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Castrol A747

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This castrol product description is worth reading before using it in a trials bike

My link

Based on the text, from your link...

"If used in lower performance, lower revving engines, excessive deposit formation may result."

It does not sound as if it is appropriate for a trials engine.

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I had the same concern which is why I asked castrol head office. It was their technical department who said for trials use 60:1. They did point out quite clearly to not use 50:1 or 40:1 as deposits will form - with any oil at these ratios.

I run a "5" plug and have never had a problem?

If you really have a concern why not use the A747 as a treat and use fully synth every now and then to burn off any build up if you get any. Personally, I give my bike a good blast up the road to clear it out after every ride. This is probably why I don't get issues as I get it hot at least once every ride to burn deposits off?

Edited by pindie

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I run shell advance kart castor oil. 80-1 premix.

Leaves a nice film of oil on the crank / bearings and runs very clean. Old fuel stays in the tank for 3-4 weeks at a time, not had any carb issues yet. Starts 2nd kick every time and I get a smell through my exhaust that turns men and women into my slaves...

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You bet, I smear spent oil from my exhaust on my neck, the scent turns my girlfreind on.

Gotta be careful though, her dads a petrol head too...

Edited by tankygsy

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http://www.shell.com.au/home/content/aus/products_services/on_the_road/oils_lubricants/advance/product_range/racing/

Have a look at the above link and the mix ratios. These oils and castrol as well have a significant additive packages that won't burn off in normal trials usage. Running them at lean ratios compensates for this to some extent as it lessens the amount of additive.

Why buy an expensive oil for hard use lubrication then throw much, maybe all of that benefit away by lean oil to fuel ratios?

Cheers

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http://www.shell.com.au/home/content/aus/products_services/on_the_road/oils_lubricants/advance/product_range/racing/

Have a look at the above link and the mix ratios. These oils and castrol as well have a significant additive packages that won't burn off in normal trials usage. Running them at lean ratios compensates for this to some extent as it lessens the amount of additive.

Why buy an expensive oil for hard use lubrication then throw much, maybe all of that benefit away by lean oil to fuel ratios?

Cheers

I wouldn't spend

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The shell stuff sounds like a 100% castor oil like the old R30 castrol oil. That is a nightmare on any bike.

A747 is only 20% castor, the rest is made up with petrolhead pixie dust and lovelyness. I reckon if I was going to have "problems" I'd have had them by now. All I seem to have is a well protected engine with no loss of oil film on crucial moving parts.

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"what it means is that you can run leaner fuel / oil mix to effectively burn more fuel unlocking power from the engine whilst still maintaining protection and minimalising engine wear."

That statement is simply just not fact.

Engines make more powrer at 20:1 fuel:oil than they do at 50:1 - ask any professional tuner.

More oil in the fuel = less wear

Moving from a ratio of 25:1 to 50:1 increases wear by a factor of 200 to 300%.

Cheers

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Anybody know anyone with any real evidence to support spurious claims one way or the other?

We all know there are high tech fully synths but they simply don't have the queer old smell castor brings. I understand as well that you may not want to only ever use castor based oils in an engine that only ever ticks over - no 2t engine likes this no matter what oil is in the fuel as they all oil up eventually.

No one has commented on bike age, maintenance schedules, genuine problems encountered etc. There is lots of copy and paste going on of various slanderous comments but none seem to actually has any real evidence.

Any tuners or engine repairers got anything to say?

In all my years of two strokes of all different types I have never has a problem. For me A747 (or any other castor) is a treat to use and everyone around always ask "eh mate what oil is that it smells awesome".

Another thing is I run chainsaws on A747 at 50:1 and these can sit on the shelf for months unused. Chainsaws are far more picky as the carbs are minute but again I have never had an issue in running or starting. Come to think of it I have never had piston, ring, plug or bearing issues with anything I run the oil in.

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"what it means is that you can run leaner fuel / oil mix to effectively burn more fuel unlocking power from the engine whilst still maintaining protection and minimalising engine wear."

That statement is simply just not fact.

Engines make more powrer at 20:1 fuel:oil than they do at 50:1 - ask any professional tuner.

