stg 4 on bgm or ve cylinder

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paul213
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Joined: Wed Jan 07, 2009 11:22 am
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has anyone done a stg 4 tune on a bgm or ve supplied cylinder .
I have just measured 4 p200 cylinders 2 piaggio 1 bgm and 1 ve .
the ve and bgm both have the exhaust and transfer ports higher than a piaggio cylinder . this means to jack up the cylinder by 1.7 mm you are already over the 170.6 deg exh mentioned in the artical also it states that the bgm is 0.7mm shorter and my example is only 0.25mm shorter .
tinkering with what I have measured in a timing calculator
0.5mm packing 166 exh 122trans
1.5mm packing 171 exh 127 trans
so I am after opinions as to the ideal height for this tune or timings i can calculate the correct height

many thanks
Paul
grimspeed
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Posts: 192
Joined: Sun Dec 13, 2009 12:46 pm
Main scooter: gp 283 kx
Location: clitheroe lancs.
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with what you have there there would not be much difference.
500 rpm to where the powerband starts and ends.
What i would sugest is you see what the timings are with the cylinder packed so the bottom edge of the transfers are level
with the top of the piston at bottom dead center.
i have a horrible feeling.things are going to go bang
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