Author Topic: Gtr oil feed  (Read 397 times)

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Offline AlanJohn

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Gtr oil feed
« on: December 24, 2018, 07:43:29 AM »
I'm looking for some advise please.
I've replaced the oil lines on one of my Gtrs and the left hand side feed to the motor keeps getting air locked,if l hold the pump open on tickover l can watch the oil pump up to the union (which isn't blocked)l took it off run the engine and watched it pump oil through, but whatever l do it loses about an inch of oil from the pipe within aprox l hour and overnight about half the pipe is empty.
Is this normal the oils not leaking out l can't understand it.
I've got 20/1 in the fuel as l've rebuilt the top end and the last thing l'm going to do sieze it up.
I've a few of these bikes and the rest have oil in the pipes all the time.
Thanks in advance.
Alan.
« Last Edit: December 24, 2018, 01:24:42 PM by AlanJohn »

Offline OldSwartout

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Re: Gtr oil feed
« Reply #1 on: December 25, 2018, 05:39:31 PM »
If there doesn't seem to be a leak indicated by oil collecting around the line across the engine, the check valve or in the carburetor cavity, then it has to be going into the engine through the check valve.  That can't happen if the check valve is operating correctly.  Does the left side smoke excessively after it starts? 

Karl Swartout
Mooresville, IN
BS175 Roadracer. BS200RS, BS175HS
BS350 GTR

Offline AlanJohn

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Re: Gtr oil feed
« Reply #2 on: December 26, 2018, 04:06:12 AM »
No it doesn't it actually seems to smoke less than the left side ,when the revs are increased you can see movement of oil at the union,as you say it must be going somewhere.or not having enough pressure to pump up past the union.
The right side smokes more as there is oil in the fuel as well and it's getting fed from the pump and the fuel l've got a feeling that the left isn't getting it from the pump but only the fuel.
Do the pumps get weak and become not strong enough to do the longer run to the left side?
Or do they either work or not with no imtermediate faults?
Is there a correct way to fit the unions to the engine.is it the hollow well type resorvore facing upwards or downwards there obviously made that way for a reason maybe l've got them upside down.(hopefully )
« Last Edit: December 26, 2018, 08:58:41 AM by AlanJohn »

Offline BRT-GTR

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Re: Gtr oil feed
« Reply #3 on: December 26, 2018, 05:40:54 PM »
         I always fit the unions with the flat side uppermost against the seal washer and checkvalve head ;  open side down against the engine drilling. No real reason why, that's the way I've always found them fitted.
         The pump can only supply oil at a single pressure (as generated by the spring on the plunger shaft). This is fed alternatively to either cylinder so they both recieve the same pressure.

         My initial thoughts on the apparent oil leakback from the engine end was to suspect an air leak on the checkvalve sealing washers, the ball in the valve or even up the 8mm thread from the crankcase.  I don't think oil can leak back past the distributor valve and you can't find any external leakage so where's the oil going?     Karl may well be right that it is bleeding/syphoning forwards into the engine.
       Pull the checkvalve and rinse well in paraffin or similar. Do not put an airline on it, it will wreck the valve, just blow it through by mouth using a spare piece of tube.  If clean, it should provide an airtight shutoff when blown from the 8mm engine end. If you then suck you will feel slight resistance before the ball lifts and allows forward flow.

     
Unspoiled by progress.
I'm so glad I grew up in the 60s & 70s. I did so much stupid stuff and there's no record of it.............Anywhere !!

Offline AlanJohn

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Re: Gtr oil feed
« Reply #4 on: December 28, 2018, 05:13:18 AM »
Thanks for your advice but l can't get it right and for now l give up.
Will it do any damage using the bike with a 20/1 oil fuel mixture so it's running basicly without the oil tank connected?
Although it is connected but has an issue and probably not working correctly.
Thanks.
Alan.

Offline OldSwartout

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Re: Gtr oil feed
« Reply #5 on: December 28, 2018, 07:48:55 AM »
IMO, you can run without an oil feed and not hurt the pump.  The pump drive gets oil from the crankcase and should keep the internals oiled, including the pumping components. Others may have some experience they can relate.
Karl Swartout
Mooresville, IN
BS175 Roadracer. BS200RS, BS175HS
BS350 GTR

Offline AlanJohn

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Re: Gtr oil feed
« Reply #6 on: December 28, 2018, 11:28:09 AM »
Thanks.
l watched the oil pump up to the union today but l don't think it's going past the union and then very slowly drains down the tube a couple of inches.
Do the pumps get weak over time?
If so a replacement pump and check valves will have to be done.
Thanks for your help.

Offline CL-100

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Re: Gtr oil feed
« Reply #7 on: December 28, 2018, 02:13:45 PM »
Would it make sense to swap the two unions around and see if you get different results?  It may help pinpoint a bad check valve or perhaps an air leak in the line somewhere.

Offline AlanJohn

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Re: Gtr oil feed
« Reply #8 on: December 28, 2018, 02:30:43 PM »
Thanks but l've just found that both check valve (bolts) are the wrong ones for this bike hopefully that will cure it l'll let you know.

Offline AlanJohn

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Re: Gtr oil feed
« Reply #9 on: December 28, 2018, 02:31:29 PM »
Thanks but l've just found that both check valve (bolts) are the wrong ones for this bike hopefully that will cure it l'll let you know.

 


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