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Discussion Starter #1
Well Last weekend took the 250 out to race in the MRA, Had to use the stock bodywork, Tyga rearsets, Two Brothers Exhaust, used some plastic spacers to provide pre-load on the front forks,used vinyl on the front headlight, took all the rear assy. off, no modifications done to engine other then safety wire on necessary components...

First race against all the Ninja 250's, finished 8th, second race finished 7th, now all these Ninja's are race prepped put out about 30hp at altitude, which is considerable since we are at 5500 feet....

I could not hang with them on the straights, but made up considerable time in the corners, even scraping foot pegs, muffler, and boots!!

Next round we will have the bike down to a better racing weight, also take all emission pieces off, shave the head to raise the compression, elimante the stock dash and use a GPX Pro....

Used Pirellis for the first race, worked really well, second race used a new series of Dunlop race tires, better feel, softer tire, both sets 110 front 150 rear....

Few pictures, rash on exhaust, one of the 250, one of my main race bike 08 CBR1000rr
 

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Those are some great results from a brand new bike. Congrats freddiewest!

You found the first design mod needed for the Two Brothers exhaust, I see. :D

I don't know how many miles you've got on the odometer, but I bet you will need to adjust your valve shims before the next round. I just got my bike back from it's 600 mile (750 actual) service and they had to make adjustments to mine all around. Now the butt gauge tells me there is a bit more response to the engine.

I can't wait to hear your results after the next round. Good Luck!


 

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Those are some great results from a brand new bike. Congrats freddiewest!

You found the first design mod needed for the Two Brothers exhaust, I see. :D

I don't know how many miles you've got on the odometer, but I bet you will need to adjust your valve shims before the next round. I just got my bike back from it's 600 mile (750 actual) service and they had to make adjustments to mine all around. Now the butt gauge tells me there is a bit more response to the engine.

I can't wait to hear your results after the next round. Good Luck!


im glad you posted this, i just got mine back from the 600 mile service (820 miles) and they said my valves were 'in spec' and didnt need adjusted

maybe there were just too lazy :eek:
 

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Thanks for the update, do you think the cbr250 had to shift less or could use its power in the corners better than the ninja or was it that you could ride it better? I think this guy does almost the whole track in 4th

 

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Re map?

Did you do anything with the fuel map or just let the O2 sensor correct for the new muffler? Any dyno print outs yet? I am also trying to find out about the front sprocket. Is this a shared part with other Hondas so that they would be available under a different model? The dealer said he didn't know. I am looking for a 16T if it would fit. Stock is supposed to be 14T.
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Well Last weekend took the 250 out to race in the MRA, Had to use the stock bodywork, Tyga rearsets, Two Brothers Exhaust, used some plastic spacers to provide pre-load on the front forks,used vinyl on the front headlight, took all the rear assy. off, no modifications done to engine other then safety wire on necessary components...

First race against all the Ninja 250's, finished 8th, second race finished 7th, now all these Ninja's are race prepped put out about 30hp at altitude, which is considerable since we are at 5500 feet....

I could not hang with them on the straights, but made up considerable time in the corners, even scraping foot pegs, muffler, and boots!!

Next round we will have the bike down to a better racing weight, also take all emission pieces off, shave the head to raise the compression, elimante the stock dash and use a GPX Pro....

Used Pirellis for the first race, worked really well, second race used a new series of Dunlop race tires, better feel, softer tire, both sets 110 front 150 rear....

Few pictures, rash on exhaust, one of the 250, one of my main race bike 08 CBR1000rr
 

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Discussion Starter #12
Thanks for the update, do you think the cbr250 had to shift less or could use its power in the corners better than the ninja or was it that you could ride it better? I think this guy does almost the whole track in 4th

YouTube - ‪
I was using 4th through 6th gear on this particular race circuit...HPR Track Details and Location | High Plains Raceway | Your Colorado Performance Driving and Racing Future

It has decent elevation changes and I did have difficulty staying with the Ninja's out of corners but made it up in braking maneuvers and corner speed.. meaning I was trying to retain corner speed by not bleeding off to much speed on entrance to the corner and getting on the throttle as quickly as possible...

I think we will have a better race weekend after eliminating the non essentials
to lighten the motorcycle and increase performance...
 

