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Old 04-01-2013, 07:43 PM   #46
Scootern29
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This thread is starting to deliver.
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Old 04-01-2013, 11:09 PM   #47
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I run Blendzall (castor) at 32:1 mixed with non-Ethanol premium.
Never use it in the bike after 24 hours.
Gasoline destroys the lubricating qualities of bean oil.
Old gas goes in the lawnmower.
It makes mowing the lawn a sort of non-racing pleasure
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Old 04-02-2013, 05:30 AM   #48
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Quote:
Originally Posted by Twin-shocker View Post
Gordon Jennings testing on 2T oils is nearly 40 years out of date and bears little relevance to 2013. Contrary to popular belief most modern 2T "fully synthetic" oils are anything but, and have low smoke additives, which are generally thinned down with up to 20% kerosene. This leads to a very thin oil also suitable for use in 2T injection systems, but far from ideal for use in off road bikes, which may be used infrequently as the very thin oil provides little long term corrosion protection.

Using more oil than is required in low heat motors (trials, enduro, fun bikes) will quickly result in badly clogged exhaust systems, and excessive carbon build up in exhaust ports. All 2T motors tend to put about 25% of the intake charge straight out through the exhaust port, if you running 50% more oil than it required the end result of this is pretty obvious!

Too much oil tends to weaken the air-fuel mixture, and to compensate less than optimum carburetion settings are required, which will reduce power and make motors feel dead and unresponsive. Modern fully synthetic oils work very well indeed, and there are even specially developed oils which will greatly help with getting accurate plug colour readings if you chose to use modern E fuels, rather than specific race types.

10 years or more ago the idea of castor/synthetic hybrid oils was state of the art, but today pushing this is little more than a marketing scam, as advances in full synthetic technology mean modern full synthetic oils are superior to the hybrids, and far more suitable for serious competition use as varnish build up on internal parts is eliminated entirely, and if something like Castrol XR77 is used, its also far easier to get accurate plug readings if you are using pump fuel.
So then. What do you run and at what ratio?
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Old 04-02-2013, 09:30 AM   #49
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Looking back on this thread,I guess I need to take some of my own advice....what engine, what rpm, how is it being used. I tend to think in terms of of full tilt, built to the ragged edge race motors. One's that may be getting their jetting adjusted from early morning practice to late morning practice and again to afternoon race time. Engines that get a fresh set of rings after each race weekend, a complete top end after every two-three weekends and a lower end rebuild about every 4-6 weekends. Engines that if they drop only a couple of hp it can mean the difference in a podium or not.

I would be interested in reading more on this claimed effect of viscosity on fuel flow. Got any links to any articles. Familiar with the %oil:air/fuel affecting jetting, but have never heard of this viscosity having any kind of significant effect on jetting.

As for fule flow thru the jets, IIMHO, other factors play a much more important role in the efficiency of flow and atomization of the fuel charge. The most signifcant being the old volume versus velocity debate. Most carbs operate off of Bernoulli's principle and are designed to offer maximum flow and optimal atomization at a certain velocity of air flow over the jet orifice. Folks tend to think that going to a larger carb will mean more fuel and more power. Quite often its the opposite that is true. The larger venturi carb may make more power at near max rpm where the velocity is sufficient, however at low-mid-range rpm the velocity is not sufficient for the carb to flow fuel and properly atomize the mixture. Most riders spend much more time in the mid-range, where a smaller diameter carb will likely improve perfomance as the smaller carb increase the velocity, improves the fuel flow thru the jet and improves the atomization of the fuel. WIth the larger carb, they think they are burning more fuel and making more power beacuse they had to go to a larger size main, where in reality, they had to go to a large size main because the lower velocity results in a less efficient flow of fuel and the larger main was needed to compensate for that decreased efficiency.

Pipes, you are right, like i said most are built for safety. Companies don't want the average Joe rider to go out and repeatedly stick his motor. They are at best compromises between safety and performance. Kinda of off subject, but wasn't there an aftermarket pipe builder that sold a kit with varying length spacers to place between the pipe and the cylinder to offer more tuning.

