how to raise max RPM's

everything costs money! :laugh:

Patton wrote:

Increasing length of stroke increases the piston speed during each crankshaft revolution, and thereby reduces maximum sustainable rpm.

For example, the long-stroke (under-square bore-to-stroke ratio) v-twin Harleys have a relatively high piston speed, and operate at lower rpm's.

Whereas the Japanese bikes mostly adopted shorter strokes (square or over-square bore-to-stroke ratio) with a relatively slower piston speed, which allowed operation at higher rpm's.

As understood way back in the peanut gallery. :lol:

Good Luck!

Different engine builders seem to have their own opinions on the subject. I know this much, stroking blows the torque through the roof.

Japanese bikes do have higher rpm's, but it doesn't mean they have power in the upper rpm range. With these bikes we are not talking about a chevy size piston, like the Harleys.

Patton, have you looked at the piston speed for a KZ-810cc with a -1/4" stroke?

It is 44CI., 3,752FPM and 62.5FPS, the CI goes up but everything else goes down.

Myself I don't care so much about the rpm's, but you are adding 225cc to the motor or 1.5 cylinders. Thats a racers dream come true. Very streetable depending on compression ratio an

PLUMMEN wrote:

everything costs money! :laugh:

My answer is, most people don't think about, they will be spending $2000 or $3000 on the motor, before they buy the turbo. That may be for only round one! A turbo sounds great, but how many average street riders, can really handle a turbo?

Plummen at your age and skill level, with a slick and wheelie bar, do you truely think you could handle a hot turbo bike? I couldn't, I would find some younger guy with skill's.

Wouldn't 69mm Bore x 60.35 Stroke, still be over square?

I certainly understand where you are comming from. I would probably run a turbo around 7-10 psi. I am not looking to build a 210mp rocketship like lorcan's it just seems when you get into a certain level of $$$ a turbo is the best dollar for hp solution.

But I am still learning so I honestly could be very wrong. And anyway, there are no plans to go turbo this winter; however stroking or de-stroking is something I may consider.



De-stroking the motor would also be an interesting idea.

I have been reading a book by Kevin Cameron. He points out that peak pressure comes in about 14* after TDC on the powerstroke. He also shows that 80% of the energy you get out of combustion comes from the first half of the power stroke.

Wouldn't that go to say that a shorter throw would help you take advantage of the easy power from an engine? When the piston is closer to tdc?

BTW, I am not trying to take a point opposite yours to piss you off. I am just trying to have a conversation about stroking/de-stroking and what they mean for power.

Thank you for your help and input!!

kzz1p wrote:

PLUMMEN wrote:

everything costs money! :laugh:

My answer is, most people don't think about, they will be spending $2000 or $3000 on the motor, before they buy the turbo. That may be for only round one! A turbo sounds great, but how many average street riders, can really handle a turbo?

Plummen at your age and skill level, with a slick and wheelie bar, do you truely think you could handle a hot turbo bike? I couldn't, I would find some younger guy with skill's.

only thing limiting me is my pacemaker! :woohoo: im 44,got my 1st basketcase z1 at 13-14 so ive been making and learning from my own and everybody elses mistakes for 30 plus years! :laugh: remember not all turbos are 400hp unridable beasts,you can turn down the boost and ride it around all week on pump gas to school,work or even the grocery store.if you feel spunky on the weekend you can crank up the boost,retard timing and go racing.a turbo motor doesnt need all the fancy stuff a motor with carbs needs to make power you could take a stock 900-1000 motor weld the crank with stock pistons with low boost and a little bit of headwork on exhuast ports even run stock cams and dust off most good running 1075 motors.think of it this way:

1.stock bottem end with welded crank and good clutch plates,maybe aftermarket studs and maincap brace if youre gonna run sticky tire or lots of boost
2.stock bore/pistons if bore is good and round or a set of turbo pistons if youre running lots of boost.heavy cylinder studs again if running heavy boost
3.stock cylinder head with good valvejob,if money allows id do a little porting on exhuast side and go 1 size over on exhuast valve .intake side is force fed so it dont need much
4.stock cams,stock buckets and shims much easier than having to pull out cams to shim valves with those 435 cams you need with high compression motor with big carbs that makes less power than a turbo anyway (:woohoo: )

