Stroker crank?

[MidnightBusainSD]

Just curious if anyone has done this or not i just wanted to throw some more umf on my bike i was thinking of doing some cams and the idea of a mabey doing a stroker crank also but leaveing the rest stock. i don't plan to do nos or anything. has anyone done this? what do you think the results mabey? would it still be a good daily rider or what do you think?

any input is greatly appricated and thanks again

 

[TheNOSman]

I don't think a stroker crank is what your looking for. The general consensus is that you loose streetability with a stroker due to the higher heat generated from it. Besides that a crank is a big move for a street bike anyway. I would do a big bore kit before a crank. It will be more streetable and I think you will like the bikes reaction to it better. Depending on what you want to do or spend$$ you may want to look at Brocks 190HP drop in kit. It's a very clean and simple installation and comes with everything you need. It will maintain the stock bore and stroke also but bump your HP up a bit.

 

[MN72Busa]

Todd, here's my input...I have no input on this matter for ya...lol...is it still appreciated

 

[MidnightBusainSD]

Well i have done big bore before and well for what i have spent to do big bores granted i have done rods and pistons at the same time i was not impressed with the HP increase for the cost thats where i thought if i did just a stroker crank granted i have not heard enough about stroker setups yet to see what there gains over the HP but i know they do gain alot more tourqe.

Guess i should do more research hmm mabey i will just add higher compression pistons then i don't know i have heard of 1507 that are running on the street anyways granted i don't know how much on the street they are running either.

 

[TheNOSman]

Hey Midnight...

How much $$$ are you looking to spend?

How much HP are you looking to get?

I am in the process of building up my bike as well. The big difference is that my bike is mostly for the track and not street but I am building a 1507 motor. By the time I am all done including all the extra parts I should have arou nd 245HP or so. I plan to run in the high 8's in the 1/4 mile. If all you are doing is street riding with no racing a 1507 would probably be too much. But I have done a ton of research on all of the different types of mods from all motor to nirtous to turbo so I might be able to help you out more if I know what you are trying to accomplish.

 

[MidnightBusainSD]

Well i'm looking for the most bang for the buck with out alott awork involved i mean ok big bores are a pretty easy 3000 bucks? correct and i have had a 1363 before and i loved it. it had nos but i barely ran a bottle through it ove the 2 years that i owned it. So i know nos is not for me. I already own a turbo bike so no need for another one. I was looking at just doing cams they cost about the same as doing a stroker crank i don't plan to do the rods or the pistons i just wanted to see if i could throw the stroker crank in and not have much of any issues and just taking a estimate that should make the bike like what 1409cc? well i though it really shouldn't have any heat issues since it's still running the stock jackets and everyhtinb but the tourge and the power should be close to 200hp? wouldnt it? i mean normal 1397 motors make 200-210 hp on pump fuels. and well a stroker crank cost ya about 900 bucks so money to power i think it makes sense mabey i'm going about it all wrong through i don't know. I'm not a motor guru i'm just making a assumption of what i have all seen from Overboar motors and overboared stroker motors

as for what i wana spend like i said as little as possible but to be reliable lol i know them 2 phrases don't always go tother the best

 

[busa crazy]

I HAD A 3MM PISTON KIT WITH A STROKER CRANK THAT MADE AROUND 220HP WITH STOCK HEAD!! BUT IF YOUR PLANNING ON RUNNING ON THE STREET I WOULDN'T SUGGEST IT,THE ONLY PEOPLE I KNOW THAT RUN THEM ON THE STREET ARE STREET RACER AND THEY HAUL THEM ABOUT A MILE FROM WHERE THEY ARE GOING TO RUN SO THE OTHER RACER THINKS THAT IT'S JUST A REGULAR STREET BIKE.

 

[PocketRocket]

Interesting!! I am learning about the bikes and parts as well. What can a person do to get 200 HP on a stock motor? What does a big bore Complete kit cost ? What does it contain? Thanks for the advise!!!

