Crankcase Separation

[nathan89]

I am going to take my engine apart soon just to inspect everything in the bottom end, since it has never been opened. I know I am going to need a flywheel puller and I already have the clutch basket holding tool, but is there any other special tools that are needed for this job? I have never opened a 250R crankcase. Will I need a puller to get the center cases apart? Any help is appreciated. Thanks.

[Grande Huevos]

might depend on when the last time it was opened up? If its been many years it could be stuck pretty good! I used a rubber mallet and gave it some gently taps and it worked pretty Nice! I was fortunate w the entire thing the whole motor came apart fairly easy and the crank popped right out. I guess somtimes they can get stuck in one of the case halfs and this can be a pain in the a**? I did not use any special tools other then the fly wheel puller and a couple of pennies (to wedge between gears)

[sand_blaster]

I will be tearing apart my 250r cases tomorrow. Going to try the rubber mallet beating and maybe a putty knife. I dont think my cases have been torn apart for maybe 12 years lol. Not trying to hijack your thread, just adding to this I guess.

[nathan89]

last time my cases were apart was the assembly line in japan! so it's been 25 years....

[stever250r]

Mallett always worked for me as well, but below is a link to the tools that would make the job much easier with less chance of damaging anything..

Tools are made by Tusk, and sold by Rocky Mtn. Atv.

Case Splitter,
Crank Puller...

http://www.rockymountainatvmc.com/productDetail.do;jsessionid=804BC95525489AC681D2C0 079EB02A93?webCatId=22&webTypeId=140&navTitle=Tools/Shop&navType=type&prodFamilyId=17167&stockId=143201&ref=gmc

[nathan89]

Originally posted by stever250r
Mallett always worked for me as well, but below is a link to the tools that would make the job much easier with less chance of damaging anything..

Tools are made by Tusk, and sold by Rocky Mtn. Atv.

Case Splitter,
Crank Puller...

http://www.rockymountainatvmc.com/productDetail.do;jsessionid=804BC95525489AC681D2C0 079EB02A93?webCatId=22&webTypeId=140&navTitle=Tools/Shop&navType=type&prodFamilyId=17167&stockId=143201&ref=gmc

those are the 2 tools that i have my eye on..... i'm just hoping that i don't 'need' them.

[wilkin250r]

And those tools aren't absolutely necessary, but they ARE handy, I've known people that have successfully pulled many engines apart without them.

But I can tell you from experience, because I HAVE both of those tools and I've used them, that they do make life a whole lot easier. Sometimes engines come apart easy, sometimes they go back together easy. But sometimes they don't, and when they don't, these tools make a world of difference.

[nkillian9]

i used a wutomotive flywheel puller to split the cases on mine, hardest part was finding bolts that wer long enuff for it tho, as easy as it came apart it probally would have came aprt pretty easy with a rubber mallet,

[nathan89]

thanks guys.

[All250R]

Originally posted by nathan89
I am going to take my engine apart soon just to inspect everything in the bottom end, since it has never been opened. I know I am going to need a flywheel puller and I already have the clutch basket holding tool, but is there any other special tools that are needed for this job? I have never opened a 250R crankcase. Will I need a puller to get the center cases apart? Any help is appreciated. Thanks.
Hi. The response here for you isn't complete. With an OEM crank, the left side crankshaft is designed to be press fit into the main bearing. Do NOT use any type of mallet to remove the crankshaft from the left side, or you run the risk of throwing it out of true. It is designed to be pressed out, not tapped out because the operator assumes it is supposed to be loose. Lastly, buy a service manual. It's a required tool for inspecting and assembling the engine correctly.

[nathan89]

so how do i press the crank out of the left bearing? and i take it the right side main bearing is not a press fit, correct?

[sand_blaster]

I just split my cases, i used heat to get my crank out and a hammer. Everything was bad in the bottom end to start with, so I didn't have to be gentle.

[All250R]

Originally posted by nathan89
so how do i press the crank out of the left bearing? and i take it the right side main bearing is not a press fit, correct?
A press and some wood blocks to place the left case half onto honestly is the way to do it... There might be another way, but that's the most straight forward that I know of. It doesn't take any time at all when you have the right tools.

The right side of the OEM crank is slip fit and is secured by the crank bolt. So when the engine is assembled the OEM crank is secured steadily to both main bearings, but at disassembly, the right half can be slipped off easily to get to the transmission.

