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A rev box is useless on a stock motor in my opinion. You should only get one if you at least have a light bore kit.

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you will be wasting money on it without a cam ,valve springs and hi compression piston.

best advice is keep saving, dont let the money burn a hole in your pocket.

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First of all don't listen to anyone who says not to get one and it doesn't make a difference. If you don't believe me then just line up a stock one bike with one against one without one. I wonder who will win?......... You don't need any other after market part to go with it. Even if your bike is stock it will be faster. Here is a experiment we did we lined up the stockers and the outcome is was it works. Next we got a bike with just a 81cc kit against a stock 50 with a Yoshimura muffler and a cdi w/rev cut. The out come was the 81cc in 1st gear took the lead. In 2nd the bikes lined up. In 3rd it was all over the bike with just a muffler and a CDI with a stocker 50 killed the 81cc crf and just pulled away with like 70ft and every second more and more. And Why would a bike with just a muffler and a CDI win? How much power could a muffler and a CDI produce? 31cc disadvantage! Well really a 50 is a 49cc and the 81 is really a 81.5. The CDI has over rev and the stocker cdi stops it.END OF STORY.

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My brother and I both have 2001' XR70's and whenever one of us mods one bike or the other we race to see if it actually worked. I also check top speed with my GPS. Last summer I purchased one of the aftermarket cdi box's, well, guess what? It made no difference what so ever.

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Big gun cdi box hands down. not sure exactly how much it cost. About $60 probably. i got one. it works great. but then again i have an 88 kit :p my 50 is sik. got a trail bikes 88 kit, sp-5 forks, ishock, 12inch front wheel etc. kicks :thumbsup::bonk: it's awesome. :thumbsup::eek:

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The problem w/ the comparison mentioned above is there are 2 different riders and the engines are the same or pretty close. The race would all come down to who shifted the fastest at the correct time. One person might shift earlier than the other and now wind the engine up enough.

It will do nothing on a stock bike except for raise the rev limit which you don't need b/c the stock engine stops making power b/4 the stock rev limiter.

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The problem w/ the comparison mentioned above is there are 2 different riders and the engines are the same or pretty close. The race would all come down to who shifted the fastest at the correct time. One person might shift earlier than the other and now wind the engine up enough.

It will do nothing on a stock bike except for raise the rev limit which you don't need b/c the stock engine stops making power b/4 the stock rev limiter.

Both of our bikes are stock except for a few airbox mods and the needle clip set at the second slot. When testing, we leave nothing to chance, and with the XR70's, this included shifting at the same time [both bikes are dead even ], switching riders and racing [even though we both weight the same] and racing about 10 times for a baseline, then switching over to the rev box and then racing 10 more times and then back to stock again, then doing it all over again with the rev box on his bike. As you said earlier melloyellow, it does nothing for a stock bike, not even for top end. The one we tested was the Kitaco.

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:thumbsup: Well here we go again. First of all like I mentioned before with the comparison we did switch riders many times with many people the out come was always the same. Even when some one shifted slower on the other bike the stocker still spanked the 81cc. We put the stocker back in and it lost. We switched rider and everything. I out weigh the other rider by 40lbs too. It was final :thumbsup: . Dyno it if you think different. Write a magazine about it. If you think it doesn't make a difference take it out use a stocker one then. This is just a forum and do not need to get heated and every one is entitled to there opinion :bonk: .

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hsb ur trippin, theres no box that can make more that .25hp on a stock bike(dyno proven), even that is huge considering its only got 2.5 stock! 2.75hp vs 3hp at least that the 81 would put out.

i dont want this guy to be dissaponted like everyone else expecting gains.

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:bonk: Well here we go again. First of all like I mentioned before with the comparison we did switch riders many times with many people the out come was always the same. Even when some one shifted slower on the other bike the stocker still spanked the 81cc. We put the stocker back in and it lost. We switched rider and everything. I out weigh the other rider by 40lbs too. It was final :eek: . Dyno it if you think different. Write a magazine about it. If you think it doesn't make a difference take it out use a stocker one then. This is just a forum and do not need to get heated and every one is entitled to there opinion :thumbsup: .

