main bearing failure right side 2006 ec300, rebuild tips needed.

[hillbilly]

Recently bought little used ec 300. UK based.
Third time out, trail riding, clouds of smoke and rumbling. Crept home ok, strip both sides and right side seal in bits and bearing worn with cage breaking up. no major damage luckily.
Is this common 300 fault, wouldn't expect this on 6 year old bike. Any design issues as with 99 bikes, I had one with mains issues, that was wrong bearing type and small oilways.
Not split yet to replace bearings. Working away at present.
Any tips before I start?
Read a lot here but have slight concerns as some mention crank alignment and main bearings not needing to be up to back face in crankcase. Think it's roller on right side (06 bike) so assume this not an issue, or is it?
Service manual states seal with lip outward, is this right? Mine destroyed and can't see. Not pulled flywheel yet to check left side.
Also some references to gearbox problems with these bikes, what should I be looking for when split?
Looking to keep cost down, any issues with buying off the shelf bearings and seals from local bearing suppliers. Someone said heavy duty bearings available, sounds sensible. Also references to different tolerances for higher temps, is this obvious from bearing markings?
Service manual states 'mark clutch basket before removing', didn't do that! What's that about?
Home in a week and want to be armed with as much info as poss before I start.
All comments appreciated.
cheers
Simon

[roostafish]

It's been a few years, but I had a real dog of a Gas Gas 250. That bike ate crank bearings like they were candy.

What I remember is that, yes, you can use off the shelf bearings as replacement. There are two acceptable ratings after the part number: C4, and C3. I prefer the C3. It is a looser tolerance. Looser is better in this case, the engine isn't really a high rpm machine, so the tolerances are better served to be on the loose side. Can be slightly more noisy from mechanical whirr, but barely noticable unless you are really picky about it.

Disassembly can be difficult, so heating all the parts up in an oven was my favorite thing to do (also a favorite of my wife at the time. ). The bearings, or what is left of them will literally fall out if you heat them in the oven to 400 degrees F for an hour. Conversely, when assembling, you can heat the cases up to 300 degrees F and put the bearings in the freezer. DO NOT BEAT THE BEARINGS IN! They will fail from side load.

If I think of anything else, or you have any specific questions, I can try to remember. Currently on my 4th Gas Gas with absolutely no problems to any of them except that one bike, a '99 XC 250 Six Days. Which, by chance, had some of the best forks I've ever ridden, bone stock. The WP Extreme 50mm conventional fork.

[hillbilly]

Thanks for the info, your troubles sound the same as I had with 99 250. Gas GAs Uk helpful on that, was a design issue with bearing spec tolerance too tight and oilways too small, end float issue too. Fitted different bearings, drilled oilways out and thicker gasket and never missed a beat until it was stolen. Lovely bike to ride as is 300.
My main concern about this one is whether there is an underlying cause for bearing failure as in design fault. Will conjtact Gas Gas Uk when I get home for advice before I start rebuild.
cheers

[GMP]

Bearing failures were more commonn on the older (pre '02) bikes, and were almost always limited to the ignition side. The '06 uses a two piece roller bearing in the ignition side, and a ball bearing in the primary side. You say the bike has little time on it and its an '06? In the UK? I could go out on a limb here and say that moisture/corrosion killed that bearing. I've seen it before, from improper washing (water in crankcase) and/or storage. Do you know the detailed history of the bike? It could have been drowned also, which most often leads to bearing failures later from dirt being carried in with the water.

[hillbilly]

A mate knows the guy I bought it off, even older than me late fifties. Not a racer had it from year old, few trail outings a year, not used for last year. That could be the problem could it not? Who knows it may have been drowned too. Not worried about those issues as that's sort of normal causes. More concerned to find out if there was a common design or incorrect parts/tolerance issue with this model that I should be aware of before buying spares etc. Think my past experience with 99 bike making me more wary than I need to be. What about manual stating lip of crank seals facing outward is this correct?
Love the bike to ride though, shame about the usual gas gas iffy plastics fits and odd size bolts etc. I can live with that though, all reflected in the price, on a tight budget so 06 bike for ?1400 very attractive.
cheers

[Harry]

Hi I have had the same issue - corroded bearings from long term storage.

See this thread http://www.gasgasrider.org/forum/showthread.php?t=10575

Use industrial bearing on ignition sode with heavy duty brass cage. Rebuild is quite simple, Good luck.

[wasp4banger]

I did mine on my 06 300 last year, my local dealer reckoned that 5 years from a set of bearings isn't bad. Apparently they quite often give a bit of noise before they let go.
Heated the casings in the oven on mine to fit the new bearings. Overall not a difficult job to do.

[Eric]

My mains went last year in my 03 because they were rusty from sitting around too, the guy I bought it from hadnt used it in close to a year, if this is what caused yours to fail it will be easy to spot the bearings will be rusty.
Since we're talking about crank bearings rusting I've heard running amsoil dominator will cause this if your bike sits around for a long time between rides, it has no anti corrosion additives, its a non issue if the bike gets used fairly often tho, theres even a disclaimer on the botte to cover amsoil but lol.
Every owner of my bike ran dominator, I still run it but my bike doesnt go more than a couple of weeks between rides, if im ever going to store it for long I will fog the motor with a can of that engine fog stuff to keep it from rusting.

[GMP]

I've run Dominator in every GG I've had with no issues. My current '07 sat for over a year while I healed from injury and surgeries. The crank looked fine when I did a top end after that, no rust or corrosion. It still runs hard today, on the same lower end. My wife's 250 Pampera runs Dominator as well at 80:1 and only gets ridden a couple times a year, and its ten years old now.

What oils I would be concerned about are the ester base oils, like Motul 800. Ester will absorb moisture from the air rapidly.

What killed my friend's KTM was using one of those air box covers that replace the filter for washing. Short story is it leaked and he didn't realize it, and parked the bike with some water in the lower end.

[hillbilly]

Thanks to all you gents for the info. Should get home over weekend so will strip the beast out.
Anyone know what size thread flywheel puller is?
All put mind mind at rest about any potential design or bearing spec issues being the cause.
Will go for heavy duty versions as recommended if I can get them, seals are Viton, correct. Not standard type.
What about my question regarding manual stating you should mark clutch basket before taking off to make sure refitted same position. Why is that, don't see anything that should align with anything else on it. Too late anyway, didn't mark it.
As for oil, never seen Amsoil Dominator in UK, I run Putoline MX5 at 40:1 or 50:, as do most of my mates.
Post my findings once I get into it.