the blaster motor is way out of square, this limits the power you can get out of it. try and understand this if you can
consider this, the stock 250r motor is pretty strong, the la sleeve blaster cylinders have for the most part better 250r port layouts... the blaster bore and stroke is 66 x57 and is 195 cc the 250r is 66 x 72 for 246 cc. your just not going to add 15 mm to the stroke of a blaster.
there is a term used in motors called "square" this is when a motor has the same bore as stroke, say 66x66 this is the most balanced combination.
longer stroke favors a lower reving torquier motor, while shorter stroke will produce a higher reving peak hp motor.
the 240 kit, while capable of producing more power puts the motor so far out of balance that it has its limitation, due to the mass of the piston changing direction and short rd deflection angle etc.
ideally, if one were to use the ct/la sleve 200cc aftermarket cylinder with the honda style porting (reported for application), and a +4 or 6 crank with a significantly longer rod coupled with a button flywheel ignition a much better advance curve, and custom pipe, you could spin the blaster motor 10~1100 rpm and make some SERIOUS power.
a typical 125 mx bike has a bore of 54mm and a stroke of 54.5 mm, 125's make around 35 hp stock, and rev to the moon but you have to be in the revs to make the power.
Now consider the blaster at 66x57, thats basically a 250r piston stuck on a 125 ( actually a 66.5 mm piston (2nd bore) on a 54.5mm 125 bottom end would be 189 cc's) thats 6 cc's different than a 125 and 51cc's different than a 250r... that should put things in better perspective. now if you have ever seen a 125 piston, its pretty small, the blaster piston is a LOT bigger, i cant find the weigt specifics with a quick seach but you are probably doubling the mass, thats a lot more weight switching direction 8000~10000 times a minute. add in the 72 mm 240 piston and it gets even worse.
By building the motor closer to square by leaving the bore alone and increasing the stroke as much as possible with a longer rod to reduce deflection you make the downwards power stroke much more powerfull, and decrease the effect of a big chunck of alum switching directions.
this type of motor will rev higher and provide the best balance of low end and top end while significantly increasing top end due to the 2000 extra rpms you can gain.
To put that in realistic terms:
with stock tires/gearing at 7500 rpm the blaster goes 52.2 mph
with stock tires and gearing at 10000 rpm the blaster would go 69.5 mph
now change the counterhsaft sprocket to a 14.. @10000rpm your doing 75 mph
125's run mid 30's hp numbers @11500 rpm or so, with a longer stroke and bigger bore, say 63x66 if you can get it to spin to 9500~10,000 you would be seriously trucking
the real trick would be getting a 65 mm bore, that would keep legal in the 200 class with major power.
imagine kicking ass on all your buddies with big bore kits, and you have a kit making your bore SMALLER than stock.
Im not an engine guy, suspension is my thing, so these are just ideas
consider this, the stock 250r motor is pretty strong, the la sleeve blaster cylinders have for the most part better 250r port layouts... the blaster bore and stroke is 66 x57 and is 195 cc the 250r is 66 x 72 for 246 cc. your just not going to add 15 mm to the stroke of a blaster.
there is a term used in motors called "square" this is when a motor has the same bore as stroke, say 66x66 this is the most balanced combination.
longer stroke favors a lower reving torquier motor, while shorter stroke will produce a higher reving peak hp motor.
the 240 kit, while capable of producing more power puts the motor so far out of balance that it has its limitation, due to the mass of the piston changing direction and short rd deflection angle etc.
ideally, if one were to use the ct/la sleve 200cc aftermarket cylinder with the honda style porting (reported for application), and a +4 or 6 crank with a significantly longer rod coupled with a button flywheel ignition a much better advance curve, and custom pipe, you could spin the blaster motor 10~1100 rpm and make some SERIOUS power.
a typical 125 mx bike has a bore of 54mm and a stroke of 54.5 mm, 125's make around 35 hp stock, and rev to the moon but you have to be in the revs to make the power.
Now consider the blaster at 66x57, thats basically a 250r piston stuck on a 125 ( actually a 66.5 mm piston (2nd bore) on a 54.5mm 125 bottom end would be 189 cc's) thats 6 cc's different than a 125 and 51cc's different than a 250r... that should put things in better perspective. now if you have ever seen a 125 piston, its pretty small, the blaster piston is a LOT bigger, i cant find the weigt specifics with a quick seach but you are probably doubling the mass, thats a lot more weight switching direction 8000~10000 times a minute. add in the 72 mm 240 piston and it gets even worse.
By building the motor closer to square by leaving the bore alone and increasing the stroke as much as possible with a longer rod to reduce deflection you make the downwards power stroke much more powerfull, and decrease the effect of a big chunck of alum switching directions.
this type of motor will rev higher and provide the best balance of low end and top end while significantly increasing top end due to the 2000 extra rpms you can gain.
To put that in realistic terms:
with stock tires/gearing at 7500 rpm the blaster goes 52.2 mph
with stock tires and gearing at 10000 rpm the blaster would go 69.5 mph
now change the counterhsaft sprocket to a 14.. @10000rpm your doing 75 mph
125's run mid 30's hp numbers @11500 rpm or so, with a longer stroke and bigger bore, say 63x66 if you can get it to spin to 9500~10,000 you would be seriously trucking
the real trick would be getting a 65 mm bore, that would keep legal in the 200 class with major power.
imagine kicking ass on all your buddies with big bore kits, and you have a kit making your bore SMALLER than stock.
Im not an engine guy, suspension is my thing, so these are just ideas
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