Like pipes, carbs are typically jetted for safety and are on the rich side. Beside too much fuel, there can also be too much oil. Too much fuel cools the temperature, which then results in a less efficent burn. Then the oil, which there is too much of do to the rich condition, burns much slower than the air/fuel mix and gets deposited as a black damp crust on the piston, gums up a ring, and becomes the dreaded spooge throughout the exhaust system. So the average rider decides there is way to much oil in the premix and dramatically rduces his ratio to cut down on the spooge. THen he goes out and pins it on a long straight and sticks it. He applied the wwrong solution to the problem. The proper solution would have been to correct the jetting.


Got to get back to work here, but interesting thread and it goes to show that there is no simple answer to the age old question of what oil and ratio do you run!
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Old 04-02-2013, 01:08 PM   #50
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Most people dont ride bikes with highly strung race motors, so its a big mistake posting up things that apply to a very few riders, who if they are serious racers will know exactly what oil ratio to use and why anyway.

In the main more problems are caused by using too much oil, than too little, and the spurious stuff related to testing carried out nearly 40 years ago, is still being brought up to support using excessive amounts of oil.

Main things to remember when it comes to 2T oils, is to use an oil to suit your application (full synthetic pre-mix only is perhaps the best for any sort of competition bike), and a mix ratio to suit the use you will be putting your bike to.

Motors which run at high rpm for extended periods of time, and generate plenty of heat, obviously need more oil than low rpm low heat motors.

I suggest anyone reading this thread who is running a low heat 2T motor on 50:1 or greater mix ratio, should get some fully synthetic PRE MIX ONLY 2T oil, and see how much better their bike will run on 70:1 mix. It really does make a big difference, especially so if exhaust duct is properly cleaned out before starting to use less oil.
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Old 04-03-2013, 06:45 AM   #51
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Quote:
Originally Posted by Twin-shocker View Post
Most people dont ride bikes with highly strung race motors, so its a big mistake posting up things that apply to a very few riders, who if they are serious racers will know exactly what oil ratio to use and why anyway.
Just as most do not run hi-strung motors, most also do not run low heat trials bikes either. SO perhaps it is a big mistake to post up thigns that only apply to trials bikes.

Quote:
In the main more problems are caused by using too much oil, than too little, and the spurious stuff related to testing carried out nearly 40 years ago, is still being brought up to support using excessive amounts of oil.
Lets see what the average rider will experience.

Too much oil:
1. fouled plugs
2. gummed up, stuck rings causing low compression
3. gummed up, malfunctioning power valves, if so equiped
4. the dreaded exhaust spooge
5. splattered oil stains on the back of their $100 riding jersey.

Too little oil:
1. Piston seizure
2. Cylinder wall damage sufficient to require possible boring or replating of nikasil, etc
3. Lower rod bearing seizure

Boy, I think I'll stop there as it is obvious you are correct, spooge and fouled plugs are much more serious problems

Jennings writings are from the late '70s, but their is plenty of supporting documentation out there that is from within the last 5-10 years, or newer. But hey, at least these folks are looking for and providing supporting documentation, unlike others. Oh, that reminds me, where is the supporting documentation that I politely asked for regarding mix ratio affecting fuel flow thru the jets.

Quote:
Main things to remember when it comes to 2T oils, is to use an oil to suit your application (full synthetic pre-mix only is perhaps the best for any sort of competition bike), and a mix ratio to suit the use you will be putting your bike to.

Motors which run at high rpm for extended periods of time, and generate plenty of heat, obviously need more oil than low rpm low heat motors.

.
Seems we have heard that before. Few folks reading this thread run the hi-strung road race engines or the low rpm trials bikes. So most will likely end up with a premix ratio somewhere between my road race 16/20:1 and your trials 70/100:1.

Hopefully they will take into consideration a number of factors discussed in this thread and make an informed decision on what they feel comfortable with.
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Old 04-03-2013, 01:40 PM   #52
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Other than reduced performance, and dull dead feeling motors, there is nothing negative about using excessive amounts of 2T oil, at the same mix ratios popular 40 years ago.

