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XR100 Engine Performance Suggestions

This is a discussion on XR100 Engine Performance Suggestions within the Bigger Minis Forum forums, part of the General Talk category; I need some ideas for an XR100 endurance engine. I am restricted to 110cc in my class and want more power (like who doesn’t). I ...

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  1. #1
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    Skid's Avatar

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    XR100 Engine Performance Suggestions

    I need some ideas for an XR100 endurance engine. I am restricted to 110cc in my class and want more power (like who doesn’t). I am thinking I am going to use the Powroll piston (brings me up to 107cc) and camshaft, but I would like to know what others are doing about the head. I have heard that it will be the next part holding the performance back. Porting? Replacing with aftermarket? Thanks for the help.



    BTW, this is what I have ended up with so far. I still need to do some tweeking on the suspension, but it is comming along.





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    Re: XR100 Engine Performance Suggestions

    The takgawa super head is real nice,that and a high compression piston, and monster cam you should be good.
    crf150R its not a mini but its not a full size either its just right!

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    Re: XR100 Engine Performance Suggestions

    The question becomes, where can I get just the head without having the buy the whole kit? Thanks.

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    Re: XR100 Engine Performance Suggestions

    Im sure theres someone who seels just the head, but they should change the rules to run at least 115cc, cause that kits like $650
    crf150R its not a mini but its not a full size either its just right!

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    Re: XR100 Engine Performance Suggestions

    I haven't found anyone yet. That is why I was wondering if there were any other mods.



    Yea, but I doubt they are going to change the rules. The 115cc would bump me up to a class running up to 135cc 4-stroke air cooled bikes.

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    Re: XR100 Engine Performance Suggestions

    F it 124 super head kit and move up ah class.
    crf150R its not a mini but its not a full size either its just right!

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    Re: XR100 Engine Performance Suggestions

    I tried a couple of different kits in the XR100 but none of them really fits your requirements but I can give my thoughts on them.



    BBR 120 ( stock head): all low end power, didn't rev and didn't have top end.



    takegawa 117: came with head, piston, cam and cylinder. Had a nice hard hit and rev'ed good, very nice power band and felt alot faster than the BBR120



    kitaco 145 SE: head, cylinder, piston, cam, stroker crank. This is what we are running now and its awesome. I am running it with a 26mm carb but I think it would run even better with a 28. Very nice bottom as well as top.



    I think the key to you getting better performance out of 110cc is going to be finding a good head and cam. Not sure if you could get a kitaco or takegawa head with out the piston and cylinder and how good it would work with a stock size piston but you should look into it. Just be careful also if you do find a head to match the piston to it. Because if you use a flat piston with a domed head you are going to loose compression and it will probalby run worse than stock or not much better.
    2006 Reeg 70

    2003 XR50

    2004 CRF50

    2003 CR250

    2002 CR125

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    Re: XR100 Engine Performance Suggestions

    The limiting factor of the stock head is the valves and the arrangement in the combustion chamber. You could port the head but with the valves being so close together, there isn't really any room to go bigger AND run a bigger camshaft.

    You could make the Super Head work with the stock piston. Although you would have to modify it or you could purchase an aftermarket hi comp piston and mod it.

    You will lose some compression with this set up, but with a few other mods your bike will still make loads of power.

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    Re: XR100 Engine Performance Suggestions

    The Powroll piston is 11.5 compression and 55mm bringing me up to 107cc. I figured that it would help out with the low end, but because of the stock head I figured it would run out of energy quick. I checked with classic honda and they said they could get just the Takegawa head for $342 but it could take up to 6 weeks.



    It is looking like bumping up a class might be the cheapest and easiest way to go.

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    Re: XR100 Engine Performance Suggestions

    The 6 week part sucks, but an Akunar is available with a big enough dome to work with the Tak or Kitaco head and be class legal. Might find a buyer for the 115 kit jug and piston? Like Dood said, the stock head is a turd. I'm swapping on a Lifan head with 30/25 valves for just such a class legal ride. Running the 80 5th gear? Lighten the crank?



    How aboot a 115 kit and a de-stroked crank? There are 1mm offset pins in the XR size, and it's a piece of cake while it's apart for a lightening job...

    That or offset boring the much lighter 80 crank for the bigger 100 pin, 1mm closer to center. 57x43=109.74



    58x41=108.3 might be a fun way if you start with just a new head.





    BTW, Nice looking bike!

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    Re: XR100 Engine Performance Suggestions

    Aren't supermoto bikes supposed to sit really low?

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    Re: XR100 Engine Performance Suggestions

    that bike looks intense. my xr100 is on 17s. you may want to run an xr80 swing arm to shorten your wheel base. whats the mod list on that bike? the flat track class i run most guys have 120 kits so i have to do some sort of engine mods for next year.

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    Re: XR100 Engine Performance Suggestions

    would the tire still clear? mine is pretty close as is, how much shorter is 80 swinger?

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    Re: XR100 Engine Performance Suggestions

    Not to long ago I was researching aftermarket cyclinder heads and cam shafts. I did find a new head offered from Kitaco!!http://www.kitaco.co.jp/english/cata...2008-VOL06.pdf

    After search the mini performs web site, I had no luck with any info.

    Finally Honda mini trail contacted Kitaco...in Japan!

    It was like $850!(or so they told me) STICKER SHOCK! (145 se kit is a $1000)

    But now that BBR is a Kitaco dealer, They maybe worth a try! But it's out of my budget right now.



    The Takagwa head 115 kit is a good buy,and sell the cyclinder and piston



    Firepower 354: How did your lifan 100 head work out?? Got some details...

    Any performance reports?

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    Re: XR100 Engine Performance Suggestions

    I was waiting on my 55.5mm pistons to verify and mock it all up. Should have a runner in the next month. The heads are proven, the bottom end is proven, it's just a matter of finding out if the zipper holding them together will hold




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    Re: XR100 Engine Performance Suggestions

    Check the mini section on supermoto junkie I saw a 4 valve head for the Japenese version(which is stret legal) it's over 1,000 bucks though.

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    Re: XR100 Engine Performance Suggestions

    So Skid, what did you decide to do about your XR100?

    I just picked an NSF100 and I am not sure what to do with it.

    I'd like to make it a 106 with a super head with a high comp piston, but

    I am not sure how to get there.

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    Re: XR100 Engine Performance Suggestions

    thats a nice looking 100 already

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    Re: XR100 Engine Performance Suggestions

    firepower what did you have to do to get the lifan head to work?

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    Re: XR100 Engine Performance Suggestions

    Quote Originally Posted by smrmx14
    firepower what did you have to do to get the lifan head to work?


    Too much to want to do it again...

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