Where to get better crank bearing seals?

M

Mozenrath

New Member
I just got a new 66cc HT, and now that I know better, I'm doing a complete teardown of the motor to do my own quality control.

I want to replace the crank bearings with ones that will last longer and tolerate heavy use, and perhaps provide a slightly smoother experience.

I noticed that the outer rubber seals are separate from the bearings and are attached to the halves of the "crank case". Where can I get quality replacements for these? I would like seals that will not only last longer but will tolerate ethanol fuel.

Also, I'm pretty sure that the bearings are 6202-2RS. Does anyone know where I can buy ones that are good quality and will tolerate high RPMs?
 
Since nobody has been able to answer my question so far, I'll simplify it.

I'm looking for non-Chinese replacements for these seals:

1zbv2x2.jpg


17fr0x.jpg


The seals that I have right now in my new engine are not bad or used yet, but since I have my new engine torn apart I'd like to start out with the best parts I can get(minus the crappy pot metal castings LOL).

Also, is there any particular procedure to remove the current ones? Do I just push them out somehow? They seem well-wedged in there. They didn't even come out after all the tapping it took to get the crankshaft out.
 
You can just pry them out with a screwdriver or similar tool but you'll destroy them. They are driven in place with a special tool. A seal driver should be used to seat the new seal into its bore without cocking it or damaging the outer metal housing.

I've only had one seal failure using the factory seals and that one was because the seal wasn't seated properly and the magneto rotor (magnet) rubbed it and caused it to fail. I replaced it with a new one from PistonBikes ( http://www.pistonbikes.com/category-s/10.htm ) and that seal now has over a thouand miles on it without a problem.

There was a post some time back by a member who found double lipped seals to replace the factory item but it was an old post in a thread that I can't find. My experience when looking for a replacement locally was I could find the correct diamater but not a seal with the required thickness. They were either too thick or too thin for the application.

Good luck.

Tom
 
I bought two new main bearings from some company. Unfortunately I will have to go through my email to possibly find the vendor, but these two bearings have an integral seal on between the inner and outer casing (rings). My engine runs fine without an extra seal, although it may perform better if I had one. So far, this bearing has not exploded and came apart like the crappy one that came with my kit. I'll see what info I can find in the near future.
 
UVsaturated said:
I bought two new main bearings from some company. Unfortunately I will have to go through my email to possibly find the vendor, but these two bearings have an integral seal on between the inner and outer casing (rings). My engine runs fine without an extra seal, although it may perform better if I had one. So far, this bearing has not exploded and came apart like the crappy one that came with my kit. I'll see what info I can find in the near future.
Click to expand...

I'm a bit confused. Does this mean that your bearings have their own seals and are not exposed to the fuel-oil mixture in the crankcase? I hope I'm just misunderstanding because that sounds like a bad idea in the long-run. Also, what extra seal are you referring to? Is there no seal as part of the crankcase, like in my photos?

I would be interested in the vendor you got the bearings from.
 
Mozenrath said:
I'm a bit confused. Does this mean that your bearings have their own seals and are not exposed to the fuel-oil mixture in the crankcase? I hope I'm just misunderstanding because that sounds like a bad idea in the long-run. Also, what extra seal are you referring to? Is there no seal as part of the crankcase, like in my photos?

I would be interested in the vendor you got the bearings from.
Click to expand...
Your are correct. If the bearings are sealed and are not exposed to lubrication they will fail eventually. All bearings come from the factory pre-lubed, sealed or not but they need periodic lubrication, hence the open type used in the engine from the factory.
I also doubt that a sealed bearing is an effective barrier against crankcase pressure/vacuum.

Tom
 
Mozenrath said:
I'm a bit confused. Does this mean that your bearings have their own seals and are not exposed to the fuel-oil mixture in the crankcase? I hope I'm just misunderstanding because that sounds like a bad idea in the long-run. Also, what extra seal are you referring to? Is there no seal as part of the crankcase, like in my photos?

I would be interested in the vendor you got the bearings from.
Click to expand...

When I bought my kit, I bought it at the lowest price possible, so I got what I paid for - so 'they' say. That is sad, service, but it is what it is. Nevertheless, the original bearing I got with my motor had only one seal on one side and not the other. Because both sides of the crankcase are almost identical, you would think that they would endeavour to put a bearing and a seal of good quality here where it counts, but alas they did not.


I will look up the vendor I got my bearings from for I recommend them as they were cheap and good quality. $5/per bearing.


So because they make bearings which are both heat resistant and able to seal the vapor of the crankcase at a mere few hundred degrees F, I see no need to purchase both bearings and seals separate. What you want to do is find a bearing that is sealed in itself - all-in-one like this:
Sealed bearing
sealed.jpg

Without seal
noseal.jpg


..........and the crankcase pressure cannot get through this quality bearing, therefore you do not need another seal also. (referring to the top picture)
 
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There's shaft seals and then there's sealed bearings they are not the same.
You will still need crankcase seals.