Want to trade a brand new Kitaco for whatever it is your using [or smoking]? :thumbsup:

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First of all don't listen to anyone who says not to get one and it doesn't make a difference. If you don't believe me then just line up a stock one bike with one against one without one. I wonder who will win?......... You don't need any other after market part to go with it. Even if your bike is stock it will be faster. Here is a experiment we did we lined up the stockers and the outcome is was it works. Next we got a bike with just a 81cc kit against a stock 50 with a Yoshimura muffler and a cdi w/rev cut. The out come was the 81cc in 1st gear took the lead. In 2nd the bikes lined up. In 3rd it was all over the bike with just a muffler and a CDI with a stocker 50 killed the 81cc crf and just pulled away with like 70ft and every second more and more. And Why would a bike with just a muffler and a CDI win? How much power could a muffler and a CDI produce? 31cc disadvantage! Well really a 50 is a 49cc and the 81 is really a 81.5. The CDI has over rev and the stocker cdi stops it.END OF STORY.

i find that hard to beileve

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Well believe what you want. It cuts the stock rev that is 9800rpms and adjust the ignition curve through the power band. So if any increase in the powerband and aceleration would mean what? It doesn't work? I never said it was like nitrous, but that it pulled through. If you don't want to agree then fine. Are you using it? I think we spent enough time on this. I guess I am crazy and just like to waste money and don't know I am talking about.

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Well believe what you want. It cuts the stock rev that is 9800rpms and adjust the ignition curve through the power band. So if any increase in the powerband and aceleration would mean what? It doesn't work? I never said it was like nitrous, but that it pulled through. If you don't want to agree then fine. Are you using it? I think we spent enough time on this. I guess I am crazy and just like to waste money and don't know I am talking about.

I bought it, I tested it, it didn't work. And no I'm not using it, do you want it? I'll give you a really good deal!!

And Actually yes, it would take nitrous to get a stock 50 to beat one with an 80cc big bore kit as you describe.

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First of all don't listen to anyone who says not to get one and it doesn't make a difference. If you don't believe me then just line up a stock one bike with one against one without one. I wonder who will win?..... we got a bike with just a 81cc kit against a stock 50 with a Yoshimura muffler and a cdi w/rev cut. The out come was the 81cc in 1st gear took the lead. In 2nd the bikes lined up. In 3rd it was all over the bike with just a muffler and a CDI with a stocker 50 killed the 81cc crf and just pulled away with like 70ft and every second more and more. And Why would a bike with just a muffler and a CDI win? How much power could a muffler and a CDI produce? 31cc disadvantage! Well really a 50 is a 49cc and the 81 is really a 81.5. The CDI has over rev and the stocker cdi stops it.END OF STORY.

Oh, and incase you forgot what you had said, I quoted it for you.

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Anything else?

Nope, I've already said you're full of crap every nice way I could think of.

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Both of our bikes are stock except for a few airbox mods and the needle clip set at the second slot. When testing, we leave nothing to chance, and with the XR70's, this included shifting at the same time [both bikes are dead even ], switching riders and racing [even though we both weight the same] and racing about 10 times for a baseline, then switching over to the rev box and then racing 10 more times and then back to stock again, then doing it all over again with the rev box on his bike. As you said earlier melloyellow, it does nothing for a stock bike, not even for top end. The one we tested was the Kitaco.

Good debate guys. I have to vouch for Racer on this one - I was there when they tested the box on the 70 and it made no difference whatsoever. The brother men are very similar in height, weight and riding ability and they did indeed switch riders as mentioned in the quote. Actually, it was all done fairly scientifically (obsessively perhaps? heh) with wind speed, fuel weight, terrain, individual engine performance, and body mods taken into consideration.

Then again, the test was done on a '70, not on a '50 as HSB's test was so who knows - maybe such a mod would indeed make a 50, almost literally, fly. 70 (seventy) ft/s is however, quite unbelievable. If it's true then, wow. :thumbsup:

...best advice is keep saving, dont let the money burn a hole in your pocket.

Sounds like good advice to me.

:thumbsup:

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