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Discussion Starter #1
So I've been reading up on the 250R for the last few hours and interested in the engine specifications. I build and tune cars for a living, primarily Hondas (own a Honda with quad throttle bodies myself) and it's fun to see other Honda engines because you can instantly see things that are similar between their bike and car engines. Since the bike hasn't been released here yet, I'd like to clear a few doubts with people who've already got the bike.

Is it 2 valves per port or a single valve per port?

What is the diameter of the throttle body?

Any pics of the engine internals? Not talking about the pics released by Honda, but by others who've opened the engine themselves?

Any pics of the ECU?

Any pics of the air intake with the airbox taken off? I'd like to see if they're running a velocity stack there or not.

Overall, I believe this bike is going to give me loads of fun because so much of what I've learnt about Honda's car engines is going to apply here. Making it go faster once I'm used to the stock performance will be a great experience and I hope to share many secrets with you guys here.
 

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So I've been reading up on the 250R for the last few hours and interested in the engine specifications. I build and tune cars for a living, primarily Hondas (own a Honda with quad throttle bodies myself) and it's fun to see other Honda engines because you can instantly see things that are similar between their bike and car engines. Since the bike hasn't been released here yet, I'd like to clear a few doubts with people who've already got the bike.

Is it 2 valves per port or a single valve per port?

What is the diameter of the throttle body?

Any pics of the engine internals? Not talking about the pics released by Honda, but by others who've opened the engine themselves?

Any pics of the ECU?

Any pics of the air intake with the airbox taken off? I'd like to see if they're running a velocity stack there or not.

Overall, I believe this bike is going to give me loads of fun because so much of what I've learnt about Honda's car engines is going to apply here. Making it go faster once I'm used to the stock performance will be a great experience and I hope to share many secrets with you guys here.
I can be of some help: the motor is 4 valves per cylinder, intake 30mm, exh 24mm. The throttle body is 38 mm. The Honda Worldwide site has some pretty good information on the engine design as well as other significant details concerning the 250's design package......
 

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I dont think anyone here has exact measurements.. Try to contact some of the guys from Thailand, to get them to open up their bikes, if their willing too , and get them to snap some pictures!
 

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Discussion Starter #4
Wow, a 38mm throttle body sounds nice. I've got 4 x 42mm on my car :D

The stock static CR is 10.7:1 which I believe can be played with go get some more out of the motor. Funny thing is that the bike has a bore of 76mm which is pretty close to what I work with on my cars, so it should be fun to try some nice things with it. We've already used some CBR1000RR pistons on cars, so why not the other way round :D

I'm also interested in knowing the length of the connecting rod to find out the rod:stroke ratio. I've seen the service manual but it's in Thai, so if someone can post a few specs from it, would be great. The short stroke of the bike coupled with some nice valvesprings and short skirt pistons should allow the bike to rev quite high.

Once the warranty period of the bike is over, I'm planning on sending the cams to a cam grinder friend in the US who might be able to get some fun out of it. Being fuel injected means that I can use my skills gained in mapping car engines here.

Apologies if I'm rambling on and on about things which might be obvious to you guys, but this is my first bike and the first bike engine I'll be working on, and some of the specifications just excite me because when working with Honda car engines, we always wish that certain things were done in a different manner and here with this bike, it's made like that from the factory :D
 

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Just do a little research on the CBR250r. The ratio is 76 X 55. It's an over square design that enables it to quickly rev. You might also be "cranked" to know that it has solid mains, a first on bikes but std on car engines.
 

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Discussion Starter #6
Yeah I know the bore and stroke of the engine. I work with an undersquare engine which I rev to around 9000 RPM. So you can imagine what I'd like to do with an oversquare engine :D

Interested in the rod-stroke ratio as that will help me calculate a lot of things on my simulator where I design cam profiles, exhaust lengths, etc. You are talking about the bore x stroke ;)

The length of the rod / stroke gives you the rod-stroke ratio which helps you in understanding the nature of the engine and ultimately, refining the performance of the engine.

The great thing is that this bike is being sold around the world, so a good amount of information about the engine internals can be expected very quickly. With my car (I live in India), the problem was that it was sold in about 3-4 countries, most of which have a language barrier and most Indian people are just too secretive and will not share any details about the engine/internals.
 

