Displacement / horse power increase - swappable parts

Quimrider · 11-14-2008, 05:53 PM

To avoid any confusion with this topic:Convert your GZ250 into a 346cc!!! THERE IS NO BIG BORE KIT FOR THE GZ250. ALSO TO ABOUT 99.999999991% OF THE POPULATION THE COST THAT WOULD BE INVOLVED IN COMING UP WITH YOUR OWN BIG BORE KIT DOES NOT MAKE SENSE. If you would like to discuss the nonexistence of a big bore kit or the fact that modifying the engine is too expensive, please do so in the thread above.

This thread is to discuss which engine parts are/are not interchangeable with the GZ250's engine and various methods one could do to increase displacement and/or horsepower. Additionally I'd like to entertain the topic of potential engine swaps as a means to get more juice out of the GZ250. For example I have read about a Honda Rebel that had a diesel engine shoe horned onto it.

Please minimize speculation/opinion and stick as close as possible to the facts.

One engine of interest is that from the DR350. It is very similar to the GZ250 engine. The DR350 has a 79mm X 71.2mm bore and stroke. The GZ250 engine is 72mm x 61.2mm bore and stroke. Aside from custom exhaust work, the main obstacle from simply swapping the top half of the engines is that the DR350 engine has a 10mm longer stroke. If I ever get my hands on a DR350 cheap enuff I will attempt to put the DR350 engine on the GZ250.

mainlinecoffee · 02-14-2014, 12:28 AM

If it's not too late to revive this thread,has anyone tried a adjustable cam plate or a cdi with a higher redline? Hell for 3k you could bolt on a turbo..

Water Warrior 2 · 02-14-2014, 12:41 AM

Quote:

Originally Posted by mainlinecoffee

If it's not too late to revive this thread,has anyone tried a adjustable cam plate or a cdi with a higher redline? Hell for 3k you could bolt on a turbo..

For 3K you might be able to buy an old Honda Turbo 650 that was purpose built. If you think you need a turbo you have the wrong bike. The GZ is just what it is and a bunch of cash thrown at it won't change that.
A higher red line will just make the engine explode sooner.
You might enjoy the Ninja 250 though. It has a much higher red line and more power overall.

mainlinecoffee · 02-14-2014, 12:56 AM

If I need a Adrenaline fix I hop on my chopped goldwing,personally I think the meager 22hp is more than enough for the job but I love wondering what if, costs too damn much to find out the hard way.

Water Warrior 2 · 02-14-2014, 01:42 AM

Quote:

Originally Posted by mainlinecoffee

If I need a Adrenaline fix I hop on my chopped goldwing,personally I think the meager 22hp is more than enough for the job but I love wondering what if, costs too damn much to find out the hard way.

I will find out the hard way with my new to me Money Pit used 1983 Honda 650. I can see an easy $1000 going into it with just repairs and maintenance to begin with. Yup, that sounds dumb but at least I will have a bike sometime this summer that is safe to ride and everything working as it should.

mainlinecoffee · 02-14-2014, 03:10 AM

The 83 was the first real motorcycle I have ever owned,gave a guy a shotgun and fifty bucks to drag it out of a barn, my friends laughed at me when they saw it,dead snake behind the headlight and meow mix in the airbox, everything broke rusty or covered in mouse shit...I don't think you will be disappointed, the cb650 is a wonderful machine. If you ever need any help or just a different perspective give me a shout,I know that machine better than my own body.

Water Warrior 2 · 02-14-2014, 07:25 PM

Quote:

Originally Posted by mainlinecoffee

The 83 was the first real motorcycle I have ever owned,gave a guy a shotgun and fifty bucks to drag it out of a barn, my friends laughed at me when they saw it,dead snake behind the headlight and meow mix in the airbox, everything broke rusty or covered in mouse shit...I don't think you will be disappointed, the cb650 is a wonderful machine. If you ever need any help or just a different perspective give me a shout,I know that machine better than my own body.

