Suzuki 2 Strokes

My 71 T350 gets air in the oil lines. Heres how it goes, when I run the engine and hold the pump lever in the fully open position, the bubbles are forced through and all seems well. However, when I release the lever and operate it with the throttle, as in blipping the throttle, when the revs drop, bubbles appear in the lines near the fittings at the base of the cylinders. Holding the lever on the pump fully open will again purge the lines of air. Bad oil pump or bad fittings on the lines? Is there a correct way to flush out the lines/fittings without destroying things? The fittings do not seem to be removable. Thanks.

Could be a couple of things - I'm assuming you have tried new sealing washers on the fittings ? And that they are tight ? if they are at all loose or if the washer is not sealing then you'd see this problem. If that is OK, then it could be the check valves - best thing would be to first make sure you have good seals, and if that doesn't fix it then take the line off completely and try to (very) gently rinse them with methyl hydrate in both directions. Don't blow them out with air - you will ruin them. Here's a photo of a typical injector oil line end (off a GT750 in this case)

Thanks for the tip. Yes, I installed new sealing washers, although the old washers were nylon and the new ones were alloy. Are the alloy ones the correct ones? According to the parts fiche, they are correct. P/N ending in 06004. Methyl hydrate, is there another name more commonly used and will I find it at my local big box hardware store? Thanks again.

Not sure what else it would be called - you normally find it in the paint section of any hardware/lumber/big box store. Its used as a solvent for shellac but is also the main ingredient in gas line antifreeze.

I meant to put my post here.
I went thru all that, replaced the valves, cleaned them, checked for leaks, still got air. I knew there had to be a leak somewhere I just couldn't find it. I finally took some liquid electrical tape and painted the 1 into 2 joint and have had no leaks since. At least on mine, and probably most others I don't think the valves have anything to do with it. I think there is a very tiny crack or hole some where in the joint allowing air to get in. I think any type of sealer, paint or whatever around the joints going into and coming out of are going to solve your problem. And, it will cost you nothing to find out.