Yamfan- If it's the paper I'm thinking of, it was "sponsored" by Yamaha.  I believe they donated a water-cooled 125 engine.  It was not an official Yamaha publication or study.  Please correct me if I'm mistaken.  It's been years since I read it.

BelRay was famous for destroying big end rod bearings back in the day...  they were one of the first synthetic "low smoke" oils and likely contained high levels of...  or if I remember correctly from the article... high molecular weight...  polybutene.  (Couldn't remember the name polybutene until you mentioned it)

And yes, polybutene is still used today...  many "low smoke" two stroke oils use a polybutene base.  Those oils are the hardest on rod bearings at high speed/high load.. It's old technology but that doesn't mean it's not still being used today.  (I suspect modern Yamalube 2s is a polybutene based oil.)

Legend uses a highly refined mineral oil base.  I spoke to the owner several years ago and he told me that removing the impurities is how they achieve low smoke...  Polybutene achieves "low smoke" because it doesn't burn off...  Highly refined mineral oil achieves "low smoke" because it burns clean. 

In any case, these old Enduros don't stress oils anywhere near what a high output two stroke does....  HP levels and RPM levels are relatively low.  Even a polybutene base oil is not likely to cause any bearing issues in these old Enduros.  The old BelRay worked great in the Enduros and bigger motocross bikes that probably didn't see much over 6,000 rpm...  it was the highly stressed 10,000+ rpm 125 motocross racing engines that overheated the rod bearing with early BelRay oil in my experience.



 

Sometime 1983, 1984. I was using Bell Ray. It was Paul Thede at Race Tech who suggested Golden Spectro. My race bike he did numerous modifications on was a 1983 HONDA CR 125. It was a great bike indeed, before and after his extensive engine, clutch and suspension work..

asco

BelRay famous for destroying big ends....

God something else to be paranoid about....

You are probably right about highly stressed racing engines suffering.  I used to buy my BelRay from my then local Yamaha dealer Padgetts of Batley.  

The Padgett family are very well known in road racing circles and  own a few world championship professional racing teams.  One of their sponsors was BelRay and it was Clive Padgett that recommended it to my dad.
At that level, the engines will be overhauled after every race weekend, so any wear or overheat will become apparent and be no big deal.

I used BelRay Si7 for many years and  many 1000s of miles in my injected DT, RD200, 250  and GT380 roadbikes and BelRay MC1 in my premix bikes -  Yam FS1E moped, TY175,  Montesa 248, Bultaco 250, 325 and 350.

Only time I ever had a crank fail was when MC1 was temperarily sold out and I bought a bottle of PJ1 Goldfire for the  Bult Sherpa T 350.  It knocked out the big end before the bottle was empty.

As you say these are not highly stressed racing engines, although the way I treated my poor Fizzy and RDs you would think they were.  My throttle tended to be fully closed or wide open everywhere I went.  I look back and wonder how I survived.

One thing I note.  The familiar BelRay exhaust smell  I knew so well from my youth is no longer present.  It is almost odourless now, much to my disappointment.

What I mentioned about BelRay was an issue in the "early days" of MC1 when it first came out as a new product in the 1970's. It was one of the first "50:1" oils. I believe it has been reformulated a few times over the years?

Golden Spectro was also mentioned... that's what I switched to after I got tired of dealing with the hassles of using Castrol R40 premixed at 16 or 20:1 depending on the race. Loved the smell of the Castrol, nothing matches it. Golden Spectro is also good stuff.

Heck, just about any oil these days will work great.

You glad you got involved in an oil thread?   

Yeah,  I mentioned PJ1 destroying a big end.  I was just unlucky. 

The UK PJ1 distributor lived just around the corner and was instrumental in setting up the motorcycle activity center where I worked and was very generous in his " trade discounts" to us.  We bought it at cost.

We were 100% PJ1 oils on all our off and on road bikes.  We used PJ1 silverfire as both an injector and premix oil.  Never had one problem  that was directly oil related in 12 years.
Unless you are at top level, most quality oils these days are just fine.

We were once part of a real world castrol test of a new formula of racing two stroke oils.  It was arranged by one of our directors wanting to make a name for himself.  Great for castrol.  A public test in a controlled situation where usage hours were documented.
Great for us because I was sitting on 50 litres of free, latest rinkydink synthetic two stroke oil.  My maintenance and utilisation budget breathed a sigh of relief.

It was a disaster, for some reason it did not like exhaust port areas, esp bridges and wore them away like crazy.  After a lot of ringadingdinging, I stripped one of the test bikes and phoned in my report.
One of their guys came with five new barrel kits for the test bikes, swapped the barrels over and departed with the worn ones.  His parting shot was that it had all gone as expected...they knew about the exhaust issue and not to worry about damage anywhere else.
My poor bleedin bikes.

Back to silverfire and normal service resumed.

RIP Richard Thorpe.  UK PJ1 oil distributor, championship winning trials rider and a top bloke.

I am using Lucas semi-synthetic and all my motors seem pretty happy

I saw this when looking for the Legend ZX-2R 'semi-synthetic' (still haven't found any) and appears to be of a similar product using a non-synthetic base stock and would hopefully 'burn off' somewhat over the full synthetics and reduce the ooze & goo from 'em.

I've been using this lucas stuff for last 4 years
very unscientific but when I melted the piston of my dt360 at the beginning of my yamaha addiction, crank bearings and big end (wrist pin took a molten aluminum spray) were perfect so I assumed it is good stuff and bought a case of  4 x 1gal from Summit, which btw will import Valvoline 10w30 VR1 into the peoples republic of CA for my flat tappet souped up bug!

Oh no another oil thread, I will throw in my .02¢ when I was 12-13 years old in 1976 and bought my first real Yamaha enduro it was a 1975 DT400, I bought it for $300.00 from my paper route money, I don’t know if I was being cheap or didn’t know any better (probably both) I would buy a qt. of 30 wt. oil at the local 7-11 convenience store it was in a yellow generic bottle like the stuff you see in those cost plus 10¢ grocery stores it was labeled (recycled oil) and was something like .39¢ a quart, I ran dozens and dozens of bottles of that oil through my Injector tank and never had a issue until the cops confiscated my bike because I didn’t have a drivers license, last I ever saw of that bike.

Sad story… dog gone police… I lost a Polish made… WSK? The same way..
Sneezles61