larger crank

[tmac20031]

If larger carburators are used can a larger crank work with stock banshee pistons?

[Bansh-eman]

If larger carburators are used can a larger crank work with stock banshee pistons?

the carbs have nothing to do with the stock pistons on a bigger crank...

 

if you get a 4mill storker crank your pistons will smack to head when it spinns over... to compinsate this you need blaster pistons or 795 series pistions, these have the position of the connecting rod moved 2mm deeper inside the piston. that still leave you wth 2mm you take up, this is where the spacer plate or cutting the domes comes into play...

 

you can run stock bore pistons , but not oem stock pistons... for stock bore they are the 795 series....

 

also if you do this you will need bigger carbs... your going to starve your motor running 26mm carbs on a stroker

[tmac20031]

the carbs have nothing to do with the stock pistons on a bigger crank...

 

if you get a 4mill storker crank your pistons will smack to head when it spinns over... to compinsate this you need blaster pistons or 795 series pistions, these have the position of the connecting rod moved 2mm deeper inside the piston. that still leave you wth 2mm you take up, this is where the spacer plate or cutting the domes comes into play...

 

you can run stock bore pistons , but not oem stock pistons... for stock bore they are the 795 series....

 

also if you do this you will need bigger carbs... your going to starve your motor running 26mm carbs on a stroker

I figured the connecting rods would have to be changed I just wanted to see if a stock 350 would be able to handle a larger crank as long as bigger carbs are used. Because me personally, Ive never believed in all that " my engine is bigger than yours" stuff, I believe more in revolutions.

[dajogejr]

I'm confused as all hell?

 

Porting and exhaust have more to do with the "need" or "use" of bigger carbs more than the crank.

 

What exactly are you trying to figure out/contemplate?

[tmac20031]

I'm confused as all hell?

 

Porting and exhaust have more to do with the "need" or "use" of bigger carbs more than the crank.

 

What exactly are you trying to figure out/contemplate?

Well, Ive always thought that when you use a larger crank, one rotation takes longer and the crank is heavier thus needing more fuel in order to power the piston enough to make the rotations easier and faster.

[dajogejr]

Nope...not so the case. Stock carbs will power a stroker just fine.

 

Now...if you want to talk about power gains, sure...bigger carbs help if the engine is setup to breathe properly, a la porting, etc.

 

Longer stroke, longer rods generally ad a few HP and some torque...but they won't set your hair on fire. I think I read a 4mil long rod crank is good for 7% increase in power. Nothing earth shattering...

 

A good port job, pipes and bigger carbs are where the power is.

[Bansh-eman]

on a storker crank the rod has been moved x amount of mm down on the crank... so when the motor turns it is now x amount of mm higher in the cylinders making your displacment higher... now the distance that the new crank is lifting the pistons too has to be compensated or the pistons will smack the head and break your motor... so to fix this you got to get pistons that are either blaster or 795 series. these pistons have the point where they connect to the rod moved 2mm deeper( towards the top) now if you have a 4mm stroker you still got 2 more mm to takeup...4mm minus 2mm is 2mm .... so to makeup for this 2mm that will still hit the head you get either a spacer plater for your jugs... or you have the domes cut to take the extra 2mm this makes the pistons not hit the head....

Edited November 15, 2006 by Bansh-eman

[tmac20031]

Nope...not so the case. Stock carbs will power a stroker just fine.

 

Now...if you want to talk about power gains, sure...bigger carbs help if the engine is setup to breathe properly, a la porting, etc.

 

Longer stroke, longer rods generally ad a few HP and some torque...but they won't set your hair on fire. I think I read a 4mil long rod crank is good for 7% increase in power. Nothing earth shattering...

 

A good port job, pipes and bigger carbs are where the power is.

But what if you use something like 14 mm?

[dajogejr]

To be honest, if you're going to use a 14 mil crank, you're already going to have an aftermarket cylinder.

I'm not 100% sure if you can change the porting on a stock cylinder to 14mm port timings.

I think 10 is as big as you can realistically go on OEM jugs.

 

That being said....

 

Once you go that big, you're going to get a cylinder already ported, or that needs to be ported to run right, and you're talking about a drag race quad, so...larger carbs are a given.

 

 

It's a given, just as saying "well, you have a keith black top fuel Hemi motor"...

You wouldn't put the Holley 650 off your daddy's 350 chevy on that thing?

 

Once you get into 7mil and larger strokes, you're in drag bike/hard core dune bike territory and aftermarket cylinders. Bigger carbs are a must....

[tmac20031]

To be honest, if you're going to use a 14 mil crank, you're already going to have an aftermarket cylinder.

I'm not 100% sure if you can change the porting on a stock cylinder to 14mm port timings.

I think 10 is as big as you can realistically go on OEM jugs.

 

That being said....

 

Once you go that big, you're going to get a cylinder already ported, or that needs to be ported to run right, and you're talking about a drag race quad, so...larger carbs are a given.