My bad. Should have specified GL 650. The Half Wing thing.

mainlinecoffee · 02-14-2014, 10:17 PM

Gl looks awesome but I have no earthly idea about what makes them tic,I am supposed to rebuild the water pump on my gl1200 next week but I burned up the clutch in my truck yesterday so it may take priority. I always thought the 650 would be beyond badass in a Amin frame with the front end raked to hell.

mainlinecoffee · 02-15-2014, 08:03 PM

To rase compression couldn't you just shave a bit off the head?

Water Warrior 2 · 02-15-2014, 08:47 PM

Shaving the head might work but I don't think it is a wise solution.
Will you still have room for the valves to open without hitting the piston?
Also, would there be a lot of slack in the timing chain? The auto adjuster might reach it's limits a lot sooner.

11-14-2008, 05:53 PM	#1
Quimrider Senior Member Join Date: Jun 2007 Location: Toledo, OH Posts: 198	Displacement / horse power increase - swappable parts To avoid any confusion with this topic:Convert your GZ250 into a 346cc!!! THERE IS NO BIG BORE KIT FOR THE GZ250. ALSO TO ABOUT 99.999999991% OF THE POPULATION THE COST THAT WOULD BE INVOLVED IN COMING UP WITH YOUR OWN BIG BORE KIT DOES NOT MAKE SENSE. If you would like to discuss the nonexistence of a big bore kit or the fact that modifying the engine is too expensive, please do so in the thread above. This thread is to discuss which engine parts are/are not interchangeable with the GZ250's engine and various methods one could do to increase displacement and/or horsepower. Additionally I'd like to entertain the topic of potential engine swaps as a means to get more juice out of the GZ250. For example I have read about a Honda Rebel that had a diesel engine shoe horned onto it. Please minimize speculation/opinion and stick as close as possible to the facts. One engine of interest is that from the DR350. It is very similar to the GZ250 engine. The DR350 has a 79mm X 71.2mm bore and stroke. The GZ250 engine is 72mm x 61.2mm bore and stroke. Aside from custom exhaust work, the main obstacle from simply swapping the top half of the engines is that the DR350 engine has a 10mm longer stroke. If I ever get my hands on a DR350 cheap enuff I will attempt to put the DR350 engine on the GZ250. Login or Register to Remove Ads
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02-14-2014, 12:28 AM	#2
mainlinecoffee Senior Member Join Date: Oct 2013 Location: lexington ky Posts: 223	If it's not too late to revive this thread,has anyone tried a adjustable cam plate or a cdi with a higher redline? Hell for 3k you could bolt on a turbo..
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02-14-2014, 12:56 AM	#4
mainlinecoffee Senior Member Join Date: Oct 2013 Location: lexington ky Posts: 223	If I need a Adrenaline fix I hop on my chopped goldwing,personally I think the meager 22hp is more than enough for the job but I love wondering what if, costs too damn much to find out the hard way.
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02-14-2014, 03:10 AM	#6
mainlinecoffee Senior Member Join Date: Oct 2013 Location: lexington ky Posts: 223	The 83 was the first real motorcycle I have ever owned,gave a guy a shotgun and fifty bucks to drag it out of a barn, my friends laughed at me when they saw it,dead snake behind the headlight and meow mix in the airbox, everything broke rusty or covered in mouse shit...I don't think you will be disappointed, the cb650 is a wonderful machine. If you ever need any help or just a different perspective give me a shout,I know that machine better than my own body.
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02-14-2014, 10:17 PM	#8
mainlinecoffee Senior Member Join Date: Oct 2013 Location: lexington ky Posts: 223	Gl looks awesome but I have no earthly idea about what makes them tic,I am supposed to rebuild the water pump on my gl1200 next week but I burned up the clutch in my truck yesterday so it may take priority. I always thought the 650 would be beyond badass in a Amin frame with the front end raked to hell.
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02-15-2014, 08:03 PM	#9
mainlinecoffee Senior Member Join Date: Oct 2013 Location: lexington ky Posts: 223	To rase compression couldn't you just shave a bit off the head?
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02-15-2014, 08:47 PM	#10
Water Warrior 2 Senior Member Join Date: Dec 2006 Location: Squamish B.C Canada Posts: 11,409	Shaving the head might work but I don't think it is a wise solution. Will you still have room for the valves to open without hitting the piston? Also, would there be a lot of slack in the timing chain? The auto adjuster might reach it's limits a lot sooner.
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