So... do you think we will see some Big Bore Kits in the near future?
I'd love to see an increase in the displacement and would do it in a heartbeat.
The CBR250R's balance shaft wasn't designed to quell vibration with a larger piston. It would likely be more vibration prone. A big bore will increase torque, but will probably only marginally increase horsepower. Based on my experience having sampled an Athena kitted 166cc big bore Honda CBR125R - the bike had tons more torque, and could cruise easily at a higher topspeed - this part was great. But the bike showed much more vibration in the upper rev range to the point where I was concerned that the bike might vibrate apart (I never came close to bringing it to redline for this reason). As a result, the kit really mellowed the bike out - I felt I had to ride it like a low redline, high torque, V-twin cruiser which took something away from the high revving nature of the bike and robbed it of its stock character. Based on this experience, I felt the roughness just wasn't worth the additional power and torque to me. Either way - this would be a concern for me.
Mike
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The CBR250R's balance shaft wasn't designed to quell vibration with a larger piston. It would likely be more vibration prone. A big bore will increase torque, but will probably only marginally increase horsepower. Based on my experience having sampled an Athena kitted 166cc big bore Honda CBR125R - the bike had tons more torque, and could cruise easily at a higher topspeed - this part was great. But the bike showed much more vibration in the upper rev range to the point where I was concerned that the bike might vibrate apart (I never came close to bringing it to redline for this reason). As a result, the kit really mellowed the bike out - I felt I had to ride it like a low redline, high torque, V-twin cruiser which took something away from the high revving nature of the bike and robbed it of its stock character. Based on this experience, I felt the roughness just wasn't worth the additional power and torque to me. Either way - this would be a concern for me.
Mike
Now if the material the stock piston is made of is heavier then aluminum they could potentially make it the same weight. I guess we will have to wait and see.
__________________ 2011 CBR250R- gas saver 2001 Audi S4- Twin Turbo 318hp/382 torque 1994 Jeep Grand Cherokee- Work in progress 1994 Suzuki RF900R - Work in progress
Sendler had posted about this in the CBR500 thread, but I figured it would be useful to have it in this thread for obvious reasons. I'm thinking kit + fuel controller + exhaust + dyno tuning = a lot of money to spend on a $4k 250cc bike. The question is would it be worth it? Anyone have thoughts?
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C'mon, sko sko sko!
Last edited by Rusty Shackleford; 10-10-2012 at 12:24 PM.
You can always have the crankshaft balanced for the larger piston by adding weight. I seriously doubt Honda really did any crankshaft balancing which is why the tend to vibrate at 5K.
this topic came up alot during my scooter riding days. People starting on 50cc bikes quickly find them lacking and dangerous in anything but stop and go traffic. So a malossi 78.8cc kit is installed and its great. much more torque but still no increase in top end. More upgrades are needed like final gearing and in the end it comes down to it is cheaper and better in the long run to just get a bigger bike.
I went thru that whole upgrade-itis thing. 50cc>78.8cc kit to a 150cc bike to a 460cc bike and now the CBR. Now trying to decide if i want to keep the 250 for another season or get a new 650cc sport tourer for 2013.
Will we see Big Bore Kits?
