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1996 cr250 engine rebuild time questions

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about to rebuild a 1996 cr250 engine as part of a total bike restoration.  The bike has been sitting with the cylinder off for about 5 years.  Lower rod bearing is bad for sure, haven't split the cases yet, but am close.  Been trying to decide whether I am going to have the OEM crank rebuilt and balanced or just use a hot rods kit.  Questions:

-THe more expensive wrench rabbit kits include all the transmission bearings.  Other than if they are visibly rusty when I split the cases, does anyone ever replace these bearings?

-If I don't need tranny bearings, the hotrod complete rebuild kits are pretty appealing and seem to contain everything needed, thoughts on this kit?

-My other option is to rebuild the oem crank and buy the gasket kits, bearings, piston, etc separate, is it worth the extra hassle to use the OEM crank instead of just buying the hotrods kit?

-Does having the rebuilt or hotrods crank balanced make a lot of difference?

-Does the hotrods kit and wrench rabbits kits include water pump rebuild parts?

-Any other parts I should be considering for this rebuild.

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I just used a Hot Rods complete lower end and for the money on my 125....it seemed like the better option for me vs rebuilding my stock crank. The cost of that, wait time and purchasing all the gaskets, seals and bearings just wasn't worth the savings, if any. Now, some swear by sticking to OEM but from my initial impression of their products, everything went together well and my bike is running perfect. I checked my trans bearings and everything was still good to go so I didn't replace them. No water pump parts came with my HR kit, but again mine was fine so I just reused it. One thing that did come in handy was a $30 or so complete body fastener kit I bought on eBay that contained a ton of flange bolts, copper washers and other bolts that I replaced on my side, clutch and stator covers and other areas around the motor. I soda blasted my cases, cylinder and head while it was apart to clean everything up. Ended up with a brand new looking motor......

 

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I have never soda blasted, but your results look great.  Thinking about picking one up just to clean up the engine.  How much soda did you go thru to do the engine?  Looking at Harbor Freight style they come in a 40# tank and a 15# tank.  Also, I have a smaller compressor, not sure if it would handle it.  Does it go thru as much air as a sandblaster?

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I used about 20 lbs or so of media at my father in-laws workshop. He has a large air compressor in a really nice shop out back for working on his heavy equipment. Has to be at least a 60 gal plus Atlas Copco industrial unit. Not sure a small 5 or 10 gal Craftsman type would be able to keep up without having to stop a bunch of times for the tank to re-pressurize. I ran it at 90 psi. I rejoined the cases temporarily without the crank in it, taped off the cylinder and reed block opening and reinstalled the side covers without the clutch or stator installed to keep as much soda out of the internals....it makes a mess. Worth it in the end and took about 30-45 minutes or so to blast everything.....washed it all down with a little Simple Green afterward and painted the head. I'm sure others have used the HF units with smaller compressors, but I'm sure it'll take a bit longer to do though. The cases are magnesium and I initially tried Napa Aluminum Brightener after great results on the frame, but it didn't do anything to the magnesium. Thant's when he suggested I bring it up to the shop to blast it instead.

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Probably nothing wrong with tranny bearings.  Done lots of wrench rabbit kits and never use tranny bearings.  I picked up 96 last summer in peices case's broke from kid useing screwdriver to pry apart :thumbsdn: got cylinder and carb from a salvage yard in PA. Put wiesco kit in it got off eBay for 300. Pro circuit works pipe and factory 304 . Vforce,and perfect jetting.  Thing rips and still does . Although I don't ride it much. Paid 400$ got 1600 in all together . 

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Edited by Motox367
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On the Hot Rods kit I've had some issues with Vertex base gaskets too thick and a bad seal, it wasn't a CR250 kit though it was CRF450.  The CR125 kit was good however I used Cometic top end gaskets.

If you put those cases in your BBQ for a while those old bearings will fall right out, and the wife won't get upset you used her oven.  Swingarms and linkages same thing.  Much easier than a blind hole puller.

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So when I heat them up to remove the crank main bearings, likely all the bearings will be coming out

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7 minutes ago, ulmanb said:

So when I heat them up to remove the crank main bearings, likely all the bearings will be coming out

Or just lay on Flat wood bench watch the Dowell pins and drive out with hammer and socket.  Takes 2mins

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53 minutes ago, ulmanb said:

So when I heat them up to remove the crank main bearings, likely all the bearings will be coming out

Yes you'll have to keep gravity in mind when you do this, but I really ought to have clarified more.  Your seals are probably Buna N aka Nitrile aka NBR which are typically good for a in service temperature of around 250F.  You can probably get them hotter without ruining them, my grill thermometer usually says about 300F.  I'm not sure how hot the cases actually get.  When I do this I put some aluminum foil over the grill so I have a clean surface and I keep the burners turned down.  I'm not putting them in an uncontrolled BBQ that gets 600F inside and throwing the cases on a filthy carbon coated grill.

I've used a press, and I've also used a hammer.  You can get it done this way, but it does have risk.  Also you shouldn't just push on the inner or outer race of a bearing you intend to use, you need to apply force to the portion that's a press fit or both.  It's also easy to get things in crooked with hammers and even a press at times.  You also need to be cautious of what part of the cases are taking the load and whether a gasket surface crosses a hard surface.  With hot cases the new ones just drop in.

Edited by mxaniac

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Soda blaster question,  the smaller harbor freight model says 9cfm at 90psi, my comp is rated 5.5cfm at 90psi, will it not run the blaster?  Or will it run it for short stints and I will have to wait for it to catch up?  Max psi of comp is 135

Edited by ulmanb

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