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What size ? I have heard that a 250 has a 38mm throttle body and in the specs so does the 300. Then some aftermarket people have a bored out throttle body which is 44mm and they state a stock 250 0r 300 have a 40 mm throttle body, then another company say they have a 400cc injector for the 250 0r 300. My question and it seems nobody knows what the stock injector size is on a 250 or 300. I got larger injectors for my SV650 racer and the same people can supply me with larger ones for a CBR250R but nobody knows what the stock size is ??? Who would know that ?
 

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Discussion Starter #5
Injector size. I know the throttle body is 38mm for the 250 and 300 but can not find out what size the injector is for either.
 

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Just to let you guys know, I am installing a 380cc injector into stock throttle body, with Bazazz auto tune it should work good. Need something to keep up with the R3's
 

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Discussion Starter #7
Went with a 400cc injector to go along with the 305cc kit and cams.
 

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Went with a 400cc injector to go along with the 305cc kit and cams.
Hello bat,
Hope you can answer my queries?

What BBK suppliers you use for 305cc. I have the Takewaga 305 with racing cams.
What makes you think you need the larger injector??
I have a F1 CON ECU taking care of the ECU
Regards
Tom
 

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Discussion Starter #9
Hello bat,
Hope you can answer my queries?

What BBK suppliers you use for 305cc. I have the Takewaga 305 with racing cams.
What makes you think you need the larger injector??
I have a F1 CON ECU taking care of the ECU
Regards
Tom

I have the same kit as you, the injectors are only 20cc more but make the cams work better with the 305 kit. I run a Bazazz with Auto Tune. I race at 4000 to 5000 feet and all together work great. I have a guy who builds bikes for MotoAmerica who advises me. The stock throttle body and injector restrict the mods. We also removed the top of the air box. We are porting a bit different from the norm. Check out Moto Tune USA and see what we are doing. I have been building stuff forever and have a few old timers that have dyno's and flow benches and say I am doing the right thing to get the HP out of the little bike.They did say the extra gas metered right help with top end performance.



I am excited, our track days start this month and our races start in March. We will see how it works against the all the other 300's. We have the weight advantage and I am trying to make mine lighter everywhere i can.


Are you racing yours ?


Alan Dye
 

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I have the same kit as you, the injectors are only 20cc more but make the cams work better with the 305 kit. I run a Bazazz with Auto Tune. I race at 4000 to 5000 feet and all together work great. I have a guy who builds bikes for MotoAmerica who advises me. The stock throttle body and injector restrict the mods. We also removed the top of the air box. We are porting a bit different from the norm. Check out Moto Tune USA and see what we are doing. I have been building stuff forever and have a few old timers that have dyno's and flow benches and say I am doing the right thing to get the HP out of the little bike.They did say the extra gas metered right help with top end performance.

I am excited, our track days start this month and our races start in March. We will see how it works against the all the other 300's. We have the weight advantage and I am trying to make mine lighter everywhere i can.

Are you racing yours

Alan Dye
Hello Alan,

Thanks for the reply:
Coming up to 64 years old the racing on a track is over. Used to race production class 250 in the late 70's and early 80's. The picture of an old bike were my first. A YDS7 bottom end and g/box with the RD barrels, also ports opened to fit the carbs from a 350.
Nowadays I ride my bikes for enjoyment and thrills. Have a R3 in the w/shop with the CBR.
I like good grip with braking and acceleration. Top speed is no longer the golden grail. Both bikes have sintered pads and Pirellis fitted. The rear seat has been removed on both.

You say you are using a Bazzaz, I am using the FI Con that Takewaga sell, not as easy as the Bazzaz to fit. Agree that the BBkit transforms the bike, I had to fit uprated clutch springs to stop slip from take off. Also, have fitted 13T sprockets to both bikes.
The throttle body and injector change you have done is of interest to me. What model did you take the injector and throttle from and how open is the airbox.

