T500 Check Valve Spring "Relief" Specs

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BlackBearT500
On the street
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Joined: Mon Mar 13, 2017 7:24 pm
Country: United States
Suzuki 2-Strokes: 1971 T500

T500 Check Valve Spring "Relief" Specs

Post by BlackBearT500 »

Hi,

My rebuildable T500 check valves are in need of some love - the springs seem to be toast. I have found a guy that sells a kit of balls and springs for old Kawasakis that are rated to relieve at 4.5-4.6 psi (not dry, but with oil in the lines).

He said customers have had luck with the rebuild kits in their Suzukis, but disregarding his statement, I was wondering if that pressure spec would be sufficient/too strong for the T500. What do you all think? Will the specs work for my check valve repair?

Thanks in Advance!
Trenton
argo1974
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Joined: Fri Nov 07, 2008 3:01 am
Location: Tallinn, ESTONIA

Re: T500 Check Valve Spring "Relief" Specs

Post by argo1974 »

I've been using Kawi specs for years on my T500 without any issues.
1x T500 Cobra (1968)
4x T500K (1973)
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akendall1966
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Posts: 242
Joined: Sat Jun 28, 2014 1:22 am
Country: United Kingdom
Suzuki 2-Strokes: T500_MKIII

Re: T500 Check Valve Spring "Relief" Specs

Post by akendall1966 »

On my test ring I generally measure closing pressure 2~2.5psi vaccum on the non rebuildable valves (not cailbrated in any way). You might find the kwak valve pre-load the springs a bit more than using them in a suzuki or vice-versa. So the spec of those springs will be for Kwak valve and won't mean a lot when put in Suzi valves without measuring the actual closing pressure.

My takes has always been the check valve is there to stop the oil tank emptying into the engine so the closing pressure of the check valve need to be higher than the static head pressure of a full tank of oil. Being a type of piston pump the 'dead head' pressure developed will only be limited by leakage or component failure. Generally piston pump are the highest pressure producing of the various pump designs. So I doubt a few PSI makes any difference, as the pump will easily develop sufficient pressure to overcome the opening pressure of the valve. As long as they are all similar and oil flow isn't biased towards one line because of a big difference between valves, I think you would be good to go.
Warehouse1001

Re: T500 Check Valve Spring "Relief" Specs

Post by Warehouse1001 »

Kawasaki specified 4.6 psi crack pressure in later years (1974 +)according to experts on the Kawi 2 strokes blog. Most of the early Kaw triples (pre-74) seemed to be in the low to high 2's from the factory according to these same folks with a spec of 2.8 psi. Stretching the spring ever so slightly can get you to the low to mid 4's which seems ideal for all purposes including keeping oil consumption more reasonable. I now purchase new Kawasaki check valves and either use them as is or strip them and use the spring, ball and sometimes the seat. Did a combination of the two on my recent GT750 oil line rebuild. The spring, ball and seat were used on the odd "in-line" valve used on one of the GT750 lines. The entire valve was used on the five other lines. I use just the spring and ball on my Kawasaki triples with rebuildable lines. Although sometimes the seat is bad and they still won't seal with a new ball. I have measured mid to high 3's psi crack pressure with these valves as is. You can order the valves directly from a Kawasaki dealer. Not cheap however. Think I last paid around $14 per valve.
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