bore and stroke of china kits?

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Wickedest1

Wickedest1

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Oct 31, 2012
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anyone have info on what the bore and stroke of the chinagirl kits are?

or what the differences between them are?

id like to know to see what moped top ends would be interchangeable...

I know the puch hitorque heads fit with a lil bit of drilling the stud hole out...

which makes me think that if the stud spacing is the same why would the cylinders not fit?

puch e-50 is 38mm x 43mm stock

once I know what the bore stroke and bolt patterns are I can and will compile a list of potential top end upgrades...

how awesome would it be to see a motor assisted bicycle with like a 74cc Athena reed kit with a 21 del?

please leave your comments, opinions and input here...come on guys...you know u wanna put reeds on ur isht

thanks guys/gals
ken
 
Wickedest1

Wickedest1

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Oct 31, 2012
688
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Greg58 said:
The link below has some good info.

http://3cyl.com/mraxl/manuals/bell/performance-tuning-graham-bell.pdf.
Click to expand...
I tried on 3 different devices to open that link and I get failure notices on all 3..cant open that link...

still searching tho...seems most ped top ends don't have quite the bore(x)stroke these ht engines have...some are close but im not sure theyd work...piston slap and whatnot...don't want to spend the money on a hard to find top end only to either destroy it or have it not be a viable option...

im more curious to find out whether or not the puch stuff would work...its more available parts wise, and if I could find donor parts solely for the purpose of experimentation I would video document and do a full write up on what works and doesn't...

im gonna crosslink a thread in buy sell specifically to those curious in whether this would work...

keep em coming guys...

thanks greg...
 
maniac57

maniac57

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Oct 8, 2011
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I've often wondered why there were no cylinder swaps available from the moped world.
My understanding is nothing will fit without major redesign.
Considering how far off the deep end some of our members have jumped, I can't imagine it has not been tried here before, with no success as far as I know.
You might want to contact Frederic Chelmiski for more info as he is currently the go-to guy for ht upgrades. Might try Dax as well, but Fred seems the better bet.
 
Greg58

Greg58

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Yea, I was kinda doing math in my head. Are there only two different stroke lengths or are there more?
Both of my 48cc engines are different, one is a grubee the other is from bgf. The pin placement in the piston and port height are different.
 
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Wickedest1

Wickedest1

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Oct 31, 2012
688
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@ mbr thanks for the input...
@maniac, thanks for the direction...ill definitely look into contacting them

This is all viable info guys

Ive never set a micrometer to my engines but the few ive torn down have all been slightly diff

Im still gonna try some stuff but need a bottom end and cdi if anyone has them layin around ppm me

Keep it coming guys...lets make this a reality
 
S

sublunacy

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Sep 12, 2013
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Greg58 said:
Yea, I was kinda doing math in my head. Are there only two different stroke lengths or are there more?
Both of my 48cc engines are different, one is a grubee the other is from bgf. The pin placement in the piston and port height are different.
Click to expand...
So the rod/ cyl/ piston and head are different. the crank pin should be different then? The grubee crank seems nicer as it is a solid 3pc crank vs the 5pc crank. Is that correct? Plus 40mm intake? correct? anything else?
 
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T

Theon

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5 pc crank is better in my opinion, much better primary compression.
40 mm inlet don't make any difference unless your looking at a large reed valve.
Different piston pin height goes with different rod length.
And no Gruby aint better.
5 pc crank likely to be 40mm stroke.
3 pc could be either.
 
Greg58

Greg58

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The grubees that I have built are machined better, the piston skirt clears the intake port at tdc and all the rough casting left on some engines has already been removed. The no name engines I have built need a little more work but do run well after a few modifications. On the bgf engine the piston skirt covered 1/4 of the port at tdc so that had to be trimmed, the fins on the cylinder were crude and sharp. That being said I think all use the same bearings made in China, I'm building a grubee now using fag bearings made in Germany. They seem much better, time will tell.
 
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Theon

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Not familiar with BGF, sorry
The motors we get could be different than the ones you get.
My GT5 was obviously a Knock off cause it was crap.
 
Greg58

Greg58

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Bgf is a eBay vendor here in the states, they now only sell parts on eBay but have their own web site for engine kits.
 
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sublunacy

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i believe it has been updated to take a piston windowed reed valve but i need an "old"american generic version to double check my thoughts on the subject.

anyway i will be staying w my tightcase/balanced crank w 19mm reed and tillotson- grubee that i build. my reed kit is the bees knees/ as it will fit the standard 19mm walbros stocked on medium sized chainsaws making 6 hp a reality at my shop.
.shft.
 
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