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Discussion Starter #13
Did you do anything with the fuel map or just let the O2 sensor correct for the new muffler? Any dyno print outs yet? I am also trying to find out about the front sprocket. Is this a shared part with other Hondas so that they would be available under a different model? The dealer said he didn't know. I am looking for a 16T if it would fit. Stock is supposed to be 14T.
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It is definitely a different front sprocket, I have not personally seen one like this,
it was pointed out to me that it was similar to a dirt bike front sprocket... There is no O2 sensor on the exhaust pipe or muffler, we will have it on the dyno hopefully this coming week and I will make that available to all here...

Gearing is not bad at all, at least on our track, next round is at a similar type of track so we will see how it performs there in two weeks from now...
 

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Sensor location

It is definitely a different front sprocket, I have not personally seen one like this,
it was pointed out to me that it was similar to a dirt bike front sprocket... There is no O2 sensor on the exhaust pipe or muffler, we will have it on the dyno hopefully this coming week and I will make that available to all here...
The O2 sensor screws right into the head at the exhaust port. It is a wide band, heated four wire closed loop system. Automatically fine tunes to set the mixture to the map, which is probably 14.7:1 everywhere, regardless of intake, exhaust back pressure, fuel, altitude, temp,ect. The ecu probably has some memory to learn and anticipate. There is talk that Honda dealers wil sell programming kits to unlock the maps of the stock ecu for racers to input their own values for mixture. This might be cheaper than a logging Power Comander or Juice Box.
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Next time you have the exhaust off, see if there is anything of the catalyst positioned in the stock pipe or if it was only in the muffler section that you discarded.
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Let me know if you come up with a source to put a 16T front sprocket on my bike for fuel economy.
 

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Discussion Starter #15
Completely missed the O2 sensor!! The catalyst seems to located in the exhaust canister, not in the exhaust header that I could see.... but we now know how good my eye sight is :)
 

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HMF Engineering made an exhaust for my bike and added a Dobeck fuel optimizer. Per the dyno I'm getting +3hp. They disconnected the stock O2 sensor. However, on the track the FI/engine light comes on. Seems like it's at the higher speeds and rpm, for example at 9.5K rpm in 6th gear. The bike doesn't seem to suffer any performance, but the engine light bothers me because I'm wondering what else might be degraded/disabled since the ecu thinks there's a problem. I'm wondering if I should try removing the Dobeck and plugging the stock O2 sensor back in?

BTW, in case you're wondering... Dobeck competes with juice box and dynojet's power commander.
 

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Still looking

I am racing the Honda too and I'm interested in playing with the sprockets. Please post up if anyone finds a source for them :)
I went to Honda but the parts guy didn't know of anything. The shaft measures 21mm diameter and has 11 teeth. When he saw the two bolts holding it on he thought it looked like something from an old three wheeler.
There is room for a 15 in the case. I don't know if a 16t will fit.
I am going to contact some sprocket companies to see if they can match something up.
 

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Auto Tune

HMF Engineering made an exhaust for my bike and added a Dobeck fuel optimizer. Per the dyno I'm getting +3hp. They disconnected the stock O2 sensor. However, on the track the FI/engine light comes on. Seems like it's at the higher speeds and rpm, for example at 9.5K rpm in 6th gear. The bike doesn't seem to suffer any performance, but the engine light bothers me because I'm wondering what else might be degraded/disabled since the ecu thinks there's a problem. I'm wondering if I should try removing the Dobeck and plugging the stock O2 sensor back in?

BTW, in case you're wondering... Dobeck competes with juice box and dynojet's power commander.
It would be nice to have an Auto Tune/ Power Commander on the bike in order to log and fine tune the mixture program. That is the only system I know of that will give you a read out of the actual mixture as measured by a wide band O2 sensor and log it and allow you to reprogram the maps yourself. I wrote to them today to ask if the stock O2 sensor would work so as to keep from drilling the exhaust and they said no but I think they just say no to anything they really don't know one way or the other. The warning light being on should trigger a substitute program. Hopefully it doesn't enter a limp home program for the ignition too. You got a good power increase so it all must be working ok. Can you post a screen shot of your dyno run?
 
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