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XR100 Exhaust---Stock or Aftermarket?

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I recently picked up a '00 XR100 with a grenaded top-end for my son(first bike :thumbsup: ). A few parts were missing from the bike--the exhaust being one of them. Which do you guys prefer? Are the power gains worth the $$$. Also, If anyone has an old exhaust system that they are willing to part with drop me a line as my son is "chomping at the bit" to ride! Thanks in advance jsproch1@yahoo.com.

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In my opinion, aftermarket exhaust for a XR100 with a stock engine is a waste of money. What will you pick up? 0.2 horse power, if that? The $200 to $300 you'd spend on a aftermarket exhaust would be better spent on something like the TB 115 bore kit with cam.

The heads on XR100's have such tiny ports, an aftermarket exhaust will not help that much.

Having the head ported / flowed, and a big bore kit done first, THEN add the aftermarket exhaust will make a difference.

Sure, there are people that will disagree with me, but the new exhaust "sounding cool" will not make those little bikes go faster, or increase HP. "Bling" to the ears or eyes doesn't make for performance. The best performance bang for the buck is all internal and unseen.

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I agree with Mike. The big high preformance 4-strokes get 5 hp with a pipe... But an XR100 will get little if any.

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pipes do make a difference....maybe not as much as a bigbore kit.....but a "seat of the pants difference".. :applause: . I've noticed it everytime.. :applause: ..Including taking an FMF pipe Off of an xr100 I just bought....sure enough it softened the power noticeably. It might only be .8 or 1.2 HP (absolutely more than .2 ) :applause: ...... and yea, Bigger bikes will gain more ponies ... BUT .... the reason for that id that the power Gains are a Percentage thing....Not a HP numbers thing ..... a 1 HP gain on an 8 HP bike is like a 13 or 14 % gain .... that's huge :ride: ...

On the other end....just keep this in mind.... more power = more heat and usually shorter engine life... it's all a trade off....But you got this goin for ya'

IT's a HONDA :thumbsup: good luck and let us know how it turns out

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Yes it makes a huge difference. Stock is about 6.5 hp. Jimmy lewis when he worked at Cycle World about 8 years ago or so, did a dyno test on a bunch of pipes. He came up with about .8 - 1.2 HP increase. This is huge on a 6.5 hp bike. That about 18%!!!!!!!!!!!!!!! I have the article somewhere with the exact numbers and which pipe did what etc. But it might take me a while to track it down. Plus, the pipes built today are a little better than back then, since there is more competition. Nowadays, it's the big bikes that don't gain that much, because the stock system are really good or better that the after market systems. Also, what company claims they can get an extra 5 hp out of 450 with a pipe????

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Thanks for the replies...keep 'em coming! 18% increase is impressive. The stock exhaust must be quite restrictive. What about noise level? Obviously, the aftermarket pipes tend to be louder by nature; but are there any that are quieter than others? Gotta keep the neighbor's in mind...

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Seeing as they use the same pipe for the 80's and 100's I figure it's got to be on the too restrictive side for a 100.

Unless you believe back pressure is a good thing. :thumbsup:

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YOu could always get a stock pipe from ebay and put a diff insert in it like the one that www.powroll.com makes. May not be quite as nice as an aftermarket exhaust but it will be a lot cheeper and will run almost as good.

Opening up the airfilter and airbox will help quite a bit also. Stock filter cage is really restrictive.

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Thanks for the replies...keep 'em coming! 18% increase is impressive. The stock exhaust must be quite restrictive. What about noise level? Obviously, the aftermarket pipes tend to be louder by nature; but are there any that are quieter than others? Gotta keep the neighbor's in mind...

Big Gun evo is supposed to be pretty quiet.

http://www.biggunexhaust.com/product_info.php?cPath=16_17_19&products_id=424

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Just got a line for a like new pipe off of a '04 CRF100. Will this work on an '00 XR100?. I don't mind fabricationg new exhaust mounts...just wondering about clearance issues with kick starter, ect...? Anyone done this?

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For those who say pipes and what not don't make much difference. Here's a dyno chart. I can't really say what we did (it's a secret), but mainly it was only a head pipe mods and manifold mods. As you can see, just little things like that after about 50 runs, can make an average motor a step above the rest. Of course, it's a combination of everything together and not just one thing that makes a major power.

Dyno1.jpg

I just noticed the date . . . 2002. Where does the time go???? :thumbsup:

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OK...gonna go with the CRF100 pipe and see how it works. Thanks for all the input! The inserts for the stock pipes are not a bad idea. Cool dino graph SocalXr...impressive for a little understressed 100. I've had quite a bit of experience with 2-stroke pipes and know they can make quite a significant difference. I have an old RZ350 and MC28 NSR250 with HRC race kit sitting in the garage. Close to 90 bhp...not bad for a little 250:) As the future of the two-strokes is quickly fading, I'm familiarizing myself with the 4-strokes. This little XR100 seems like a good starting point...

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I'd like to see someone run a dyno on the following.

Step 1) "Off the showroom floor" XR100.

Step 2) Factory exhaust, remove exhaust baffle, open up air box, rejet.

Step 3) With an aftermarket pipe, jetted acordingly.

I'd be willing to bet the difference between #2 and #3 wouldn't be worth the cost of an aftermarket system. The money spent on the new exhaust would be better spent on making the XR100 a 115. It's about the same cost.

Step 4) Go back to Step 2 with a 115 kit installed.

Compare step 4 with step 3.

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Depends on what brand pipe and what brand 115 kit. Takegawa kit? Trail bikes kit?? I had two Trail bikes kits and they are slow, but so is a stock motor with only a pipe. The only way to get decent power is a 120cc kit or takegawa kit with head, carb, and pipe. If you want top fuel dragster power get a kitaco 145cc kit.

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