Why block oil injector?

Crazy Chicken

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Apr 4, 2011
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Midland, MI
I'm new to this. Why do you block off the oil injector? What are the benefits? And how does the bottom end get its lubrication?:-/ Thanks for any info. Still got lots to learn. Just love Blast'n.
 
Boomer | Rydin Dirty

Nearly everyone complains about the oil injector (Autolube) that comes stock on every Yamaha Blaster. Some say it is unreliable, and will break. Others say that the 20:1 mix ratio puts too much oil into the motor. Many people block off the injector for this reason, there are many kits avaliable to do this.

As a Blaster owner for two years, an everyday reader of the Blaster Central BBS, I belive I have heard nearly every argument for and against the oil injector.

In the past few years I have heard of 3-4 people who say their injectors have gone bad and caused their motors to sieze. Most of the time they do not even consider that other factors could be involved. The just assume that the injector must have quit, every so-called expert says it isn't any good. Still, no one has ever proved that the injector was at fault.

Even IF it was, improper care usually causes failure. I have to wonder if the operator was carfull when he filled the tank up, or if he filled it while the quad was dirty and droped bits of mud into the tank.

I belive the Blaster's oil injection is 100% reliable. While I realize anything, and everything can fail, I do know that the injector system is no more likely to fail than any other engine part.

The fact is, my own 1998 Yamaha Blaster's oil injection system has held up to 5175 miles of use, without a single problem.

The first ATV ever to finish the 6000+ mile Paris to Dakar rally was a 1997 Yamaha Blaster. He ran oil injection, and the quad ran fine the entire time.

I sure hope that dispells the reliability myth.

Most people belive that the Blaster's 20:1 Gas:Oil ratio is too rich. They say the motor gets too much oil. I want my motor to get all the oil it can. The more oil If it costs my 1HP, then fine.

Wait a second, it won't cost me horspower!! I might actually lose power by running a leaner ratio. I know you don't belive it, that's why I have proof. Tests have been done on an lder RM125, and these are the results:

20:1 Gas:Oil ratio (same as a Blaster) gave 23.2HP 16:1 Gas:Oil ratio gave 23.6 HP 27:1 Gas:Oil ratio gave 21.4 HP

At the 27:1 ratio the piston "showed signs of scuffing bad enought to deter me from testing at 32:1."

If you think I made all of this up, take a look at page 169 of Two-Stroke Performance Tuning by A. Graham Bell. The book is avaliable on Amazon.com for a fair price.

Any other questions about the injection system. I have proved it to be both reliable, and that it does not cost power. Now I'll tell you why people say they remove it:

* Looks, they say it looks bad.
* Weight, it weighs a few pounds.

It doesn't look great, but it doesn't look terrible, at least not to me. On a tricked out quad, it might detract from the appearance a bit.

Hmmm... I guess it does weigh 2-3lbs, and full of oil, mabey 6-8. So that's a valid complaint.

There, now I have told you both sides of the story, make your own desicion. I just don't want people to spend their time and money taking off the injector before they hear the other side of the story.
 
^^^ good info


basically people block it off because the pump likes to fail... which intern seizes ur engine while ur riding it. the bottom end gets its oil from its own supply which you need to learn how to change and fill... now after you block the oil injection you can then premix your own gas and can be sure that your 2 stroke engine is getting the oil it desperately needs
 
Not wanting to argue the reliability of the oil pump,
But if it does fail you will need new rings, piston, bore job, and bearings.
Also the $$$ to replace the parts on the oil pump system like you should every now and then.

OR

Block it off and mix your own oil and gas for free and use the gas in your blaster you use for every other 2 stroke you own.
 
previous owner blocked off the one on mine after it friend rings in the winter when the oil got too thick for the injector because of temperature
 
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this topic is all over this forum. prolly more than any other subject. ive never heard of an oil injec. fail. ppl mix their own to feel safe in knowing that theres oil getting in there or with the mods they have that a certain amount of oil needs to be fed in whether it be more or less. (IMO)
as for the bottom end its a different oil. NOT 2S. that oil lubes.. the bottom end. some ppl thought the premix is oil for the whole motor. huge mistake.
 
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Actually if the bottom end means the crank then it does lube that. And I just stated above my oil injector failed before it was blocked off
 
I had my bike for 13 years and had no problem with it.... you do have to be careful when adding the oil in the back. Make sure the filter is in there and not to make a mess and get dirt in there....<<<<<<-- you can still see it in my pic..
 
umm another huge reason is that you can only run the stock carb with the oil injection, and theres alot of people that have bigger carbs.
 
