokenut said:

When I raced moto I used Benol at 28:1 with no spooge in a modded 300SX. Not sure how anything can top pure castor and the smell is awesome. Stuff is too dirty for the hard enduro stuff I do now. I run Legend oil which is a snowmobile oil in my TPI.

 

What was the contest again?

You can't use snowmobile oil in a KTM. Motorex only or Bel Ray but you'll need to change the plastic color to use Bel Ray.

[2strokenut]

43 minutes ago, shrubitup said:

You can't use snowmobile oil in a KTM. Motorex only or Bel Ray but you'll need to change the plastic color to use Bel Ray.

Explosion immenent 

[jaguar57]

"Legend ZX-2R is an ultra premium, non racing, 2-cycle lubricant formulated for the ultimate in engine protection. Recommended for older engines, trail, and other non racing applications."

"Legend ZX-2SR is a high performance 2-cycle lubricant formulated for racing and maximum performance. Recommended for newer engines and high RPM applications."

[shrubitup]

Likely acquiring a 1982 Yamaha IT250 on Monday so I’m curious on oil ratio for air cooled trail bike. Oil is either silkolene Pro 2 (fully synthetic ester) or maxima castor 927. thanks!

[jaguar57]

for 9000 rpm both need 40:1

[ss-racing66]

On 10/1/2018 at 10:52 PM, jaguar57 said:

12,000 RPM water cooled Castor 927 45:1 (so you are probably getting spooge at 28:1)

I’ll be honest, I think your spreadsheet is flawed. I’d never run a 125 at 45:1 and here’s a data point for you, I ran the 927 @28:1 for 3 hours yesterday and the result was just some chocolate colored soot at the silencer outlet.

[jaguar57]

I have no problem with constructive criticism. OK so you got some chocolate colored soot at the silencer. If you want to use more oil than is necessary and have to deal with soot and deposits and spark plugs that foul more often then that is completely your choice and I support your right to decide for yourself. Be aware that using too much castor also means you have to take the engine apart more often and clean the rings and their grooves.

[ss-racing66]

1 hour ago, jaguar57 said:

I have no problem with constructive criticism. OK so you got some chocolate colored soot at the silencer. If you want to use more oil than is necessary and have to deal with soot and deposits and spark plugs that foul more often then that is completely your choice and I support your right to decide for yourself. Be aware that using too much castor also means you have to take the engine apart more often and clean the rings and their grooves.

I can’t quite imagine what your agenda is with this thread, I haven’t even seen anyone ask you about your qualifications to recommend lubrication advice for racing engines, but I’ve been racing 2-strokes for over 40 years and can count the number of plugs fouled on 1 hand. Over a decade of that was at national level competition, and I never knew any of my friends and competitors running trendy oil ratios in the 50:1 range. Always high quality oils at 28-32:1 , always. And you want to know why?, because that’s what the guys like Ed Toomey, Rick Schell, Van Gilder, and companies like Swedetech and Yamaha who built the engines told us to mix. IMO, you’d have to be a fool to run a 125cc 2-stroke racing engine at 50:1.

Your calculator may be spot on for trail riding, and things like scooters, outboards, and other low stress engines, but It doesn’t seem to be suited to racing applications. 

Why starve your engine of oil? Wouldn’t that be great seizing a crank bearing on the face of a big double? Or 20 miles out in the wilderness? Think about it.

Edited October 6, 2018 by ss-racing

[Motox367]

12 minutes ago, ss-racing said:

I can’t quite imagine what your agenda is with this thread, I haven’t even seen anyone ask you about your qualifications to recommend lubrication advice for racing engines, but I’ve been racing 2-strokes for over 40 years and can count the number of plugs fouled on 1 hand. Over a decade of that was at national level competition, and I never knew any of my friends and competitors running trendy oil ratios in the 50:1 range. Always high quality oils at 28-32:1 , always. And you want to know why?, because that’s what the guys like Ed Toomey, Rick Schell, Van Gilder, and companies like Swedetech and Yamaha who built the engines told us to mix. IMO, you’d have to be a fool to run a 125cc 2-stroke racing engine at 50:1.

Your calculator may be spot on for trail riding, and things like scooters, outboards, and other low stress engines, but It doesn’t seem to be suited to racing applications. 

Why starve your engine of oil? Wouldn’t that be great seizing a crank bearing on the face of a big double? Or 20 miles out in the wilderness? Think about it.

+1 ??  25 years of mx only A class for some good years but just part time B racer anymore.  Wouldn't ever dream of anything over 32:1 125 or 250 engines wouldn't last . Oil is power people dont understand that ?