Understanding bore and stroke

[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?

[ringadingh]

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]

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]

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]

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]

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! :lmao:

[cnc]

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

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

[GIBBY]

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

:lmao::lmao:

[Yellow Jacket]

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! :D

[dshelly]

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

Entirely TMI .......... :wtf:

[schoeney]

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

[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/mild-to-wild-kawasaki-mean-streak-motorcycle-makeover

[MAS Tequila]

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]

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/mild-to-wild-kawasaki-mean-streak-motorcycle-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]

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

[ponch]

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

Wasn't talking about going from a 1500 to a 1600, just any bike that has superior function. I spent a lot of time and money on a KZ1000 that ended being a ZRX1200 at best. While the ZRX wasn't around yet, the ZX11D was...So it goes. As for being real, my RT makes about 40 more HP and probably just as much torque as the 1600 with almost 400 fewer CCs and is over 200lbs lighter. Stops and handles better too. CJ found the same satisfaction going to the Limited. Everything he wanted in his Nomad was standard from the factory on his HD. There's nothing wrong with owning and riding a Vulcan, none at all, but at some point when what the bike is and what a rider wants deviates so much it's better off starting off with something else.

[glwilson]

I would agree Ponch; however there are always those who like the adventure of tinkering with things to see if they can improve it. For those, I cannot take that away from them.

However, for most, who do not have that level of skill, they should look for another bike.

Besides, the most problems I hear about, no matter what bike, is when someone "tinkers" a little too much. I ride mostly stock bikes for that reason.

For those that say; "I cannot afford a different bike". I would suggest they look at the cost of the modifications.

[ponch]

I would agree Ponch; however there are always those who like the adventure of tinkering with things to see if they can improve it. For those, I cannot take that away from them.

However, for most, who do not have that level of skill, they should look for another bike.

Besides, the most problems I hear about, no matter what bike, is when someone "tinkers" a little too much. I ride mostly stock bikes for that reason.

For those that say; "I cannot afford a different bike". I would suggest they look at the cost of the modifications.

I used to tinker, then I got married and had kids…And realized that for the money I put into stuff I could have started with what I really wanted in a factory bike. The other thing is time. If I spent the amount of time on bikes, both riding and tinkering as some people I know, I'd be divorced. Time has its own costs beyond money.

[RACNRAY]

Bottom line..."TO EACH HIS OWN".

All of us have priorities in life, performing that balancing act that is needed makes us all different.

I find that a good thing.

RACNRAY

[ponch]

Bottom line..."TO EACH HIS OWN".

All of us have priorities in life, performing that balancing act that is needed makes us all different.

I find that a good thing.

RACNRAY

Absolutely Ray.