2 stroke oil injector bypass...

[mwm1977]

Hey all...I picked up a 1965 yamaha Y-A6 125cc yesterday. Bike doesn't run at the moment. It's been sitting for the past 20 years. Tank needs a good cleaning along with the carb and the oil injector. I have 3 questions though... 1. I am curious on how to test if the oil injector works? 2. Is it better to just premix so you know its getting oil to the head? 3. If I want to bypass the injector, how do I go about doing that? Thanks!

 

[interceptor]

This subject seems to come up a lot. Consencus says to leave oil pump in place. Some bikes needs it as the two stroke oil lubricates the crank bearings also. Plus, its easier to fill up the reservoir rather than mix it yourself. And, I also use mixed fuel in the beginning just to make sure.

 

[Sonreir]

Some bikes you can premix and some you cannot. Better to not, unless you know that your bike is one of the ones you can. I think (but don't quote me on this) most Yamahas are OK to premix, but it's the Suzukis you want to avoid.

 

[jpmobius]

Likely the pump will need to be rebuilt, but it will also likely pump oil. The seals are old, and if they are not actually bad now, they probably will be once you run it. Most pumps are easy to put seals in, but do have tiny spring loaded parts. Some people put them in a clear ziplock bag (after loosening screws) to disassemble them, which i suggest if you are unsure of the process. I recommend using the pump, though I believe pre-mix is ok on this bike. Engines that have to use the pump have oil lines that go to the crank bearings (Suzuki), but if the only line(s) go to the carbs or intake manifold(s) than pre-mix should be fine. I have seen a lot of bikes that simply started using premix and stop filling the oil tank, but I would remove the pump and install a block off plate. Running the pump dry likely will eventually cause it to fail possibly causing other mechanical problems, though I can't say I have seen it happen. I always prime the lines manually and do not use pre-mix "to be sure". Either take the supply line from the tank free at the pump to make sure it is full of oil, or remove the bleed screw (if it has one) from the pump. Make sure the throttle is wide open, and that the associated mechanism on the pump is as well when you turn the throttle. If you can run the pump by hand, do so until oil comes out of the injector line(s). Otherwise kick it. May be a good idea to substitute clear line at least temporarily to see that the pump pushes oil. Most have pistons, so the oil flow is in pulses, not continuous. It may take a bit of doing before the pump fills with oil and you see results. You will not have to start the engine. If you have not had the engine apart, and it has set for 20 years, the crank seals are or will be bad, so take it as given that you will need to take it apart to replace the seals. The crank seals are not for keeping oil in, but keeping air (and usually transmission oil) out. Super cheap now, super expensive (maybe) later. Then the engine should have more than enough "pre" oiling from assembly oil that you should have no start up issues.

 

[mwm1977]

Thanks for the input guys! From the little info I have found on this bike, its seems the injector is strictly for mixing fuel and oil at precise increments with the rpm's of the engine. I am gonna rebuild the injector and carb and go from there. I should be getting into this bike once I move my stuff into my new shop this week. I will let you know how it goes or what I find out...thanks again!

 

[stroker crazy]

Good advice from jpmobius!

Crazy