The Oil Thread

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Arnadanoob
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The Oil Thread

Post by Arnadanoob » Sun Jun 07, 2009 7:30 pm

I've recently had an unusual amount of emails regarding 2 stroke oils and thought I'd share my personal thoughts and experiences with them. I am not and will not claim that I'm a oil expert nor an expert in chemicals. I will however share my observations regarding taking visual cues from carbon buildup, scuffing, excessive wear on the bore, rings, piston and the like. This post is biased to those with other than stock engines using aftermarket bores, carbs, pipes, etc.

Let's start by dispelling the myths.

Q: Are all oils the same?

A: Of course not. That's like saying all colas are the same, all coffee is the same, all vanilla flavored ice cream is the same. You can naturally tell the differences. Just because you can't tell the difference in 2 stroke oils doesn't mean your engine can't tell the difference. Imagine drinking Pepsi that has too much sugar or Coke having too much caffeine, the end result is easily detected in our mouths and may alter what may or may not sit well with our tastes.

Q2: I use the cheapest 2T oil because I don't see any difference in using a pricey synthetic. In fact I can tell you that my bike actually ran better on the cheap stuff than the supposedly better stuff.

A2: Oil formulations are different. In the most primitive example, you can tell the way oils run (viscosity, thus thickness) which in itself may alter the results you get from using it. Thicker oils may offer better film strength than one that is runny like water, however thicker oils may impose internal drag to the moving parts which may degrade power at the cost of better protection. Conversely a thinner oil may impose less drag to moving parts, however it may come at a cost of weaker film strength at higher loads and temperatures which may result in more power and more wear where friction is greatest.

Some oils do burn cleaner than others, some oils leave more of a mess after being burned than others. No matter what the company or anyone else you speak to says about it, the one consistent thing you want to avoid are the ones that leave a lot of mess (carbon) behind after combustion. The type of carbon buildup is also important to look at, the flakey, loose type is fine, the softer carbon buildup (at the top of the piston) is fine, the hard-baked, cement-like hard, dense carbon is bad.

With mopeds the ultimate goal of tuning is providing what your bike really wants and needs, however you need solid mechanical experience and the observation skills that come with that experience.

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You may have seen engines where the top of the piston, inside of the head, the area around the exhaust port is just caked with hard, thick carbon. This is usually the result of a combination of 2, maybe up to 3 things. The first is the strong possibility of the jetting in the carb being incorrect. The second is the possibility that it's the oil. The last being a result of using a particular type of fuel. In Hawaii we don't have a lot of variety with fuels so at most it becomes the issue of the type of additives each fuel company blends with their product, however those of you in the states have access to a much greater variety of fuels so your results may vary a lot more.

I've seen many articles from differing websites where the author tests different types of oils and compares their results, the most common ones I find of are from RC airplane engines. Naturally switching from oil A to oil B to C (etc.) will naturally give you differing results because they most often fail to mention the jetting used. This is why you might see oil A to look very heavy on carbon while oil B might look a lot cleaner. Everytime you switch to a different oil, you need to at least put some thought into what you might need to do in order to keep your engine running at peak levels. In many situations, I've had to adjust the jetting everytime a different oil was used, even if the oil ratio is kept the same. At the very least I've had to alter the air screw position some, and with others a pilot, main or needle taper change is needed.

With a stock engine using the stock oil pump, I wouldn't worry too much since the motor is often limited in terms of power output, it may be restricted, the stock pipe will usually result in much lower revs (and thus lower temps), the overall gearing will be short (11 to 1) and such. For your annual checkup, you should consider removing your pipe and take a mirror and a light, and peer into the exhaust port to visually inspect for any signs of unusual carbon buildup. There should be some but not to the point where there's a lot of loose carbon chunks falling out.

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Tips to jetting

The general idea (this isn't the rule, but it does appear to be a consistent method) is that thicker oils would require smaller jetting on the pilot, and larger on the main. This also appears to hold true for those moving up in oil ratios, like from 50:1 to 32:1. The reason for this is simple, if you use a larger pilot for a thicker and/or heavier oil to fuel ratio, it will be very noticeable when you're idling. It will smoke a lot (from the result of using more oil) and may sputter off the line producing an impressive cloud of smoke. At wide open throttle (WOT), the end air to fuel mix will be lean which means you'll need to upjet (go larger) on the main jet. On race bikes that don't often see a lot of idling from stop and go traffic, it's common to find them jetted rather large on the pilot (to help with cooling during decel).

