Piston Hitting the Head?

835
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835
Edited Date/Time 1/25/2012 9:06pm
I just blew my bike up and when taking it apart after 3hrs of riding I found that the Piston apears to have been hitting the rim of the Head. I just put in a 270 kit from athena. How can I get around this. The whole Motor was completly redone and only had 3hrs on it.

My thoughts were using a double base gasket.
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mxtech1
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mxtech1 8/19/2011 1:22pm
8/19/2011 1:22pm
What kind of bike? you shouldn't have this sort of problem with an Athena kit.

Maybe it was a valve hitting the piston and not the piston slapping the head? this would be more common.
project racer 8/19/2011 4:35pm
8/19/2011 4:35pm Edited Date/Time 8/19/2011 4:37pm
Two stroke? If the kit did not include a head matched to the overbore piston, squish is probably too tight.

Four stroke? Piston / valve contact will be very obvious.

Usually one kiss between those two is all it takes to bring things to a sudden, violent stop.

Two base gaskets may get you enough clearance on a two stroke, but this will slightly lower compression, and advance port timing somewhat.
mx5471
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mx5471 8/19/2011 5:26pm
8/19/2011 5:26pm
Athena makes junk.You can't even get replacement parts. You probably got several base gaskets with your kit, as we did with our 144 kit for a 125. You need to put the gasket on and measure the clearance between the piston and the head, and make changes with the gaskets accordingly. The 144 kit destroyed our 125 Yamaha, but it was cheap to fix. I would never put that junk in a four stroke. On top of the time bomb already waiting to happen, you add one of those kits, and you have an impending disaster.
mxtech1
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mxtech1 8/20/2011 8:18am
8/20/2011 8:18am
mx5471 wrote:
Athena makes junk.You can't even get replacement parts. You probably got several base gaskets with your kit, as we did with our 144 kit for a...
Athena makes junk.You can't even get replacement parts. You probably got several base gaskets with your kit, as we did with our 144 kit for a 125. You need to put the gasket on and measure the clearance between the piston and the head, and make changes with the gaskets accordingly. The 144 kit destroyed our 125 Yamaha, but it was cheap to fix. I would never put that junk in a four stroke. On top of the time bomb already waiting to happen, you add one of those kits, and you have an impending disaster.
Nothing personal, but I couldn't disagree more. I have installed dozens of athena kits and used lots of their products.I have never had one bit of troubles with anything from them.

I know Athena will claim a "true bolt on" with alot of their big bore kits, save the 2 stroke kits because they require case matching, but any good mechanic will take the time to set the engine up right. this includes gauging piston to head clearance, measuring valve travel as they run through the cam lobes, and calculating adjusted compression ratios based on gasket(s) thickness. There is alot more to be done then simply bolting a kit on and hitting the track whether its a claimed bolt on or not. The average mechanic won't do all this work and this is where all the problems occur. then people bad mouth Athena, or any aftermarket engine product supplier for that matter, for making piss poor products that blew up their engine. It doesn't matter how good or bad the product is, the final responisibilty comes back to the engine builder who will take all these aspects into consideration. I've personally dealt with a couple engines where the owners wanted to big bore this, stroker crank that, different cam here, and just go out and buy all these aftermarket parts and want a hot rod engine when they have no comprehension of mechanical fundamentals of how the engine works. It's up to the mechanic to make it all work and this is where the good mechanics shine and the average mechanics fail.

