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OlaGB

Changing the small end bearing on the rod, possible?

8 posts in this topic

As topic.. Possible to change it out, or are we talking splitting the motor and sending in the crank for changing out the rod completely?

It rattles and makes noises i dont like, and i could see wear in the bottom of the bearing when changing my piston (oil drain plug "left the building" on my way home this winter), so i guess it`s do or die...

Ola

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Hi,

I just rebuilt my 2005 model WR 450 engine after 115h of use. Rod has only one real bearing which is between crank. Crank can be split in a press, but please use someone who has done these before. That was only thing where I needed help on my rebuilt. :thumbsup:

Here is a list that I changed:

Piston + rings + pin + lock rings

Timing chain

Rod + pin + bearing

Crank bearings

Transmission bearings

Gaskets

Timo Mc

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Ok.

I will split my motor soon then.. before it grenades on me..

How experienced mechanic are you? Used to do this kind of work?

I`m a hobby mechanic, self learned by several years of 50cc bikes, and turbo cars, and used to solve problems, but i must say that i`m a little worried about splitting this motor..

Is it an "easy" task similar to other motors, or does it take a lot of knowledge for exactly this type of motor?

for example, changing the piston, was very easy IMO..

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Hi,

First of all buy a puller for flywheel. For everything else you survive with normal garage tools, you need some torx-tools to get bearing holders out. Engine it self is very simple 4-stroke. You might have to heat crank bearings just a bit to get crank out. Trickiest parts for me was getting gears, fork shifters and shifter cam into place. Because you have to put them all together as a package. Cam timing and balance weight timing is piece of case. Instructions are very good.

Timo Mc

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Hi,

First of all buy a puller for flywheel. For everything else you survive with normal garage tools, you need some torx-tools to get bearing holders out. Engine it self is very simple 4-stroke. You might have to heat crank bearings just a bit to get crank out. Trickiest parts for me was getting gears, fork shifters and shifter cam into place. Because you have to put them all together as a package. Cam timing and balance weight timing is piece of case. Instructions are very good.

Timo Mc

Thanks for the advise..

Any good tips on the actual splitting, for example wich side the motor should be on when pulling it apart, to mess as little with the gears as possible..?

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Hi,

Now when I have do it once I would probably split case from magneto side. This way you can leave gears and shifters on clutch side case on their place. I used a small propane torch to heat up those crank bearings. They just need to be warm not red hot or even changing colour. You should warm those bearings when you put crank back to them too. It helps a ton. Balance weight will fit when crank is on its place. So get those cases together with gears and crank and then put balance weight on its place and time it right. Don't put too much engine silicone between cases. When removing crank, cluth axle etc. bearings tap with punch to those locking screws before trying to twist them open (owner of a bended torx).

Timo Mc

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I've rebuilt my 426 motor (split cases, rebuilt trans & reassebled) without issue with no mechanic training. I know I'm a competent mechanic by nature and knew I was capable of the job... and you sound the same. If you get into trouble then have a qualified mechanic help you through that particular aspect and then take it home and continue on.

As for the crank..... if the lower end bearing is failing then buy a new crank. The cost difference between rebuilding the crank and buying new was about $70 in my case. I'd rather spend an extra $70 for piece of mind knowing some kid didn't press my crank together correctly. The only part of assembly I had trouble with was holding the gear shafts in while putting the cases together and another set of hands was real helpful there. Other than that it was business as usual.

Freeze the bearings, heat the journals with a hot socket of the same diameter and they'll be much easier to install. Replace the timing chain while its apart and check the timing chain teeth on the crank for wear. If they're shot then you have no choice but to replace the crank. And take pictures of everything! It helps if you get stuck and the manual diagram isn't showing what you want.

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Thanks alot guys!

I took out the motor, and started the work tonight.. Only worked for 3 hours or so, but i am ready for splitting it now.. Only issue so far, was to get the flywheel off (it was`nt easy to get loose, thats for sure..) , and now the clutch basket.. I`ll borrow a air wrench tomorrow, then i guess it will come off.. Had some problems holding it steady while loosening the nut..

Everything looks perfect so far, only some wear in the lower side of the small bearing in the rod, shows that its something wrong.. Clutch basket and reg. chain looks perfect, but i will buy a new chain anyway..

I was actually thinking about this crank thing.. Perhaps i`ll buy a new one, as you say.. Should i buy a 03 crank, or a 04? does a 04 fit in my 03 motor, or is it different? Just thinking of someones post here at TT forum, claiming that a 04 crank is stronger?

Any tips where to buy my parts in USA wich sends parts international? TT perhaps? Does TT have these kind of parts for me?

I prefer net-shops, with pics and a little spec list on the parts, so i know for sure what i`m buying..

So far it seems that i need new bearings for gear and crank, a crank, gaskets, piston-pin and clips, and a woodroof key for the flywheel.. Perhaps something else will show when i get into the gear box..

Any updates/upgrade tips are welcome here! hehe

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