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Crf150R Rebuild

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I have decided to give the Lad's bike a makeover after over 100 hrs of use.

It was getting harder to start and the compression was way down.

The Forks were setup for his weight 2 yrs ago and now bottom out.

The swingarm bearings and steering bearings have never been greased or even looked at.

The Radiators have been bent more times than I can remember so they will be getting changed also.

I opted to pull the whole motor out for the exercise. I have never attempted a 4t rebuild before so didn't want to have to negotiate the job with limited vision and things in the way. Plus the frame was filthy dirty. The carburettor has a whole mass of stuff hanging off it and connected to it. So this was left in the bike.

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I took note of the valve clearances and have found the exhaust valves to be completely closed and the inlet to be at .o9mm. They are supposed to be .16mm.

After achieving TDC. I painted a dot on the cam chain in line with a mark on the cam sprocket and wired the chain to the side of the motor.

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After removing the cam chain tensioner. I started to work on the head. Removing the cam sprocket and cam chain.

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Taking off the decompression weight,

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Making sure nothing can fall into the bottom of the motor.

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I keep pulling things apart until I end up with this.

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The piston, although plenty of carbon and crap on will clean up nicely and not need replacing.

The bore still has all it's lovely cross thatching and isn't glazed so will only need a mild touch up on the bottom edge.

The oil rings are shot. So they will be replaced. So far so good.

The valves on the other hand may need a bit of attention.

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have pulled the valves out and decided they are still worth saving.

Will clean everything up and re-seat the valves with a bit of fine grinding paste.

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The con rod pin is in good condition as is the lower bearing with no lateral movement. So more good news.

The valves and piston cleaned up a treat. So will purchase new rings and shims on Monday to complete this part of the makeover.

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Had a couple of hrs spare at the end of the day today. So thought I would get on with stage 2 of the makeover.

Swingarm and linkage bearings.

This proved to be a worthwhile exercise even tho the bearings were still in great condition.

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Taking the swingarm off was very easy. The engine mounting bolt already loose and just a hose clamp to open up.

The linkage was also easy to take off. As the bearings were all in such good nick it was as simple as.

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I don't get too fancy when it comes to the type of grease I use. Good HTB Grease does the job.

And as I have not looked at these bearings for over 100 hrs. should see him out for a while to come.

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I sometimes clean out all the old grease with a bit of turps before applying new grease. But this is usually when the bearings are full of crud. Seeing as they were in such good nick. I just pushed the old grease out as I added new.

All back together again with plenty of grease in the bearings.........And on the bike and me lol

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Still had a few minutes to spare.

So next on the list was the front Forks.

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My Son was complaining about bottoming out on the last ride. So this was a must do on the list.

I turn both the comp screw and damp screw all the way down.

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Loosen the top bolt on the triple clamp to take pressure off the cap but not the fork.

Then loosen the top cap of the forks.

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Then you are ready to slide the forks out.

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Holding onto the body of the fork leg so it does not drop down unscrew the cap all the way.

Pouring out the oil giving it a few pumps as you go

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Once all the oil is out you are ready for the next stage. One of the forks has a leak so may have to change lower seals yet.

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But can understand why it was bottoming out.

Out of a possible 357mls of oil, there was only 225mls of contaminated cruddy oil in each fork. Yikes. Should not have let them go quite so long before looking at them.

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Anyway. That is as far as I got today.

Will have some parts and look at steering bearings on the next installment.

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Great work Cruiser! Looks like it was time for a bit of TLC, I am sure the young bloke will be most impressed when he takes it for its maiden ride post re-build!

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okay i have a curiosity question if the valves are zeroed out what is the cause of this? is it the valves pocketing into the seats or is it slight stretching of the valve itself?

This was on my mind today cause either way just re lapping in the valves you'll still be zeroed out when you reassemble.

I also want to know the answer for myself for when it comes time for me to do a top end

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Good question Toey,

I went in search of shims today but came up with the same conclusion.

The valves have worn in the seats. This causes them to need shimming. But if they have lost their hard edge and worn too much. No amount of shimming will fix this.

Just for piece of mind. I have ordered new valves today. and will probably take the head down to my local mechanic to make sure they are seating well and have the correct amount of clearance.

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Top work cruiser, Zac wont know him self :) just make sure the valve seats are not flogged out and need replacing. look for a lip just on the out side edge of the insert. if there is no lip then thats a good sign.

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Your doing a good job there cruiser, just a tip for you when you lap the valves very slight pressure is needed and if your using the old stick-suction cup tool it will only need a few seconds i have seen valves and seats buggered by to much lapping.

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I would also be in two minds about putting that piston back in.. with 100 odd hours thats is quite a bit over the recommendation and i have seen them break which will undo all your good work.. I was going to say be a good idea to replace the valves, as they are a coated valve, and if you lap them in you have basically removed the coating and they will wear out very quickly.

Tim

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Thanks for the info blokes.

Yeah! Have been in two minds on the piston since I took it out. Still looking at it and even tho it still looks in spec. 100hrs is a lot of work. I will ponder on that one for another day or so. Then make a decision on it.

Damige, I used a suction cup tool to lap. Didn't go to hard, or too long. But I am convinced the valves are beyond any serviceable life. I put in the smallest shims I could find and it still didn't come up to spec.....So new valves will be going in.

On a brighter note. His new radiators arrived today from Shangai China.

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His old radiators look like they were used in a football match lol.

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To keep his new Rads looking new for a bit. I got some protection.

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Today had a look at front forks. took them apart and filled them with nice clean oil.

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One side has a leak. So spent a bit of time cleaning out the seal. But too far gone. So put them back together again and will order new seals and put them in as well.

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hi chris, just priced the parts for you...

$140 for pro-x piston kit (65.99mm) 165rrp <--- can get wossner same price

$65 for pro-x top end gasket kit 85rrp

not as cheap from the states but cheaper than dealer. can have parts overnight

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Thanks for posting Mp.

But all parts were ordered and in by the time you posted up,

I have sent the head off to get re-seated for the new valves. And also have the bore checked for gap with the new piston today.

Put a new oil seal in the leaking front fork tonight........bugger is still leaking......so might have to get the fork leg checked out. Hmmmmmm.

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haha Bit hard to order parts on a Sunday?

I would be if I didn't have to rely on others. Now that I have had to go with new piston and valves. I got to wait for them to be checked for specs.

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Went back to the front fork that was still leaking after I replaced the oil seal on Friday night.

Pulled it apart again to see what the issue was.

As I pull things off the fork I place them down on the bench the way they come off and in the order they come off. This takes any guess work out of what way is up and in what order they should go on.

When I took the old fork seal off I took note that the spring on the seal was facing down. So when I took the new seal out of the pack I made sure the spring was pointing down.

What I didn't notice was that the new seals had a spring on both sides of the seal. And the old seal was in fact missing it's inner spring.

So after I realized I had put the seal in upside down. I was quite relieved. Put it all back together and presto. All working good.

Next on the list was the steering bearings. Having a 30mm nut on the stem meant purchasing a spanner for the purpose. Or I could use my old truck tool I had which was for removing the bull bar bolts when tilting the cab. It worked a treat.

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Tying the bars back to the roof of the garage made it simple to get to the lock nut.

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Pulled the old bearings out. They weren't in pristine condition. But good enough to last another 100hrs of use.

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Cleaned the bearings and casing with a bit of turps and re-greased everything.

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Then all that was left to do was put it all back together using the forks to align everything up.

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