rattle noise at idle?

[Hardcore]

You guys have helped me out with my 87 banshee, now how about help with a friends' Blaster?

 

It's a 1996 blaster. Single cylinder. I just started it up after a minor tune up and the thing has a major rattle in the top end. My buddy has another blaster I tuned up yesturday and it sounds normal. What could this noise be? (the bikes were given to me to clean up for the coming riding season - I have never heard them run before so I assume this has been rattling for a while).

 

The compression checks out at 140psi and everything else is normal. This noise is real loud at idle and seems to smooth out when I rev it up.

 

Top end bearing, cracked piston skirt,bottom end stuff??????

 

Any input would be great.

 

Thanks,

[Shee-Male]

It might just be the slide in the carburator, it rattles as air passes around it.

[POLKY]

I HAD A RATTLING ON MY BANSHEE AFTER MY REBUILD, HERE IT WAS MY LEFT SIDE HEADER RATTLING. I MUST HAVE STRECHED THE SPRINGS. STILL RATTLING KEEP FORGETING TO ORDER SPRINGS.

 

SOMETIMES NOISES COME FROM THE STUPIDED PLACES.

[Capone]

Kickstarter?

[snowfoxsx]

my shee had a rattle in it too, one of the pipes was ratteling. something broke lose inside the pipe, check yours out, mine went away after i put pipes on

[Hardcore]

Thanks to all the replies so far. I checked things out for external rattles but came up short. While I had it running I did the old screwdriver to the ear trick and poked around the top end and noticed the noise loudest right at the top of the cylinder and head area.

Sooooooooooo.

I ripped the top end apart to check it out. There is no play in the top bearing but there is just a little, tiny bit of play in the bottom bearing when I pull derectly up and down. Just enough that it can barely be felt. I'd guess a one to two thousandths of an inch.

 

I know the side to side and rocking back and forth play is normal but straight up and down? Can there be any play there at all? Is this normal?

 

I ask because there is a hell of a lot of play between the piston and the cylinder wall. I know there is supposed to be some for the rings to soak up but I think there is too much and this is my problem. I plan to order the next bore size piston, rings, etc and get it bored over to match the piston and reassemble.

 

Any thoughts here? Do I need a bottom rod bearing relaced or just the top-end as I suspect?

 

Please help.

 

Hardcore.

[fastbanshee4u]

Your crank bearing will get worse as time .You noise was probally piston slap.I have seen some noisy motor last quit a while,then the next not.Just remember good 2 stroke oil and the right amount lubricates your bearings.If you can afford to fix the crank now is the time.

[Wicked98Shee]

Your crank bearing will get worse as time .You noise was probally piston slap.I have seen some noisy motor last quit a while,then the next not.Just remember good 2 stroke oil and the right amount lubricates your bearings.If you can afford to fix the crank now is the time.

495362[/snapback]

 

 

[Hardcore]

Well I fixed it. The piston measured out to be 0.007" smaller than the cylinder bore - way too big. The new piston calls for 0.0015" to 0.00175" clearance but I asked to bor it to 0.0025", the other just seems too tight for an air cooled 2-stroker.

 

The rod bearing play is normal as per the Yamaha dealer, a race engine builder and a machinist. I thought it might be but these guys have all the experience and wanted to make sure.

 

Just thought I'd share this all with yas.

 

And when I say rod play, straight up and down there is just a minor amount that you can barely feel.

 

Cheers folks.

[Capone]

And when I say rod play, straight up and down there is just a minor amount that you can barely feel.

 

Doesn't matter how minor, you shouldn't be able to feel it at all. If you can feel the movement that means you can measure it. Squish clearence is usually only .040-.050 if the rod moves more than that.. you'll be in trouble.

[04TeamYamahaShee]

My 'Shee rattles a little bit.. my kickstarter is what's making the comotion.