But go ahead and try your idea, you'll soon be looking for proper seals.
 
Norman said:
There's shaft seals and then there's sealed bearings they are not the same.
You will still need crankcase seals.

But go ahead and try your idea, you'll soon be looking for proper seals.
Click to expand...

Hey Norman, my engine didn't have a single crank seal installed from the factory. When the bearing came apart it caused a huge vacuum leak. The bearings I installed are a sealed bearing, much better than the metal seal the engine came with. I am still not running any crankcase seal without any problems. My engine does not lack any power from idle through WOT.

The funny thing about this forum I've noticed, is that everyone sticks to the book and never tries anything to see if it will work or not. That is the only way to find out how tolerant things actually are.

So with this, I will say that you can run without seals if you have a good quality sealed bearing. I've put several hundred miles on it this way. My magneto is completely dry (no fuel/oil), and I have no problems with my clutch getting wet with (fuel/oil).
 
Like I said go ahead with your sealed bearing, you will need real shaft seals before long. Sealed roller bearings are not designed to seal like shaft seals.

So you have a couple of hundred miles on it with no problems.... how do you determine the mileage?

You can get away with using something not designed for the use intended for a while........ for a while.

I would not recommend anyone do this to their engine.
 
Norman said:
Like I said go ahead with your sealed bearing, you will need real shaft seals before long. Sealed roller bearings are not designed to seal like shaft seals.

So you have a couple of hundred miles on it with no problems.... how do you determine the mileage?

You can get away with using something not designed for the use intended for a while........ for a while.

I would not recommend anyone do this to their engine.
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Well then time will certainly tell. I know my mileage because I keep a logbook of each ride on a spreadsheet. Like I said, the engine had no seals, straight from China. That is the quality we should come to expect from the HT motor unless it is bought through a reputable reseller who goes through the engine and does some quality control on it.

If I had the money to invest, I would build a test rig to measure the pressure loss between using seals and using sealed bearings to get an accurate figure. That would tell all. Alas, money is tight with this economy so I make due with what I have available. I will certainly write about it if they fail.

In this endeavor, I am writing a manual on these and it is very difficult to sort through all the information for every circumstance, because some people claim this will work and some people claim, 'no it won't'. The only thing I can rely on is first-hand knowledge. We'll see what happens though. My magnetos give me more of a headache than anything. Burned up two of them so far. I'm gonna wind my own here soon and test them out to see if the failures are just due to substandard wire from China. You got to realize that wire is .005" in diameter. It would be nice to wire them up with something larger than #36 gauge, but I haven't studied upon that yet.
 
Just an observation, but your original bearing likely failed because they weren't seal by a crank seal.
 
Bikeguy Joe said:
Just an observation, but your original bearing likely failed because they weren't seal by a crank seal.
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It failed because half of the bearings were missing from the race, straight from the factory. I know this because after tearing the engine down, the bearings were not present anywhere else. If it had lost these bearings while running, it would have destroyed the inside of the engine in the process.

The lack of bearings made the bearing susceptible to engine vibration which ultimately destroyed the metal shield around it. The engine still ran and turned over, but had a huge vacuum leak through the bearing after that. It was plenty well lubricated, I can tell you that much.
 
coils are easy to rewind. It's cheaper to buy a coil than to rewind them, the price of copper wire is high compared to buying a manufactured coil.
starting a coil
windingmachine005.jpg

all of the fine wire on the coil
windingmachine019.jpg

you will want a way to keep track of the number of turns.
windingmachine020.jpg
 
Norman said:
coils are easy to rewind. It's cheaper to buy a coil than to rewind them, the price of copper wire is high compared to buying a manufactured coil.
Click to expand...

Thanks for the pics. Yes, I have found prices for the wire I need and it is definitely more to rewind than buy a new one.

Just had magneto #2 burn out on me. I've only got one spare now to run on the bike, so I need to get with winding my old ones soon or I will be buying more.

I am thinking the coil failures are mainly caused by the quality of the wire they use. If the wire is made in China as well, then I can imagine the quality control on the diameter is poor.
 
All of the failures are right under the wire terminal ends. One is where the heavy #26 wire attaches to the metal frame, the other is under the insulation on the fine wire where it solders to the metal lug for the blue wire. Haven't found any shorts in the coil itself out of the 15 or so I done. So I don't think the wire is at fault by breaking some where in the middle of the winding, it maybe more of the insulation breaking down when soaked in fuel or water and the rotten soldering jobs. the coils I rewound didn't have any water or fuel damage, just broken solder joints or at the blue wire lug the fine wire had been broken probably by rough handling.
 
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I'm kinda wondering how the sealed bearings are holding up for you? I still have to replace mine, and would love to just use a sealed bearing sans crank seals. My buddy in the bearing business tells me that he doesn't really know if it will work, however he can tell me the sealed ones are not completely impermeable to oil and vapor. I suspect the crank seals aren't all that great at it either though.
 
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