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Enduro Engine - 2 stroke Cylinder, Piston, Tranny, Bearings, Clutch, Pipes & Silencers, etc.


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  #1  
Old 11-11-2007, 11:46 AM
BIG TOOL BIG TOOL is offline
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Unhappy 2007 EC250 Crank Bearing?

Hi Guys,
I just found out that my 2007 EC250 Left side (ignition) crank bearing is bad. It sounded a little loose since the bike was brand new, and it finally worked the crank seal out of its bore. Thats a first for me! Anyway, after pulling the stator plate off, I found the crank bearing to be loose but not yet a catastrophic failure. I remember a few years back there was a rash of bearing failures, does anyone remember what the fix was? And, does anyone know what part # I should give to my local bearing house to get my replacement part? Thanks, I'll let you know how it all turns out...
P.S. should I replace the other side bearing while I'm there?
FYB


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Old 11-12-2007, 07:34 AM
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Thats really odd for a newer bike. The newer bikes use a two piece roller bearing for the ignition side, like a KTM. Download the shop manual and you will see you have to remove the inner race from the crankshaft and bearing from the cases separately. My '03 and '07 had/have very noticable radial play when new, but its normal for a bearing like this. By ball bearing standards, grabbing and moving the flywheel will tell you the main is shot, but not so. Are you sure the bearing went bad and disloged the seal, or the seal was improperly seated and came out? How many hours on your bike? Premix ratio? My old '03 has well over 200 hrs on the original mains and feels like new. '07 has 45 hrs now, no problem. Unless your absolutely sure the bearing is bad, replace the seal and ride it.
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Old 11-12-2007, 08:10 AM
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I thought this was odd too, But I'm sure the bearing is bad... As I got deeper into my tear down last night, I found the big end rod bearing was bad as well. In fact, I've never seen so much movement in a rod bearing that wasn't yet completely failed! The small end rod bearing and wrist pin look brand new, so I don't believe its an oil problem, but I never say never... The motor has less than 20 hours on it, I run 40:1 premix, and I can only hope this was a freak thing. My '01 XC250 had well over 300 hours on the original crank and rod bearings using the same 40:1 premix. In fact, it is still riding around out here!
On a side note, the coating on the piston was starting to come off in a couple of places as well. I'm not sure if I'm a fan of that stuff (anti friction coating) or not. Now for a complete crank rebuild...
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Old 11-12-2007, 06:54 PM
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I would say you bike was running very lean.

The wrist pin bearing looks "good" because it does not rotate/spin like the connecting rod bearing.

Be sure you find out the cause before you ride the bike.

RB-Designs does an inexpensive crank rebuild ($35).
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Old 11-12-2007, 06:56 PM
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Quote:
Originally Posted by gasgasman View Post
Be sure you find out the cause before you ride the bike.
Never mind, looks like the crank seal was your initial issue.
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Old 11-12-2007, 09:01 PM
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Sorry to hear that. You might ask Ron about pulling that race off the crank, looks like it could be a PIA without the correct puller or a press and jig. The piston loosing coating is normal, as long as its not scored. Might as well replace that too and start out fresh. I'm doing mine soon as winter sets in, probably near the 60 hr mark.
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Old 11-12-2007, 11:29 PM
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Yeah, was a little tough to get the inner race out, but we have LOTS of tools at the shop, and I'm not afraid to use 'em! I took the pieces to our failure analysis people, and they seem to think that the roller bearing was the initial cause of failure, that in turn put unusual forces on the thrust washers, then the seal went, etc... ( then my money went! ) Oh well, its all water under the bridge. I'll be interested to know if anyone else has similar issues or, if I'm just "special"
I don't know Ron or his work, but $35 seems almost too cheap for a crank rebuild. I have a shop that I have used in the past with good success. They cost a bit more, but I think with machinists you get what you pay for. But I could be waaay off, maybe Ron doesn't need to charge as much because of his business model... I'll have to send him some projects and see for myself.

FYB
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Old 11-13-2007, 07:45 AM
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RBDs (Ron) price is labor, you need to add the rod kit. I can tell you that his work is impeccable, he is very meticulous. He does run his op a bit different that saves overhead(no credit cards, etc.) but its the first place I would inquire about MC related machine work.

Bearing failures in the past have been due to improper press fits(tight), and seal installation where the oil hole was partially blocked. Some also claim bearing bore alignments. That was awhile ago though on the older ball bearing cranks. Havn't heard of any problems with the newer roller bearing motors. Anything is possibe though.

Did the bike ever suck water or dirt?
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Old 11-14-2007, 09:45 AM
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Ron is a great guy & does great work. I had him mod a carb for me & he went so far as to run down some small parts I was missing, & send them to me for free w/ a diagram of how to install them.
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Old 11-23-2007, 02:47 AM
Leon_gasgas Leon_gasgas is offline
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Hi!

150 hrs on a 98 250 and everything was great at tear down to fix gearbox (my fault...). 130 hrs on a 07 ec250 and no problems until the bike was stolen. I just bought a 07 ec250 again. Always run premix 50:1 with castrol TTS or Motorex crosspower.
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