What would adding 3mm to a crank add CC's?

[Jgringo]

I am new to adding mm to the crank for power. Can anyone explain this to me? Does it just reposition the crank so that it is at a different degree angle in the power stroke?

[ohsobad_chevy]

Originally posted by Jgringo
I am new to adding mm to the crank for power. Can anyone explain this to me? Does it just reposition the crank so that it is at a different degree angle in the power stroke?

The name for this is "stroking" because your giving it a longer stroke. ;)

[nicker71]

Im going to be adding a +3 stroker crank to my yfz, it will make it a 471CC.
It makes the stroke longer giving me more tourqe.

[archie21]

yes it changes displacement... the formula for calculating displacement is ~3.14*r^2*h

so adding 3mm to the crank (h is measuring stroke) would increase displacement accordingly

also stroking motors are much less reliable than boring for displacement

[Jgringo]

How would it make it less reliable? Just puts more pressure on the cases and bearings? I am just curious to see because Max-power's big bore adds 4mm to the crank also for the "521" or whatever cc's... Is this not a good route?

[archie21]

well don't get me wrong, it's not like adding a stroker crank is going to instantly ruin your engine... its just that its less reliable than boring your cylinder... a longer stroke crates more mechanical moving mass and creates greater stresses on engine components...

[pro-rider46]

a stroked motor can be much more reliable than a bore job, it just has to be done correctly, and i dont think that a 471 is obtainble asuming that its on a 05, a honda with a stroker (+3) is a 471, and it has a longer stroke from factory, and is 449 cc stock, and the yfz is 439, so i think a +3 stroker in the 05 yfz would calculate to 460

[nicker71]

the yfz hotrods +3 crank will make a 471 no mater what year it is. Its doesnt matter if its a 439 or 449 the older yfz motor have a smaller stroke, (not bore).

From what I read about the +3, it can be kept reliable my running a stock pistion and keeping the upper end stock.

[Idaho_Outlaw]

Does any one know for sure how much they took off the connecting rod? was it 1.5mm or less or more. Just wondering how much squish/quench is left in it.

[pro-rider46]

the 05 hotrods stroker is only a 450cc total displacement and they 06 stroker is +3mm and gives it a 471cc displacement, the 05 stroker is only +1.4. so only on the 06 is 471 achievable

[Ride1Rob]

Originally posted by pro-rider46
the 05 hotrods stroker is only a 450cc total displacement and they 06 stroker is +3mm and gives it a 471cc displacement, the 05 stroker is only +1.4. so only on the 06 is 471 achievable

From the way HotRods explains it is that if you have a stock 04/05 it's a +3 crank. If you have an 06-08 it's only a +2 crank because they already have a longer stroke. My bike is an 04, but I have the WR crank which makes it a TRUE 450 like the 06-08's so if I were to use that crank it would only be a +2 for me. The crank is the same for each bike no matter what year.

[ohsobad_chevy]

Originally posted by Ride1Rob
From the way HotRods explains it is that if you have a stock 04/05 it's a +3 crank. If you have an 06-08 it's only a +2 crank because they already have a longer stroke. My bike is an 04, but I have the WR crank which makes it a TRUE 450 like the 06-08's so if I were to use that crank it would only be a +2 for me. The crank is the same for each bike no matter what year.

Exactly how I understand it as well. :cool:

[pro-rider46]

Originally posted by Ride1Rob
From the way HotRods explains it is that if you have a stock 04/05 it's a +3 crank. If you have an 06-08 it's only a +2 crank because they already have a longer stroke. My bike is an 04, but I have the WR crank which makes it a TRUE 450 like the 06-08's so if I were to use that crank it would only be a +2 for me. The crank is the same for each bike no matter what year.

im probably wrong on this cause im a little slow...but i think it says that the true 450 stroker is the hotrods stroker and not the +3.

check it out for yourself

http://www.hotrodsproducts.com/index.cfm?fuseaction=cProducts.view&productid=490

[Ride1Rob]

Originally posted by pro-rider46
im probably wrong on this cause im a little slow...but i think it says that the true 450 stroker is the hotrods stroker and not the +3.

check it out for yourself

http://www.hotrodsproducts.com/index.cfm?fuseaction=cProducts.view&productid=490

You're confusing yourself! The crank you have posted is the same crank that the 06's - 08's already have. That crank bumps the 04&05's up to a TRUE 450 as it states in the add.

This is the crank in question Grasshopper ;)
http://www.hotrodsproducts.com/index.cfm?fuseaction=cProducts.view&productid=524

[Idaho_Outlaw]

Year dosent matter a +3 is a plus 3. Stroke and bore determine the displacment. So if your still stock bore then only thing changing is stroke. you can put a +3 in a 04 or an 08 and there both going to be 471cc. Pro's More torque Con's more stress on Cylinder and mid stroke because the rod is shorter and stroke longer.

http://www.hotrodsproducts.com/images/products/4173_1175263558171.jpg

[pro-rider46]

oh ok, i see, i thought that they were two different cranks. and not the same for all years. sorry, im a honda guy so i dont know all of this yammy stuff. and i thought in 06 they tottally redid the yfz like the hondas... sorry... and thanks for straighting me out. haha

[ready4oryou2]

Somebody correct me if I'm wrong but I think I heard that by adding stroke to the 04 & 05 means you also have to watch your valves so the piston dosen't hit them. Again not sure so correct me if I'm wrong.

[WOLFPACK]

Not so much with the small amount of stroking we are talking about here. We just built a Raptor 250/300 (jointly with MaxPower) and added 6mm of stroke to it. To accomplish it we had to add a spacer plate. Thats alot of stroke and time will tell the reliability. What everyone is talking about here is just a small change and it won't effect reliability very much. If you'll recall there was a ton of speculation about Gust's Yoshimura 450 when they first put it together because it was stroked. It turned out to be more reliable than even Yoshimura had thought.

If you want to increase reliabilty then do the oil mod update. You don't have to purchase a new side cover. We machine the old cover to accept the new oil nozzle. It's cheap insurance!