high compression vs. stroker?


46 replies to this topic
  • jeffboyd47m

Posted October 03, 2008 - 03:05 AM

#21

I have an 08 with the Athena kit and HotCams. I looked into the Stroker kit and was tempted but chose to stay with just the big bore kit. Falicon does excellent work and has a great reputation but they are located in florida. The closer alternative would be Crank Works out of Arizona, http://www.crankworks.com/.
I talked to them and they were very helpful and can tell you the pros and cons of every stroker option.
Let us know how everything turns out.

  • ThumperKid250F

Posted October 04, 2008 - 06:56 AM

#22

you mind if i ask how much that cost you?


ok i got the custom forged 1pc knife long rod,crank is blueprinted/balanced/welded, got the spaceer plate, longer cam chain. and the install parts like longer bolts and such.. it cost me right around $900.00

im also useing a CP Hi comppiston..

give them a call and let them know what u want to do and they will give you straight no bullcrap answers..

  • yz480doinwork

Posted October 05, 2008 - 08:06 AM

#23

is your timing still the same with the spacer and longer chain?

  • ThumperKid250F

Posted October 05, 2008 - 06:56 PM

#24

is your timing still the same with the spacer and longer chain?


i dont see how it would change the timing? the only reason you need the longer chain is because your increasing your stroke of the motor and when you increase the stroke you need to increase your cilinder hight by adding a spacerplater, then when you have the spaceplate your stock timing chain is not going to be the right size so you need a longer one..

did you call them up?

  • yz480doinwork

Posted October 05, 2008 - 07:26 PM

#25

i have heard that a spacer messes with your timing because of the cam angles but you know how the internet is. no i havnt made the call yet. i will soon

  • grayracer513

Posted October 05, 2008 - 07:55 PM

#26

i have heard that a spacer messes with your timing because of the cam angles but you know how the internet is. no i havnt made the call yet. i will soon

It could, but it depends on how the extra stroke is handled.

When you increase the stroke by 3mm, the piston goes 1.5mm farther down, and 1.5mm farther up than it used to. Since there is nowhere near that much room between the piston and head, something has to be adjusted. The options are:

> Shorten the rod. This works, but is a bad idea unless you are building a very low RPM engine.

> Move the wrist pin up higher in the piston. Requires a cu$tom made pi$ton, and without using a single compression ring configuration, there is no room for this in the big YZF.

> Raise the cylinder. The complication here is that the crank and cams get moved farther apart. If this is done with the stock rod length, what happens is that both cams are rotated slightly forward (advanced) as the cylinder is raised. The difference will not be great just by raising it 1.5mm, but it could be enough to matter in some cases.

The difference with the Failcon set up is that they lengthen the rod, which you would want to do anyway, not to fit the stroke under the head, obviously, but to generate a little more top end with the longer stroke. This requires the extra long timing chain (one link on the front side, and one on the back). If they have paid attention, the cylinder will have been raised by the same amount as the chain pitch, and the timing will be spot on.

Ask them about it.

  • yz480doinwork

Posted October 06, 2008 - 04:57 PM

#27

man the failcon kit is pretty expensive. i have been looking at the hotrods kit which retails for $359 also my dad is a dealer for them. it would be easer for me. but if it is a short rod maby it wont hold up???

  • jeffboyd47m

Posted October 07, 2008 - 02:36 AM

#28

man the failcon kit is pretty expensive. i have been looking at the hotrods kit which retails for $359 also my dad is a dealer for them. it would be easer for me. but if it is a short rod maby it wont hold up???



I was told by Crankworks that the Hotrods crank kit is hard on piston skirts and the cylinder.

  • ThumperKid250F

Posted October 07, 2008 - 11:59 AM

#29

man the failcon kit is pretty expensive. i have been looking at the hotrods kit which retails for $359 also my dad is a dealer for them. it would be easer for me. but if it is a short rod maby it wont hold up???


hey its up to you but i wanted my crank done by one of the best..

i havent really heard anything on hotrods cranks

  • grayracer513

Posted October 07, 2008 - 12:46 PM

#30

man the failcon kit is pretty expensive. i have been looking at the hotrods kit which retails for $359 also my dad is a dealer for them. it would be easer for me. but if it is a short rod maby it wont hold up???