 

[DonnieF]

I am no "HAYABUSA" expert as i havent even take a head bolt off mine. But i have been drag racing since i was 17 and building my own race motors fpr 15 years and i would like to address a few comments here. First off you cant change to a longer stroke with the stock wrist pin centers in the piston without beating the cylinder heads off the block , you will have to change pistons along with crank shaft. Second why would a stroker crank not be streetable or create all this heat like was mentioned above?

Now , for all you horsepower seekers out there ... Ive seen the big bore and stroker question asked alot on this board and always the owner isnt impressed with the results ..... Now you can either read this and say this crazy SOB has no idea what he is talking about and go about your day or you can listen to someone who isnt a stranger to a superflow 600 bench and a dynomometer. Again i am not a hayabusa expert and there are far more guys on here with more experience with busa motors than me , but a combustable engine is a combustable engine ..... Engines are designed on a few variables , rod to stroke ratio , cylinder volume and fill with head flow in cfm AKA Volumetric efficiency , compression and timing. You arent going to see a huge difference with a big bore kit or a stroker motor without touching the cylinder heads. When you create more cylinder volume or cubic inch displacement and you cant fill it with cylinder head flow , you are pissing in the wind (excuse french). Now when you create more air flow along with that extra Bore or stroke then you will see a considerable difference. I know some of you guys i am not telling you anything , but im going to break it down for the people wanting to learn. A engine is a big air pump thats all it is , Nitrous , turbos , superchargers , whipple chargers etc. all do the same thing , they just introduce more air into the cylinder. Superchargers and turbos force more air and nitrous injects it , that along with more fuel creates horsepower. Now going about this the naturally aspirated way is a little more complicated then a fogger nozzle or bolting on a big hair dryer. Its a trick to create more air flow while keeping good velocity in a cylinder head and is why i dont reccomend home porting your heads. WEhich puts me back on topic , if i were to choose between a big bore kit or a stroker crank .... I would choose the crank , the extra stroke will create more torq , which is what you feel in the seat of your pants when you crack the throttle. So basically to answer your question , if you are looking for more power , then stroke it and get the heads ported but dont stroke it and leave everything else stock or you will be very UNHAPPY for the money you have spent.

Ok im done babbling , sorry guys i just wanted to address the threads i have read over and over again on this.

 

[warwgn]

I got lost on the extra heat issue as well??

Going along the same lines as what DonnieF said, not a busa motor expert, but I am in the process of stroking my raptor motor. I will take it from 660cc to 720 cc by way of a +4mm stroker crank and the 102mm piston(which I already have currently a 686cc). This along with port work on the head will take up to the 60-70hp range (dont laugh, thats alot for one cylinder!!, and stock on my raptor is only 38hp)

Anyway, point being you still need to match your parts and mods or it's all for nothing. I agree you will get a bigger gain out of stroking it though.

 

[TheNOSman]

Well to be honest I don't know for a fact it creates more heat. I have some other threads on here talking about what I am doing to my motor and people keep telling me that so I figured I'd pass it along hoping for a better explaination. If it matters I'm still going to stroke mine as well. 1397 big bore plus +5mm stroke for a total 1507 plus NOS! Thanks for the info DonnieF!

 

[TheNOSman]

(PocketRocket @ Nov. 11 2006,17:24) Interesting!! I am learning about the bikes and parts as well. What can a person do  to get 200 HP  on a stock motor? What does a big bore Complete kit cost ?  What does it contain?  Thanks for  the advise!!!

I'm a little confused at getting 200HP on a stock motor? If the motor is stock then all you can do is use a power adder of some kind (turbo, NOS).

For the big bore kit I am personally going with Brocks package. The cost is around $4,000 but it is VERY complete. Carpenter also has a very nice package for about the same cost. You can check them both out online.


www.carpenterracing.com

 

[Mr Brown]

(TheNOSman @ Nov. 13 2006,13:29) For the big bore kit I am personally going with Brocks package.    Carpenter also has a very nice package for about the same cost.  You can check them both out online.

