R.I.P little piston.

[RubberSalt]

161334161335

Not 100% sure of the cause just yet. Got nearly 2 years out of it. Crank is hard to turn over. Gotta split the case for this 1. Jug is fine, rod appears fine. Heck, the jug still has the cross hatch from when it was bored. I ran mostly the lucas 2 stroke oil. Kinda doing a review on it. I'd say total hours is somewhere near 40-50 of hard riding. This was a 66.25mm OEM Piston.

Just ordered me a 66.25 WSM Platinum piston for a blaster :) <--- edit - wrong piston lol

My guesses on the cause. At the dunes, my intake ripped and it started dieseling. The piston was not chewed up from this. Possibly weakened. I recently cut the head, it's at 130-135psi, my guess is the squish changing a hair. at the RPMs it ran. Time to research squish angles. . .


I've since buried the piston in the yard next to the cat, the dog, grandma, and the crank from my first YT175.

[3Wheelermaniac3]

Ha ha ha about the burial.

[GO OVRIT]

Sorry about your loss. Why the blaster piston?

[El Camexican]

At the dunes, my intake ripped and it started dieseling :wondering

[M.Pargiello]

We are running Namura pistons in a couple machines, just did another last weekend :)
161345

They seem to work great, let us know how it turns out

[RubberSalt]

The blaster piston is a cheaper better quality piston, they also allow for after market :) I run a 66.25mm bore, 1 size over. They use a flatter dome, but that allows for the transfers to flow better. Cut the head to make up for it. They also use a thinner ring. Less ring flutter, higher revs.

It gives a difference of about 2k RPM on the top end.

[Chazz of Blades]

:wondering

Heats up to the point that it's still running out of control even after the ignition has been cut. Ala spark plug so hot it turn to a heat plug.


My Fo-Hundy Husky did that one time screaming wide open and wouldn't die. Scariest ride of my life.

[RubberSalt]

I didnt have the carb suspended well enough, vibrations make carb want to go up and down. Rips boot open. Sucks in air, bike runs lean, it heats up. Hot. Diesel
kill the gas and hold the throttle wide open. To much air will make it die.

[M.Pargiello]

Now that you edited your first post it makes mine look completely irrelevant haha

[just ben]

Did you find the cause yet? It's pretty obvious if you dont know. Cross hatch marks or not I'm willing to bet the cylinder needs a bore. There is only one reason for the skirt to break and that is piston slap

[RubberSalt]

@ M.Pargiello - Yup lol
We've ran Namura also. Havent had a failure with them or a WSM. :) WSM was the only one, besides OEM, to offer a 66.25 bore.

@Just ben - detonation? atleast thats what i want to believe. just cut the head.
I'm going to check the bore here in a minute. I dont want to believe it's a loose bore. The hatch was put on when it was bored :( Off to investigate.

[RubberSalt]

The results are in!! The bore is like a fat guy on a moped. Looks bigger the middle. Poop.

Imma go cancle that 66.25 piston and drop in 1 of our wisecos.

@Just ben - Upon further inspection. The cross hatch is worn on the exhaust side around the port. Extra 3 thousands more than the rest of the jug.