How To Adjust A Oil Injection Pump

Could just eliminate the injector system entirely and run pre-mix, might have to re-jet the carb since she'll probably be lean.

wirefryer#85 said:

Could just eliminate the injector system entirely and run pre-mix, might have to re-jet the carb since she'll probably be lean.

Click to expand...

i second that but it would probably run even better rather than being to lean.... in all my nixing of the injector pumps. but i could be wrong, wouldnt be the first time.. besides i was always worried about the injector pump failing and killing my bike. with pre-mix its all on you nuthin to worry about

I was reading up on the injector pump on my '76 TM400 and it seems the pump is designed to put oil directly on the crank bearings and meters oil according to load, I.E. via throttle position. Since the oil doesn't pass through the carb, jetting isn't affected by the oil mixture. Therefore, if you add oil to the fuel, both will have to pass through the jetts, leaning the fuel to the cylinder. Right?
At any rate, I think people override the injection system because of a lack of confidence that an adequate amount of lubricant is being delivered to the engine. I would advise trying to ensure that the system works properly and then use it!
BTW - I think the consumption is adjusted via the throttle cable. I can check the Clymer manual for my 400 if you think yours works the same.

Hmmm...
I take off all of my injector systems. I dont trust them.

There are a couple of types. Some do feed the crank bearings directly like my S2, and some feed a small jet in the intake tube.... There are various ways to go about it. Some manuals suggest removing the cable from the injector, and leaving it in place so it does actually run at minimum flow for the crank bearings while also pre mixing the tank gas. What IVe done almost all the time though, is to remove the pumps and plate them off.
I run 32 to 1 with a modern synthetic oil with great results.


as far as carb adjustments after removing an injector pump and running pre mix? Never heard of that. Never had to make a change and ive done it dozens of times.

When you say lean or rich in regards to jetting the carbs, you are talking air/fuel ratios, not fuel/oil. Change a pipe, work the ports, use a pod filter instead of the factory air box, then you need to worry about jetting.

If you have an injector system thats feeding too much oil and remove it and use premix there is no need to change the jetting on the carb because the air/fuel ratio has not changed, only the fuel/oil ratio.

2stroke said:

If you have an injector system thats feeding too much oil and remove it and use premix there is no need to change the jetting on the carb because the air/fuel ratio has not changed, only the fuel/oil ratio.

Click to expand...

As Lou would say, I'm no rocket surgeon but....

Changing the fuel/oil ratio does change the air/fuel ratio. I would guess probably not enough to require a jetting change but that would also depend on the design of the injection system and whether the bike was already on the lean or rich side to begin with.