Athena 170Cc Big Bore Kit, Some Observations - 125cc Sportsbikes Forum

125cc Sportsbikes Forum: Athena 170Cc Big Bore Kit, Some Observations - 125cc Sportsbikes Forum

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Athena 170Cc Big Bore Kit, Some Observations

#1 User is offline   banzairx7 

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Posted 13 January 2013 - 05:49 AM

Having lived with the athena kit for awhile I've discovered some things about it that really put it in a bad light. The port locations are off by 3mm, as in they sit 3mm too low in the cylinder. I think I have figured out why the Athena kit port location is so terrible. Our 125 has a 50.7mm stroke, The WR & DT 200's are 57mm. Thats a 6.3mm difference from our 125. Since both motors use the same cases the crank centerline is the same. If the stroke is 6.3mm longer on the 200's that means the piston will travel down an additional 3.15mm as well as up. Funny how that lines up exactly with how much the Athena cylinder is off. Makes me think the Athena big bore kit is just a DT200 clone. As in they put zero engineering into and are just selling aftermarker DT cylinders. Notice I said DT. In doing some more research it turns out the WR200 and DT200 cylinders are different. The WR has more aggressive porting with additional exhaust ports. Kind makes me want to say a big FU to Athena. I also wonder why no one else has noticed the port mismatch in the 125.

#2 User is offline   Snooperstar 

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Posted 29 May 2013 - 10:44 PM

so is it possible and how hard would it be change the stroke to match or is it just a pointless journey?

#3 User is offline   JiMBONiO86 

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Posted 30 May 2013 - 04:37 PM

I was looking at the big bore kit but have heard about the ports. How does it go with the big bore on it? Much quicker? Think im gunna keep a eye out for a dt200 engine

#4 User is offline   banzairx7 

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Posted 31 May 2013 - 02:11 PM

It's a lot quicker but I did so many other things at the same time it's hard to tell what mod did what. Go for either the DT200 or you could try this also- http://www.ebay.de/i...=item231c1a5f39

#5 User is offline   JiMBONiO86 

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Posted 31 May 2013 - 06:44 PM

Sounds good might have to try that! Get my mod1 out the way this week then see what funds allow

#6 User is offline   Snooperstar 

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Posted 01 June 2013 - 09:48 AM

Not even done my theory yet, need to study for that first. Then its the choice of sell up n get a ninja 250 or get a bigger top end, im leaning more to the top end but without all the machining work banzair went through to fit yours. Its a beautiful bike to ride as it is

#7 User is offline   Dangerous Dave 

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Posted 02 June 2013 - 03:15 AM

Very interesting, but very pricey! The big question of course is about the port timing. If it truly was designed from the git-go as a big-bore kit for a 125, it would probably be money well spent if it was in one's budget.

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