06 WR450 - Cracked Piston

[bergermeister]

Oudy fellas,

A mate of mine has had a bit of bad luck with his 06 WR450. Went riding recently and for no apparent reason the bike just stopped. Managed to push start it and it ran for a few minutes, but since then we had no luck.

Upon further inspection we've found that the piston has cracked. Its only hanging on by about a 1/4 inch (on the piston skirt).

To cut a long story short, the bike is actually an 05 model, however within the first week of ownership the gearbox seized whilst on a transport section (doing 70 mph on bitumen). Luckily he didn't come off. He skidded to a halt and buggered up the rim in the process. Fortunately, Yamaha came to the party and replaced the rim and the entire engine with a new 06 engine under warranty.

So my question is this, has anyone out there experienced a similar problem?

The bike is well maintained. Its done approx 1300 miles. He doesn't do the maintenance himself, he leaves that to the dealer. He does his oil changes at 300 miles (which isn't quite as often as I would personally recommend) but nevertheless I know many that do theres less frequently. He uses Motul 5100.

The bike has always sounded as if it were jetted correctly. It definately does not sound as if it is running lean (no popping). The spark plug showed no signs of detonation either. It was a perfect tan colour.

As for fuel, he does not use premium unleaded. Just the standard stuff, which probably doesn't help matters. But having said that, neither do I or most people I ride with. I am a proud 05 WR250 owner. My mates ride YZ 250 / 450s and abide by similar maintenance schedules, using similar fuel, oil, with no dramas.

Is my mate just unlucky?

[PBDBLUE]

My guess is the piston cracked due to detonation from running low octane fuel. The engine compression is over 12:1 and requires premium fuel.

[bergermeister]

PBDBlue,

I kinda agree with you. This leaves me a bit worried, as I only run standard fuel too. I do this intentionally as it is often difficult to purchase the high octane stuff when you go to refuel out in the sticks.

What's everyone else running?

[123BigcoopDawg576]

I run premium when ever possible. The only time I don’t is when I absolutely can’t like when in Mexico and all you can get is a gallon of gas out of a barn for 5 bucks! But as soon as I get home I empty the tank and run some premium through!

[GCannon]

Burritos and Gasoline, Life's simple pleasures:applause:

[ajetmech]

I run VP 95 octan (3.5 gal) to VP 100 octan (1.5) and no problems the lowest I run is 92 octan

[MaxPower]

do you guys really call asphalt, bitumen?As if riding on the wrong side of the road wasnt bad enough

[bergermeister]

do you guys really call asphalt, bitumen?As if riding on the wrong side of the road wasnt bad enough

My word we do mate!

To be perfectly honest though, many call it bitumen and others call it asphalt (50/50)... it really depends on what mood your in at the time.

As for driving on the left side of the road... we've definately got that one right!

Thanks for the feedback on the fuel guys. I'm still quite miffed by the fact that the spark plug shows no sign of detonation though. I would have expected to see some signs of pitting / white deposits.

123BigCoopDawg576,

Now that fuel looks really average... your poor bike. I know exactly what you mean though, some times you've just got to make do with what's on offer.

Please tell me you didn't try one of his Burriotos aswell!

Bergermeister

[123BigcoopDawg576]

123BigCoopDawg576,

Now that fuel looks really average... your poor bike. I know exactly what you mean though, some times you've just got to make do with what's on offer.

Please tell me you didn't try one of his Burriotos aswell!

Bergermeister

nope didnt eat the food, did at another spot and it was goooooood! actually the gas isnt that bad in mexico. all the gas comes from one location as the gas stations are all owned by the government. all that guy does is go to the local station and fills up a big container and then sells it for 5 bucks a gallon to riders haha smart guy! for sure though i would not make it a habit. premium when ever possible amigos

[bergermeister]

nope didnt eat the food, did at another spot and it was goooooood! actually the gas isnt that bad in mexico. all the gas comes from one location as the gas stations are all owned by the government. all that guy does is go to the local station and fills up a big container and then sells it for 5 bucks a gallon to riders haha smart guy! for sure though i would not make it a habit. premium when ever possible amigos

Hmm interesting! Thanks for the reply.

As for the whole Burrito thing, I guess I shouldn't laugh too hard. Judging by the state of my mates piston, I reckon he'd been better off trying to run the thing on that blokes Burriots than whatever fuel he's been sticking in it... the results couldn't have been much worse. He's up for a new piston and barrell. Live and learn I guess!

Bergermeister

[Ferd Woodstock]

Old thread but I put in my $.02. You may want to try some octane improver if you have to buy sub 95 octane stuff. Probably cheaper just to buy the good stuff. The short skirt pistons in short stroke bikes have some serious G forces working on them when the engine hits the rev limiter. I think a manufacturing defect is not that unlikely.

[bergermeister]

Thanks for your post Ferd Woodstock!

[OringGroove]

I'll take a bite on the Asphalt issue too! Bitumen is a slightly different road surface to what is in the USA Not many roads are concrete like you see in the USA either! Just miles of dirt (Gravel) with the occasional roo serving steaks by the side of the road!

Now if anyone needs to purchase some roo feathers let me know?

[viktobravo]

I'll take a bite on the Asphalt issue too! Bitumen is a slightly different road surface to what is in the USA Not many roads are concrete like you see in the USA either! Just miles of dirt (Gravel) with the occasional roo serving steaks by the side of the road!

Now if anyone needs to purchase some roo feathers let me know?

A few of the old timers call asphalt "oil." "Running on the oil" I like that term:thumbsup: As far as the Burritos at Ramona's, they rock:thumbsup: when she has them, but I have put a bit of water in my tank from that same gas shed:eek:

[bergermeister]

A few of the old timers call asphalt "oil." "Running on the oil" I like that term:thumbsup: As far as the Burritos at Ramona's, they rock:thumbsup: when she has them, but I have put a bit of water in my tank from that same gas shed:eek:

viktobravo,

I'm glad your still here to tell the story mate.

As for you orgingroove, I like your sense of humor!