Picked up a bottom end in my search for replacement gears. Drained the gear oil and was shocked when several teaspoons of clear water came out before the oil!!

A dreadful feeling of d

Steve. Did either of these engines have a breather for the gearbox?

Wayne....

I can tell you for a fact it wasn't coolant cos it hasn't got any,

Bloody power washers they normally cause all the problems..

Power washer is one thought....

I usually end up with my motor at least half submerged in every Trial I ride. I change the primary and gear oil after each one.

Alan

Hmm ok, power washers, submerging, can't help I guess.

No breathers on either motor.

The moral of the story is regular oil changes! Which after you've spent days/weeks/months rebuilding a motor is something I would not hesitate to do.....

Steve

I'm never surprised at what comes out of a second hand bike gearbox. One 348 I bought had forks that didn't move up and down. When I took the caps off I found why - they were completely full of water (the air valves had let water in from rain and the forks were jammed from the steel bits rusting up). As well as that someone had fitted fork spring preload spacers so long that the springs had been coil-binding severely and been ruined in the process (bent springs).

348 and 349 gearboxes do have breathers, but they don't have hoses on them to reach above water level! Have a close look at the rear of the gearbox casing about where the swingarm pivot is and you should see a little hole there which is the breather. Another 348 I bought had that hole sealed up with araldite (and no other way of preventing pressure/vacuum issues within the gearbox)

By the way, the cream colour of the oil means that it is doing its job of preventing water contacting metal. The properties of the oil cause water to be broken into microscopic droplets (surrounded by oil) so that only oil is in contact with metal parts.

my in progress Cota 330 (Similar engine) has a breather for the gearbox which has about 18" of plastic tubing on it. This tubing was routed up the rear loop tubes and tucked under the tank. Pic attached of the engine end.

Wayne....

Edited March 15, 200917 yr by wayne_weedon

I found that breather while transporting my 348 on its side in my estate car!

That mod on the later engine should be easy to do next rebuild.

should be easy to drill and tap a blanking plug in the caseing then fit a breather and rubber snorkel.

I have two engines for my bike and both have 'historic' rust inside.

OK interesting stuff, thanks

My original engine has no breather, the slightly newer one just aquired does.....but .... looking inside the cases it doesn't seem to actually link to the gearbox chamber!

I will have a better look and work out whats happening, and design something suitable for my rebuild.

Steve

My 349 Parts book albeit for the MH349, does show 2 breather nipples on the exploded diagram.

It's worth retrofitting something in anycase.

Wayne...

And here is what a 348 gearbox breather looks like (small shiny hole). Photo taken fron underneath