32:1 PJ1 VS 50:1 Motul – The results are in!

[El Camexican]

I’ve been looking forward to this rebuild for 2 years. Not because I enjoy the thrash (I think we all wish engines would last forever), but because this is the first time I’ve ever gotten to do a real long term comparison of 2 stroke oil brands and ratios. While my methods and results would get laughed out of a lab they tell me what I needed to know for my engine and riding situation.

Here are the piston, ring and power valve comparisons from the 2010 rebuild
Engine One 2010
- New Wossner Piston
- Refinished nikasil cylinder
- Ring ends gapped at .013”
- Oil PJ1 Gold Mix used at recommender 32:1 ratio
- Engine was then used for approx. 160 hours of trail riding

Findings during 2012 Rebuild
- Ring gaps were between .023” and .028”
- - Signs of blow by were almost no existent
- Piston was extremely worn on the exhaust side, no vertical scratches, but there was a at least a .003” of wear on the exhaust side that started a half inch below the rings and continued down near to the bottom of the skirt. Almost exactly the same shape as the exhaust port. (more on that later)
- Power valve was extremely dirty. At least 1/8” of more of buildup. Exhaust port and pipe were also covered with thick deposits. The pipe was so plugged up I decided to replace it rather than clean it (it also had some bends and dents)
- Piston crown and head were very clean.

Piston, ring and power valve comparisons from the 2012 rebuild
Engine Two 2012:
- New Wossner Piston
- Ring ends gapped at .013”
- Motul 800 2 Stroke Oil used at recommender 50:1 ratio
- Engine was then used for approx. 180 hours of trail riding

Findings during 2014 Rebuild
- Ring gaps were between .028” and .032”
- Considerable blow by below lower piston ring
- Piston is slightly worn on the exhaust side, no vertical scratches. There are still faint factory machining lines on most of the exhaust side and even the grey coating Wossner puts on the piston was visible in many areas.
- Power valve has very little buildup on it. No more than 1/16” and barely anything other than a sticky film in some spots. Exhaust port had only a brown oily film that wiped off with a rag and brake cleaner. The pipe has deposits, but only about ½ what the PJ1 pipe had.
- Piston crown had considerably more deposits on it than the last one, but they were evenly spread and brown. Head had a slight frosting of carbon that wiped off with brake cleaner.

I should point out that a number of mods were made to the engine in 2012 including a reshaped combustion chamber (that added considerable compression), porting and some case stuffing. All these changes should have equated to greater engine wear, yet they didn’t.
The only reason I wanted to run 50:1 is so that I don’t need to bring a gallon of oil with me on my rides. I was certain the reduced oil content would cost me in reduced piston and ring life, but considering the additional 20 hours the 50:1 engine had and that the only measurable difference to the reduced oil ratio was slightly more ring wear I will never go back to 32:1.

I said I’d get back to the piston wear on the exhaust side of the first engine. I’m thinking that the carbon buildup in the 32:1 engine may have caused that as I recall smooth carbon formed around the port that was likely wearing on the piston.

It also seems that Motul deserves a shout out here. Seems they make decent oil that doesn’t cost a lot more than others. However I’m not sure if I should use it again, or try an 80:1 Amsoil oil to see what happens. On one hand 80:1 would be so easy to carry around in my backpack, but on the other hand we do a lot of high speed riding between trails and I cringe at the thought of being pinned out at 80mph for 5 minutes at that ratio. Maybe better to let someone else do that test.

[Blue Viffer]

I am questioning the 32-1 ratio also as in the 80's we ran 40-1 and did not seem to have problems. I think that your comparison would be better if you had done the testing with the same brand of oil, but your results are impressive. Thanks for your posting this, as it comes at a time when I am just getting back into the 3 wheels and will be looking for all the advice I can get with results that back up the advice.

[El Camexican]

I am questioning the 32-1 ratio also as in the 80's we ran 40-1 and did not seem to have problems. I think that your comparison would be better if you had done the testing with the same brand of oil, but your results are impressive. Thanks for your posting this, as it comes at a time when I am just getting back into the 3 wheels and will be looking for all the advice I can get with results that back up the advice.

As far as 40:1 goes, yea people run it. They also run 16:1, 20:1 etc. PJ1 middle of the road recommendation for Gold Mix is 32:1 and Motul specs the 800 at 50:1 to 60:1. Motul also sells a road race oil that is hard speced at 32:1, but it is for a different application.