The reverse is also true. If you switch to a much thinner oil, you'll end up moving up on the pilot jet size however you might find it sometimes necessary to move down on the main jet size. It all depends on how much different the previous oil's thickness was in relation to what you're using now. The same for the oil ratio... if the change is small, the adjustment needed may be small, etc.

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Oils used in Hawaii

Oils are often chosen by one or more of these factors. Price, smell, protection. The best smelling oils are the ones with Castor oils in it. The priciest oils are those which are ester-based like Motul 800, etc.

1. Castor 927 is by far the most impressive oil we use here for a number of reasons. The cost is decent, the smell is awesome (sweet smelling), although it does smoke a little more (which is a good sign since it tells us the engine is being lubricated) and the high temperature protection is second to none. This product is PREMIX ONLY. Since it doesn't snow or get near freezing here, we don't have to worry about fuel separation at lower ambient temps. 32:1 ratio seems to be best. This oil is very thick.

What's so special about castor oil and why is it that I hear bad stuff about it? Well castor oils are incredible because as the temperatures rise (350F and up), when the oils actually start to break down (losing water molecules), they form into a better lubricant in the form of an ultra slippery varnish. The insides of the bore look crystal clean with the only exception being at the top of the piston where the carbon buildup is usually the result of the fuel and not the castor oil. The exhaust ports will not have any carbon buildup so a rebuild is very easy to do since you won't be spending time scraping off carbon with a knife, grinder and the like. When your bike is running a bit lean and the temps are high, the film of castor oil varnish may be the only thing that prevents your engine from seizing. This alone is unique only to Castor oils.

The bad part is that castor oils do tend to plug up your exhaust pipe faster and it's noticeable at the tip of the exhaust. This isn't so bad with those that use pipes that have no baffles or have no baffling material. The biggest gripe comes from those with power valves (dirt bikes) which we moped riders don't have. Power valves may get gunky because most dirt bike riders may not have jet their carbs correctly in the first place making the issue worse.

2. AMSOIL (Dominator) is perhaps the 2nd most common I see. The price is cheap (around $12/qt) and it works well. This oil is very thin (since they're designed to be used as premix or injector) so in order to use this product, regardless of what AMSOIL claims (50:1), I've found the best results to be around 28:1 to 25:1. There is noticeable wear using at their recommended 50:1 after 15,000 miles on the piston versus using it at 25:1 (and carb rejetted to match). The piston looks almost brand new at the latter mix ratio.

The bad news is the smell from the exhaust smoke is absolutely terrible. While we can all agree that nobody has any business inhaling large amounts of exhaust smoke, it's one of those distracting factors since you don't want to follow a bike using AMSOIL too closely since it stinks really bad. The carbon buildup from using Dominator isn't too bad if you jet for it correctly, the type of carbon I see usually scrapes off with a hard plastic putty knife with the rest coming off with carb cleaning solvents.

3. Klotz Super Techniplate is one of those hybrid oils with 20% castor oil. It smells nice as a result of using Castor and the company claims less buildup from using less castor oil however the buildup from it is normal of any other type of synthetic oil I've seen. This oil is PREMIX ONLY and a tad on the thick side.

4. Bel-Ray H1R is another oil that I've seen a lot of guys using. It's on the runny side but not AMSOIL thin, PREMIX ONLY.

5. Motul 800. Smells great but it's very pricey ($20 qt) and is about medium in terms of its thickness so I've rarely had to make any major jetting changes when using this product. The company boasts using synthetic esters which are theoretically the best thing to use in our engines. When used correctly the end results look similar to using Bel-Ray H1R.
Reliable and dependable tuning from 15+ years of experience.

Kenny_McCormic
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Re: The Oil Thread

Post by Kenny_McCormic » Sun Jun 07, 2009 8:31 pm

Have you ever played wit heavier mixes used in kart racing? 16:1 is about as light as they go. one would think that 16:1 would be a fogger, but in my limited experiments with an old 2 stroke generator that calls for 16:1 it only produces a blue haze with the mixture set right. White fog seems to come with running too rich.
I am not a mechanic, nor do I play one on TV. Actually my advice is probably worth slightly less than what you pay to view it.

