Check valves

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Glyn.G
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Check valves

Post by Glyn.G »

Hi all,
I decided to check the oil lines for my GT380 rebuilt engine before fitting them, and it came as no surprise that after priming them using a syringe then hanging them up the oil just flowed through with no pressure needed. The check valves are completely gummed up and stuck in the open position. I have removed the valves and left them soaking in diesel but I don't think it will do any good.
My question is has anyone tried the new ones that are advertised on ebay from Dudley and are they any good.
Regards,
Glyn.
Vintageman
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Re: Check valves

Post by Vintageman »

Some of us had luck with those. I did not dare to use them and here was my reasoning->
http://www.suzuki2strokes.com/forum/vie ... =2&t=11362" onclick="window.open(this.href);return false;


I found that ones from Kawasaki work and replace them on two bikes a T500 and a T350/GT250. I think the triples are the same check valve but you would need to verify that

http://www.partzilla.com/parts/detail/k ... 8-009.html" onclick="window.open(this.href);return false;
And my post to the point ->
http://www.suzuki2strokes.com/forum/vie ... =2&t=11362" onclick="window.open(this.href);return false;
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Glyn.G
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Re: Check valves

Post by Glyn.G »

Hi,
I've been trying to verify that the T500/ GT250 use the same check valves as the GT380 but Suzuki only list part numbers for the complete oil line set ( no longer available ). There doesn't seem to be a separate part number for just the valve.
Is there anyone out there that can confirm that they are the same and that the Kawasaki ones will fit my 380.
Cheers,
Glyn.
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Re: Check valves

Post by Vintageman »

If Dudley claims his fits either I deduce Kawasaki will too. I have a few lines from Ts and GTs and I am pretty sure I have swapped them about looking for one check valve that doesn't leak to replace one that does. I think chances are good they are all the same. Buy just one I suppose and test it.

I think one of the lines on the GT750 (far left) is just a banjo without a check valve... well not sure what this has to do with this post other than to be 100% sure about things in live if that is ever possible.


I am so glad Kawasaki still makes theirs (while supplies last?). But when I go this route I change all at once just to be sure the break open pressure is the same all lines for not sure of Suz and Kaw are the same on this spec. You should question Dudley's to this point. If it matters much????
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tz375
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Re: Check valves

Post by tz375 »

FWI,

On that one odd cylinder on a GT750, the check valve is inside that short "connector" mid line. All 6 lines have check valves.
Glyn.G
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Re: Check valves

Post by Glyn.G »

Cheers for all the info, I think I will be ordering a Kawasaki set from Partzilla. I contacted the seller in Dudley and he informed me that his valves need to be used first before they will seal properly. Not sure I like that, surely they should work properly straight from the packet.
I could do with hearing from someone who has tried the Dudley ones to give me an option to use them or not.
Vintageman
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Re: Check valves

Post by Vintageman »

I think others at the time of my old post claimed Dudley's worked (anyone?). The issue to me is when your bike sets a while will it smoke heavy when first started? That requires you to de-coke your engine more frequently as I have learned. It makes a mess of things

Changing oil lines on a GT750 is not easy as a T500 for example if they did not come into it. The spider lines with Dudley's new check valves I bought leaked very very very quickly ala hang tes. I just did not want to chance it. Also I don't think you have more that one shot before you need to change the plastic lines too.

In this case my original GT750 lines were tested and did not leak and did not have any issue before so I put back on... I was doing this mainly to changed my carb jetting and once that far change starter brushes and once that far why not change ... etc.

I think I am the only one who has used the Kawasaki lines I know of. Oldjapenesebike claimed he was going to try on GT750 and have not heard anything. send him a PM.
Current Bikes
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77 Yamaha RD400 (Daytona Cyls),
Glyn.G
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Re: Check valves

Post by Glyn.G »

Having ordered a set of valves from Partzilla I decided to strip one of the old valves to see what's what. They seem pretty basic inside and the only thing I can see that can wear is the ball bearing which is easy enough to replace, and the spring which may lose it's compression strength over years of use. I was wondering if anyone has tried to replace this spring and if so where did they get them from.
I seem to remember a previous post on this subject where the person was asking for any old check valves to be sent and he would have a go at refurbishing them, purely for his own personal use though. I wonder if he had any luck?
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akendall1966
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Re: Check valves

Post by akendall1966 »

I seem to remember a previous post on this subject where the person was asking for any old check valves to be sent and he would have a go at refurbishing them, purely for his own personal use though. I wonder if he had any luck?
Hi Glyn,

Yes it was me who was after old check valves to refurbish, no offers, so I bough a set of GT380 oil lines for the purpose of salvaging the valves, but haven't arrived yet. I did refurbish the 4 valves from my own T500 project OK though.

They are pretty easy to disassemble as you have found. they are standard imperial ball bearings I bought stainless 316 balls from a bearing supplier, although given they sit in oil regular hardened steel would be fine.

