jasonp
Well-Known Member
Well after getting a bunch of pm's about some people wanting to know about building up the 350cc engine and now having a little push from dave to get me going I've decide to help some people out. Hopefully we'll get some guys like Dave, Griff and others to chime in as well.
Figure out what you want and how much money you can reasonably spend on you're build. Also truly ask yourself what type of riding you do and what rpms do you want the most power in or where the engine spends the most rpm in. Be honest with yourself. Don't always think bigger is better. Also ask yourself what type of gas do you want to run as this will play a big part in picking out the compression you want to run for a new piston.
I would say most of you guys are going to run on pump gas and will want to spend the least amount of money but still have great performance.. I think we can do that.
Piston choice are Wiseco and JE. There are others out there like CP that can custom make you a piston which is great but there going to be a little more money then the other two manufactures.
Since were going for maxium HP and torque with little money lets go for the Wiseco, it's got 10.2:1 compression and comes in many over bore sizes. When installing a new piston you should always do a bore and hone job as it will straighten the liner out and you will get a much better ring seal. Make sure you take the cylinder and piston with the spec sheet to the machinist.
Personally I go with the largest overbore as this aids in compression and plus gives you that extra 17cc.
Next thing will talk about is deck clearance. This is when the piston is at the very top of the bore. TDC and you measure the distance from the top of the piston to the head or liner then take into account for head gasket thickness. This measurement should be close to .040". The closer you get the better and the more compression you will have. Also the engine will run a little cooler and it will resist detonation. The reason why this is important is because of the quench zone, which is the flat spot on the sides of the head (combustion chamber) get closer to the piston at TDC and will cause air to be push and mixed around very violently making the air fuel mixture mix better. To do this will use some custom made gaskets by Cosmetic. You'll have to figure out what you need.. For are propose I'll say we have .075" of deck including are stock .043" head gasket and stock base gasket of .020". Will go with there .010" base gasket,.018" head gasket and plus the .012" piston we now have are .040". You could even take the base gasket out and use sealer if you could not get that thin of a head gasket. This is key to having the engine perform right here folks is getting that .040" of deck.. Also a thing to note is that don't go under .035" of deck. Metal does expand and as you start to rev the engine harder things may touch.. So be careful.
So we spent 80.00 dollars on a new piston.
50.00 for the bore and hone job.
25.00 dollars in gaskets.
Around $150.00 bucks and I'm guessing around 11:1 compression just right where you want to be. Next will talk about cams.
Figure out what you want and how much money you can reasonably spend on you're build. Also truly ask yourself what type of riding you do and what rpms do you want the most power in or where the engine spends the most rpm in. Be honest with yourself. Don't always think bigger is better. Also ask yourself what type of gas do you want to run as this will play a big part in picking out the compression you want to run for a new piston.
I would say most of you guys are going to run on pump gas and will want to spend the least amount of money but still have great performance.. I think we can do that.
Piston choice are Wiseco and JE. There are others out there like CP that can custom make you a piston which is great but there going to be a little more money then the other two manufactures.
Since were going for maxium HP and torque with little money lets go for the Wiseco, it's got 10.2:1 compression and comes in many over bore sizes. When installing a new piston you should always do a bore and hone job as it will straighten the liner out and you will get a much better ring seal. Make sure you take the cylinder and piston with the spec sheet to the machinist.
Personally I go with the largest overbore as this aids in compression and plus gives you that extra 17cc.
Next thing will talk about is deck clearance. This is when the piston is at the very top of the bore. TDC and you measure the distance from the top of the piston to the head or liner then take into account for head gasket thickness. This measurement should be close to .040". The closer you get the better and the more compression you will have. Also the engine will run a little cooler and it will resist detonation. The reason why this is important is because of the quench zone, which is the flat spot on the sides of the head (combustion chamber) get closer to the piston at TDC and will cause air to be push and mixed around very violently making the air fuel mixture mix better. To do this will use some custom made gaskets by Cosmetic. You'll have to figure out what you need.. For are propose I'll say we have .075" of deck including are stock .043" head gasket and stock base gasket of .020". Will go with there .010" base gasket,.018" head gasket and plus the .012" piston we now have are .040". You could even take the base gasket out and use sealer if you could not get that thin of a head gasket. This is key to having the engine perform right here folks is getting that .040" of deck.. Also a thing to note is that don't go under .035" of deck. Metal does expand and as you start to rev the engine harder things may touch.. So be careful.
So we spent 80.00 dollars on a new piston.
50.00 for the bore and hone job.
25.00 dollars in gaskets.
Around $150.00 bucks and I'm guessing around 11:1 compression just right where you want to be. Next will talk about cams.
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