Is this Blaster Crank/Rod Bad?

[jlsparky7]

I have attached a picture and a video of my blaster bottom end crank. Is this crank bad? The rod moves side to side a little as you can see in the video but the actual crank in the case does not move and is solid. everything moves smoothly and does not bind or rub. The only thing that moves is the actual rod connected to the crank. Thanks for the help! I had a top end with no compression because the piston was rubbing and just want to make sure the bottom end is good before I put the top end back on.
Thanks for the help!

Video Link:

 

[yamahaman126]

Put a feeler gauge in between the rod and crank journal and report back.

 

[yamahaman126]

Side to side isn't that big of deal but the up and down on the rod is. Did you check the small end at the wrist pin for damage or out of round?

 

[yamahaman126]

What was the piston rubbing?

 

[jlsparky7]

There is no up and down play to my knowledge. Unfortunately the blaster is at the weekend house 200 miles away. I will be up there the first week of November so I will take the feeler gauge with me and check it. I know the spot that you are refering to. As to where it is rubbing i attached a picture. It rubbed on both sides of the cylinder/piston this is just one side.

 

[yamahaman126]

Was the bike warmed up when it quit running? It looks like someone rode the piss out of it before it was warmed up. Piston is aluminum and expands faster than the cylinder was and cuzs the piston to do the above.

Or was this a fresh piston in a honed cylinder that wasn't bored?

 

[jlsparky7]

no this bike was rode for 2 years after the last rebuild....another person on here a couple months back when i took it apart said the same thing. that it was not warmed up properly before being ridden. the bike would not stay running and if i remember correctly the compression was like 80ish psi.so yea from now on it will be warmed up properly b4 being ridden so that makes sense...ill still double check the crank with the feeler gauge b4 i put the top end back on.

 

[yamahaman126]

I:I I'd say your crank will be ok. Just make sure and warm that beast up before given her hell! I:I

 

[jlsparky7]

thanks i will do you happen to know what the specs are for the width that i am measuring with the feeler gauge as to what is good and what is bad width?

 

[yamahaman126]

I'll go find my manual and let you know.

 

[yamahaman126]

Big end side clearance .016 - .028 in.

 

[gonzo]

if its modified no less than .023 then it can get lube, that was a little tight and like he said, looks like a 4 corner seize, starting it up and whalin it.

 

[Tim Lutz]

The best way to check the condition of the big end bearing is to check the small end radial play. The Yamaha shop manual shows how to do this with a dial indicator. Is that the only area on the piston that is scored? You may have a bent rod or a bad small end bearing.