Port timing

[ottoman]

Hi I have been racing my scooter with a stock (unported) Malossi Big bore 77cc kit.
I now have a 44mm crank and piston to make it 86cc and a R86 Roost pipe.
My question is what are some good starting numbers for port timings on this cyl with this pipe?

 

[Pronk]

What is it now? I think it's best to ask the developer of the exhaust...Roost in this case. But a normal/basic porttiming for a dragscooter is around 132/198 but i think it's better to first start around 130/195...

 

[nastykilla]

Hi I have been racing my scooter with a stock (unported) Malossi Big bore 77cc kit.
I now have a 44mm crank and piston to make it 86cc and a R86 Roost pipe.
My question is what are some good starting numbers for port timings on this cyl with this pipe?

sorry but here is NO hope for making a 77cc to a 86cc, the porttiming is not good. and youcan't get it like it should be.

 

[sbk replica]

wont work beqause of youre spooling ports wil go up waaaaay to far!

better of getting a 86cc bb and tune that one

 

[nastykilla]

wont work beqause of youre spooling ports wil go up waaaaay to far!

better of getting a 86cc bb and tune that one

yes, your exhaust port wil be over 202 or 202 degrees! and otherwise the piston will be far over the cylinder deck

 

[ottoman]

Thanks guys!! I have the correct 86cc bb on the way