Landracing Forum
Tech Information => Technical Discussion => Topic started by: Moonshiner on October 25, 2009, 08:24:17 PM
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Hi everyone , i have a tech question , i have a 83 750 cc DOHC Honda engine , with the stock gearing at red line ( 9000 rpm ) it tops out at about 130 mph , by replacing the sprockets with 18 teeth on the front and a 34 on the back my calculator says that should be 160 mph on the top end , by replacing the 16 inch tire with a 18 it should be 175 mph , i need more than that , any one here know if the gears out of a 78 750 k touring Honda 4 SOHC will work in the DOHC trans, " my 78 Honda SOHC ran about 160 mph at 8500 rpms with the wiseco big bore cylinder , wiseco racing pistons , cam and standard gearing :evil: ", or where can i buy taller gears or a primary for the DOHC engine . :wink:
thanks
Keith
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Any Honda dealer should be able to tell you if the sprockets are interchangable. Sprocket Specialist or Sprocket Specialties will be able to sell you almost any gearing set up that you can dream up for your Night hawk.
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Any Honda dealer should be able to tell you if the sprockets are interchangable. Sprocket Specialist or Sprocket Specialties will be able to sell you almost any gearing set up that you can dream up for your Night hawk.
18 teeth is the largest i can run on the gearbox , the smallest i can find for the back rim is a 32 teeth , that only gets me to 180 MPH with the stock gearing , i need a higher geared trans like on the 78 750 k Honda , i may just find a SOHC 750 k to build for LSR , the DOHC nighthawk seemed to have the greatest potential to go fast because it makes a wider power band that seems to be maximum at red line . :?
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As mentioned, Sprocket Specialists might be a good source, they can also make you custom sprockets provided you can go below a 32 tooth without your chain chewing into the rear hub.
Good luck with your project.
Scott
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I noticed you are on the east coast....there is a company named Rebel Gears that we have had great luck with getting odd stuff cut for the dirtbike. Believe it or not, cheaper and faster than SS.
Mark
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That's one fast Nighthawk!
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That's one fast Nighthawk!
130 MPH fast ? that's all the Nighthawk will do right now , but i am working on it , i just found a deal on a 1980 Honda CB 900 custom with a 10 speed gearbox ,no kidding , this LSR racing is about to get very interesting :-D
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Hey Moonshiner,
wolbrink471 is right on about Rebel Gear and he is close to you in Crossville ph number is 931-788-1617. He use to run Sprocket Specialists years ago. Great people. If you are ever a little further west stop in, I am in Lawrenceburg, TN. We specialize in air cooled 2 Strokes but LSR guys are the "salt" of the earth and valves or no valves, you are welcome.
John Ritter
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Hey Moonshiner,
wolbrink471 is right on about Rebel Gear and he is close to you in Crossville ph number is 931-788-1617. He use to run Sprocket Specialists years ago. Great people. If you are ever a little further west stop in, I am in Lawrenceburg, TN. We specialize in air cooled 2 Strokes but LSR guys are the "salt" of the earth and valves or no valves, you are welcome.
John Ritter
thank you John ,we will try to get over your way when we can ,i will gave him a call , hey we love two strokes as well , my wife has a 78 Kawasaki KE 100 , we may run it too , my wife and i are both motorcycle nuts ..lol .
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Sounds good Keith, shop number is 931-374-8164, web is www.vintageporting.com The KE100 is a tough little bike.
John Ritter
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What is the chain size you have? Could you use a different pitch and get a bigger front sprocket to fit? Have you tried a larger front, years ago we were told the old ZX10 couldn't use anything bigger than an 18... we put a 20 on it.
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What is the chain size you have? Could you use a different pitch and get a bigger front sprocket to fit? Have you tried a larger front, years ago we were told the old ZX10 couldn't use anything bigger than an 18... we put a 20 on it.
it has a factory 18 on the front and a 44 on the rear , i don't know what the pitch is on them , the chain is a 520 , all of it will be replaced , i think if a 19 or 20 would fit on the front and a 30 to 32 on the back ,that would probably be as fast as it could run out on top , i might be able to use a little smaller chain and gain some clearance .
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The Honda 900 is not a true 10 speed. It is a five five speed with a transfer case. The lower range is good for riding around town or pulling a sidecar. The top range is like a normal bike. It is Honda's answer to a question that nobody asked. They are heavy sluggish touring bikes. Honda makes a lot of bikes that are more suitable for land speed. The nighthawk is a better bike.
It takes a lot of work to go really fast, like 150 or 160 mph. It is my guess, that when you get to that stage, custom lightweight wheels will look like a good option. There are many that can be easily fitted with small sprockets.