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where does it travel before it gets to the top of the head. the crank on mine was not getting much oil either. why did this happen to a perfectly good motor that was taken apart to put a crank and cam in an installed to the factory specs with all new gaskets an seals.
 

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so far this has been a fucking nightmare with this atv. all i wanted to do is soup up the motor with parts that say they fit it like oem. and now i am ready to throw it out of the back of a truck at 80, or shove it off the tallest cliff i can find. this must be yamahas most piss poor design if you cant do anything to it without it fucking up and it stop pumping oil.
 

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so far this has been a fucking nightmare with this atv. all i wanted to do is soup up the motor with parts that say they fit it like oem. and now i am ready to throw it out of the back of a truck at 80, or shove it off the tallest cliff i can find. this must be yamahas most piss poor design if you cant do anything to it without it fucking up and it stop pumping oil.
If I were you I would be a little gentler on the language, I can't do anything but others can.

As far as your oiling problem, you are going to have to figure that out, there is not much I can do from this end since I can not see the engine or its internals I have had tons of these engines apart and never had oiling problems...................
 

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You need to replace the oil strainer. It seems that any and all debris gets caught in there and eventually gets around the screen, goes into the pump, siezes it up and strips the plastic pump gear. You put a new pump on, start it up and it will sieze up again. You have to replace the strainer on this motor.

You can crack the case, look inside and it may look perfect and clean. But open up the strainer and you will poop your pants when you see whats in there.

I have heard this story over and over. Something failed prompting a bebuild, the motor was rebuilt but failed again after an hour of run time. Now I know its because the old strainer was used again.

Its a $10 part. It is not that big a deal to crack the case, replace the strainer and puter back together. Its not any worse than pulling off say...the clutch cover.

I am going thru this now. I am thinking of putting JB weld around the circumference of the new screen. The way it is designed, there is a series of spot welds around the circumference. This debris can go around the screen between the spot welds. In my case, there were only a few spot welds still attached, the rest were broke loose. But what if the JB weld comes loose? Don't know what to do yet.

I had my valves springs break. I did not know there were chuncks of spring and metal valve seals in my strainer. There was not a speck of anything any where else. I did a top end rebuild, puter back together and lost oil pressure after about an hour. Not good. Tore up my new 685 Cam and rockers.

Don't loose faith in the motor. Its weekness is the rod, the oneway and strainer. I have put mine thru pure hell, and it looks really good still....except for the cam.
 

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were else in the motor can stop oil from pumping to the top of the motor. my case has been split for the 4th time and i needed to now were i should start looking for the 3rd time while the case is still split. it will pump oil till the motor warms up then stops. it has every new gasket avalable new pump and seals an still no oil after it warms up. is this somthing that happens when you split the case so that yamaha makes you to take it to the dealer for some 5cent part and then charge you something retarded to split the case. i am ready to shove it off a cliff so any help would be great.
 

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This is what I would do:

Take apart the strainer and make sure it is clean.

Check the oil pump to make sure nothing got in there? Make sure it turns free.

Check to make sure the plastic oil pump gear is not spinning on the oil pump shaft.

Check to see if you are getting oil to the transmission at the same time you are not getting oil to the cam. If so, it could be a sheared pin on the small rotor in the oil pump.

Larger chunks can get pulled into the rotor siezing it up, then the chunks fall out and there is enough friction bettween the stripped oil pump gear to turn the pump. As it warms up, the chunk gets sucked back in.

Blockages are unlikely. There has to be something going on with the pump. There is no magic trick to getting oil pressure.
 

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You have to take apart the strainer. It will be full of chunks. There will be no chunks anywhere else in the crankcase area. It will look clean as can be. They all get sucked inside the strainer where they are hidden. You can flush and blow everything, but as soon as you start it, the chunks in the strainer will take out your new pump from yamaha. I am guessing this is what happened to you.

The strainer will need to be replaced. The screen has likely been detached from the strainer allowing debris to get into your pump. If you have the cases split, there are two phillips head screws holding the strainer on. Take it off and pry it apart. Then be prepared to change your shorts when you see whats in there.

You should have oil pressure within 10 seconds of starting. There is no need to prime or anything. If you don't get oil pressure, then something bad happened to the pump or gear. There is no other reason for no pressure.
 
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