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This might be a stupid question but how much of a difference is it performance wise between slip ons and a full exhaust? Will it be a big difference even if its just for the 250? I heard from some guys riding literbikes that there is noticeable difference in theirs.
 

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there is a small hp difference between the two. but a lot of riders dont have the confidence to push it that far anyway so the extra hp isnt really used. they both cost about the same. the full exhaust usually cost just a little more.
 

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cans

Not a dumb question. The bottom line is a matter of availability of total engineered modifications to augment any exhaust change. Hanging a cool looking can is mostly cosmetic without fuel metering compensation. Getting that done by a competent tuner is the real trick. A can or a full pipe system will do the trick and get you some hp if properly tuned. Get the tuner and a chip, then find a system or a can. I prefer a full pipe system as it is obviously a cleaner flow and for me looks better than those trashy cans.

bella
 

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This might be a stupid question but how much of a difference is it performance wise between slip ons and a full exhaust? Will it be a big difference even if its just for the 250? I heard from some guys riding literbikes that there is noticeable difference in theirs.

Odds are a full exhaust will be better but I'd wait until some tuners or racers have a couple mongths in the spring to come up with solutions that work.

If they can crank this puppy up, it ought to be good for an easy 28-32 hp with a system plus intake work, and maybe a few other tricks.
 

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I'll mount a 140 decibel air horn under the plastic like I do on all my bikes. Then I can make some noise when I want to. Like when some idiot starts taking my lane or another looks anxious to pull out or turn in front of me. It has saved my butt before & will again I'm sure.
 

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With regard to ECUs and the like, to compensate for the lost compression ratio, word in Thailand is that Honda will be introducing different fuel maps for the ProGraMmable-Fuel Injection and you can take your CBR250 to selected dealers and have them put on the bike for only a few $.

Word is that that's the (near) future.

I personally will be going for a full exhaust system and airfiler (probably K&N) and whatever is available with regards to mapping the fuel. Either ECU or hopefully able to reprogram the PGM-FI. I don't want to go too far off the stock compression ratio of 10.7:1.
 

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Has any of you thought about how much more fuel you might burn and how much mileage you'll lose to gain a few hp? Honda has gone to lengths to make this competitive & frugal with fuel. It may be cheaper to buy a 600.
 

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Honda has gone to lengths to make this competitive & frugal with fuel.
Absolutely.

Adjusting the c. ratio to match a new breathing system isn't going to halve your fuel economy.

You'll probably notice it a bit, but it's so efficient from the outset that altering it isn't suddenly going to turn it into a gas guzzling monster.

I checked my millage at the beginning so I'd know what it usually does and also could inform others if they were interested. Since then I just fill up, and when it runs out I fill up again. It's so cheap to run that it isn't even worth noting.
 

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What size is the header pipe for a slip on to fit? Who makes a slip on the fit this Honda? I haven't seen any exhaust ads list the CBR250 as of yet.
 

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Has any of you thought about how much more fuel you might burn and how much mileage you'll lose to gain a few hp? Honda has gone to lengths to make this competitive & frugal with fuel. It may be cheaper to buy a 600.
I agree, if you really want a fast bike then just move up to the 600 :):):)
 

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I agree with FUBAR'ing the ratio and flow that Honda has setup for sound and a few HP... But then again that never really crosses anyone's mind when they modify anything for that matter of fact.
 

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I can't say it wouldn't be fun if a few more HP could be had to help you shred that 250 Ninja at those speeds where the tests claimed the Ninja could top the CBR!
 

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I agree with FUBAR'ing the ratio and flow that Honda has setup for sound and a few HP... But then again that never really crosses anyone's mind when they modify anything for that matter of fact.
The compression ratio is 10.7:1.

The pipe and breathing system is highly restrictive due to emission laws. Not to mention heavy. Freeing up the breathing system isn't modding the engine to extremes, it's simply allowing it to breath as it should.

Once this is done it's breathing a lot easier, but the stock CR will be messed up. The ECU will allow for some change but not much. Getting a new fuel map installed, or a powercommander/juicebox will sort this pretty easily. Hence the engine is running perfectly (as you wish as you're programming the compression ratio) and it's breathing freely without enforced restrictions.

It isn't changing the engine to perform beyond it's means, it's allowing the engine to run as it should without being choked up by emission laws.

Am not too sure why people need to say it's better to buy a 600cc than free up the 250cc engine to run as it should.

BTW, Honda made it very easy for a pipe change by placing the lambda bung on the exhaust manifold and not the pipe, allowing the O2 sensor to inform the ECU without major surgery. :D
 

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Compression Ration stuffed up by an exhaust change?

I would like you to say why?

Compression ratio (static) is set by the stroke and piston, head gap, all physical features of the engine. Exhaust will not change it.

You then have dynamic compression which can be changed by stuff that happens when you get the bang so intake cam timing, ignition timing, exhaust might play a tiny part in that if any.

What will change is your AIR TO FUEL ratio, and the ecu should be able to compensate around 15 to 20 % i would take a stab at. Depending on the code in the ecu some are strict and give check engine lights and cut the engine to a restricted mode.

If your really worried you would throw it ona dyno after to check the air fuel ratios
 
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