5.run it on pump gas during the week ,if you want to go racing dump in good gas ,tweak the timing and hang on.

versus the carbed version

1.same basic bottem end as turbo

2.high compression pistons with deck and head milled to get every bit out of it

3.cylinder head ported to within an inch of its life.clearanced for cams.heavy springs ,shim under buckets and keepers to go with the large by huge cams
4.ungodly set of cams with lobes that look like 2x4s laid on edge

5.34-36mm carbs that are absolutely worthless on the street but youll need em to gain some some high end hp against that mild mannered little turbo motor

6.a header that looks and sounds like it belongs on a blown bigblock chevy
7.you finally decide its such load unstreetable tempormental beast you make a drag only bike out of it! :laugh:
granted those are very simplistic build lists but it should give you some sort of idea of the 2 differant directions the builds take .anyway im on my 3-4th kz street turbo build for myself.i made a couple mid-low 8 sec passes in the early 90s on a 2v progas 1197 turbo toget my license before deciding that was too freaking fast with that skinny of a front tire,but what i did learn was that little 1197 in a well setup chassis was ahell of a lot quicker than my 1428 in the ill handling wrong chassis would ever be.thats why ive often said on here that all the power in the world is worthless if it wont hookup and go straight,tiresmoke and ill handling dont win races. i did run a few 6.10s-6.20s at our local 1/8 mile with reaction times like my dead grandpa and smoking tire 1/2 track on an 1197 turbo in stock chassis a while back,if all else fails illget racer54 to ride for me!

PLUMMEN wrote:

kzz1p wrote:

PLUMMEN wrote:

everything costs money! :laugh:

My answer is, most people don't think about, they will be spending $2000 or $3000 on the motor, before they buy the turbo. That may be for only round one! A turbo sounds great, but how many average street riders, can really handle a turbo?

Plummen at your age and skill level, with a slick and wheelie bar, do you truely think you could handle a hot turbo bike? I couldn't, I would find some younger guy with skill's.

only thing limiting me is my pacemaker! :woohoo: im 44,got my 1st basketcase z1 at 13-14 so ive been making and learning from my own and everybody elses mistakes for 30 plus years! :laugh: remember not all turbos are 400hp unridable beasts,you can turn down the boost and ride it around all week on pump gas to school,work or even the grocery store.if you feel spunky on the weekend you can crank up the boost,retard timing and go racing.a turbo motor doesnt need all the fancy stuff a motor with carbs needs to make power you could take a stock 900-1000 motor weld the crank with stock pistons with low boost and a little bit of headwork on exhuast ports even run stock cams and dust off most good running 1075 motors.think of it this way:

1.stock bottem end with welded crank and good clutch plates,maybe aftermarket studs and maincap brace if youre gonna run sticky tire or lots of boost
2.stock bore/pistons if bore is good and round or a set of turbo pistons if youre running lots of boost.heavy cylinder studs again if running heavy boost
3.stock cylinder head with good valvejob,if money allows id do a little porting on exhuast side and go 1 size over on exhuast valve .intake side is force fed so it dont need much
4.stock cams,stock buckets and shims much easier than having to pull out cams to shim valves with those 435 cams you need with high compression motor with big carbs that makes less power than a turbo anyway (:woohoo: )

5.run it on pump gas during the week ,if you want to go racing dump in good gas ,tweak the timing and hang on.

versus the carbed version

1.same basic bottem end as turbo

2.high compression pistons with deck and head milled to get every bit out of it

3.cylinder head ported to within an inch of its life.clearanced for cams.heavy springs ,shim under buckets and keepers to go with the large by huge cams
4.ungodly set of cams with lobes that look like 2x4s laid on edge

5.34-36mm carbs that are absolutely worthless on the street but youll need em to gain some some high end hp against that mild mannered little turbo motor