Or you could contact Golden Child (Cloud 9) who sponsors this board................

 

[Professor]

I won’t even start to claim to be an expert in Hayabusa engines. I have had a bit of experience with stroked and destroked V8s. Putting a 5mm stroke on a stock bore will yield about the same size engine (about 1401) as a stock stroke 3mm over (1397). I can’t believe there would be much if any difference in heat. Everything else being equal I would expect a bit higher peak horsepower out of the 1397 and a bit more peak torque out of the 1401. Then you start throwing all of the possible variables at it. Piston dwell time would be a bit longer for a longer stroke, does the larger bore eliminate some flow restriction because of shrouding of the valves etc. Regardless the big change in both torque and hp is still going to come from the added displacement.

If you stroke it, you are going to have to buy pistons or shorter rods. Carrillo makes a 2.5 mm shorter rod for the stock compression height piston with the common 5mm stroke. You are going to have to buy a billet or welded stock crank to stroke the engine.

So to gain 100 cc.
1) With pistons and welded crank $1400.
2) With block and pistons $875.
3) With rods and crank $2000. But you’ll you want pistons anyhow $2500.

I really don’t see the value of swapping the crank unless you are after something way bigger (1500+)

 

[DonnieF]

professor
You are right , piston dwell will be a bit longer but not enough to not gain benefits from the extra displacement plus with the stroke dont forget your piston skirt will be raised and less reciprocating weight and friction will be introduced when stroking. And a bigger bore actually helps UNshroud the valves but just slightly , you are still restricted by combustion chamber ... its a easy rememdy with back cut valves , multi angle valve seat jobs and reshaping of the combustion chamber but bore isnt an issue really in this case.

I personally as a rule of thumb try to keep cylinder wall thickness as much as possible , we all know that the rod is the weakest link in a motor then cylinder wall, i would much rather have the stroke then the bore.

 

[IFLYLOW]

Donnie, where in AL are you located? You have a shop? I'm interested in a big bore kit, how streetable is a stroker kit? Can it be riden on minimum 100 miles summer trips? Would the cams need changing? What do you recommend for a reliable 80% street/20%strip motor?

 

[mountainmotor]

Proffessor - DonnieF,

Guys ...... a stroker crank does not increase piston dwell time , it decreases it . Using a 5mm crank with the stock lenght Busa rods will make the numerical rod ratio smaller . Using the 2.5 mm stroker rods will decrease the numerical rod ratio even more and maximum piston speed will change because the piston accelerates away from TDC in comparison , more quickly.

Because of this it deluxe affects camming choice leaving room for longer enertia fill time which has little to do with porting and changing the minimum cross section of the Hayabusa's converging inlet throat , an area that can be ruined very easily in context of port velocity .

Now mathmaticaly you could "increase" the piston dwell time of a 5mm stroke Busa engine by using a longer than stock length rod but thats just it . You would be increasing the rod ratio only in comparison and over what the rod ratio was when using stock length rods and the rod angularity would still not be what stock stroke/rod length angularity is .

A 1.95 rod ratio will have more dwell time at the bottom and top of the stroke than 1.8 rod ratio as example and you cannot get the 5mm strokers up to the stock rod ratio for several reasons .

Hope this clears some confusion .

 

[Professor]

My bad, I guess I confused myself.

Thanks for setting it straight.

 

[mountainmotor]

(mountainmotor @ Nov. 14 2006,11:18) Using the 2.5 mm stroker rods will decrease the numerical rod ratio even more

I needed to fix this because I left a key word out
" shorter " .

The 2.5 mm rods are 2.5mm ".100" shorter than stock stock rod length .

 

[MidnightBusainSD]

Well thanks everyone seems like we all got some good information on the topic now. i talked to one mechanic who had done this to a couple motors with alotta success.

but in the end i have decided to not go that route i actually plan to sell that bike now with just a stock motor in it