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Post by whydidibuyaeton on Dec 20, 2012 21:31:23 GMT -5
hi new to the forums and new to moped engines but ive been searching for a few hours about to just throw this 70cc polini kit in the garbage lol, i need a crankshaft since my stock one i can move the conrod at least 2mm without the crank moving. I wanted to get a performace crank so my engine lasts longer, but every crank i find is 41.4mm or more making it a stroker i guess stock is 39mm, my question is can i buy the 41.4mm bolt everything up and itll run or do i need a spacer and if so is there a certain name for it? or should i just buy another stock crank and run it i dont know what to do and its driving me insane
any advice is very helpful, thank you
i have a 08 eton matrix no numbers on my engine except ka50 after hours of research im saying its a 1e40qmb 13mm 17spline 10mm wrist pin
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Post by 90GTVert on Dec 21, 2012 0:13:03 GMT -5
 to the forum. I've never used a 41.4mm, but I suspect it may need slight adjustments. Check out www.RacingPlanetUSA.Com . They have a selection of stock replacement cranks that are better than stock. I know Naraku has a couple that myself and other members have used and been pleased. Mine was much better made than the original crank. |
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Post by teddy554 on Dec 21, 2012 5:51:40 GMT -5
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2tfvr
Scoot Member
Posts: 30
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Post by 2tfvr on Dec 21, 2012 6:04:48 GMT -5
Yes i'd get a replacement stock crank as what 90gtvert said if you want a straightforward build. If you choose to go for the 41 then welcome to scooter tuning  |
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Post by bradswims11 on Dec 21, 2012 15:30:42 GMT -5
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bare
Scoot Member
Posts: 55
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Post by bare on Dec 22, 2012 13:50:38 GMT -5
Interesting.
Never thought anyone would bother with a 2.4 mm 'Stroke' IMO causing more issues than it solves. Regardless just my Opinion.
Other FAR more important factoid regarding Any crank install is to NEVER use anything other than KOYO or NTN brand Japanese bearings.
OR possibly Oem bearings in a sealed oem package as the frugal alternate
Chinese Bearings have a long ugly history of damaging failures
Caveat Emptor.
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Post by bradswims11 on Dec 24, 2012 6:17:30 GMT -5
The bearings that are supplied with the crank are TPI brand bearings manufactured in Taiwan. All of the Taiwanese parts that I have obtained for Carlos at Autotech355 have been really good quality and have worked better than the KOSO parts I had installed on my 125cc 4 stroke. Just remember that KYMCO parts are all Taiwanese too.
I think that stroke helps a lot, because as you increase your bore size you are changing your stroke/bore ratio. A 250cc 2 stroke will not have a massive bore and still use a 39.2mm stroke, but will have a longer stroke to make sure that it is more proportional to the size. Yes it is only a small 2.4mm increase but at the same time that increase already equates to .8Nm more torque or 0.6ft/lb just from the stroke, not to mention increased displacement.
Thats just my 2 cents. I did a lot of research before I stroked my 1e40qmb and I like the results. Want to do a 8.2mm stroker on my 58.5mm bore on my BBK 125cc so it will go from 155cc to 180cc. That will be fun!
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Post by jmkjr72 on Dec 24, 2012 9:47:53 GMT -5
there are tons of 39mm cranks out there where are you looking
get in touch with enviromoto sp or racingpalnet
spy has them gforce should have them any one that sells brand name scooter parts will have them
tons of people with the zuma run upgraded cranks and stay at 39mm stroke
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Post by jmkjr72 on Dec 24, 2012 9:50:12 GMT -5
what are your port timings what were your port timings with a stock crank bet its not reving no where near as high as it should be and being he is going to use a polini kit it doesnt have very agressive port timings as it comes from the factory so a longer stroke will mess it up even more and it will rev even lower |
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Post by bradswims11 on Dec 25, 2012 4:15:21 GMT -5
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