6.a header that looks and sounds like it belongs on a blown bigblock chevy
7.you finally decide its such load unstreetable tempormental beast you make a drag only bike out of it! :laugh:
granted those are very simplistic build lists but it should give you some sort of idea of the 2 differant directions the builds take .anyway im on my 3-4th kz street turbo build for myself.i made a couple mid-low 8 sec passes in the early 90s on a 2v progas 1197 turbo toget my license before deciding that was too freaking fast with that skinny of a front tire,but what i did learn was that little 1197 in a well setup chassis was ahell of a lot quicker than my 1428 in the ill handling wrong chassis would ever be.thats why ive often said on here that all the power in the world is worthless if it wont hookup and go straight,tiresmoke and ill handling dont win races. i did run a few 6.10s-6.20s at our local 1/8 mile with reaction times like my dead grandpa and smoking tire 1/2 track on an 1197 turbo in stock chassis a while back,if all else fails illget racer54 to ride for me!

the voice of experience....the man knows his stuff....

kzz1p wrote:

Wouldn't 69mm Bore x 60.35 Stroke, still be over square?

Anyone willing to answer my question?

hardr0ck68 wrote:

BTW, I am not trying to take a point opposite yours to piss you off. I am just trying to have a conversation about stroking/de-stroking and what they mean for power.

Thank you for your help and input!!

I would think by now, that you would have your own line of thinking, maybe you could share some of that?

I opened the door for people to take a shot at me, when I posted my ideas.

I hope you remember, there are more then two sides to a coin.

keith1 wrote:

PLUMMEN wrote:

kzz1p wrote:

PLUMMEN wrote:

everything costs money! :laugh:

My answer is, most people don't think about, they will be spending $2000 or $3000 on the motor, before they buy the turbo. That may be for only round one! A turbo sounds great, but how many average street riders, can really handle a turbo?

Plummen at your age and skill level, with a slick and wheelie bar, do you truely think you could handle a hot turbo bike? I couldn't, I would find some younger guy with skill's.

only thing limiting me is my pacemaker! :woohoo: im 44,got my 1st basketcase z1 at 13-14 so ive been making and learning from my own and everybody elses mistakes for 30 plus years! :laugh: remember not all turbos are 400hp unridable beasts,you can turn down the boost and ride it around all week on pump gas to school,work or even the grocery store.if you feel spunky on the weekend you can crank up the boost,retard timing and go racing.a turbo motor doesnt need all the fancy stuff a motor with carbs needs to make power you could take a stock 900-1000 motor weld the crank with stock pistons with low boost and a little bit of headwork on exhuast ports even run stock cams and dust off most good running 1075 motors.think of it this way:

1.stock bottem end with welded crank and good clutch plates,maybe aftermarket studs and maincap brace if youre gonna run sticky tire or lots of boost
2.stock bore/pistons if bore is good and round or a set of turbo pistons if youre running lots of boost.heavy cylinder studs again if running heavy boost
3.stock cylinder head with good valvejob,if money allows id do a little porting on exhuast side and go 1 size over on exhuast valve .intake side is force fed so it dont need much
4.stock cams,stock buckets and shims much easier than having to pull out cams to shim valves with those 435 cams you need with high compression motor with big carbs that makes less power than a turbo anyway (:woohoo: )

5.run it on pump gas during the week ,if you want to go racing dump in good gas ,tweak the timing and hang on.

versus the carbed version

1.same basic bottem end as turbo

2.high compression pistons with deck and head milled to get every bit out of it

3.cylinder head ported to within an inch of its life.clearanced for cams.heavy springs ,shim under buckets and keepers to go with the large by huge cams
4.ungodly set of cams with lobes that look like 2x4s laid on edge

5.34-36mm carbs that are absolutely worthless on the street but youll need em to gain some some high end hp against that mild mannered little turbo motor

6.a header that looks and sounds like it belongs on a blown bigblock chevy
7.you finally decide its such load unstreetable tempormental beast you make a drag only bike out of it! :laugh:
granted those are very simplistic build lists but it should give you some sort of idea of the 2 differant directions the builds take .anyway im on my 3-4th kz street turbo build for myself.i made a couple mid-low 8 sec passes in the early 90s on a 2v progas 1197 turbo toget my license before deciding that was too freaking fast with that skinny of a front tire,but what i did learn was that little 1197 in a well setup chassis was ahell of a lot quicker than my 1428 in the ill handling wrong chassis would ever be.thats why ive often said on here that all the power in the world is worthless if it wont hookup and go straight,tiresmoke and ill handling dont win races. i did run a few 6.10s-6.20s at our local 1/8 mile with reaction times like my dead grandpa and smoking tire 1/2 track on an 1197 turbo in stock chassis a while back,if all else fails illget racer54 to ride for me!

