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Rusty Main Bearings


portman
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Thinking about it I believe condensation is the cause and I have two theories.

Firstly that Sherco (and perhaps others) have come across the rusting problem (and possibly the carbon particle problem) and have determined that sealed bearings will overcome this. I reckon that water cooling causes more potential condensation problems than with an air cooled motor as the former will take longer to warm up and possibly not run as hot.

Secondly I sense that modern petrol absorbs moisture from the air more than past fuels. That would mean that condensation would be more problematical. I have seen that an open pot of petrol in contact with air turns milky in no time, but it never used to. I sense that is water being absorbed, but I could be wrong.

One puzzle remains - I had failed to mention that the crank webs also have shown signs of rust (but not excessive) but why do the big and little end remain unaffected (so far)?

Thanks again for all your help fellow spanner wielders!

I'm not familiar with this problem with other engines and I find it very interesting, especially as to why it is occuring, even considering the possibility that it is related to oxygenating pump fuels. I'm reluctant to offer this suggestion as it only relates to a possible cure for the symptoms, rather than finding the cause of the condition. When we store racing two-stroke jetski engines after a race (and they deal with a LOT of water) we use what's called a "fogging oil" in the intake, specially designed to displace internal moisture in personal watercraft engines or engines put in storage. I've liked the Kawasaki brand and it's easily obtained in shops. It's sprayed into the intake with the engines running to coat the insides and although it's recommended to put in a new plug if you are re-starting after "winterizing" the engine for long storage, they usually crank up easily. Maybe this might help the older engines? Luckily, if I'm way off-base here, Copey will help me find the folly of my ways......:D

Jon

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My experience is VAST! Which makes me an expert at NOTHING!

Rust BAD!

Water causes Rust!

Once pitted, bearings deterioriate quickly!

You better figure out the water source! Could be fuel(ethanol related), could be short runs and condensation to a point, as you need to get some heat in the motor. Could be your maintenance regime(not to be accuseatory) but I hear self denials all the time.(I pulled out early?) :D

Reports indicate that the pure synthetic oils may not offer as good static runoff protection as others? Maybe the Yamalube 2R semi synth will help?

Those sealed bearings may be the ticket? But I have run these bikes since '01, trading up every couple of years on average, and never had that problem on any of them. Including the wifes 125, which I had from '02- '07 . And yes, I figured out early on just what a good washing can do as you least suspect the water from a simple hose carrying the grit through the filter and sticking the throttle wide open on a 2.9. It can get your attention just after the first josstle that dumps all the crud straight to the carb slide!

As I am way too lazy to take the things apart for the hellovit, unlike some ratchetheads, I suppose I have them on the '07? I have never had to disassemble one ov the beasts for anything. Yes they are pretty straightforward and I do much worse on a daily basis, but cross fingers! I figure the sustainability factor is quite high on these machines. Just as Jon still runs the '02 Gasser.

And that's all I can tell you about that!

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In my humble opinion, its got to be the modern 2stroke oil. I have a 20 odd year old bike, head has never been off it. Run it on 32:1 old fashioned 2 stroke, yes it does smoke a bit, the rest of the problems reported when using these ratios of oil just dont matter to me.

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  • 6 months later...

I've just been doing some research on the SKF website......

Are you guys talking about a Sealed Bearing or Shielded Bearing?

According to the SKF information.....

"Sealed bearings

The bearings with shields or seals on both sides are lubricated for life and are maintenance-free. They should not be washed nor heated to temperatures above 80

Edited by Neo
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Hi,

Does anyone have the answer to my questions above :rolleyes:

Also, I need to know the type of seals I should use for the main bearings and will I be able to get these from the bearing shop too???

Best of balance.

Neo

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Gday Neo, mains would be shielded, not sealed if specified sealed. Sealed ones wouldn't last in the heat. I think there was some talk of this somewhere else in the forums. For crank seals go with the Sherco parts, often crank seals are a special and that's the best way to ensure you don't have to redo the job later. The bearings will have a number on them along the lines of this - 6204 C3 - which you can match at your bearing shop. The first number (4 digits) is the bearing size and the C# is the fit, make sure this is the same. Most Crank bearings are C3, but this can vary. Otherwise you can match dimensions, most (but not all) bearings are commonly sized. Honda are good at making unusually sized ones... If you get stuck measure them (ID, OD and width) and I'll look them up in my bearing book for you. Important thing is to fit the bearings and seals carefully and square in the bores. It pays to send your missus out for the afternoon and use the oven to heat the cases. Be prepared to be in trouble when she gets home and can small the results... Heat them to about 100C and your bearings should drop in. Let them cool and use a good-fitting socket or similar to carefully drive the seals in. Make sure they face the correct direction - have a good look at the ones coming out to get this. Lubricate them with a smear of grease before putting the crank in! Make sure also that all gasket surfaces are scrupulously clean as well. A kitchen scourer works well for this and wont damage the gasket faces. Use those green scotch pads from the supermarket (not the steel ones!) After all that, don't force anything - if things wont fit, stop and have a look what's going on before resorting to the big hammer...

