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Discussion Starter #1
Hey all, I am very interested in buying a big bore kit for my DRZ400. Can big bore owners please post:
-what kit you have
-how many miles do you have on it
-what type of power gain. (bottom end, top end mid range etc.)
-any warnings or possitive notes anyone has heard (nice to hear from some real owners though.. of course)
-and please anything else you want to share regarding big bore kits.

thanks all:bike:
 

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I've got the Athena 440. Not really a bore, but a whole new cylinder.

about 1500 as of this evening.

well... the 3x3, FCR, full Yosh, the 440 and cams were all done at once so I can't tell you how much just the 440 did for it, but it is no where near a stock DRZ. Seriously, it is a completely different machine.

You won't be able to use 87 octane anymore, that's about the only downside other than cost. I liked the idea of the Athena kit because instead of boring out the stock cylinder, it replaces the whole cylinder. No weakened metal or anything like that.
 

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Discussion Starter #3
that's what I thought would be good, the kit with a complete new cylinder. My bike is totally stock, can you give me an idea of what the difference would be from mine to yours, I want to do all the mods you have anyway. Do the cams have to be done with this kit? as for fuel, I don't care about buying premium for my toys. thanks
 

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Cams don't have to be done, but from what I've read, without the cams (a great time to install a MCCT if you haven't yet!) the power hits a flat spot at about 3/4ths throttle.

Seriously, the bike looks the same and handles the same. I know people say this with only rejeting and doing the 3x3, but the honestly is a different bike. My friend who got me into supermoto races a CRF450 and even he kept going on about how nice it is.

However, this won't give you 450 power. BUT, you get 400 reliabilty. Only thing I've done since I've got it was change the oil. I think I'd take the little performance hit to not have to do rebuilds as often as him. ;)
 

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how is mileage affected with the big bore kit?
If you mean gas mileage, its not too bad. I generally get between 45 and 50 mpg. I've got the Clarke tank anyway I generally start thinking about gas around 150 miles.
 

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Discussion Starter #8
Cams don't have to be done, but from what I've read, without the cams (a great time to install a MCCT if you haven't yet!) the power hits a flat spot at about 3/4ths throttle.

Seriously, the bike looks the same and handles the same. I know people say this with only rejeting and doing the 3x3, but the honestly is a different bike. My friend who got me into supermoto races a CRF450 and even he kept going on about how nice it is.

However, this won't give you 450 power. BUT, you get 400 reliabilty. Only thing I've done since I've got it was change the oil. I think I'd take the little performance hit to not have to do rebuilds as often as him. ;)
So in your opinion you wouldn't loose much reliability? That is my biggest concern and why I started this thread.

Anyone else have some big bore experience?
 

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I read a lot about it before I bought mine, and everything I came up with seemed to be positive. Even Eddie over at thumper talk didn't have anything bad to say about the Athena kit.
 

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Hey all, I am very interested in buying a big bore kit for my DRZ400. Can big bore owners please post:
-what kit you have
-how many miles do you have on it
-what type of power gain. (bottom end, top end mid range etc.)
-any warnings or possitive notes anyone has heard (nice to hear from some real owners though.. of course)
-and please anything else you want to share regarding big bore kits.

thanks all:bike:
M/T 436 7000 miles no problem , just overhauled the head had to put a new piston in as its was slightly worn and using a bit of oil but the bore has O wear good to do another 7 k :D
 

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just put in 440 big bore. I noticed it when i THOUGHT I was in 3rd gear and clutched it up and rode a little wheelie, then I realized i was in 4th.
So far only 250 miles. Dont know if the problem is related but since I installed it I cant wheelie more than 1/2 mile before oil drips into the airbox and chokes out the exhaust. Never happened before. I used to wheelie for 3 miles no problem until i burnt up my piston.:D
 
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