Good evening! 1972 R5 - I can not for the life of me figure out what I'm doing wrong. My left cylinder oil line keeps getting air pockets, starting at the left cylinder side. I have replaced all of the hardware. I put clear Hipa lines on it (1/8") so that I can be put at ease that it's getting oil. It'll be fine at first, but after getting on the throttle, air pockets begin developing. The air is not coming from the pump (pump is rebuilt), I have watched it closely to make sure. I also swapped the lines at the pump, and it continued getting air in through the left side only. I'm using the stock setup with the circular metal sleeve that slides over it. Does anybody have a solution to this? Is there a different fitting I can use that won't allow air in? I eliminated the pump as the issue by switching the lines. Any help would be much appreciated!

Yamaha used black lines for a reason... what you're describing is not unusual... it's always the longer hose.

I've only seen one person ever solve it. Here's a link to his solution. (Mine is use OEM hose and clamps... OEM hose has a smaller ID which I believe helps...)

www.2strokeworld.net/forum/index.php?topic=2106.0

Thanks for leading me to that forum! I went through the comments, and someone posted a link for some Yamaha oil check valves. I'm going to order one for each side, and hope that solves the problem. I wish my brain would just stop being paranoid and use the OEM lines, but I just can't bring myself to do it. Not after all the hours I put into the engine. Thanks again!

I'm with Mark on this one, my '72 Yamaha has black lines but I had to replace the very small diameter molded lines on my '72 Suzuki 185 with lines like yours and no matter what I do (and I've done a lot), I get air bubbles in them and have learned to ignore them by now.

In that line of thought, small diameter lines don't seem to have the problem but you can't find any to fit the banjo bolts or other barbed fittings so not much to suggest on that front.

For anybody else that sees this, here is the part number for a Yamaha oil pump check valve: 8CH-1316A-00-00 I will update once I receive and install it.

I liked your idea of a pair of valves. Adding more restriction to the longer line only might be a mistake.

As far as being paranoid... if pump does ever fail it's not likely the clear hose will help.

Best "paranoid" method is run premix and the pump. If jetted right you can run a ton of quality oil and it won't smoke bad or foul plugs.

That's true, Mark. I'm going to see how the check valves perform and go from there. I like your idea of just adding some premix to be sure, which is what I'm doing right now since the weather is perfect here in New Mexico and I've been itching to ride for months. Thanks for the response, cheers!

I do know that HVC carries the line and the little metal clips, if you can't find them elsewhere.

Yamaha still sells the clip-clamps and original hose too

+1

If my memory isn't playing tricks on me, part number has superseded at least once and you'll be supplied with a fixed length that you cut as required - you'll get more than is needed.

Same caveat on the memory front, I think that it is the same hose as supplied for carb breathers.