Crank bearings / rebuild

[destey]

So I was trying to get the flywheel off with a puller (for cr250 ignition upgrade), had it on so tight the crankshaft started to mushroom. So I tapped around the outside with a hammer, which was not bright at all. After the flywheel was not loose, but the shaft had all kinds of freeplay. I assume I ruined the crank bearings. So the motor now is out of the frame and sitting on a pallet waiting to be rebuilt

Anyone have any tips regarding a rebuild? I plan on buying a clymer manual for the step by step. Should I replace more than the two crankshaft bearings? I see on ebay there's a kit for $99 that's got a bunch of bearings and seals. I just became the owner of this quad so I don't know what's been done as far as service. I'd just assume rebuild everything possible since the motor is out of the frame.

thoughts?

[JohnBeton]

I bought the kit for my atc250r, with that kit you have all the bearings and oil-seals for your engine.
For that money I wouldn't doubt and replace everything while its appart.

[destey]

that sounds like the way to go. I think I remember the guy saying he hadn't done anything with the lower half (just cylinder)

is there anything I should check or pay special attention to while I have it apart? The shifter shaft has a lot of in / out freeplay... is that worn gears?

I have a feeling that this motor was run hard from the stories the guy was saying

[86 Quad R]

end play is normal for the shift shaft.

when you have the engine fully apart and in the process of cleaning everything. take thise oppertune to inspect all of the bearings in the cases, making sure they are free of trash ect ect. replace those with slack. inspect the mating surfaces of the tranny gears, and the drive/driven gears on the clutch side. pay special attention to the counter balancer bearings and rebuild if needed. at this point i would opt to either replace the crank or have a reputable builder rebuild the crank. hope this helps :cool:

[89rwfo]

If you dont have the correct tools this job is going to be complicated and possibly costly. might consider sending it off to be rebuilt. I have seen many of engine cases broke due to improper tooling.

[All250R]

I've seen it done and even recommended that the flywheel be torqued with an impact gun. This is horrible advice and what makes the R that much more likely to wind up on ebay in parts when the owner is tired of struggling with previous bad installations. If your crank is screwed up because you were beating on the end of it you're going to be out some more money to get that crank rebuilt or replaced. The flywheel puller should pop the flywheel off without any serious effort.

[destey]

Originally posted by All250R
I've seen it done and even recommended that the flywheel be torqued with an impact gun. This is horrible advice and what makes the R that much more likely to wind up on ebay in parts when the owner is tired of struggling with previous bad installations. If your crank is screwed up because you were beating on the end of it you're going to be out some more money to get that crank rebuilt or replaced. The flywheel puller should pop the flywheel off without any serious effort.


What size die does the flywheel crank take? shouldn't have to junk it because of a couple bad threads

[86 Quad R]

it's a 12mm x 1.0 p i believe. i'll have to look when i get home this evening. i agree with you. as i've fixed them before and ran them. in fact, my sons R has one in it. been running it for 3 year now. :cool:

[All250R]

Oh, somehow I read that the crankshaft bearing might be bad somehow, but I think I just read it too fast. Yea, as long as you didn't damage the journal or items related to the rod, a couple threads shouldn't matter. The nut turns past the first few threads anyway. Yea, I believe 86R is right at 12mm, 1p, but I'd have to double check too.

[jcs003]

this is what i was taught. if it seems like it is taking too much effort to get something apart and their is a chance of damaging it. take it to a machine shop.

[86 Quad R]

took me a bit to find me die..... the threads on the crank are actually 12mm x 1.25p :cool:

[destey]

thanks just the info i was looking for.

should I order up a new clutch kit, or wait for when i tear it down and judge whether it needs it or not? whatda guys think?

[destey]

$37 freakin dollars!

http://www.mcmaster.com/itm/find.ASP?tab=find&context=psrchDtlLink&fasttrack=False&searchstring=2573A673

edit: phew, never thought i'd find snapon being the cheapest...

http://buy1.snapon.com/catalog/item.asp?item_ID=9655&group_ID=1145

[All250R]

You can find run of the mill tools on ebay or if you have a harbor freight close to you, you can get things cheap there. You should be able to get a whole set for not a lot of money.

[destey]

I ended up getting the M12x1.25 die off snapon.com for $4.10 shipped. Great service, it arrived 2 days later!

[timfo1]

when u put the flywheel back on does the nut press it back in place? if not how do press it back on?