the voice of experience....the man knows his stuff....

burned up lots of money and parts and long nights to arrive at my simple aproach! either build a low compresion big inch motor or a turbo either way you can run it on pump gas and easier to ride /maintain than the other option

PLUMMEN wrote:

keith1 wrote:

PLUMMEN wrote:

kzz1p wrote:

PLUMMEN wrote:

everything costs money! :laugh:

My answer is, most people don't think about, they will be spending $2000 or $3000 on the motor, before they buy the turbo. That may be for only round one! A turbo sounds great, but how many average street riders, can really handle a turbo?

Plummen at your age and skill level, with a slick and wheelie bar, do you truely think you could handle a hot turbo bike? I couldn't, I would find some younger guy with skill's.

only thing limiting me is my pacemaker! :woohoo: im 44,got my 1st basketcase z1 at 13-14 so ive been making and learning from my own and everybody elses mistakes for 30 plus years! :laugh: remember not all turbos are 400hp unridable beasts,you can turn down the boost and ride it around all week on pump gas to school,work or even the grocery store.if you feel spunky on the weekend you can crank up the boost,retard timing and go racing.a turbo motor doesnt need all the fancy stuff a motor with carbs needs to make power you could take a stock 900-1000 motor weld the crank with stock pistons with low boost and a little bit of headwork on exhuast ports even run stock cams and dust off most good running 1075 motors.think of it this way:

1.stock bottem end with welded crank and good clutch plates,maybe aftermarket studs and maincap brace if youre gonna run sticky tire or lots of boost
2.stock bore/pistons if bore is good and round or a set of turbo pistons if youre running lots of boost.heavy cylinder studs again if running heavy boost
3.stock cylinder head with good valvejob,if money allows id do a little porting on exhuast side and go 1 size over on exhuast valve .intake side is force fed so it dont need much
4.stock cams,stock buckets and shims much easier than having to pull out cams to shim valves with those 435 cams you need with high compression motor with big carbs that makes less power than a turbo anyway (:woohoo: )

5.run it on pump gas during the week ,if you want to go racing dump in good gas ,tweak the timing and hang on.

versus the carbed version

1.same basic bottem end as turbo

2.high compression pistons with deck and head milled to get every bit out of it

3.cylinder head ported to within an inch of its life.clearanced for cams.heavy springs ,shim under buckets and keepers to go with the large by huge cams
4.ungodly set of cams with lobes that look like 2x4s laid on edge

5.34-36mm carbs that are absolutely worthless on the street but youll need em to gain some some high end hp against that mild mannered little turbo motor

6.a header that looks and sounds like it belongs on a blown bigblock chevy
7.you finally decide its such load unstreetable tempormental beast you make a drag only bike out of it! :laugh:
granted those are very simplistic build lists but it should give you some sort of idea of the 2 differant directions the builds take .anyway im on my 3-4th kz street turbo build for myself.i made a couple mid-low 8 sec passes in the early 90s on a 2v progas 1197 turbo toget my license before deciding that was too freaking fast with that skinny of a front tire,but what i did learn was that little 1197 in a well setup chassis was ahell of a lot quicker than my 1428 in the ill handling wrong chassis would ever be.thats why ive often said on here that all the power in the world is worthless if it wont hookup and go straight,tiresmoke and ill handling dont win races. i did run a few 6.10s-6.20s at our local 1/8 mile with reaction times like my dead grandpa and smoking tire 1/2 track on an 1197 turbo in stock chassis a while back,if all else fails illget racer54 to ride for me!

the voice of experience....the man knows his stuff....

burned up lots of money and parts and long nights to arrive at my simple aproach! either build a low compresion big inch motor or a turbo either way you can run it on pump gas and easier to ride /maintain than the other option

It seems like we came a long way, from more rpm's to turbos. There is more then one way to skin a cat, I guess it's just what kind of cat skinner, you want to be.