I have never held one to compare but if you search kawasaki check valves on Ebay there is a guy selling springs and ball having had replacement springs manufactured which I have read are pretty close to suzuki. The Suzuki springs are phosphor bronze I believe so unlikely to have corroded. More likely they have been treated to extreme prejudice with compressed air or something prodded down the hole deforming the springs. I had no issue reusing mine, but that was only a sample of 4 hence why I'd like to do more to see if my success can be repeated.

I found the valve seat had to be replaced to get a decent seal, this also has the advantage you can make the seat a bit longer to give the spring more pre-load to compensate for its age. About 0.5mm increased the cracking pressure by about half a PSI. I can't prove it but either the seat corrodes through some thing like dezincification or removing it distorts the hole, but reuse of the seat after its removed is a waste of time IMHO.

As you observed the valve a is pretty simple a ball seating in a hole, but this means the quality of the seal achieved is very dependent on the quality of manufacture. A perfectly round ball sitting in a perfectly round hole will achieve a complete annular contact ring and a good seal. Lack of flatness, surface finish, perpendicularity of the hole, roundness of the ball or hole all detract and create leakage paths.

I can't do much about the balls other than buy the best grade available. But I hand finished the seats to ensure the best possible seal. Probably OTT but a 46 year old bike is not going to be a daily rider for me, so having confidence the oil will stay where its supposed to be for several weeks between use is worth the effort.
purely for his own personal use though
True - but I don't want to claim I can offer something until I am sure I could deliver reliably.

Cheers
Adrian
Glyn.G
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Re: Check valves

Post by Glyn.G »

Cheers Adrian, Thanks for the info.
I was contemplating trying to re-seat a new ball bearing in the old seat by the old fashioned method of a dab of grinding paste and using the ball to re-form the seat. Much the same as reseating new valves in a cylinder head.
Regards,
Glyn.
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akendall1966
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Re: Check valves

Post by akendall1966 »

Glyn.G wrote:Cheers Adrian, Thanks for the info.
I was contemplating trying to re-seat a new ball bearing in the old seat by the old fashioned method of a dab of grinding paste and using the ball to re-form the seat. Much the same as reseating new valves in a cylinder head.
Regards,
Glyn.
That might well work as you would make the sealing area much greater, not something I have tried myself.

AK
Glyn.G
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Re: Check valves

Post by Glyn.G »

Hi all, Short update on my check valves. The valves arrived from Partzilla yesterday ( 16128-009 Kawasaki valve ) and they clicked straight into the oil pipes, 2 clicks then tap down the collar " marvellous ". All six done I decided to do the leak down test, and you guessed it 2 leaked worse than the old ones I took off. 1 feeds oil to the crank and the other feeds oil to the carb intake but not on the same cylinder. I'm wondering if like the ones from Dudley they need to be run in before they seal correctly.
I'm at a loss and now have no hair left !
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akendall1966
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Re: Check valves

Post by akendall1966 »

In my opinion (and its only that can't offer any real evidence) yes some oil passed through them helps. The springs are awful fine when disassembling you can see the surface tension of the oil can cling enough that they extend when pulling them out of the banjo. Oil may help the ball find its way into the seat a bit better, or just just could be a bit of crud / dust.

I have been connecting each valve to a length of PVC screen washer hose, pushing the other end over the spout of my oil can and gently flushing them through with 2t oil with 4 or 5 squirts. Generally none or little oil is lost after that when hanging from a tube primed with oil.

Opinion again, but until all the internal parts are wetted with oil and the valve has cycled open/close a few times, they may not shut off effectively.

If you can get the 2 out that are misbehaving again, might worth a try to flush and leak test them again on a length of PVC hose before refitting.
Glyn.G
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Re: Check valves

Post by Glyn.G »

Thanks for all the great info on these check valves.
Yesterday I decided to cycle some oil through the lines and valves by connecting the pump shaft to a cordless drill and ran nearly half a litre through them then did another leak down test. You guessed it, the oil pi---d out. As a last resort I cleaned out all the lines and valves with a thin liquid degreaser and then re-primed them with 2 stroke oil and hung them up again. " Bingo" no leaks.
Now I'm worried that when I do put the refurbished engine in the bike and fire it up the valves will leak again after a few cycles. Surely they didn't have this problem when the engines were first assembled, or did they just trust to luck they didn't leak.
My heads done in.
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Re: Check valves

Post by Vintageman »

I don't think on their birthday and through their early years they leaked.

If you truly cleaned them, ran some more oil through them, and hung them for many hours and they did not leak: You are good to go :up:

If you bike smokes of 2 stroke oil like crazy, at first starting, after setting a long period of time they leak. If you see air bubble in line it may be a bad check valve too.

I wonder if you pumped that cleaner and maybe some diesel though the line with a drill to the pump as you did, if that won't fix most that leak due to being gummed up? Changing them is bit of a pain.
Current Bikes
74 GT250 (T350 upgrade),
76 GT250 (T350 upgrade),
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77 Yamaha RD400 (Daytona Cyls),
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