Understanding bore and stroke

**Jared** · 06-11-2014, 01:18 AM

There is a discussion on VBA's fb page about the Thunder Manufacturing bore kit. Can someone shed some light on why someone would choose to bore out a 1500 engine vs getting a 1600 which, from my understanding, is all the same, but with a longer stroke. Seems like with the rpm restrictions a longer stroke would produce more power, right?

**ringadingh** · 06-11-2014, 08:05 AM

Because increasing the bore is the easiest way, to increase the stroke a different crankshaft is required, and or longer rods, which then require a taller cylinder. Its probably only worth boring if you have to rebuild the motor anyway after it is worn out, a couple of pistons is all thats required to increase the size, rather than messing with all the other stuff .

RACNRAY · 06-11-2014, 09:31 AM

YEP....big bore piston kits are relatively easy. I am not experienced in knowing if a 1600 engine will fit into a 1500 frame or will all of the electrics/electronics etc. will work. That would certainly be easy if it was a true drop-in.

In "stroking" an engine a different crank (such as installing a second gen Busa crank into a first gen engine, 2nd gen Busa engines have a 2mm longer stroke)) or having the crank stroked by a company such as Falicon or Marine Crankshaft.

Stroked engines will require SHORTER not longer rods or cylinder base spacer plates to compensate for the longer stroke.

Either method of increasing displacement will offer gains, but there are so many other factors involved and how the engine is gonna be used that will ultimately determine the quality and quantity of power gained.

RACNRAY

Yellow Jacket · 06-11-2014, 03:26 PM

1500 specs:

Displacement: 1470 cc
Bore x stroke: 102 x 90mm

1600 specs:

Displacement: 1,552cc
Bore x stroke: 102.0 x 95.0mm

The only difference is a 5.0mm longer stroke for the 1600.

A 1600 engine will fit into a 1500 frame.

RACNRAY · 06-11-2014, 05:17 PM

Me thinks ur calculator needs new batteries...there is a 5 mm difference in stroke between the 2 engines, not 3mm.

Jus sayin...

RACNRAY

blowndodge · 06-11-2014, 08:30 PM

Quote:

Originally Posted by Jared

There is a discussion on VBA's fb page about the Thunder Manufacturing bore kit. Can someone shed some light on why someone would choose to bore out a 1500 engine vs getting a 1600 which, from my understanding, is all the same, but with a longer stroke. Seems like with the rpm restrictions a longer stroke would produce more power, right?

It's simply really. A bore is talking to Kris. And a stroke is something I had after Kris "pimped" his ride!

**cnc** · 06-11-2014, 10:05 PM

Quote:

Originally Posted by blowndodge

It's simply really. A bore is talking to Kris. And a stroke is something I had after Kris "pimped" his ride!

Brad your an Ass, but funny. Yeah a funny Ass.

**GIBBY** · 06-12-2014, 07:26 AM

Quote:

Originally Posted by blowndodge

It's simply really. A bore is talking to Kris. And a stroke is something I had after Kris "pimped" his ride!

Yellow Jacket · 06-12-2014, 02:39 PM

Quote:

Originally Posted by RACNRAY

Me thinks ur calculator needs new batteries...there is a 5 mm difference in stroke between the 2 engines, not 3mm.

Jus sayin...

RACNRAY

Nah, I was using the "new math" where a close answer is as good as an exact answer!

dshelly · 06-12-2014, 03:23 PM

Quote:

Originally Posted by blowndodge

It's simply really. A bore is talking to Kris. And a stroke is something I had after Kris "pimped" his ride!

Entirely TMI ..........

**schoeney** · 06-12-2014, 11:36 PM

Hey you guys quit picking on my buddy Kris and his baby blue alligator trimmings.:cool::cool:

gcsteve · 06-13-2014, 11:16 PM

Years ago when I had an 04 meanstreak, motorcycle cruiser magazine did an article on the thunder kit. They said the horse power from the kawasaki 1500 and 1600 were the same. They took a1500 Meanstreak to Thunder mfg installed the kit and on the dyno it hit 100 hp. Entertaining article.

http://www.motorcyclecruiser.com/mil...cycle-makeover

**MAS Tequila** · 06-19-2014, 09:18 AM

The shorter stroke on the 1500 will wind out and hit it's HP faster.

I know of a 99 1500 Nomad that had the Thunder kit and an assload of porting along with bigger valves installed.

The owner also had a V2k, and the built 1500 would stay with it.

MT

ponch · 06-19-2014, 12:50 PM

Quote:

Originally Posted by gcsteve

Years ago when I had an 04 meanstreak, motorcycle cruiser magazine did an article on the thunder kit. They said the horse power from the kawasaki 1500 and 1600 were the same. They took a1500 Meanstreak to Thunder mfg installed the kit and on the dyno it hit 100 hp. Entertaining article.

http://www.motorcyclecruiser.com/mil...cycle-makeover

I bet reliability would be affected over the long run. It could be money better spent on a bike that has the performance from the factory.

**MAS Tequila** · 06-20-2014, 02:54 PM

Quote:

Originally Posted by ponch

I bet reliability would be affected over the long run. It could be money better spent on a bike that has the performance from the factory.

Your right, but the difference between a 1500 and a 1600 is minimal. I've had both engines in the same bike and 1500 feels a little quicker.

Where the Thunder kit really makes more power is in the included cams.

