Disaster strikes
 

After a pleasant ride out this afternoon I descided to change the oil, along with the old oil out came about a teaspoon full of fine rubber particles, about the size of coffee grounds. In the previous oil change the old oil was clean. I assume that the timing chain tensioner blade is disintergrating, if there's a bright side there was no metallic particles present. Anybody had an OHC motor apart yet?

Jonathan.

How many mi/km's do you have on it? Sometimes it's almost eaiser to spend a couple of hundred bucks and install a new powermill. However I would ride it a bit and change the oil again before writing it off. Maybe the rubber on the cam chain tensioner isn't absolutely neccesary and it will function without it?
Joe

Thanks for the input Joe, the bike has done 904 miles, if there had been fewer particles I maybe would have run it for a bit longer to see if things got worse, after 29 years in the motor trade you gain a "nose" for sniffing out trouble, and for that amount of rubber particles something is definitly not right. Complete motors here in the UK are a very different price to what you pay in the States, typically about $650-750. I'm about to start dismantling so there maybe pictures by this afternoon.

Jonathan

Maybe you could enlighten the rest of us on how to adjust the cam chain tensioner on these OHC engines. I believe the phillips head screw at the back left of the engine is the adjustment, but I have not made any adjustments yet because I'm not sure how to proceed with this specific engine.

Jason

More info
 

I've taken the motor as far down as I can, I'm stuck for a big bolt to pull the generator off before I split the cases. The timing chain tensoiner blades are perfect. I'm now at a loss to what it could be, there were some bigger pieces of rubber in the bottom of the clutch housing, these have sparp edges and corners and I get the impression that whatever has disintergrated was circular. If you follow the link there's a picture of the bits, I salvaged about a third of the total, so it was a good spoonful. The spring washer is 6mm to give an idea of the size.

http://www.geordielad.plus.com/bits.jpg

Jonathan.

You are definitely in umcharted water now. Good luck!

interesting --- gotta wonder how important that seal was anyway. I'm guessing it's been gone from it's normal duty for a little while - and if you didn't notice any performance changes in the motor or clutch/tranny. Things that make ya go Hmmmmmm.

please take tons of pictures of the internals
 

From what I've read, these engines are poorly documented, at least by the Chinese. Maybe they are better documented from Honda!

As for the seal, perhaps it prevents excessive oil flow between the crank area and the primary or the gearbox?

Not bits of stator? It has plastic parts.

The only other parts that may may plastic, that I'm aware of, are the ignition pulse pick-up, the cam chain tensioner.

Some of these motors have gear indicator switch assemblies in them. If you have a ribbon wire exiting the left case cover by the front sprocket, you have a gear indicator switch {whether you have the gear display or not}. I have never seen one, but I would bet they are plastic too.

Hi Jonathan
I just posted this to the Yahoo Jetmoto group also.
I looked at the pic you posted. Is this stuff soft & rubbery? or is it hard? I have seen something like this before on a Honda TRX250EX 4-wheeler, except it definitely was a rubber o-ring that ended up down in the internal engine filter area. The o-ring was almost complete but some of it was shredded like yours. I talked to a friend/technician of mine at a local Honda dealer, he looked at the piece that came out of this engine and neither of us with the book or microfiche could find where it went. I put the engine back together and it hasn't had a problem since, {about a year ago}.
There are no rubber o-rings in between the transmission gears or any place by the crankshaft. To split the cases you don't need to remove the flywheel. You will need to remove the clutch assembly but be careful, without the correct tools you can break parts. If you have any questions feel free to contact me.

Ride Wild and Fly Like an Eagle! 8O
Bruce

I have the cases apart, I left the primary drive on so all the innards are
in the right side. As suspected there's nothing amiss in there, the centrifugal oil filter was full of rubbery sludge and I've fished some more
larger pieces out of the bottom of the cases, so whatever it was must have
been a fair size. My theory is; during assembly at the factory some rubber
component has found it's way inside, this is not as wild as it seems, many
years ago when I started in the motor trade and cars were built by people
and not robots, you could always find "extra" parts beneath carpets, in door bottoms etc.. The fun now starts I have to find some gaskets to put it back togeather. I'm 75% sure that the Honda CRF230 is identical, but then the CRF230 is not a UK model.
The reason I asked about BTS Motorsport is I think they've gone belly up. Nobody answers the phone (no answering machine), the fax line is dead, the China-Parts web site won't let you buy anything and they have nothing for sale on E-Bay.
I'll post some pictures shortly as some have expressed interest in what's inside the motor.

Jonathan

OOOh!!!!! I've just noticed I've gone from being a "newbie" to a "regular". I must point out though there's nothing regular about me!

Jonathan

Just wait until you are deemed a "cool boy" and the fun really begins!!

I am disappointed to hear about BTS. I think the CRF230 is made in Brazil, and are plentiful in the US. There shouldn't be a problem getting one of us to get you the gaskets.

Just out of curiousity, is all of your dip stick still in tact? Dad's was broken off and we weren't sure if the broken parts were in the crank case or not. Nothing has shown up in the oil and he's got about 2000miles on his.

Good point. I do believe the dipstick also has a rubber o-ring.