However using the correct oil at the right mix ratio is a win win situation, as this will improve performance as well as drastically reducing maintenance requirements.
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Old 04-03-2013, 01:50 PM   #53
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Quote:
Originally Posted by Twin-shocker View Post
Other than reduced performance, and dull dead feeling motors, there is nothing negative about using excessive amounts of 2T oil, at the same mix ratios popular 40 years ago.

However using the correct oil at the right mix ratio is a win win situation, as this will improve performance as well as drastically reducing maintenance requirements.
SO, if we get back into road racing, I should run your 70+:1 oil mix?
DO you have stock in Wiseco or sell Amsoil, btw??
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Old 04-03-2013, 05:33 PM   #54
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The oil used is very important (notwithstanding ridiculous advertising blurb), and mix ratios need to be adjusted to exactly suit specific use.

For serious road racers who need to adjust carburetion for specific tracks and atmospheric conditions, using the correct oil is even more important, as modern fuels make taking plug readings very difficult, unless oils developed to help provide accurate readings are being used.

However I would imagine as most serious 2T road racers will already have a pretty accurate understanding of lubrication matters, they wont need to ask questions on forums like this one.
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Old 04-04-2013, 05:09 AM   #55
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Quote:
Originally Posted by Twin-shocker View Post
The oil used is very important (notwithstanding ridiculous advertising blurb), and mix ratios need to be adjusted to exactly suit specific use.

For serious road racers who need to adjust carburetion for specific tracks and atmospheric conditions, using the correct oil is even more important, as modern fuels make taking plug readings very difficult, unless oils developed to help provide accurate readings are being used.

However I would imagine as most serious 2T road racers will already have a pretty accurate understanding of lubrication matters, they wont need to ask questions on forums like this one.

So we have discovered one thing here, our Mr. Know-it-all expert doesn't know the definition of sarcasm.
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Old 04-04-2013, 05:45 AM   #56
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I cant document it either , but 30+ years ago I was removing the oil injection from an RD and was told by a few different mechanics about increasing jet sizes to compensate for the oil increasing the fuel viscosity. Believe they were telling me about 5% increase.
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Old 04-04-2013, 07:46 AM   #57
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So we have discovered one thing here, our Mr. Know-it-all expert does know the definition of sarcasm.


Fookin' n00bs
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Old 04-04-2013, 09:23 AM   #58
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Originally Posted by joexr View Post
I cant document it either , but 30+ years ago I was removing the oil injection from an RD and was told by a few different mechanics about increasing jet sizes to compensate for the oil increasing the fuel viscosity. Believe they were telling me about 5% increase.
Now that I could believe, as you are going from an oil injection system in which there is only straight fuel going thru the jets to a premix in which there is a fuel oil mix. But changing from say 32:1 to 40:1 altering the fuel flow thru the jet...well I would like to see some supporting documentation.
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Old 04-04-2013, 09:45 AM   #59
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Now that I could believe, as you are going from an oil injection system in which there is only straight fuel going thru the jets to a premix in which there is a fuel oil mix. But changing from say 32:1 to 40:1 altering the fuel flow thru the jet...well I would like to see some supporting documentation.
Well , thats a 20 or 25% difference , depending on which way you look at it.
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Old 04-04-2013, 10:16 AM   #60
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Originally Posted by joexr View Post
Well , thats a 20 or 25% difference , depending on which way you look at it.

SOrry, but you are talking apples and oranges here. You are referring to the change in oil added to the premix as a %. What we were talking about is the change in ratio affecting the fuel flow through a jet.

That and while it may be a 20-25% change in the volume of oil using your comment, in terms of oil to gas mix in terms of percent, it's less than 1% change. 32:1 premix contains 3.13% oil. A 40:1 premix contains 2.50% oil. So in terms of the amount of oil present in the volume of fuel, it is only a change of 0.63%

Hope that make sense.
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