The Hodaka Club Forum

My owner's manual for my Road Toad 100 outlines the procedures for purging air from the line between the oil pump and the manifold. The manual says .... "When oil trickles out of the line without air bubbles, the line may be re-installed on the manifold fitting." This bike hasn't been run (until this past weekend) for 24 + years so right now I have pre-mix in the tank and also have the pump oiling system hooked up and working, it is "trickling" out of the oil line when I have done what the manual says to do.

Here's my question though, what sort of oil flow does a novice like me expect to see coming out of that oil line? The manual's use of the word "trickle" is pretty generic. I remember having a little Kawasaki 100 years back and I think I remember some spec in that manual where you could actually measure the oil output of the pump at a certain engine speed and for a certain amount of time.

Any advice or help with this is appreciated.

The Mikuni oil pump is a positive displacement pump, so (generally speaking), when it is pumping oil - it is pumping the design amount of oil. I don't recall ever even seeing specifications for the volume of oil which should be pumped at a given engine speed, throttle position (effects pump cam position) and elapsed time. I do recall thinking that "trickle" may be somewhat of an overstatement - especially if observed at closed throttle and idle speed. I remember looking at the reflection of a shop light on the "dome" of oil at the end of the output line and seeing the slow but regular "pulse" of the change of the "dome" with each output pulse of the pump. Sooooo, my approach is . . . 1) if you see regular "pulses" of oil without bubbles, the pump is working properly and 2) if the pump actuation cam is properly set to come to rest without cable tension with the marks aligned and 3) your pump cable is properly adjusted to "activate" the pump cam at exactly the same time as the carb throttle slide starts to be lifted . . . then you are good to go.
Ed

I have followed the oil pump adjustment procedures after burning up a cylinder because of a faulty fitment at the intake manifold after Hodaka Dave had to bore a replacement cylinder. After all that, I did a down and dirty confirmatory test. I ran 10 gallons of gas after placing a pint of oil in the tank. After 10 gallons through the engine, I drained and measured the remnant oil resulting in an approximately 34:1 oil mix. This included high speed runs and tiddling about town. Not scientific, but somewhat comforting in that I was oiling. You might consider running a similar examination on your bike.

Interesting way of checking ...... one of the benefits of premix I guess is not having to worry about that. I suspect there are those that use premix, do they remove the pump altogether? I guess they might have to, it might self-destruct otherwise running dry. Maybe there is a block off plate used if somebody chose to do that?

Indeed there is. Paul sells a kit of all the parts required to operate the motor on premix. There is a blocking plate and gasket included in the set. Yes, you do need to remove the pump, tank, and lines and block the passage in the intake manifold. That's a pretty standard mod for those who race the Road Toad. I considered it, and if I have any future meltdowns, will do it. One thing you should keep an eye on. At the throttle housing, there is a second cable which operates the oiler output. My cable cover end jumped out of the housing resulting in a high rate of oil delivery an all throttle settings resulting in fouled plugs and an insane amount of jetting extravaganzas, leak down testing and the forced removal of most of my remaining hair before I discovered this simple problem. Keep your eye on this, especially if you run into plug fouling issues. In fact, it is a reasonable move to take off the pump cover from time to time and confirm proper alignment of the marks on the pump and smooth operation of the throttle/pump interface.

More good advice from the Hodaka crowd, this site is really helpful. I was mentioning my pump concerns to a parts guy at a "real" bike shop (not many of those left up here) where I picked up a new battery yesterday and he said that he had several small trail bikes of similar design back in the day with the oil injection from the factory and he used premix but kept the pump installed. He kept some oil in the tank and just routed the oil tube to the manifold back into the top stem of the oil reservoir, he said it worked fine with just that one little modification. And of course, he blocked off the manifold inlet as well. Probably better to use the procedure you mentioned above. Thanks for the help.

I'm an Old School type and therefore premix lubrication makes perfect sense. Auto oil injecton works as a plug-and-play convenience for the casual rider. The inconvenience of premix is when you need to refuel when traveling on the bike. In their craft paints department Hobby Lobby sells quality polyethylene bottles in an 8 ounce capacity which are quite leakproof and even marked at 4oz and 8oz. The mix ratio on my bike is 4oz/gallon, so these bottles are perfect to carrying extra oil while traveling without a support vehicle.