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MOgle80
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MOgle80 8/20/2011 3:42pm
8/20/2011 3:42pm
When I had a YZ125 motor and had to re-do the crank , it was the bad bearings making the piston get right against the head, Are you sure that didn't happen in your motor?
mx5471
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mx5471 8/20/2011 5:48pm
8/20/2011 5:48pm
mxtech1, when we did the big bore, a former Factory Kawasaki mechanic that sponsored us did it for us. We modified the cases, set up the head clearance,and everything was cool for 2 races until the exhaust power valve pins broke, the piston cracked and destroyed the cylinder and the head. And only after 2 races. That stuff is JUNK. If it says bolt on, it should be. We had the best pro do it for us and even he couldn't believe what happened and that there were no replacement parts available from them. I say to everyone, if you want big bore,go to one of the places that does it. Athena is junk.
EatAChode
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EatAChode 8/21/2011 5:58pm
8/21/2011 5:58pm
mx5471 wrote:
mxtech1, when we did the big bore, a former Factory Kawasaki mechanic that sponsored us did it for us. We modified the cases, set up the...
mxtech1, when we did the big bore, a former Factory Kawasaki mechanic that sponsored us did it for us. We modified the cases, set up the head clearance,and everything was cool for 2 races until the exhaust power valve pins broke, the piston cracked and destroyed the cylinder and the head. And only after 2 races. That stuff is JUNK. If it says bolt on, it should be. We had the best pro do it for us and even he couldn't believe what happened and that there were no replacement parts available from them. I say to everyone, if you want big bore,go to one of the places that does it. Athena is junk.
Brand new bikes sometimes blow up. Does that make them junk too? Stuff breaks. Also dont get all caught up in titles, cool he was a kawi mechanic. Doesnt mean he is perfect or the best one. Just means he knew enough for Kawi to hire him. In your case you should have taken it apart, learned what had failed and gone from there. Or be ignorant.
mx5471
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mx5471 8/21/2011 7:49pm
8/21/2011 7:49pm
The Kawi factory mechanic was a mechanic to the pro's that have names now, and coach the new riders now. We analyzed everything. No one is perfect. I guess Goose knows enough for Suzuki to hire him. We knew what had failed,and had to make parts to fix it because there are no replacements available. They only sell kits. I am not ignorant, but it's obvious that you have no experience with that product. That makes you ignorant. Go buy one, but don't cry when you have problems.
835
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835 8/22/2011 9:25am
8/22/2011 9:25am
Update:

First I made a mistake. It was an LA Sleaves 250 to 270 Kit.
The guy who did my Machining never machined the head so there wasn't enough clearence. All is fixed though and I just ordered the new rebuild parts. All is well again.
jonhaverkamp
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jonhaverkamp 2/17/2017 3:42pm
2/17/2017 3:42pm
mx5471 wrote:
Athena makes junk.You can't even get replacement parts. You probably got several base gaskets with your kit, as we did with our 144 kit for a...
Athena makes junk.You can't even get replacement parts. You probably got several base gaskets with your kit, as we did with our 144 kit for a 125. You need to put the gasket on and measure the clearance between the piston and the head, and make changes with the gaskets accordingly. The 144 kit destroyed our 125 Yamaha, but it was cheap to fix. I would never put that junk in a four stroke. On top of the time bomb already waiting to happen, you add one of those kits, and you have an impending disaster.
mxtech1 wrote:
Nothing personal, but I couldn't disagree more. I have installed dozens of athena kits and used lots of their products.I have never had one bit of...
Nothing personal, but I couldn't disagree more. I have installed dozens of athena kits and used lots of their products.I have never had one bit of troubles with anything from them.

I know Athena will claim a "true bolt on" with alot of their big bore kits, save the 2 stroke kits because they require case matching, but any good mechanic will take the time to set the engine up right. this includes gauging piston to head clearance, measuring valve travel as they run through the cam lobes, and calculating adjusted compression ratios based on gasket(s) thickness. There is alot more to be done then simply bolting a kit on and hitting the track whether its a claimed bolt on or not. The average mechanic won't do all this work and this is where all the problems occur. then people bad mouth Athena, or any aftermarket engine product supplier for that matter, for making piss poor products that blew up their engine. It doesn't matter how good or bad the product is, the final responisibilty comes back to the engine builder who will take all these aspects into consideration. I've personally dealt with a couple engines where the owners wanted to big bore this, stroker crank that, different cam here, and just go out and buy all these aftermarket parts and want a hot rod engine when they have no comprehension of mechanical fundamentals of how the engine works. It's up to the mechanic to make it all work and this is where the good mechanics shine and the average mechanics fail.
I'm rebuilding my bike with the Athena kit, do I use one base gasket or both that they provide in the gasket kit?
Paw Paw 271
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Paw Paw 271 2/17/2017 6:16pm
2/17/2017 6:16pm
You will have to check the head to piston clearance to know for sure.

Paw Paw

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