Stroker question

[greco400]

I was curious going threw to look at parts and i seen on powroll and it says :
4.0mm STROKER WITH POWROLL 'TOUGH ROD'

$544.50 #16092

This stroker utilizes our super-strong 'Tough Rod' (with your stock pin and needle assembly). The shorter rod allows you to utilize any 400EX piston kit (piston skirt may need to be shortened) and does not require any case or gear modifications.



4.0mm stroke = 425cc with stock piston, 440cc with 87mm piston, 460cc with 89mm piston

PISTON KIT IS NOT INCLUDED WITH THIS STROKER

INCLUDES: New Powroll Rod.

REQUIRES: Send in your crank for stroke modification. Read our Stroker Spec Page for information on shipping cranks to us.


Now when it says this 4.0mm stroke = 425cc with stock piston does that mean that they don't bore out the cylinder and you the stock piston and the stroke makes it 425cc

Im just curious if this would be could with a stock high compression piston like mine if i ever got it with a port and polish i was wonder what that ment sooo if you could feel free 2 asnwer thanks!

[TC426EX]

Displacement is not only determined by the size of the piston, but the stroke as well. Thats why if you put a stroker crank in a 425 motor it makes it a 450 and if you put it in a 440 it makes it a 465. It would work with your std. bore high compression piston, but for that much money why dont you save some cash and just get a bore job done. If you bore it out and put a Hi comp piston and then port and polish it and add a cam you will be rockin. And you should be able to do the bore kit and add a cam for less than what the stroker crank would cost. Porting and Polishing is gonna cost you between 4-5 hundred bucks no matter how you slice it or who you talk to...

[greco400]

So your saying it ain't worth the money? I just got my motor done cam high comp piston and all that and i didn't wanna go big bore but now i want more power i need more power mid to top (3-4 gear) But i was going to get a port and polish and tell the guy i need more of a mid port job ? But i don't want to go boring but i was going to see bout stroker if anybody else has a answer post it!

thanks!!!!!!!

[K_Fulk]

You will get more torque with a stroker. I have that powroll kit for my stroker motor, its a nice package but havent rode it yet to see how it runs.
You get the heavy duty rod too, I dont see why most people dont stroke them. If there getting a heavy duty rod anyway your only looking at about 200 more dollars. Might as well do it if your tore down that much to start with.

[INFANTRY RACING]

i got that kit with a 425 piston and it rocks. the rod will work with any piston accept for the oem honda piston. it will work with an aftermarket hi comp stock bore piston.

as far as port n polish go look up eric gorr's forward motion. they did my head and my powerband is smooth. it pulls hard from bottom to top and keep on going. they do great work for only 175 dollars.

[greco400]

Thanks im thinking bout that storker in the furture!! INFANTRY RACING i got a aftermarket piston just high comp soo that will work :blah: but im just worried bout relible i want something i can ride trails with put around race im gonna check with my piston compression 2marro i think its 10 8 1 if its that and that stroker will i blow head gaskets? I kno nuthing bout it do they shorten the rod so it don't hit the head or what do they do if u could explain it it would help thanks !!

[K_Fulk]

http://www.powroll.com/tech_specs_strokercrank.htm

You forgot to read this page while you were on there website, There is a lot of good information on here if you dont know much about strokers.

[INFANTRY RACING]

Originally posted by greco400
Thanks im thinking bout that storker in the furture!! INFANTRY RACING i got a aftermarket piston just high comp soo that will work :blah: but im just worried bout relible i want something i can ride trails with put around race im gonna check with my piston compression 2marro i think its 10 8 1 if its that and that stroker will i blow head gaskets? I kno nuthing bout it do they shorten the rod so it don't hit the head or what do they do if u could explain it it would help thanks !! the stroker crank is awsome. you'll have no problems with head gaskets. a stroke is more reliable than a big bore. if you go with the heavy duty rod they install a shorter rod. on their other crank they shrink your rod. i'd go with the heavy duty rod like i did.

[greco400]

Thanks!!

Ok now bout port and polish how could i contact that guy? I was gonna get like hetirck racing since i got there pipe and stuff but im looking for a port and polish that aint to expensive but i want it to pull harder in every gear soo if you know like what i tell them or w/e then post it :blah:

thanks!

[cals400ex]

Originally posted by greco400
Thanks!!

Ok now bout port and polish how could i contact that guy? I was gonna get like hetirck racing since i got there pipe and stuff but im looking for a port and polish that aint to expensive but i want it to pull harder in every gear soo if you know like what i tell them or w/e then post it :blah:

thanks!

i would contact GT thunder. the prices are tough to beat, they have a good reputation, they have a good turn around time, and the customer service is great.

[wilkin250r]

Just be careful with the high-compression piston, especially if you went with a an 11:1 or lower to run pump gas. The stroker crank WILL increase compression.

Compression is calculated by dividing the displacement by the combustion chamber volume at TDC. So if you have 397cc (stock displacement) with an 11:1 comp piston, your combustion chamber is 36cc (theoretically) Now, in theory, this combustion chamber volume should stay the same after you put in the stroker crank, only now you have 420cc with the increased displacement from the 4mm stroker crank.

So 420 divided by 36 gives you a new compression of 11.6:1

Now, somewhere around 10.8-11 is the cutoff for pump gas. The stroker crank will usually give you about another half point of compression, which may take you beyond pump gas to a 50/50 mix.

[Ryan]

Originally posted by wilkin250r
Just be careful with the high-compression piston, especially if you went with a an 11:1 or lower to run pump gas. The stroker crank WILL increase compression.

Compression is calculated by dividing the displacement by the combustion chamber volume at TDC. So if you have 397cc (stock displacement) with an 11:1 comp piston, your combustion chamber is 36cc (theoretically) Now, in theory, this combustion chamber volume should stay the same after you put in the stroker crank, only now you have 420cc with the increased displacement from the 4mm stroker crank.

So 420 divided by 36 gives you a new compression of 11.6:1

Now, somewhere around 10.8-11 is the cutoff for pump gas. The stroker crank will usually give you about another half point of compression, which may take you beyond pump gas to a 50/50 mix.


Couldn't you lower the compression ratio by getting a shorter piston skirt? And still stay at the same displacement?

[wilkin250r]

It all depends on where the pin is located with respect to the dome. By moving the pin closer to the dome, you effectively LOWER the dome within the cylinder, which will lower your compression.

Basically, my point was that with an 11 compression piston with the stock stroke, that exact same piston becomes 11.6 with the stroker crank. So if you want to keep the same compression ratio, you will need to get a different piston.

[greco400]

Thanks you guys explained it well!! Now hopefully i can find the box of my piston to see what compression hopefully it its 10 :8 1!
THe stroker seems relibile If i get it? I was just worried i would blow head gaskets ! do you think 10:8 1 would be good with that stroker and running 93 gas?


Now Do you guys think i should get this or not im still debating! I kno they shorten the rod but im worried of it breaking a rod And what the pros and cons of the stroker If i got this thanks!!

[INFANTRY RACING]

go for the heavy duty. stock rods weak. as far as gas i am probably running closer to 14:1 and i am getting by runnin 100 octane gas city race gas.

http://www.ericgorr.com/

this guys well known in the motor cycle engine builder world. he can build a killer 2 stroke. his 4 strokes aren't bad either

[greco400]

thank you guys you were a big help