More oil in the fuel = less wear

Moving from a ratio of 25:1 to 50:1 increases wear by a factor of 200 to 300%.

Cheers

In support of this, US Dirt Bike magazine did a series of dyno runs with a two stroke MX bike and found that the more oil there was in the premix, the more power it made. They went all the way to a very high oil concentration (something like 15:1 fuel to oil) and the pattern remained

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Surely this only applies when the engine is at full bore and burning all the oil with the extra heat created?

Edited by pindie

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Hi there - glad to be back - had trouble getting on since forum upgrade.

The oil issue is a bit more complicated than what burns off at high revs / heat. Also its easy to state generalities that are not true in all circumstances. Its pretty true that more oil gives more power when the engine is pulling at whatever revs. However if the large quantity of oil in a rich mix reduces the rate of burning of the fuel outside the expected range when the ignition advance curve was determined power may be lost. This is neither the fault of the oil ratio nor the ignition timing - its just the fuel burning rate is no longer matched to the ignition timing.

More oil generally means less friction - so more power

More oil generally means a better seal betwen piston / rings and bore so more compression and less blowby = more power

More oil provides a better heat path between piston and barrel (cooling jacket) resulting in lower piston temperature. This reduces piston distortion (hence friction) but also increaes charge density because the incoming mixture is kept cooler for longer. A cooler piston also reduces heating of the mixture in the cylinder before ignition, reducing pre combustion pressure meaning less power loss on the compression stroke.

Going back to the original subject of Castrol A747,(which I regard as synthetic rather than castor although it ontains castor) from memory this has a flash point of about 270 degrees C. More modern fully sunthetic Castrol power 1 racing has a flash point of only 73 degrees C and burns much faster and cleaner. Most of the moderd synthetics are designed to burn fast and clean at the temperatures / conditions found in lightly loaded water cooled barrels to enable them to meet the clean burn specs such as JASO FC and FD.

Many years ago I saw a Bultaco 250 sherpa big end wrecked after very little gentle use over 4 years. The owner was also a grass tracker and used the same shell sport R (a castor racing oil) in the Bult. The oil had turned to varnish and gum all over the underside of the piston, the con rod and big end. The gum was so thick it blocked the lubrication slots in the conrod meaning the big end ran dry and uncooled as it was shielded from the incoming mixture by gum and varnish

Cheers

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Thats a bummer for the Bult but that was on 100% castor which is like grease!

Interesting point on the flash point of oils though and it makes a lot of sense. I guess thats why no one ever gets a seize using A747? The film is thicker and sticks/spreads better without burning off.

However, make sure from time to time you give it a good blast to "clear her out" as is wise on any 2t motor from time to time. All the 2t motors I have used A747 in may have some deposits present (more colouration than what your saying) on stripping but there is never any wear.

I take the point that A747 is hard to burn but it means it is doing it's job. Really it is a semi as it is only 20% castor. The othe 80% is magic stuff that Castrol or Honda won't tell you what it is. This is one of the reasons though that from time to time I run a tank or two of fully syth oil through the bike to help clean anything up. I have no idea if it works but I have no problems or engine part bills.

Bottom line is - If you want the smell, smooth creamy power, no rattles, pinks or clatter get on A747 oil (other brands are available).

I just find when on fully synth my bike sounds like there is loads of metal wearing and suffering. I change fuels to A747 and straight away you can tell a difference in sound. It is softer and lees angry. If I remember I will record two sound bites when I swap fuels and post them.

Edited by pindie

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I gotta agree I love the smell of the castor. I tried the Maxima version and my findings were not all that great.

Even running the 80:1 mix, I had no problem with engine lubrication in a trials bike, as oil accumulates in a motor at those rpm's. I did not reallh have a problem with carbon build on top the piston, as I ho like to give them a good run.

What I have problems with is the very hard carbon buildup in the exhaust. Almost as thouth it passes the engine then bakes on! I had a helluva time trying to de-grunge the header pipe, even using all sorts of chemicals and scraping. It's gotta be hell on a midbox and muffler baffling, and them ain't cheap on a Sherco or anything else.

Suffice to say I am back on the full synthetic, no more for me, pity as the smell gives gristle! :rolleyes:

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