[briano]

I run 50:1 in every 2 stroke, always have and always will. With all of the questions about mix ratios and what is better, and break in periods, here's how I look at it. Go buy a chainsaw, not a sh!t box from a big box store but from an actual dealer. It is set up and running great when you get it, the oil ratio is 50:1, and there is no heat cycles or not running full throttle. You take your new saw and run it balls to the walls like it should be, and guess what, they will run for many trouble free years. They also run at way higher rpms than most other engines, anywhere from 12,500 to 14,000 rpms. I ran my saw for 2 hours today pretty much nonstop only stopping for fuel and it keeps on ticking time after time and year after year. I'm a firm believer in a good quality oil and the jetting setup to run a 50:1 mix, I've never had a problem with this. From bikes, trikes, quads and snowmobiles I have thousands of trouble free miles.

[6speedthumper]

I run 50:1 in every 2 stroke, always have and always will. With all of the questions about mix ratios and what is better, and break in periods, here's how I look at it. Go buy a chainsaw, not a sh!t box from a big box store but from an actual dealer. It is set up and running great when you get it, the oil ratio is 50:1, and there is no heat cycles or not running full throttle. You take your new saw and run it balls to the walls like it should be, and guess what, they will run for many trouble free years. They also run at way higher rpms than most other engines, anywhere from 12,500 to 14,000 rpms. I ran my saw for 2 hours today pretty much nonstop only stopping for fuel and it keeps on ticking time after time and year after year. I'm a firm believer in a good quality oil and the jetting setup to run a 50:1 mix, I've never had a problem with this. From bikes, trikes, quads and snowmobiles I have thousands of trouble free miles.

I've got an old MacCullah 3216 that my dad bought new a good twenty years ago. Have used that little 32cc saw to cut down trees that it was never meant to cut down and it has never been apart. I have always run 40:1 ratio, of all brands of oil in it. Haven't ever owned a 2 stroke of road machine though...

[just ben]

Great findings. I tear my topend off atleast once a year just to see what's doin. Between several different oils the only one that had a noticeable film was golden spectro. At 7-8 bucks a pint it costs a little more than some oil but less than others. I mixed it per the directions and after pulling the engine apart after many hard hours of riding(about 40) there was no wear on the piston just a thin film of oil. That came off with a rag.after spending 17 a quart for klotz r50 I will stick with the spectro. I had wear on the exhaust port side of the piston with amsoil dominator and interceptor as well as the r50.also note I usually jet slightly lean but safe

[250rmanfmf]

Very nice findings. I am not really shocked at the results. the PJ1 test, you had close to twice the amount of oil added to it than the Motul. Seeing plugged up power valves and a coated pipe is not that surprising. The only surprising thing really to me was that the exhaust side of piston more worn on the more oil motor than the less oil motor. Pretty cool findings and again thanks for the findings. I think its great when people are willing to commit to something to help themselves and others out.

[250rRoostmaster]

I'm a firm believer in 45:1 to 50:1 jetting ratios. Never had a problem in any of my machines, toys or tools.

[oldskool83]

I'm running 32:1 Honda pro oil with good jetting. I always richen it up in the cold months by dropping the needle 1. IDK about changing plugs sooner keeps the inside nice at least with 125 motors

[86T3]

What do you think about the blow by? Thats the only the only piece that doesn't fit

[El Camexican]

What do you think about the blow by? Thats the only the only piece that doesn't fit

Considering how much better condition the Motul piston was I would guess it is the different head that caused the blowby once the rings were a little worn. I don't have a compression value, but with the old head and a fresh engine I was able to start the motor by hand when warm. With this head it takes a well thought out kick to start it.

[86T3]

Giggity giggity

[Afrothunderkat]

I'm a firm believer in a good quality oil and the jetting setup to run a 50:1 mix

Yes, as long as the machine you're using is jetted for 50:1 it's a great ratio. Cost effective too. Also, an air cooled, cast sleeve 5hp chainsaw is a bit different than a nik plated 50hp liquid cooled race motor. See how many times you can kick over a liquid smoker with a forged piston and go strait to full beans throttle. Might work with a chainsaw (almost impossible to 4 corner cold seize) but not tuned performance motor.

It depends on where you ride, how you ride, duration, type of oil, and jetting of the machine. 50:1 over 12:1 power loss is quite significant BUT! try jetting a modern liquid smoker for 12:1... It may pull great numbers on the dyno under heavy load, but it's just not feasible in real world ridding.

TLDR; Pick a ratio and jet for it.

[cr480r]

Pick a ratio and jet for it.

^^this. I use 32-1. Extra oil makes me feel good, and my parts like it too..

[crackshot]

I run 40:1 dominator in my machine. It likes it. It told me.