Three Different Heads - Three Different Problems

It just means your squish is no longer around the edges, it is now wherever the closest meeting point of the piston and head are. So as long as that isn't under .5mm or .6mm whatever the minimum squish is, you're fine. And the squish affect should still work. The squish affect is there to promote better fuel mixing.

A tiny amount of fuel might get pushed away from the tighter spot toward the bigger gap at the corners (away from the combustion chamber) at the peak of the compression stroke if anything.Just potentially less gas mileage and power. May be negligible.

I wouldn't worry about it. Nothing will get damaged again as long as you meet at least the minimum squish or else predetonation will occur which means it ignites before it reaches the combustion chamber due to extremely high compression. It'll put divots in your piston and wear the crank bearings.
 


A couple of $h!# bombs in this one. NSFW. :LOL:

As was stated before all the good heads are straight plug, this is because the flame front propagates evenly and more efficiently in the center. None of the stock heads weather it's the small or large chamber have a proper squish area and neither does the blue one you have there, the above comments are not correct as the angle is matched to the piston dome from crown ideally 40 - 60% inward toward the chamber. The chamber is only the very center section where combustion is controlled after an effective squish pushes all the end gasses into it, this centering of the gasses is to keep the piston crown cool and prevent detonation in high compression setup's, will you notice a difference, probably not in a stock or mild engine build that doesn't see higher rpm. If you really want to understand the science behind this then Bell, Blair, and Jennings all have covered this in every detail but remember that they are all referring to high performance engines. Some of us here rework these engines to put out 4x the rated output and sustain higher rpm to where a proper squish and the choice of chamber style does make quite a difference in how it will preform, if you intend to rev well over 8k sustained and use high compression then yes this is a must other wise not so much.
 
As was stated before all the good heads are straight plug, this is because the flame front propagates evenly and more efficiently in the center. None of the stock heads weather it's the small or large chamber have a proper squish area and neither does the blue one you have there, the above comments are not correct as the angle is matched to the piston dome from crown ideally 40 - 60% inward toward the chamber. The chamber is only the very center section where combustion is controlled after an effective squish pushes all the end gasses into it, this centering of the gasses is to keep the piston crown cool and prevent detonation in high compression setup's, will you notice a difference, probably not in a stock or mild engine build that doesn't see higher rpm. If you really want to understand the science behind this then Bell, Blair, and Jennings all have covered this in every detail but remember that they are all referring to high performance engines. Some of us here rework these engines to put out 4x the rated output and sustain higher rpm to where a proper squish and the choice of chamber style does make quite a difference in how it will preform, if you intend to rev well over 8k sustained and use high compression then yes this is a must other wise not so much.
Thanks. The last thing I care about on a bicycle is high speed. I think people are crazy to go 50+ MPH on these things. But as I understand it, if the squish is too low it can cause problems. I realize it's not a proper squish band, but I'm getting readings between of 0.5 mm and 0.63 mm. Is this a problem? I have a 0.5 mm copper head gasket and my piston (at the edges) sits a little bit below the top of the cylinder when at TDC so I think the 0.63 mm is probably more correct. Also, now that I'm thinking about it, this squish reading was not done under proper torque. It's probably even lower once torqued.

I'm trying to find a slightly larger copper gasket 0.6 mm but no luck. I also have a 0.7 mm aluminum gasket. Do I need to worry about this?

Do you know where I can get copper gaskets in varying sizes? I just want to do all of this right the first time. Especially with my build (Mongoose Dolomite) which will not allow me to remove the head without removing the engine from the bike (and I'm adding a shift kit.) It will be quite annoying to me to have to remove and install the engine multiple times to get this right. Thanks.

Here's my thoughts on speed for me and this build: If this thing will do 40 or more, that's great. But I'll be riding at 35 or less and especially in places where the police may see me. Speed limit here is 25 mph for these. I'd like it to be able to go faster just so I know that I'm never going to be winding it out to the max.
 
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You have to remove some material from the top of the cylinder. The squish band should be the smallest next to the cylinder wall and get progressively bigger toward the center, say like 0.6mm outside and 0.7mm toward the middle. That way the fuel/air mixture is forced into the center of the combustion chamber for peak performance and power.
 
You have to remove some material from the top of the cylinder. The squish band should be the smallest next to the cylinder wall and get progressively bigger toward the center, say like 0.6mm outside and 0.7mm toward the middle. That way the fuel/air mixture is forced into the center of the combustion chamber for peak performance a

You have to remove some material from the top of the cylinder. The squish band should be the smallest next to the cylinder wall and get progressively bigger toward the center, say like 0.6mm outside and 0.7mm toward the middle. That way the fuel/air mixture is forced into the center of the combustion chamber for peak performance and power.
I realize that. I have a situation now where I think the squish is too small. I'm looking for a copper gasket thicker than 0.6 mm.
 
Thanks. The last thing I care about on a bicycle is high speed. I think people are crazy to go 50+ MPH on these things. But as I understand it, if the squish is too low it can cause problems. I realize it's not a proper squish band, but I'm getting readings between of 0.5 mm and 0.63 mm. Is this a problem? I have a 0.5 mm copper head gasket and my piston (at the edges) sits a little bit below the top of the cylinder when at TDC so I think the 0.63 mm is probably more correct. Also, now that I'm thinking about it, this squish reading was not done under proper torque. It's probably even lower once torqued.

I'm trying to find a slightly larger copper gasket 0.6 mm but no luck. I also have a 0.7 mm aluminum gasket. Do I need to worry about this?

Do you know where I can get copper gaskets in varying sizes? I just want to do all of this right the first time. Especially with my build (Mongoose Dolomite) which will not allow me to remove the head without removing the engine from the bike (and I'm adding a shift kit.) It will be quite annoying to me to have to remove and install the engine multiple times to get this right. Thanks.

Here's my thoughts on speed for me and this build: If this thing will do 40 or more, that's great. But I'll be riding at 35 or less and especially in places where the police may see me. Speed limit here is 25 mph for these. I'd like it to be able to go faster just so I know that I'm never going to be winding it out to the max.
Ok so the speed is not really a factor here it's the rpm and compression, with a shift kit and the ability to over rev in first and second maybe even third gear is where this will come into play being able to eliminate detonation and keep the pistons crown cooler. .63 clearance without being torqued to spec is a bit tight since it will shrink slightly after being run and a retorque required, I'm not sure where is best to acquire cooper gasket's, your .7 aluminum one is probably the best bet.
 
I'm looking for a copper gasket thicker than 0.6 mm.
.6mm=.023"th and .7mm=.027"th
If ya want a head gasket thicker than what is available. I think your gonna have to make your own.
BTW how thick do ya want your head gasket?
 
Actually, I forgot, you can just stack another base gasket or two on. They're cheaper too. I know those you can stack. Problem solved
A larger base gasket raised the cylinder and changes port timing. Two base gaskets or two head gaskets is more than I need.
 
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