Plastic Oil Pump Gear Replacement

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There was lots of good information on TT on replacing the plastic oil pump gears which I appreciated learning from. So I have taken some extra pictures etc in case it will help someone else. To begin, remove the kick starter pedal, drain the coolant and oil. I did not drain my oil , I layed my bike down instead but it still ran out. I had about 900 ml in there. Take the right inner clutch case off. You do not need to remove outer clutch case. Picture shows case off. The central hub has fours bolts and springs.

Edited by tonybike

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Bottom oil gear is the only one visible. Need to take out the clutch to access the oil pump gears. Remove the four bolts and springs in previous picture and lift out the hub.

Edited by tonybike

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This picture shows clutch with hub lifted out. This hub applies pressure to the friction plates and steel plates which are underneath the hub. The friction plates and steel plates have already been lifted out in this picture. I was careful to make sure no coolant poured out of the hose into the case. It is better (and easier) to take that hose off at the radiator so that won't happen.

Edited by tonybike

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This is a picture of the clutch nut that needs to be removed. I had already removed it but then started to thread it back on partially for the picture. This is a tight nut 120 NM, and has thread lock on it from the factory. I tied the break pedal down hard to stop the back wheel from turning. My bike was lying on its side so I could not stand on the break. It was hard to apply enough pressure to stop the wheel from turning but it worked in the end. I also tried sticking a 24mm spanner through the sprocket to block the back wheel. I did it wrong and it slipped and bent up my sprocket. I forgot to use 6th gear so it sucked in the wrench like a food processor.

Edited by tonybike

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Underneath the nut is a safety washer that you need to bend down before you can take off the nut. Lift off the safety washer. Now you are supposed to be able to just lift off the inner portion of the clutch. Mine was stuck. To get it out I put the hub back on and operated the clutch. I hope I did not screw anything up by doing that. The inner portion of the clutch popped up and I lifted it out.

Edited by tonybike

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This picture shows the outer clutch portion. This part turns with the engine and spins the friction disks which interlock with its teeth. The friction discs drive the steel plates which have teeth that interlock with the inner portion of the clutch. This inner portion is connected to the central shaft which ultimately drives the back wheel. I did not know that. Interesting.

Edited by tonybike

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The outer portion lifted out easily. There is a washer on top which the inner portion rides in, and underneath is a bearing and roller bearing cage which can just drop out and disappear on you.

Edited by tonybike

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This picture shows the view after the clutch is removed. The three plastic oil gears are all visible now. The top two are retained by 13mm circlips and the bottom one by an E clip. I used new circlips when reinstalling.

Edited by tonybike

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A close up of all three plastic gears.

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The upper gear is driven by the clutch.

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The middle gear is driven by the upper gear.

Edited by tonybike

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The bottom is driven by the middle gear and it drives the oil pump. I took a lot of pictures of these gears because it took me so $$!&$!! long to get the clutch nut off it seemed like the right thing to do. Note that this one has an E-clip and no washer. The other two have a circlip and a washer.

Edited by tonybike

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Picture with the three plastic gears removed. Just pull off the circlips/washers and E-clip and gears.

Edited by tonybike

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This is the inner portion of the clutch, hub, bolts, springs and also the end of the clutch actuation rod which pushes up from underneath the hub to release compression on the springs which allows the friction plates to slip against the driven steel plates. Quite ingenious. Now I have a better appreciation of the components I am grinding into dust during episodes of cursing after stalling on steep slippery inclines.

Edited by tonybike

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After 60 hours my plastic gears looked good. I replaced them because I had boiled over after one of those clutch abusing episodes and I have no idea how the plastic gears respond to excessive heat. I feel better now in any case. Each of the top gears are this size.

Edited by tonybike

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The bottom gear has a pin which slides through a hole in the driven shaft. It would be easy to lose into the case. Easy for me anyway. You can see the pin which fits into a notch in the gear.

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Edited by tonybike

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This is a close up of where the pin fits through the shaft on the oil pump drive gear. I slid the pin into the shaft for this shot

Edited by tonybike

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The new and the old gears had the same appearance. When installing the gears make sure the protrusion in the centre of the gear faces the right way. The manual does a good job of describing the whole process. All in all it was an easy job except for blocking the back wheel and bending my sprocket. It was also a pita getting the cotter pin out of the break pedal. I will install the cotter pin the other way around. Also - on reassembly I could not get the brake to hold the back wheel. I ended up just running a tie down strap from the foot peg to the sprocket - that worked really well for blocking the wheel in that direction. Thank you for reading and for all your good ideas and that allowed me to replace these gears.

Edited by tonybike

Excellent job tonybike!

You deserve a case of beer (or maple syrup?) for your effort.


I've been putting off this job for 50h just because of that clutch basket nut. 



I've put your posts in a .pdf file for easier viewing and sharing. I hope you don't mind.






Check out Boano's website I think they now have steel oil pump gears for your bike.

Wow! Great write up. Now this job might actually move from my "to do" list to my "done" list. Thank you.



Check out Boano's website I think they now have steel oil pump gears for your bike.

Glad to see that, just in case. Thanks.

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