HTH

Cheers,

Stork

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Thanks Stork,

In a way I'm looking forward to the challenge. I'm thinking of using a heat gun to get the case up to temp?

This is the first time I've opened a gearbox but I knew it would happen one day :rolleyes:

Best of balance.

Neo

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Gday Neo, mains would be shielded, not sealed if specified sealed. Sealed ones wouldn't last in the heat.

Err the new sealed Sherco Main bearings are rubber sealed!!!!!! Beta use shielded mains

SKF 6206 2RS1 E TN9 and some more digits specifying the clearance and the grease fill type, I'll get them tomorrow if I remember.

You can get info on the designation suffixes here

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According to the Sherco spare parts books and the SKF website you guys might both be right. :thumbup:

The pre 2007 parts book shows....

80/125/250/290 "CRANKSHAFT BEARING 6206.TN9 C3C3" - SKF have a 6206ETN9 as an Unsealed 30mm bearing.

2008 and 2009 shows....

80/125 CRANK BEARING 6205 2RS.C4 - SKF have a 6205-2RSL as a 25mm Low friction Sealed 25mm bearing.

250/290 CRANK BEARING 6206 TN9/C3 - SKF have a 6206ETN9 as an Unsealed 30mm bearing

So it looks like in 2008 Sherco fitted smaller 25mm Sealed bearing to their 80's and 125's but the the 250's and 290's still use 30mm unsealed.

Maybe Sherco are testing out the sealed bearing concept in their smaller bikes first....smart move I think. :rolleyes:

So my 2006 125 should have 30mm unsealed bearings but I'd like to give the sealed concept a go.

But my concern is SKF say that the sealed bearings..."should not be washed nor heated to temperatures above 80

Edited by Neo
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Now I'm really confused :rolleyes: ...got the case open.

These main bearings are "Cylindrical roller bearings" and not "Deep grove ball bearings" as the part numbers have been suggesting.

I need to re-evaluate all this before anyone bother reply. :thumbup:

Best of balance.

Neo

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According to the Sherco spare parts books and the SKF website you guys might both be right. :rolleyes:

The pre 2007 parts book shows....

80/125/250/290 "CRANKSHAFT BEARING 6206.TN9 C3C3" - SKF have a 6206ETN9 as an Unsealed 30mm bearing.

Best of balance.

Neo

Hey Neo (from experience) don't trust everything you read in those manuals ,it can be a little misleading, just do as you are doing and strip it first to see what's fitted.

previous topic

If it's any reference; I fitted open cage SKF bearings from a bearing wholesale supplier when I did my bike,and they're still sweet now.

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On the subject of not fully warming the engine.....I grew up in an area with cold winters and in an era of cast iron V8 engines. The old engines took a while to warm up and one winter I had a job just a few miles away. If I only drove to work, the oil would absorb so much mositure that it would eventaully look like milk. A good long drive would dry it out.

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Good point Ham2.....

I'm learning more and more as I go on :gay:

So it looks like the earlier bikes had rollers but then Sherco moved over to big balls :thumbup:

That 6206 number is used by many bearing manufactures for this size of bearing.

I'm told that Nachi do a rubber sealed bearing specificly for this type of application and they now handle up to 140 degrees centigrade....so this looks like the hot favourite :rolleyes::thumbup:

Best of balance.

Neo

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Another couple of lessons learned today....this is fun :rotfl:

Firstly these Hi Temp sealed Nachi bearings are so new that no one has stock of C4's yet...had to opt for the C3 instead :-(

Secondly, as HAM2 pointed out ...you can't believe all that you read in the Sherco parts book.... And it looks like the 06 and 07 manuals are wrong. 125's have 25mm bearings (not 30mm) so number 6205.

Now for some questions....

Both casings have a small port hole (close the cylinder base) which allow the 2T oil to get to the outsides of the bearings. But now that I'm using sealed bearings should I plug these holes up and if so with what?

I think it's good to do this as it will stop carbon deposits getting to the seals. But do the seals need a bit of oil too?

Best of balance.

Neo

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