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Just do a little research on the CBR250r. The ratio is 76 X 55. It's an over square design that enables it to quickly rev. You might also be "cranked" to know that it has solid mains, a first on bikes but std on car engines.
solid mains? whats that?:confused:
 

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solid mains? whats that?:confused:
"Solid" as opposed to ball bearings or anti-friction bearings commonly used in motorcycle engines. Solid bearings use a babbit metal & hydro-dynamically support the shaft on an oil film pumped under pressure to the bearing seat. The solid bearing is stiffer, quieter & more compact but more dependent on adequate oil pressure. Honda used it to minimize the size (& weight) of this engine.
 

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Discussion Starter #10
maybe this can help u lil bit bro,

Azizyhoree's Blog

there's an article opening the head of the engine, though its not showing the in-ex tunnel design hehe

eagerly waiting for any secrets u share haha :D
Thanks buddy :)

Every little thing will help. First let me get the bike, there's a big wait here lol. Looking forward to working on it.
 

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"Solid" as opposed to ball bearings or anti-friction bearings commonly used in motorcycle engines. Solid bearings use a babbit metal & hydro-dynamically support the shaft on an oil film pumped under pressure to the bearing seat. The solid bearing is stiffer, quieter & more compact but more dependent on adequate oil pressure. Honda used it to minimize the size (& weight) of this engine.
ooo it means the crank bearing, sorry for my bad english haha

concerning about that, the engine oil the main dealer in indonesia recommends their own product, a 10-30w oil...as we all indonesian riders know that their oil product sucks,what oil are u going to use later? im planning to use the 0-50 eneos pro racing, but im just still a little worried about the oil pressure againts the bearing:D
 

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So I've been reading up on the 250R for the last few hours and interested in the engine specifications. I build and tune cars for a living, primarily Hondas (own a Honda with quad throttle bodies myself) and it's fun to see other Honda engines because you can instantly see things that are similar between their bike and car engines. Since the bike hasn't been released here yet, I'd like to clear a few doubts with people who've already got the bike.

Is it 2 valves per port or a single valve per port?

What is the diameter of the throttle body?

Any pics of the engine internals? Not talking about the pics released by Honda, but by others who've opened the engine themselves?

Any pics of the ECU?

Any pics of the air intake with the airbox taken off? I'd like to see if they're running a velocity stack there or not.

Overall, I believe this bike is going to give me loads of fun because so much of what I've learnt about Honda's car engines is going to apply here. Making it go faster once I'm used to the stock performance will be a great experience and I hope to share many secrets with you guys here.
The cbr 150 uses a rubber velocity stack, so im sure the 250 would use similiar tech.

The cbr 150 valve ports are separated for the first inch or so, then become one port.

I know this isnt 250 specific, but just a few interesting points.
 

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please be aware that this is not the first time a "solid" shell type bearing has been used on a motorcycle. they have been using forced pressure bearings in bikes since forever. This is just the first time Honda has used a forced pressure lubrication system on a single cylinder engine. i suggest that people on this forum do some more research before they post. In my short time reading through this forum i have laughed my ass off at some of the poor information floating around... blind leading the blind in here...
 

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please be aware that this is not the first time a "solid" shell type bearing has been used on a motorcycle. they have been using forced pressure bearings in bikes since forever. This is just the first time Honda has used a forced pressure lubrication system on a single cylinder engine. i suggest that people on this forum do some more research before they post. In my short time reading through this forum i have laughed my ass off at some of the poor information floating around... blind leading the blind in here...
Glad the forum has been such a rich source of entertainment for you. And thanks so much for your 2 vital contributions to the forum so far.

Mike
 

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look, im not trying to rain on your parade but by thor, i cannot stand idly by and watch such mechanical nonsense be plastered around.

A little information can be dangerous and a little misinformation can be deadly.
 

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Is their anything true or accurate on the internet?
You mean like when you posted that the new liquid-cooled single-cylinder four-stroke is in the 2011 cbr is nothing like a liquid-cooled single-cylinder four-stroke built in the 1990s :D..... Or when you said that engine break-in is not just geared at the motor but also to the transmission brakes, tires and chain which require a special break in procedure.:D Or do you mean the way you consistently confuse the terms engine and motor and tell others they don't know about enigines? Is this what you are talking about?;)
 

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Morphyman your mommy called, said she needs you out of the basement stat! And put down the cheetos dammit!
Oh by the way, what kind of motorcycle do you ride?
 
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