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Post by extraniggestrial on Jul 30, 2012 20:56:42 GMT -5
I have A 08 Veken vkm 50cc that has a HS1P39QMB motor on it. I want to put 100cc BBK on it. im having trouble finding out will this work?
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Post by inkyben on Jul 30, 2012 21:30:13 GMT -5
aslong as the bbk is compatible with the 1P39QMB it should work. I never did bbk on my old 50cc but there's a bbk for every model out there.
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Post by extraniggestrial on Jul 30, 2012 21:56:58 GMT -5
the kit i ordered was for a 139qmb. I read somewhere that the p stands for a 69mm valve while the 139qmb has a 64 mm valve. im not too sure about this and cant seem to find the site where i found that info!
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Post by extraniggestrial on Jul 30, 2012 22:09:32 GMT -5
Does anyone know the true difference in these two engine types?
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Post by D-cat on Jul 30, 2012 22:14:50 GMT -5
By designation there is no difference ("P" means "Horizontal," which GY6 engines are anyway). However it seems true that a P engine is more likely to have a larger bore and the 69mm valves. That's all it is though, a statistical likelihood and not a given fact.
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Post by extraniggestrial on Jul 30, 2012 22:35:19 GMT -5
INTERESTING. So does this mean that a standard 139qmb kit will actually fit? Will the valve difference cause an issue?
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Post by justbuggin on Jul 30, 2012 22:51:51 GMT -5
if you go to scrappydawg site hehas more info on it
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Post by extraniggestrial on Jul 30, 2012 22:59:22 GMT -5
Thanks!
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Post by extraniggestrial on Jul 30, 2012 23:11:11 GMT -5
From what I read on scrappydawg website there is no difference in these two models. So what still seems to confuse me is why the HELL did they put a P in the model number?!!
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Post by D-cat on Aug 1, 2012 1:58:34 GMT -5
As said, SOME manufacturers do use it to designate the stronger engines. Others just see it as conforming to the code. You can be sure that a installing a 47mm BBK and using your stock head will give you no problems. When going with a larger bbk (like the 50mm you're looking at), you really should also have a larger combustion chamber head, and when changing the head is where the valve length might screw you up. Most kits expect you to reuse your cam and rockers, however, if you have a tall valve head, at least one of these is not going to be standard to accommodate the taller valves (usually the rockers). Most of the time switching to standard rockers will fix the issue. Else you can also sometimes request the taller valves on the new head, possibly for an additional fee. This is something to try to find out before ordering. ______________ 69mm _______________________________________ 64 mm ______________
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Post by kixome on Aug 1, 2012 2:14:58 GMT -5
Smaller chamber when compatible = more compression therefore more power.
Chevy guys use 305 heads on 350 engines because of this.
Although anyone who buys a harley is an idiot, they are usually smart enough to use 883cc heads on a 1200cc jug to up the compression and make more power.
So if it is compatible you want the largest valves the head will support with the smallest chamber to make more power.
Lot luck man.
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Post by mainepeace on Aug 1, 2012 21:55:30 GMT -5
Sure more compression = more power. Too much compression = impossible to kick start Too much compression = blown rings Too much compression = buying a hipo electric starter
Greg
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