Broken Piston

[Bmarshall]

I was recently given a 2003 Yamaha Blaster that was seized. Upon removing the top end, I found that the piston rings and cylinder wall is ok, but that the bottom of the piston actually broke and pieces of the piston fell into the crankcase causing the seizing.

My question is: Do i have to split the case or is there another way to clean out the crank case?

I am fairly mechanically inclined, I have fixed the power heads on many boats, but this will be my first ATV.

 

[Triple_B]

Yes you will need to split the cases in order to remove all pieces of the piston skirt. Also make sure your crank bearings haven't been chewed up by tiny pieces of the piston skirt. Make sure you thoroughly clean out the bottom end and you'll be good to go

 

[sporty982000]

I recently bought the blaster you see in my avatar.


As I have recently learned. you will need to look well into the rod / crank and look and see if the housing is broke or cracked. Its hard to do this with the engine in the frame.

But a flashlight and look at the center and middle and rotate the rod some.

As I have learned and read allot lately. it seems common, that what can happen, when that skirt breaks off from the piston.

Those pieces get inside and under the crank. in the inner case housing, if it did so, while it was running. there s just no clearance there.

Which means it can crack or break that case housing.

If you are lucky enough that this didnt happen too. but if it did.

Aside from taking the motor apart and splitting the cases. you might hvae to weld or get new cases.

I hope you are lucky enough, that this did not happen to yours. but seems to happen to many.

Sporty

 

[blasterdemon7]

Yuup. You will be super lucky if there's no hole or crack in the case. I would measure the bore before adding a piston.

 

[Blaaster]

In a nutshell, you have to split the cases, preferrably replace all bearings and seals as it is very hard to remove all of the tiny particles that the exploded piston has dropped.

If the cases have been damaged you will need to replace them or get them repaired.

As stated, before ordering a new piston you need to get the bore measured to make sure it is within specs.

 

[joeak47]

Start by looking at the bottom of the engine case...

Is the bottom of the engine case "pushed out" from the broken piston getting wedged between the case bottom and crank shaft?

 

[Awk08]

i've been down this road...trying to flush cases.
it's like playing russian roulette...did i get it all out ???
it didn't last 6 months and took out another fresh top end and wiseco piston when the rod bearing went, more than likely from unflushed shrapnel, or damage that already occured when the skirt dropped in and got ground up.
never again will i try to just flush shrapnel ... it just costs more in the end.
a full bottom and top end rebuild can last you years

 

[Bmarshall]

Ok Thank you for the information and tips. I will be splitting my case as soon as my case splitter tool gets here

It just seems like an awful lot of little pieces to lose, any suggestions on keeping it organized or a good detailed way to put it back together? I have the manual but all the pictures look the same..

 

[Awk08]

ken oconnor racings blaster bottom end vids.........

watch all parts 1, 2, 3, 4..ect.



our member jlsparky's vid series, scroll thru his youtube channel, he has plenty of vids on the blaster...........

this is similar and will also give you an idea of how to do this...

 

[sporty982000]

when I took mine apart last week.

I used zip lock baggies. I separated each back, with what part I took off. I kept it all separate.

Example- flywheel / stator section all into one large baggie.

Tho I used up like 12 baggies. It really helped when I put it all back together.


And I was right to take my cases apart too. I still found pieces in the bearings as they mentioned. I used wd-40 and sprayed and hand rotated the bearings. listening and finger turning slowly until and using a flash light and looking for small pieces.

I did find some and used a small dental pick and a awl to get them out. then I just repeated that wd-40 and ect looking and finger spin a few more times.

Then i Re packed them with grease.

And I used JB weld to fix the cases and I don't recommend this, I will get used cases and replace all next year.

Sporty

 

[best]

Ok Thank you for the information and tips. I will be splitting my case as soon as my case splitter tool gets here

It just seems like an awful lot of little pieces to lose, any suggestions on keeping it organized or a good detailed way to put it back together? I have the manual but all the pictures look the same..

My favourite trick is a sheet of box cardboard with a rough black marker nearly full sized drawing of the engine and/or engine compartment. I punch holes in the cardboard and stick the bolts in the holes in the drawing. Especially good for case bolts that come in 3 or 4 different lengths.