Arnadanoob
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Re: The Oil Thread

Post by Arnadanoob » Sun Jun 07, 2009 9:42 pm

Several years back in some race only setups in Japan, I've used up to 18:1 in the DIO engines mostly due to the fact that Japanese-made lubricants were in my opinion very inferior to those offered today by Europe and USA. I have little to no experience with Karts since the majority of my family were into the 50-82cc scooters (mopeds). For the current modified motors, I've had no need to go beyond 25:1 using Castor 927 in any of the race-ready bikes. I know that a lot of the older motorcycle engines used a lot more oil and turned out impressive horsepower numbers. My current direction of tuning is more towards everyday riding with the addition of some spirited sprints every now and then. Personally I see no need to use an excessive amount of oil ratios in a bike that's tuned for street riding. Castor oils blended with normal gas at 32:1 offers equivalent protection of many other oils premixed at 25:1 based on tolerance measurements taken at 30k miles between identical engine setups.

There's a lot of interesting results from using differing oil ratios, oil types, and fuel types. Other more technical attributes account for cylinder head shape, flame front, ignition timing, burn speed of the fuel (using oxygenated fuels), etc. I've wondered what nitromethane would offer for higher elevation riding however I never got around to test it first hand.
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veedubh20
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Re: The Oil Thread

Post by veedubh20 » Sun Jun 07, 2009 10:22 pm

repsol competition and Silkolene pro 2 sx are good oil.

thick oil is better than thin oil. Has better lube oil splash everywhere internal motor running crank, bearings, piston, rings con-rod bearings, and cylinder jug.

castor 927 oil is good and sweet smell. :mrgreen:

Repsol Competition 2 stroke oil is good on stock motor (auto lube) and premix oil.. Does burn very clean and runs cherry!

here is a Repsol Lab
http://www.repsol.com/imagenes/es_en/2T ... -94373.pdf

Arnadanoob
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Re: The Oil Thread

Post by Arnadanoob » Mon Jun 08, 2009 12:15 am

Agreed veedub. Reposol and Silk are very good oil products. The truth is there's a lot more in terms of good oil products than what's covered here however I haven't tested all of them since I'm the type to stick to the one that works for me until the price of that oil jumps way too high in price to force me to consider another choice. :lol:

My personal belief with oils is to be application specific as much as possible, there's a reason why there's a huge variation in the oil product line. Never believe that 1 oil does everything perfectly, even Castor 927 isn't ideal for everything. Film strength is key, since a premature breakdown of the film strength means metal is in direct contact with metal when it should be suspended by a layer (film) of lubrication.

Thinner oils that might have lower flash points might be ideal for normal bikes or engines that don't really see excessive temperatures beyond 300F. The lower temps will help to ensure that the lubricant won't break down prematurely and the lower viscosity (thinness) of the oil will ensure that the moving parts aren't fighting against an excessively thick oil to ensure maximum power transfer is occuring within the internals before it hits the trans. Using too thick an oil for your application will simply result in lower power output and lower gas mileage. A breakdown of an engine that's using oil that's too thick for its application will show excessive carbon buildup. 2 stroke oils have a range in temperature where it works ideally as a lubricant and a range in which it burns off cleanly.

Thicker oils in general offer better film strength and higher stability at higher temps, it is said that it's better to be safer than it is to be sorry. Thicker oils also offer better compression sealing around the rings than one that is very runny. However too thick may mean it may have a slight problem getting into the tightest of areas quickly enough especially when the engine is cold. Thicker oils require higher temperatures in order to flow and lubricate correctly. If the proper temperatures aren't reached, thicker oils may start to gunk up downstream of the cylinder and foul plugs prematurely.
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veedubh20
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Re: The Oil Thread

Post by veedubh20 » Mon Jun 08, 2009 1:14 am

well, what about any riders that runs on oil for 5,000 mile

the bore that running on same oil 32:1 since new bore and after 5,000 miles show some report, open up, show cylinder head, piston 4 points side views and top piston, cylinder jug 4 point and exhaust port.

we see which oils are good running. :mrgreen:

premix oil running contest :lol:

Arnadanoob
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Re: The Oil Thread

Post by Arnadanoob » Mon Jun 08, 2009 2:54 am

That's actually something good if the person doing it remembers to stop and take pictures during each teardown. The only tests I ever see are from people who do them after ___ hours after a week or so of testing with ___ brand oil.