Falicon cranks are the best going. Their Super Crank with the added weight is even better, and using a long rod is unquestionably the best approach if mid and up power is what you want.

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  • yz480doinwork

Posted October 07, 2008 - 02:32 PM

#31

does anybody know if there i a pisten company that makes a 98mm pisten that has a higher pin position so i can run a 3+ mm stroke but a stock rod?

  • yz480doinwork

Posted October 07, 2008 - 03:09 PM

#32

never mind. i just called CP pistons and they can build me a big bore piston and move the pin up 1.5 mm. i think im going to do that. buy a hotrod w/out the short rod and put my stock rod on it and run a stroker CP piston. but maby not........what you guys think? better than a short rod but not as good as a long rod with a spacer?

  • ThumperKid250F

Posted October 08, 2008 - 01:00 AM

#33

never mind. i just called CP pistons and they can build me a big bore piston and move the pin up 1.5 mm. i think im going to do that. buy a hotrod w/out the short rod and put my stock rod on it and run a stroker CP piston. but maby not........what you guys think? better than a short rod but not as good as a long rod with a spacer?


maybe im not understanding this right but if you get the piston moved up 1.5mm dont you still need a spacer because your going to hit your head?

to me it seems like you got a lot of money in your bike already? so why dont you go ahead and finish it off with the falicon setup?

  • grayracer513

Posted October 08, 2008 - 05:46 AM

#34

He's not moving the piston up, he's having the pin moved farther up in the piston. That moves the piston crown down in the bore.

  • ThumperKid250F

Posted October 08, 2008 - 12:03 PM

#35

He's not moving the piston up, he's having the pin moved farther up in the piston. That moves the piston crown down in the bore.


oo got it

  • yz480doinwork

Posted October 08, 2008 - 07:59 PM

#36

i know i sould go full out but im 15 years old and paying off my bills working at my dads yamaha shop after school everyday. dont have much money to spare so im trying to find the cheapest way that will hold together. i might end up just buying a failcon kit.

  • sandrappy

Posted October 09, 2008 - 06:43 AM

#37

I understand building a motor on a budget. I have built and raced tons of motorcycle and atv engines from mild mods to full out drag bikes with all one off custom parts. Here is a little tip i have learned. If you don't have the money to do it the right way the first time then wait and save your money to do it all at once. Reason is you have enough money to buy some parts now later on down the road you will want more and end up tearing the engine down and doing it again, thus in the long run it will actually cost you more money.

with that being said you need to add up your options. I have cp custom make me pistons all the time. A hot rod crank = $380, disaseemble and installation of new stock rod plus cost to balance and heavy metal = $230 (trust me you will want to balance this crank), custom cp piston = $260. total of $870 this are approximate prices. I believe the falicon cranks aren't much more than that, plus you will get a longer rod, and falicon can actually make you a +6mm or bigger crank. The strokers do help in power but they give you more torque than anything. If it was me i would do high compression piston, cams and good porting. You will be suprised in the power you gain as the athem pistons are junk.

Also like stated before call up crankworks and ask them about their custom stroked cranks and prices. They have done tons of yfz cranks and will be able to help you build one to suit your needs. They are typically cheaper than falicon and still do very good work.

  • yz480doinwork

Posted October 09, 2008 - 07:43 PM

#38

does crankworks do a shim, cam chain and bolts? there prices look a lot more reasonable and the cranks look like good quality. i will call them when i get back from my vacation

  • yz480doinwork

Posted October 20, 2008 - 06:45 PM

#39

back on the nos subject. boondocker's kit comes with a 20 oz bottle and they say a 16 oz will fit in most air boxes. i ran into a guy that was running noz and he said the air boxes on yzs are bigger so you can run a big nos bottle. i didnt get to talk to him much but does any one know if you can fit a 20oz bottle in the air box of a yz? or will only a 16 fit?

  • ThumperKid250F

Posted October 21, 2008 - 07:27 AM

#40

back on the nos subject. boondocker's kit comes with a 20 oz bottle and they say a 16 oz will fit in most air boxes. i ran into a guy that was running noz and he said the air boxes on yzs are bigger so you can run a big nos bottle. i didnt get to talk to him much but does any one know if you can fit a 20oz bottle in the air box of a yz? or will only a 16 fit?



um why dont you just get a 16 oz bottle and a 20 oz bottle and see witch one fits in your airbox?





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