Kawi2strokes.com Forum

Hi Everyone,

It has been a while since I posted.

My beloved 1975 H2C (original 26,000 mile) has a leaking check valve for the left cylinder main bearing. It hydraulically locked (I hadn't started it in a 8 months) and I went through the process outlined on this forum to clear it out. Dramatic but effective!

I rode it for 60 plus miles afterwards and it still smoked out of the left cylinder for a long time but finally cleared out. I guess oil in the exhaust pipe.

I tested the leak rate and it is about a teaspoon in 24 hours of Belray 2T Mineral.

Of course, this bike has the non-rebuildable oil lines. I have heard that someone in the UK can repair these but don't have contact info. Googling didn't help. I also saw that reproduction lines were available but inquiries about those remain unanswered.

An alternative would be splicing in a good check valve and banjo for this one cylinder or installing an inline Yamaha check valve (I have both from my previous H1 project bike).

Advice or resource pointers appreciated!

Tim

I put a Swagelok shutoff valve in the line from the tank to the pump, with a switch to kill spark when it's in the closed position. No matter how well you get the stock valves working, you never know when one will start leaking. Looking back all the way to the late 1970s, I remember lots of blue smoke for the first few miles. Now there's no extra smoke at the start of rides.

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If it surges, that's normal, upshift.

Hi,

A shutoff valve would be almost a last resort for me. (switching to premix would be the last resort) I would prefer to fix the problem. But if I had to, I would consider it. Does the valve include the switch or is the switch separate? If the Swagelock valve includes the switch could you provide details such as part number or where you got it?

Thanks for the reply and the suggestion.

Tim

I fixed the leaking check valve problem very carefully, only to have the valves seeping again within a year.

The Swagelok valve doesn't have a switch. It's a very high quality stainless steel valve that I happened to have a few of. I added a small Cherry brand switch on a bracket and wired it "normally closed" to the black and white wire of the ignition rectifier so it grounds the wire unless the valve is fully open.

You can find valves with built in switches, but I don't offhand know of one to point you to. I really recommend this modification to owners who leave the motorcycle parked for long periods, but of course those who prefer "correct" won't want to do it.

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If it surges, that's normal, upshift.

Fifty year old oil check valves are not worth mucking with once they go bad, been there bought the t-shirt. You likely have the later pressed together OEM brass valves. I have 4 triple and all but one have new oil check valves from Yamaha. Installing a shutoff valve in the main oil feed will tempt fate, you can do it as some people have. Since you have the 3 in one oil line you will need two Tees.

The main problem becomes the new oils, especially 0W-Nothing synthetics that will seep past any check valve. Some of the the full and partial synthetics are not good ad being held in place with check valves, and the valve seats can pit and have erosion lines in them, allowing them to "seep".

The end valves for crankcase are supposed to be air pressure released @ 4.60 lbs, AIR PRESSURE.

The Yamaha valves I use are from triple two stroke snowmobiles (and other 2T applications) and crack at 3psi. They also have rubber seats and a plunger stop which prevents spring distortion. Oil consumption is the same as a typical H1 or H2 so in that case I suspect the extra pressure rating may have helped the old brass valves seal better being something Kawasaki discovered during production. I configured the my first back in 2017 and it's still running well with normal oil consumption and no leakage. If a valve ever goes south it is easily replaced. Many others have had the same results, being totally fed up tinkering with junk. Being less dated they would be better suited to newer oils one would reason, which is what we have available these days. Suzuki and Yamaha guys use them too being that they are generally intended for 2T engines, that's where I found them lol.

Thank you!

That looks like a viable solution, I already have a few of those Yamaha check valves. On question however, should the old check valve ball and spring be removed from the
end banjo? Will I be able to remove it when I disassemble the line to remove the banjo? If the old check valve can stay why not splice a Yamaha check valve into the existing line using some tubing over a cut in the old line?

The knowledge residing with the members of this site have been invaluable to me on many occasions!

Tim

I know of 2T guys claiming to have left the leaking OEM valves in place, adding a check valve in series on on a single line (certainly not with 3 in 1). I would measure and compare the new/old output at the banjo end to be safe with a single line application. It's just not worth taking the chance speculating without first hand data. I would not recommend doing so on a Kawasaki 3 in 1 line due to space constraints and common pressure issues. That being said the sealing or pop-off value of the OEM valve can be reduced to almost nothing using excessive compressed air pressure on the line to weaken the spring. Balls and springs can be removed from the newer OEM check valves in the 3-in-1 line, it's difficult as they are pressed together but not impossible to do. If you need a new valve on the 3 in 1 line I would replace all 3 as a matched set, even though crankcase suction pulses helps average oil flow.
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