Ideally I'd like to see the condition of the mentioned parts after the break-in period, and after 5000 miles. That way we can inspect for any buildup, scuffing, type and density of any deposits left over, etc.
Reliable and dependable tuning from 15+ years of experience.

Arnadanoob
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Re: The Oil Thread

Post by Arnadanoob » Mon Jun 15, 2009 7:18 am

A new email just came in and I felt it was a very good question to post it here.
Hi! I've read your forum post and I found it very educational and from what I understand choosing the proper oil ratio and jetting things correctly is vital. I've been using 50:1 for my 72 cc Elite and I recently talked to someone who used to race 50-90cc scooters and he said he used no less than 20:1 and that 50:1 isn't enough. I tried to adjust my carb for 20:1 but even with the larger jets my temp gauge is showing that it's running hotter than it used to. I don't understand what's happening, can you help? How does this tie in with my spark plug reading?

Oh btw I use Motul 710 and premix since my oil pump broke years ago and since plugged it.
There's a huge misunderstanding amongst even the most experienced tuners about this very topic and I hope to shed some light into this matter. A bike that's built only to race on a track is not a good example to use in comparison towards the tuning approach for a mildly-tuned, street ridden moped. There's quite a few differences that warrants a certain approach towards tuning.

- A race bike will usually run a lot of oil, I've heard of guys using upwards of 16:1 to 18:1 which mandates the need for huge jets in order to run properly. The extra oil naturally offers a lot of lubrication and it aids in maximizing the seal around the piston rings for maximum power.

- Due to the huge jetting required to run heavier oil ratios, race bikes don't spend much time idling. As such it's not uncommon to find race bikes that simply won't idle when you let go of the throttle. Around a closed track the fully closed throttle position is used for brief periods where the engine is allowed to cool (richer on fuel at smaller throttle openings), however at a complete stop, you'd have to play with the throttle to keep the motor from dying.

* However if you use those heavy oil ratios in a daily, street ridden bike that does see a lot of idling, it can be a hassle to keep blipping the throttle to prevent the engine from dying, and due to the extra oil your ignition system will have to work harder to fire through all the extra oil, which means your plugs will have its greatest chance of fouling during idling and very low rpms. Not to mention the impressive clouds of smoke you'll be expelling! Race bikes sometimes use special CDI's with very powerful capacitors than most of the typical (rubbish) aftermarket units you find for 40 dollars, which are needed for those extra hot sparks to fire through all that extra oil, in addition to being able to make critical ignition curve adjustments.

- The race engines used in those bikes rev to rpms that'll likely snap your current crankshaft. Engines that spin to very high rpms (10k and above on averge) will need a lot more oil than an engine that spins around 6-8k rpms on average. Why? At very high rpms, the time in which the oil is allowed to stick to the moving parts is much shorter than when the engine is spinning at much lower rpms. This is why you can get away with lower oil ratios for most street mopeds with close-to-stock equipment, since the time in which the oil is allowed to stay on the moving parts is greater than with the race only bikes. However as you start getting into serious power, you should seriously consider moving up in oil ratio.

Here's a few things to remember.

1. Fuel is what cools, not the oil. Going heavier on oil will not lower temps, in fact it will likely increase temps. Remember, increasing the oil ratio without changing the jets means the fuel volume has dropped because there's more oil volume than before. More fuel = cooler, less fuel = hotter. This is as simple as I can make this.

2. When you adjust for jetting, the goal is to achieve the ideal combustion temperature for the application. This is done by adjusting the fuel quantity through the jets and checked at the spark plug. Spark plug readings are for fuel, not oil.

3. The spark plug and the amount of oil you use are irrelevant. Whether you are using enough oil or not is not determined by looking at the spark plug. Technically if you have achieved the proper air to fuel ratio and you're seeing a huge buildup of carbon, it's very possible that your oil product doesn't have enough detergents. Detergents are there to ensure that after combustion, the leftovers are dispersed with little to no byproducts that could buildup inside of your engine.
Reliable and dependable tuning from 15+ years of experience.

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