Trashed engine

[Fryin Finn]

I've had my WR450 in having the engine looked at as it was sounding a bit rattly. On first inspection the barrel was worn out and a new barrel piston and rings were ordered and the head sent off for new valve seals. The mechanic decided to strip the engine further as the starter wasn't sounding too good. He found what looked like very old sludgy oil and accused me of not changing the oil regularly. I denied this as I changed engine oil every 3 to 4 rides. So he split the crankcases and found about a table spoon of sand under the oil pickup. The mechanic is now compiling a new list of engine parts including crankshaft, conrod, bearings, cam chain, cams. Maybe cylinder head. Piston, rings and barrel already arrived. Or try and get whole new engine. Either way it's gonna get real expensive. Could probably buy a decent 2nd hand 2 stroke dirt bike for the money.
How did the sand get in the motor. Sabotage is a possibility but highly unlikely. It didn't get in via the airbox. The likeliest way was via the oil breather pipe sucking up sand infested water when I stalled in the bogs at last years Santoft Enduro.
Is there a remedy - yes - reroute the oil breather pipe from sump level to under the seat of 'T' of with high level pipe.
The big worry is this happening again as I didn't detect any sand in the oil during oil changes and the motor ran strong (800kms) to the end

[Ixion]

..The likeliest way was via the oil breather pipe sucking up sand infested water when I stalled in the bogs at last years Santoft Enduro.
Is there a remedy - yes - reroute the oil breather pipe from sump level to under the seat of 'T' of with high level pipe.
..

Yep, this is definately a possibility. Ask any four wheel drive off road enthusiast. When running crankcase is usually slightly pressurized. On stall the pressure drops , engine cools quickly, that creates a wee vacuum and in goes the dirty wter. Only thing is, that much sand would imply so much water that I'd have thought it would have been noticeable - even hydrolocked

[James Deuce]

That is a real bummer man.

Really sorry to hear about the poor wee thing.

[Motu]

Bummer,and the Yamaha is suppoed to be the best modern 4 stroke too.Hard to imagine how it got there,like Ixion says it wouldn't come in by itself,water is the most likely transporting agent.My DT230 has the breathers rerouted to the top of the air box,but after the previous owners last ride in a river crossing it had water in the carb.I probably have my TLR200 trials bike in more deep water than an enduro bike - last trial it was on it's side under water with the throttle wide open screaming it's head off,but no water anywhere.

[F5 Dave]

Oh Ratshit. Sorry to hear that Finn. I have heard that in immersion the water helps flow dirt & equally sand through the filter. Thinking about it some more, nah, it wouldn’t pass surely. Perhaps past the sealing surface of the airfilter, maybe.

[Ixion]

..more deep water than an enduro bike - last trial it was on it's side under water with the throttle wide open screaming it's head off,but no water anywhere.

Cos the throttle was open. If you'd killed the engine under water you'd have got some (assuming breathers, exhaust were under water.)

Mr Fryin' Finn's water/sand could have come up the exhaust pipe if it was bogged deep enough

[How many points do you lose for that ?]

[F5 Dave]

Have to pass by the piston to get to the bottom end. Where is the crankcase breather anyway?

[Ixion]

Have to pass by the piston to get to the bottom end. Where is the crankcase breather anyway?

YAh, Could have though. OP says the barrel was worn out.

[Motu]

Cos the throttle was open. If you'd killed the engine under water you'd have got some (assuming breathers, exhaust were under water.)

Mr Fryin' Finn's water/sand could have come up the exhaust pipe if it was bogged deep enough

[How many points do you lose for that ?]

Right,that's why I didn't shut it down until I'd picked it up,but I was scared of a big hunk of water getting in and a hydrolock.

A 5 - brain turned off as I had cleaned it the time before,but someone had shifted a rock in the deep muddy water...and I found it and was taken by supprise...which is no big supprise.

[Ixion]

Right,that's why I didn't shut it down until I'd picked it up,but I was scared of a big hunk of water getting in and a hydrolock.

A 5 - brain turned off as I had cleaned it the time before,but someone had shifted a rock in the deep muddy water...and I found it and was taken by supprise...which is no big supprise.

Ah . Memo to all operatives . Operation RockShift a complete success. Repeat next time.

[Fryin Finn]

Cos the throttle was open. If you'd killed the engine under water you'd have got some (assuming breathers, exhaust were under water.)

Mr Fryin' Finn's water/sand could have come up the exhaust pipe if it was bogged deep enough

[How many points do you lose for that ?]

The bike was stuck in an upright stance in the bogs - 3 or 4 times I recall and the exhaust never went under the water.
The oil breather pipe suction when stalled thing was a known problem but I was too lazy to do anything about it until too late.
I missed an entire section during the enduro but continued and finished fourth in class. Then when I got back home went to hospital to get my leg looked at after a crash in terrain test 1. Dead leg and pulled hammy.
In retrospect Hydraulicing the motor could have been a good thing - only new Barrel, crankshaft, piston etc.
Mind you the engine went for a further six months (800km) attesting to it's durability - sort of

[Paul in NZ]

I'd be amazed if the crankcase breather didn't have some sort of one way valve to make the crankcase pressure constant and prevent crud being sucked in?

PCV valves or summat? I think cars have them and you could retro fir one from a small car.

Cheers

[LB]

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Sorry to hear this Finn.....what a bummer.

Should I ever buy a dirt bike (unlikely) and do enduros (even more unlikely) I'll get my mechanic to sort my breather hoses.
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[Brian d marge]

The T piece is the way to go, Also you can buy tiny filters for the breather pipes ..looks like the pod K and N filter ..they are quite cheap ( I ll fit one one day ,,,) Another thing you will be shocked at how much grit can get in the engine through a badly fitting air cleaner ..and on dusty conditions ...alot of it DOESNT go through the engine but is held in the oil ( on a 4 stroke ) ....If you want milage out of your family car ..look at top quality air filters ( sponge /oil are the better ones )
I wish the boss would spring for a four stroke ,,,but I can make the 2 smoker pull like a 4 of the throttle ....so at moment not necc

but yes Stalling in the bogs aint a pretty site ( Ive stalled in the bogs many times )

Stephen

[Wellyman]

intresting. take it apart and try rebuild it sounds like a good start or if that doesen't seem possible part it out and use the money for a new bike. trade me have got plenty of used dirtbikes for sale at good prices at the moment.