[nathan89]

Originally posted by sand_blaster
I just split my cases, i used heat to get my crank out and a hammer. Everything was bad in the bottom end to start with, so I didn't have to be gentle.

i see. i want to be gentle with mine because i don't think anything is bad. i am only taking it apart to make sure nothing is about to let go, and while i am in there i am going to replace all of the oil seals, crank seals and water pump just as preventative maintenance.

and thanks again all250r. i don't think i will need to take the crank out of the left case because the rod feels perfectly tight and the left main bearing is 99%... i can only feel the absolute slightest play in it, and i would think even a new ball-type bearing would have a slight hint of play in the bearing itself. you really almost can't even feel it.

[stever250r]

Originally posted by nathan89
i see. i want to be gentle with mine because i don't think anything is bad. i am only taking it apart to make sure nothing is about to let go, and while i am in there i am going to replace all of the oil seals, crank seals and water pump just as preventative maintenance.

and thanks again all250r. i don't think i will need to take the crank out of the left case because the rod feels perfectly tight and the left main bearing is 99%... i can only feel the absolute slightest play in it, and i would think even a new ball-type bearing would have a slight hint of play in the bearing itself. you really almost can't even feel it.

Could be that everything is fine, but my thinking is this...

If you already have it torn down that far, Why not go ahead and replace the Main Crank Bearings as well?..Use the CR250 ( 8 ball main bearings)...A reaonably cheap upgrade and more peace of mind knowing exactly how much time are on your crank bearings...

Being so close... I would just go ahead and do it....

[All250R]

Originally posted by nathan89
i can only feel the absolute slightest play in it, and i would think even a new ball-type bearing would have a slight hint of play in the bearing itself. you really almost can't even feel it.
It does. The main bearing even when new if you install a crank into it, you can wiggle the crank slightly. So that's not a real good indication if the bearing is worn. When they're worn, the bearing starts to get some extra noise and isn't smooth as glass when you rotate it. This indicates the balls have been making metal to metal contact. Once the surfaces start on this path, the likelihood of more metal to metal contact becomes higher as the asperities become more pronounced. Replacing them is cheap insurance, but it's frustrating and time consuming to have to figure out how to get it done when you might not have the tools that make it easy. If you do order bearings, just order for the TRX, and the 8ball style will come in the mail. Honda doesn't sell the 7 ball for the TRX anymore (unless it comes in a new case half for some odd reason).

[265 sleeper]

I was trying to get some 8ball bearings back when I was build my bottom end all balls bearing are the only ones that I know of that sell 8ball bearings. The bearing that came with my hot rod crank were 7 ball bearings . Any time I split cases I change the bearings . I never like re-using bearings that have had a side load to them from pressing them out. it stretches them

[All250R]

If you order them from Honda, they'll procure 8 ball bearings for you. The current part number for the TRX250R is: 91008-KAE-731. Notice the KAE designator which I believe is sometimes used in CR's, but I'm not sure what the model designator originally came from.

The prior part number was KA4 which is the CR250. Sometimes you'll even see KV3 part numbers which is the NSR250! The point is Honda moves part numbers to different bikes sometimes as a part is considered an upgrade, and the old part number/design will no longer be associated with that vehicle.

[nathan89]

Originally posted by All250R
If you order them from Honda, they'll procure 8 ball bearings for you. The current part number for the TRX250R is: 91008-KAE-731. Notice the KAE designator which I believe is sometimes used in CR's, but I'm not sure what the model designator originally came from.

The prior part number was KA4 which is the CR250. Sometimes you'll even see KV3 part numbers which is the NSR250! The point is Honda moves part numbers to different bikes sometimes as a part is considered an upgrade, and the old part number/design will no longer be associated with that vehicle.

i see that this 91008-KAE-731 part number is also in the '01 cr250 and the '01 cr500... and 88-89 trx250r... that bearing gets around! i am going to order a set of them. took my cylinder off and when i turn the crank by pushing up and down on the rod, like i am the piston, i can feel the main bearings 'bind' and want to get stuck in a few different places, and they are noisy. so i guess it turns out they are bad.

[nathan89]

so can i use the crankcase splitter tool to press out crank from the stator side? the tool would thread into the stator cover mounting bolt holes and be able to push on the crank just like it can on the clutch side. or is the crank in the bearing too tight on the left side to do it this way?