It's a given, just as saying "well, you have a keith black top fuel Hemi motor"...

You wouldn't put the Holley 650 off your daddy's 350 chevy on that thing?

 

Once you get into 7mil and larger strokes, you're in drag bike/hard core dune bike territory and aftermarket cylinders. Bigger carbs are a must....

Well, how big do you think I can go without modifying anything but the case. The reason I want to stay at 350cc is a bit of trickery, I guess you could say( a sleeper)

 

To be honest, if you're going to use a 14 mil crank, you're already going to have an aftermarket cylinder.

I'm not 100% sure if you can change the porting on a stock cylinder to 14mm port timings.

I think 10 is as big as you can realistically go on OEM jugs.

 

That being said....

 

Once you go that big, you're going to get a cylinder already ported, or that needs to be ported to run right, and you're talking about a drag race quad, so...larger carbs are a given.

It's a given, just as saying "well, you have a keith black top fuel Hemi motor"...

You wouldn't put the Holley 650 off your daddy's 350 chevy on that thing?

 

Once you get into 7mil and larger strokes, you're in drag bike/hard core dune bike territory and aftermarket cylinders. Bigger carbs are a must....

I mean, I know I will need bigger carbs but I dont see why the pistons have to be larger.

[dajogejr]

WHAT??

 

You can run as big of a crank as you want in stock cases, but...after you go bigger than 4mil they have to be trenched, or...grooves machined into the bottom half of the case so the crank journals don't hit/smack.

 

Once you go bigger than stock crank, you'll be bigger than 350cc. Once you overbore the cylinder more than .030, you'll be bigger than 350cc.

 

Who said anything about bigger pistons? We're strictly talking about the crank.

[tmac20031]

WHAT??

 

You can run as big of a crank as you want in stock cases, but...after you go bigger than 4mil they have to be trenched, or...grooves machined into the bottom half of the case so the crank journals don't hit/smack.

 

Once you go bigger than stock crank, you'll be bigger than 350cc. Once you overbore the cylinder more than .030, you'll be bigger than 350cc.

 

Who said anything about bigger pistons? We're strictly talking about the crank.

Im missing something here, I know your a legend but your going to have to level with me, I am pretty sure cc's(cubic centimeters) are the cylinder measurements, right? The crank case is below the cylinders so why would a bigger crank ad more cc's?

[dajogejr]

I'm only a legend because I'm a post whore...LOL...

 

cc's depend on bore AND stroke.

 

Whenever you add (or...uh, subtract) from either of those, you change the cc of the motor.

 

Someone help me, I'm a little rusty and I'm not math wiz, but....

 

It's bore X bore X Stroke X .somethin to figure out displacement, right?

 

Here...this is a calculator.

 

Stock stroke on a banshee is 54mm. Stock bore is 64mm. 0 deck height, on 2 cylinders, that gives you 347cc. (The stock cc of a banshee, bone stock, rounded up to...yep, 350cc.)

 

Now, my motor is a 68mm bore, 4 mil stroke (58 mm( engine. Which, gives me 421cc.

 

If I ONLY had the 68mm pistons, it would be 392cc. But, I add 4mil of stroke, to get 421cc.

 

See for yourself.

 

http://home.earthlink.net/~jalby/puter.htm

[tmac20031]

I'm only a legend because I'm a post whore...LOL...

 

cc's depend on bore AND stroke.

 

Whenever you add (or...uh, subtract) from either of those, you change the cc of the motor.

 

Someone help me, I'm a little rusty and I'm not math wiz, but....

 

It's bore X bore X Stroke X .somethin to figure out displacement, right?

 

Here...this is a calculator.

 

Stock stroke on a banshee is 54mm. Stock bore is 64mm. 0 deck height, on 2 cylinders, that gives you 347cc. (The stock cc of a banshee, bone stock, rounded up to...yep, 350cc.)

 

Now, my motor is a 68mm bore, 4 mil stroke (58 mm( engine. Which, gives me 421cc.

 

If I ONLY had the 68mm pistons, it would be 392cc. But, I add 4mil of stroke, to get 421cc.

 

See for yourself.

 

http://home.earthlink.net/~jalby/puter.htm

O ok, this is all new knowledge to me I always just thought that cc's was JUST the amount of space in the cylinder cases. So, I can put a big crank as long as I modify the crank case and use bigger carbs? Or am I still missing something?

[dajogejr]

I think we're over thinking this a bit.

 

What exactly are you trying to accomplish, hide, do....etc.?

 

You can put a 4 mil crank in, get the ports matched on the cylinder, run 795 series wiseco pistons, and get your stock head cut and re-chambered....and NO One would be able to tell the difference on the outside....is this what you're looking for? are you looking to stay stock 350?

 

I think you're wasting time with a bigger crank, if your motor is not already ported. What type of riding is this for?

 

Give us the WHOLE story, and we can help better.....