I'll stand by a comment I've made many times, and that is, if you put 1500 meanie cams or 'A' cams in and do some porting work with larger valves you will get more results than with the Thunder kit.

Let's be real, 100 cc's isn't much of a difference, and an 'A' model puts more hp and torque out than the later 1500/1600s.

MT

06-11-2014, 01:18 AM	#1
Jared Join Date: Mar 2009 Location: Greeley, Colorado Posts: 6,772	Understanding bore and stroke There is a discussion on VBA's fb page about the Thunder Manufacturing bore kit. Can someone shed some light on why someone would choose to bore out a 1500 engine vs getting a 1600 which, from my understanding, is all the same, but with a longer stroke. Seems like with the rpm restrictions a longer stroke would produce more power, right? __________________ Jared VBA #1051 (Former President) Login or Register to Remove Ads
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06-11-2014, 08:05 AM	#2
ringadingh Join Date: Aug 2007 Location: Newmarket Ontario Canada Posts: 35,387	Because increasing the bore is the easiest way, to increase the stroke a different crankshaft is required, and or longer rods, which then require a taller cylinder. Its probably only worth boring if you have to rebuild the motor anyway after it is worn out, a couple of pistons is all thats required to increase the size, rather than messing with all the other stuff . __________________ 2002 Nomad aka Bountyhunter VBA #27 VROC #18951
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06-11-2014, 09:31 AM	#3
RACNRAY Sr. Member Join Date: Sep 2011 Location: SOUTH FLORIDA Posts: 1,210	YEP....big bore piston kits are relatively easy. I am not experienced in knowing if a 1600 engine will fit into a 1500 frame or will all of the electrics/electronics etc. will work. That would certainly be easy if it was a true drop-in. In "stroking" an engine a different crank (such as installing a second gen Busa crank into a first gen engine, 2nd gen Busa engines have a 2mm longer stroke)) or having the crank stroked by a company such as Falicon or Marine Crankshaft. Stroked engines will require SHORTER not longer rods or cylinder base spacer plates to compensate for the longer stroke. Either method of increasing displacement will offer gains, but there are so many other factors involved and how the engine is gonna be used that will ultimately determine the quality and quantity of power gained. RACNRAY __________________ "TRUE HAPPINESS IS IN THE HEART, NOT IN THE OUTSIDE FIXES" WITH OVER 46 YEARS AS A MOTORCYCLE TECHNICIAN/HI-PO SHOP OWNER I AM A PURVEYOR OF FACT NOT FICTION! "WE LIVE OUR LIVES IN CHAINS NEVER KNOWING WE HAD THE KEY"
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06-11-2014, 03:26 PM	#4
Yellow Jacket Top Contributor Join Date: Nov 2007 Location: Fayetteville, Georgia Posts: 5,792	1500 specs: Displacement: 1470 cc Bore x stroke: 102 x 90mm 1600 specs: Displacement: 1,552cc Bore x stroke: 102.0 x 95.0mm The only difference is a 5.0mm longer stroke for the 1600. A 1600 engine will fit into a 1500 frame. __________________ Bob KawaNOW/VBA 210 Green/Silver 2006 Patriot Guard Riders 2009 Last edited by Yellow Jacket; 06-12-2014 at 02:42 PM. Reason: Apparently my calculator was broken.
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06-11-2014, 05:17 PM	#5
RACNRAY Sr. Member Join Date: Sep 2011 Location: SOUTH FLORIDA Posts: 1,210	Me thinks ur calculator needs new batteries...there is a 5 mm difference in stroke between the 2 engines, not 3mm. Jus sayin... RACNRAY __________________ "TRUE HAPPINESS IS IN THE HEART, NOT IN THE OUTSIDE FIXES" WITH OVER 46 YEARS AS A MOTORCYCLE TECHNICIAN/HI-PO SHOP OWNER I AM A PURVEYOR OF FACT NOT FICTION! "WE LIVE OUR LIVES IN CHAINS NEVER KNOWING WE HAD THE KEY" Login or Register to Remove Ads
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06-12-2014, 11:36 PM	#11
schoeney Join Date: Jun 2008 Location: NW Region Posts: 5,222	Hey you guys quit picking on my buddy Kris and his baby blue alligator trimmings.:cool::cool: __________________ VBA #659 2003 Nomad 1500 (Gone but never forgotten) 2005 Honda ST1300 - Sweet and still kickin 2006 Honda Goldwing - Best Boat in the Marina
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06-13-2014, 11:16 PM	#12
gcsteve Member Join Date: Aug 2012 Posts: 217	Years ago when I had an 04 meanstreak, motorcycle cruiser magazine did an article on the thunder kit. They said the horse power from the kawasaki 1500 and 1600 were the same. They took a1500 Meanstreak to Thunder mfg installed the kit and on the dyno it hit 100 hp. Entertaining article. http://www.motorcyclecruiser.com/mil...cycle-makeover __________________ 04 Meanstreak sold Nomad sold 15 Roadmaster
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06-19-2014, 09:18 AM	#13
MAS Tequila Join Date: Jan 2009 Location: Psychiatric Ward FL Posts: 3,429	The shorter stroke on the 1500 will wind out and hit it's HP faster. I know of a 99 1500 Nomad that had the Thunder kit and an assload of porting along with bigger valves installed. The owner also had a V2k, and the built 1500 would stay with it. MT __________________ MT 2016 FLHP Psychiatric Ward FL VBA 936
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