Premix or trust the oil pump??68 yamaha trail 80 yg5t

I've been working on this little guy for a bit, the rotary valve was siezed, Opened it up, cleaned it up and got things moving.

I'm putting it back together and during that time had to clean out a lot of god knows how old oil and crap that had become like a yeast infection in everything.

While finally cleaning all the crap out of the oil pump 2 things happened.
1 i realized there is a tiny ball bearing "sall" at the end of the spring where the oil comes in, I assume it works like a ball point pen to keep fluid moving, and that I've probably lost that blasting things out while cleaning it and

2. I thought maybe I'd just be better off premixing my gas and calling it a day, but then is lube not getting to important spots? is the way the oil is introduced important? I've mainly worked on 2-stroke premix mopeds till now.


Is that sall going to kill it for me? Should I trust my new clean oil pump to do what it should? If I run premix, do I need to block off some parts that would now be introducing excess air?

THANKS.

....hope this is the last problem with the dang thing. ...

 

absurd twist of fate that changes the question a little.
I went to check out the spot where the sall sits. While taking out the bolt, the spring that sits inside sticks, falls out.
I go to look for it and find a perfect little ball bearing that fits right where the sall goes, and by that I mean that I found the sall(i think) (good thing i keep the garage clean) but now I can 't find the damn spring!

does that eff things up as well? I'm going to search with a fine tooth comb now...

 

Most of the bikes with an oil injection pump utilized the oiling system to introduce lubricant to the main bearings at the crank. Kawasakis do, suzukis do, I would hazard a guess to say your Yamaha does as well. Better to find the spring and put the pump back into service. Be sure to bleed out the air bubbles and check that it actually works before you take it out on the road, though. The pump on my TC90 appeared to work, but was in fact siezed and was not pushing oil.

 

The other problem with reying on premix instead of using the oil pump is that of mixture. With premix you'll either be too rich or too lean at some point within the rev range of your engine. That is the main reason that oil metering pumps were first developed for 2-strokes.

 

found all the pieces! it's back on. now getting everything else back together.

It did look like this provided oil to more places than the cylinder.

How can I get all the air out? Right now the system is totally empty, how can I prime it?

 

If I were worried, I'd get a bottle of AmsOil 100:1 synthetic as "insurance"
first tank blended around 75:1
second tank 100:1
then depending on how the smoke and plug looked, pre-mix leaner, or stop the pre-mix.

(simply my opinion - a little extra oil can't hurt)

 

I assume this is like the other Yamaha injection pumps I've seen. It's got a hose from the oil tank and another that ends in a banjo bolt that is connected to the cylinder near the carburetor. There should be a knurled knob on the end of the pump.

Disconnect the banjo bolt from the engine. Turn the knurled knob with your finger until oil comes out the banjo bolt, then reconnect it to the engine. If you open the throttle it will pump faster - but still takes a long time.

 

back in the day, about the same time frame as that bike, we always disconnected the injection.
ran 40:1 premix of good oil, Klotz, Bel-ray, Torco. we just pinched or plugged the hose and emptied the tank.
the good: you know your getting oil, the oil tank never gets empty at a bad time.
the bad: on a long down hill where your letting the motor slow you down, your only getting a idles worth of oil, blip the throttle or hold it just off idle.
premixing gas is a pain.
that 100:1 oil wasn't around when that bike was made, i'd stay with dino oil

 

The idea would be that the AmsOil would suplementally lubricate the motor, and after 2 tanks of gas, you would measure how much oil was missing from the oil tank into, let's say 4 gallons.

At 40:1 you should measure 12.8 OZ to top-up the oil tank.

Then you decide if the old oil pump is working, and if you can trust it.