WR 426 oil pressure problem

23 replies to this topic
  • 426john

Posted April 30, 2011 - 11:43 AM


Hi folk,my first post please help.
After rebuilding the gearbox to rectify the 5th gear problem.
I have no oil pressure.
I have been very carefull with this bike and never had a problem before.
If i crank the engine by hand oil pumps slowly out,but not enough to fill the filter housing and up the oil tube to the head.

I have checked photos of the rebuild and all o rings and dowls are in place.

The engine/oil was very clean inside so i never disturbed the oil pump.

Whats going on!!

  • Magnus78

Posted April 30, 2011 - 12:40 PM


I think you need more force then just kick it to build up some oil pressure.

  • WRF Woods Weapon

Posted April 30, 2011 - 12:57 PM


My buddy had a similar problem after rebuilding his WR426 the gearbox and we each took turns kicking like JET LEE till it fired up whoa!!!

  • 426john

Posted April 30, 2011 - 12:57 PM


Ok,your right.But i ran the engine twice last night,for about 50 seconds.Then again today,not enough oil is pumping to fill the filter housing.how can the oil pump become so poor.I took off the clutch cover again and looked at the oil pump outlet and none return valve.

I dont want to run the engine again!!

  • 426john

Posted April 30, 2011 - 01:04 PM


I primed the housing and engine with extra oil.The bike has been standing for more than ayear with damaged 5th gear.I would start and run it every month,with no problem.

Its been looked after very well,and has very light use!!!!

Its a mystery how something has been miss-assembled or the oil pump is worn out.

I think i need to remove the engine,and open it up again.

I just dont want the top end to run dry.

Why no oil pressure?

The bleed test says no oil comming out the top of the flter housing??

  • 426john

Posted April 30, 2011 - 01:14 PM


From the oil pump,through the non return valve,up a gallery to the outside of the filter housing (outside oil filter). On the inside of the filter housing cap is two holes (inside oil filter) one goes to the crank shaft the other then goes to topside of clutch case.This then splits off again to the gearbox and valve gear.Is this correct?

  • 426john

Posted April 30, 2011 - 01:31 PM


The oil and inside the engine is very clean.I found the small broken corners off the dog clutch( 5th gear slips due to worn dog clutch)and changed the selector fork.Only found tiny amount of metal flakes/bits in oil filter.Have i miss-assembled or could the oil pump have some metal particules causing a total loss of oil pressure??

  • 426john

Posted May 01, 2011 - 03:54 AM


From the filter housing one gallery passes up to the topside of righthand cover.The other gallery drops down to the spigot & seal suporting the crankshaft.I re-assembled with grease,and when removing the clutch cover to check oil pump outlet,i could see the seal (& spigot) supporting crankshaft was a good fit,it had pushed all the grease neatly to the eadge of the lip seal.I then primed the oil gallery down the center of the crankshaft,i couldnt fill it fast enough,as the oil would drain off throu the crankshaft big end bearing.


Sorry for shouting.

Edited by 426john, May 01, 2011 - 03:56 AM.

  • Birdy426

Posted May 01, 2011 - 05:19 AM


Sure sounds to me like you are missing a dowel or o-ring somewhere...

  • 426john

Posted May 01, 2011 - 05:19 AM


Also the oil tank on the chassis is half full and the oil line to the left lower case is gravity feeding oil to the left hand case.From left hand case via a dowl and o ring to gearbox case.Here i checked oil pick up,all ok.So i never removed the oil pump.If its not broke dont fix it !

Also at this time when the main-shaft,drive-shaft and primary gears were out the case,i filled the oil pump with oil and span the drive gear by hand to check "the feel" all ok,discharge from oil pump outlet and sooth operation.

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  • 426john

Posted May 01, 2011 - 05:22 AM


Ok thanks Birdy426,i can picture where they go,and no parts were left over.But something is wrong,and starting the engine again and running higher rpm to push the oil throu is out of the question.I,ve spent around 370 pounds so far,to rectify 5th gear slip,new cam chain and gasket set.I guess i need another full gasket set and tear it down again.I can also see in my minds eye,the oil just gushing out the oil pipe to feed the valve gear,like its always done many,many times before.

So close,i was thinking about riding it at last,sorted out a good clean air filter and new plug for run-in.

Edited by 426john, May 01, 2011 - 05:32 AM.

  • 426john

Posted May 01, 2011 - 08:45 AM


Im gonna get a full gasket set and tear it down again,i might have made a silly mistake,i might have missed something.Its not right,oil should pressure out (rightside case) into the oil tube that feed the valve gear and gearbox.
How long should it take to prime the filter housing,up into the top tube, 30 seconds or longer??.Their should be a strong flow of oil.

  • 426john

Posted May 01, 2011 - 02:09 PM


Im using a cheep 15w50 oil and a HF142 oil filter.

Has anybody had a problem like this?


  • 426john

Posted May 02, 2011 - 03:56 AM


Can any body help?

Is this like one of those "whats the best" questions?

Not for me its not,thanks.

  • MaxPower

Posted May 02, 2011 - 07:34 AM


[COLOR="DarkGreen"]Im only brain storming, did you check the filter that is in the frame at the bottom downtube that it was clear? Also the metal "y" of oil external oil lines are unblocked?I have never heard of this clogging but if you arent getting oil pressure the problem has to be somewhere[/COLOR]

  • 426john

Posted May 02, 2011 - 02:17 PM


Hi MaxPower, thats just what im looking for, a bit of brain storming. Yes i pulled out the oil strainer,from the frame,it was like new,screwed it back in the frame. The external "Y" oil line is all clear.But the filter case before that wont fill up.

Its crazy but the return to the oil tank is returning oil,i started the engine again for about 40 seconds,couldnt fill the oil filter case and purge out the top,but it did fill the oil tank??????????

So that means the oil pump is working on that circuit????

Im gonna tear the thing to bits again.

Please try me again any ideas.

  • 426john

Posted May 03, 2011 - 12:00 AM


Any ideas?

Its morning again here,in europe,not a single post.

You must all be watching re-runs of the Royal wedding.

  • MaxPower

Posted May 03, 2011 - 07:56 AM


[COLOR="DarkGreen"]the wedding is over . We are onto shooting our guns in the air celebrating Bin Ladens death[/COLOR]

  • 426john

Posted May 03, 2011 - 12:16 PM


Cheers dude,right in the eye.one less of them.

The Bike;

I pulled the right hand cover off again,everything looks as it should.

I need a hand to undo the large nut on the center of the clutch ,so im just waiting for my buddy.Hope he can help tonight.

Then i can check the oil pump properly.

The oil i dropped out has a small amount of metal flecks in it!!!!!

All the dowls and "O" ring were in position,and its still a mystery!

  • Birdy426

Posted May 03, 2011 - 06:33 PM


Look at this illustration:
Item no 22 is a "dowel pin", p/n 99510-10114-00. I talso gets an o-ring. Are you sure you put that bad boy in when you put the cases back together?


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