6mm crank

[panther83]

hey i was wonderin how much hassle would it be to put in a 6mm crankshaftin my blaster. my stock crank is messed up so i thought i could put a 6mm if it wasnt too hard. i heard u got to do alot of machine work to it, but i'm not sure how much. would i have to take it to a shop or could i do it myself?

 

[tryingtobefaster]

all you gatta do is put it in, if you know how to do a stock one you can do it, it should come with all the stuff, it takes a new sleeve, and a plate that makes the stroke a little longer. it should come with instructions too.

 

[chris61988kb]

Hes wrong, anything bigger than a 3mm stroker and you need to shave a cartain part of the inside of the case.

 

[Jabes]

yeah I'm not sure how much you have to shave but I would go with like a 3mm or 4mm instead because a 6mm is insane

 

[bigdblaster]

u have to shave with a 4mm.. you would really be shaving alot with a 6mm that would be insane though,i know what tryingtobefaster is talking about i have seen them on ebay they give u a plate to put on the head im not sure how that would really work out but if anyone knows how it would.let me know...

 

[rocky318]

unless your drag racing i would just do a 3mill cause that much case trenching for a every day trail rider is not very reliable

 

[rocky318]

plus you would have to port for the added stroke. but it would make a sick lil motor, it would fly.

 

[chris61988kb]

unless your drag racing i would just do a 3mill cause that much case trenching for a every day trail rider is not very reliable

why wouldnt a 6mm or 4mm be reliable for the everyday trail rider.

 

[chris61988kb]

but yea, unless you want to put even more money down to have ur cases trenched just go with the 3mm stroker, pop it in and ur ready to go, no shaving, no nothing!

 

[vspec]

Because that long a stroke will put a lot of stress on the motor.

 

[blasterboy91]

ya just go with a 3-4mm crank

 

[dblaster]

in theory it will make it have more bottom end torque more mass to turn. shouldn't the crank be supported by the crank bearings so as long as there in no shaving of this area it should be okay correct? if it comes with a piston maybe its wrist pin is moved up or down so there is no porting. at least thats the difference between small block engines and big block engines a small block will rev faster having more top end while a big block has longer stroke and bigger bore has more to move to get going more torque. my experence in the engine world.

 

[panther83]

the 4mm is a bolt on right? or is there still some shaving to be done?

 

[hickskateboarder]

the blaster motor has very little clearance between the rod and the cylinder wall and also between the bottom of the case and the crank. a stroker means that the distance from the center of the crankshaft to the center of where the rod connects to the crank is lengthened by some distance. so it brings the rod closer to the bottom of the cylinder wall and also closer to the bottom of the case, so the bottom of the case has to be trenched for the crank clearance and the bottom of the cylinder wall has to be shaved off a little to allow for the rod. i may be wrong, but i believe it is half the distance of the stroke (3mm, the difference in distance from center crank to center of where the rod connects would be 1.5mm) because it would push the piston up another 1.5mm and bring it another 1.5mm lower, a difference of 3mm, thus a 3mm stroker.

the 3mm stroker doesn't need cleared b/c the stock clearance is just enough to allow for it. but notice if you get a 4mm stroker your supposed to trench the crank i think 2mm. so the 3mm stroker has VERY little clearance.

since you have to trench for a 4mm stroker, it does'nt seem that a 6mm would be much more work, just trench out a little more. only thing is the bottom of your case is thinner where you trenched. just don't poke a hole in it lol.

and yeah like they said, you need to port for the difference in timing b/c it's a 2 stroke. change in placement and size of cylinder ports on a 2 stroke is like change of lift and duration in 4 strokes.

 

[blastermaster85]

Hes wrong, anything bigger than a 3mm stroker and you need to shave a cartain part of the inside of the case.

this is very trueI:I

 

[blastermaster85]

the 4mm is a bolt on right? or is there still some shaving to be done?

have to do shaving

 

[rocky318]

those extra couple mm dont seem like much but it just like any race engine, once you start trenchin, shaving and boring stuff you cut the reliabilty down by altering the original design and deminsions of the motor. and if you really think about it you have so many hours off riding before its time to rebuild any ways. so if you do mostly trail riding you will most likely ride it alot more so you will run up the hours on that motor fast. thats why i say it wouldnt be reliable for just everyday riding. but drag racing it would be great assuming that you dont ride it often, because your up high for a couple seconds then you shut it down, as opposed to trail riding where its hi,lo,hi,lo, up, down,up, wide open and so on. and for along period of time the heat and stres will take its toll faster. i think the safest way to go is the 3mill less to no trenching and there cheaper to, but it all depends on how you ride, what you like, and how deep your pockets are.

but what kinda fun is playin it safe, to hell with go all out lol

 

[fmxr47]

i noticed on ebay that the 3mm strokers have a plate also that you put at the base of the cylinder on the crankcase, is it necessary?, ive been hearing that there is no shaving and im considering the 3mm does this plate make up for the shaving?

 

[bkg479]

Not sure but I think they give you the plate so you dont have to do any head mods, casue when I did my 4 mm I had to have the head milled 2mm

 

[hickskateboarder]

read my last post. 3mm stroker brings the piston up another 1.5mm. if you don't space the whole cylinder up, the piston will smack into the head. or at least raise your compression to like 14 or 15 to 1 which means some serious race gas.