Bybass Oil injection?

[Tucker]

99yam has got a point Banjo. Not sure how your oiler works but the easiest way to tell if it's working is to mix up a 2-gal batch of premix in a small tank and put you fuel intake in that tank. Pull off the line from your auto oiler going into the intake (VST or whatever), light 'er up and see if any oil comes out of the line. The flow should increase when you wick the throttle. Let us know what happens. Like what was just said, keep the system clean and you shouldn't have any problems. Good system but high maintenance. My money is on the auto oiler going up.

[Banjo]

The engine had a really low burping sound when it started...hard to start, but once it did it idled very rough with that low sluggish burping and when I tried the cold start lever it either died or the sluggish burping like it was straining to stay running got worse. Then when I would put it in gear it was an almost instantaneous kill. Well I got it on the trailor and drained both the auto oiler tank and fuel tank. No trash in oiler tank or the hose leading to the pump. No water or trash in gas. Once I changed the fuel and emptied the oil tank the idle is still REALLY rough, however it runs good at a higher RMP. I have to admit, when it comes to being a mechanic I am a quick study, but entry lvl at best lol, so bare with me. I let it run a while and the longer I let it run the better it sounded. At an idle I hear tapping and sluggish low tone (i would say like burping) straining to stay started....not good..... but as I increase the RPMs it seems to go away and the engine smooths out. The RPMs are right around 800 at idle and the timing is right at 7. I am not experienced enough to "read" the plugs, so I am going to buy 3 more tommorrow, and update yall as soon as my little 2 month old boy gives me enough nap time to mess around with it.

-Banjo

[Banjo]

To: Just_In_Time

I was looking through my manual and I dont see instructions for removing the oil pump gear (for bypass purposes). All I see are instructions on how to remove it for repair. How should I leave it if I want to bypass and use a pre mix solution. Right now all I did was take the oil out of the tank.

Thanks,
Banjo

[Banjo]

***! I have 10 psi compression in second cylinder. Wonderful. Now what!?

[99yam40]

pull the head and see what happened

[Banjo]

I will do that sooner or later.....but probably later when I have some more experience under my belt. I'm switching my focus to my 40 now for duck season. Water impeller and what not needs changing. BTW I did break down the auto oiler pump and found that little worm gear and pulled it out. Then I replaced the empty housing to protect the hole. I am guessing thats what Just-In-Time was saying to do so I dont cause more problems. When I do start pulling the head off, I will def post some updates and be looking for some advice. The Motor is a 1992 70 and I didnt pay a dime for it, so I'm guessing that it would be worth it to bring it to a machine shop if need be.
Thanks again for all yall comments.

-Banjo

[Tucker]

That's exactly how to disconnect the oil pump, be sure you use the gasket that came off. About the low compression; since the motor hasn't been running, I'm wondering if there is a chance the ring is stuck in the groove. Just-in-time Richie, could this be a viable reason? If so a shock treatment of seafoam my free it. Whaddya think Rich?

[99yam40]

If his motor locked up while running it is not a good idea to run it until he finds out what locked it up. pulling the head to see what the cylinder and piston looks like is the best option for now in my opinion

[Banjo]

Yeah, I have a 2 month old (first one) at the house and I work nights and watch him during the day, working on my engines in between. It would take me FOR-EVER to break down that engine if I start now, so I will wait until my work area is cleaner and my days are a bit calmer. But the good news is that I found a machine shop that only charges 48 dollars to bore out a cylinder, and I can buy my piston and rings online for around 60 bucks or so. It looks like the old motor will be worth the time and money. My compression looks like this: How many cylinders should I bore out?

Cyl # 1 - 106 psi

Cyl # 2 - 10 psi (used to be 101)

Cyl # 3 - 92 psi

-Banjo

[Bob Bradley]

A little history

When Yamaha first introduced "oil injection" on their motorcycles and snowmobiles - very little consideration was given to the environment. It was introduced to ensure the engine was given the right amount of oil during DIFFERENT LOADING CONDITIONS. Thats the secret in that at high rev's/ no load or at low revs /high load - because the stroke of the oil pump is variable the engine gets the right amount of oil. The other reason was to reduce ash in the engines because two stroke oil then was very bad in every way compared to what is being sold today. Considering that this was also the time of magneto and even worse simple points ignition systems and with lead still in the gas - any way to eliminate or considerably reduce the burn off contanimants on the spark plug were welcomed.

If you also consider that when you mix your gas at a 50:1 mixture (you do that so the engine gets the right amount of oil at high load/hi revs and won't seize - any other time that you are running at a throttle setting thats less than full throttle you are putting too much oil into the engine and will have excessive ash/carbon build-up and definitely more ring sticking.

Now at the same time I appreciate the story of the guy that gets better engine life pre-mixing BUT - I'll bet that he works the hell out of his engines which matches the requirement of a constant 50:1 mixture. I also know that many of these "I know an guy that knows a guy etc are exaggerations and to a degree old wives tales and are in fact sometimes - just a story. But most of us as recreational boaters do not run our engines like this and this is why I would leave the oil injection intact. But do the maintenance (change the oil filters, check for cracked lines, make sure the stainless wire clamps still have clamping pressure) and most of all PAY THE EXTRA MONEY FOR THe YAMAHA OIL - Walmart oil does NOT belong in your engine.

My two cents - Bob

Correct Banjo, at idle you're at 50:1 instead of 100:1. My opinion is this is for emissions purposes only. Someone determined that a 2-cycle engine can live with that. However, there is a commercial charter guy on this forum that says he gets 5000 hrs out of an engine premixed and 3000 hrs from the same engine oil injected. That math was enough for me. This guy is a hard core Yamaha man, I believe he has 6 or 8 big blocks and declares these are the best made engines period. In addition there are some engine rebuilders that will not warrant a rebuilt engine unless the injection is disconnected.
Im sorry 99Yam but I have to disagree. The latest 2-cycle oil is designed to mix almost instantly. In fact, with the exception of the HPDI models, the oiler drops the oil in the VST where is is "mixed" with that gas before going into the injectors or carb; at least in theory. I find it hard to believe that when cooking along at about 4100 RPM you get a 50:1 "precision blend" of premixed fuel. But I have to agree, you have to do a bit of thinking when premixing. I don't have fuel mgt gauges so I go by the half a$$ fuel gages and a note pad and calculator. All of this is thrown out the window with the HPDI. That is a completely different animal and is claimed to be the best engine Yamaha has made. I'm not too familiar with it but guys who have them love them. Again, reading this forum the main problem guys have problems with is...you guessed it the auto oiler.
I stand by the conviction that says auto oilers were designed to make 2-cycles environmentally compliant. They do nothing for performance or engine longevity. This is my opinion and I welcome knowledgeble arguments that would help change my mind. I'm not a mechanic but because of forums like this we can learn from other's experiences and become grass roots experts. I have to agree with your last statement 99YAM. Do the preventative maintenace and you "should" be fine. If I can avoid another "system" to maintain and worry about, I'm going to do it. And the maintenance isn't all that easy. My oil tank was in a compartment accessed by a 10" X 10" hatch.

[broncofan80]

I have a yamaha 175 with a 25 gallon tank. The previous owner was a boat mechanic that had the same problems. He removed the oil injector and mixed it 50:1. I have had the boat now for 4 years and have been doing the same thing with no issues whatsoever. If it were me, I'd bypass and save the money.