^^^^evil clone of my blaster :p
also if u love wheelies like me, oil COULD restrict its flow to the injection, thus causing air pockets. that split second on oil deprivation could be deadly for the motor. (from what i heard)
 
people block it off because it is known to fail. It has a cheap plastic gear that breaks is not durable. Chances are, you won't have any problems, but imo you should block it off to be safe. And the bottom end oil is completely separate from the injector oil. It goes right into the bottom end on the right side whether you have oil injection or not.
 
previous owner blocked off the one on mine after it friend rings in the winter when the oil got too thick for the injector because of temperature

he didn't use the correct oil or it would be fine in cold temps

also it should have hurt the bearings if there was no oil getting to the motor

it was proly to lean for cold wheather operation
 
he didn't use the correct oil or it would be fine in cold temps

also it should have hurt the bearings if there was no oil getting to the motor

it was proly to lean for cold wheather operation

I gotta agree with this. In our sleds up here NOBODY gets rid of the oil injection. They run from +50F to -40F on oil injection. The only problem is fuel jetting running lean in the colder temps. Injector oil differs from premix in viscosity. If you use premix oil it can cause cold weather failure because it is thicker in cold weather, but you knew that right?

As for not being able to swap carbs with oil injection, not true. The oil just goes to a hole behind the carb. This can be done with any carb. Even better systems run the oil directly to the bearing fed holes so all the oil goes through the bearings.

Even with this stock system, an air bubble will not cause an engine failure. The bearing cavities and crankcase is well coated with oil while running, and take a while to clean out.

The injection system has an advantage when coasting long downhills. Fuel is shut nearly off, there is little oil. Not so with injection.

Often when folks don't understand a complex system, their response is to tear it off. Automatic chokes, thermostats, brake self adjusters, air conditioning, vacuum secondaries, safety switches and guards, park brakes, and positive crankcase ventilation valves are all good examples.
 
I gotta agree with this. In our sleds up here NOBODY gets rid of the oil injection. They run from +50F to -40F on oil injection. The only problem is fuel jetting running lean in the colder temps. Injector oil differs from premix in viscosity. If you use premix oil it can cause cold weather failure because it is thicker in cold weather, but you knew that right?

As for not being able to swap carbs with oil injection, not true. The oil just goes to a hole behind the carb. This can be done with any carb. Even better systems run the oil directly to the bearing fed holes so all the oil goes through the bearings.

Even with this stock system, an air bubble will not cause an engine failure. The bearing cavities and crankcase is well coated with oil while running, and take a while to clean out.

The injection system has an advantage when coasting long downhills. Fuel is shut nearly off, there is little oil. Not so with injection.

Often when folks don't understand a complex system, their response is to tear it off. Automatic chokes, thermostats, brake self adjusters, air conditioning, vacuum secondaries, safety switches and guards, park brakes, and positive crankcase ventilation valves are all good examples.

i dont know what oil he ran. however oil injection isnt any better with engine breaking because the oil goes straight into the bowl doesnt it? it just mixes in the bowl instead of the tank? i may be wrong but this is what i thought
 
i dont know what oil he ran. however oil injection isnt any better with engine breaking because the oil goes straight into the bowl doesnt it? it just mixes in the bowl instead of the tank? i may be wrong but this is what i thought

No, the oil does not mix in the carb bowl. The oil goes to a small port (tube) just behind the carb into the rubber carb boot, just before the reeds. Even if you run out of fuel, it still puts a small drip of oil with every revolution of the engine regardless of fuel, and even more as you open the throttle.

Good system, huh?
 
No offense. But u are the second the person I've ever in my blasters life heard defend the injection system. Every1 is entitled to their opinions though I've personally never heard someones system failing besides one member here
 
No offense. But u are the second the person I've ever in my blasters life heard defend the injection system. Every1 is entitled to their opinions though I've personally never heard someones system failing besides one member here

No offense taken, but maybe you should change who you are listening to?
Many years ago I started with an automotive tech course, but realized there was more money as a certified machinist and industrial mechanic/millwright and electrician.
I have even worked at improving production and industrial reliability at a major factory.
While this has little to do with two strokes, 35 years of running (oil injected) sleds and bikes has.

I didn't work as an automotive or small gas tech, other than my own projects (that is a 1974 Maverick with a 1970 4v 351C in the avatar).
Besides the KTM/Blaster, I currently run several KTM bikes, and help my son with his stock Blaster, DT200 and oil injected 377 Safari SkiDoo.
This should give some idea of how deep I get into things: How to build your own 4x4 van


If you are taking a poll, you will find lots of people repeating the things they have heard. Look for someone that has experience and training.
Really listen hard to their reasons for their opinions. Experience? Training?

I see lots of experience in this forum, well worth listening to, but forget the "take a vote" approach to decisions...
 
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I have always used the oil injection system. Never had a problem, and I have quite a few miles on my blaster. Also I have used it in the winter (below 0 temps) without problems running AMSOIL inteceptor oil.