Thanks again for the reply. Take care and ride safe
 

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Discussion Starter #11
Hey, I am 67 and still going. Yea I have a Bazazz with a auto mapper. So I don't have to take it to a Dyno guy. The injector is a 400cc and it is installed in the stock throttle body. I am installing a slipper clutch and a Factory Pro Shift Kit while it is apart. The 305 kit and cams are installed and waiting for a clutch holding too to install slipper clutch. I am running Sava race tires. I also have titanium motor mount bolts, caliper bolts, sprocket and disc bolts along with ceramic bearings back and front. Nobody makes a 415 sprocket kit so I decided to try these other things, trying to get the revolving weight down as much as the 415 kit would. Really close to same price. I was hoping to have it ready for a track day this weekend but all the stuff isn't here. Ari got his 250 to under 300 lbs I was told. Can't find the info on that, but feel mine will be around 300. Every 7 pounds is a horsepower. I didn't do the porting I wanted to, next time. Woodcraft is making me a a keyless ignition harness, I have removed stuff on the frame which was a pound or so. I want it done.



I also have a tick SV650 I race, won a championship with it a few years ago, it right at 318lbs 85 hp. I got a Kevlar tank and PM aluminum wheels that really help. On the CBR air box, I also am going to add some those UNI small round filters too. I race at 4200-5000 feet and need more air.



I will let you know the weight as soon as I get it all together. Oh yea, I run 110 race gas. Got to to beat all the other 300's. I am 155-160 lbs and am trying to get that down too.
 

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Hey, I am 67 and still going. Yea I have a Bazazz with a auto mapper. So I don't have to take it to a Dyno guy. The injector is a 400cc and it is installed in the stock throttle body. I am installing a slipper clutch and a Factory Pro Shift Kit while it is apart. The 305 kit and cams are installed and waiting for a clutch holding too to install slipper clutch. I am running Sava race tires. I also have titanium motor mount bolts, caliper bolts, sprocket and disc bolts along with ceramic bearings back and front. Nobody makes a 415 sprocket kit so I decided to try these other things, trying to get the revolving weight down as much as the 415 kit would. Really close to same price. I was hoping to have it ready for a track day this weekend but all the stuff isn't here. Ari got his 250 to under 300 lbs I was told. Can't find the info on that, but feel mine will be around 300. Every 7 pounds is a horsepower. I didn't do the porting I wanted to, next time. Woodcraft is making me a a keyless ignition harness, I have removed stuff on the frame which was a pound or so. I want it done.



I also have a tick SV650 I race, won a championship with it a few years ago, it right at 318lbs 85 hp. I got a Kevlar tank and PM aluminum wheels that really help. On the CBR air box, I also am going to add some those UNI small round filters too. I race at 4200-5000 feet and need more air.



I will let you know the weight as soon as I get it all together. Oh yea, I run 110 race gas. Got to to beat all the other 300's. I am 155-160 lbs and am trying to get that down too.
Bat,
That sounds interesting the route you are going down. Takewaga say with the cams, controller and larger piston power is upped from 24 to 35, what are you getting with your filter mods and and auto mapping??.

Injector 400cc can I ask what model of bike that came from, engine size and year. Better if you have a part number. Living here in the sticks, rural Thailand I have to go to the main dealers about 160 miles away to get any technical help. All the honda dealers around me sell scooters and bikes at 115cc.

Any help would be great. Good to see age is not slowing you down.
Ride fast, ride safe
 

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Discussion Starter #13
Bat,
That sounds interesting the route you are going down. Takewaga say with the cams, controller and larger piston power is upped from 24 to 35, what are you getting with your filter mods and and auto mapping??.

Injector 400cc can I ask what model of bike that came from, engine size and year. Better if you have a part number. Living here in the sticks, rural Thailand I have to go to the main dealers about 160 miles away to get any technical help. All the honda dealers around me sell scooters and bikes at 115cc.

Any help would be great. Good to see age is not slowing you down.
Ride fast, ride safe

Steady Garage has the injector that is plug and play. It fits right into the 250 throttle body. They have it listed with the big bore kit.
 

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Steady Garage has the injector that is plug and play. It fits right into the 250 throttle body. They have it listed with the big bore kit.
Hello Bat,
Cheers for the quick reply, unfortunately there are no link to Steady Garage, whom I would assume is in the US of A? Do you know if it may not be a Honda injector??

Cheers again
Tom:smile2:
 

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