Scooterotica

i have been reading about the suzuki conversion on here which i will have a go at at some piont
the question is about the widths of the port in the cylinder,reading dave webster tuning manual it gives hieghts of ports but no mention of widths,how would i work them out
cheers john

But he does give you % of bore details for exhaust port width in the porting chapters, which then needs to be applied to any piston/bore diameter that you port.

You'll find that most people today will suggest that you can go wider with decent modern rings, however, you then get into a debate about port shape and how many miles you should expect out of a kit before it drops a ring and knackers itself! Dyno figures always show a power increase from wider ports... then again, many people waiting on the hard shoulder might think differently.

Good question... no simple answer

Adam

PS - I might be thinking of a different 2-stroke tuning bible (certainly does) but I think Dave does make comment in the tuning chapter.

If you're interested I can take the measurements from the port map I made of my SR190 barrel which has been tuned by Harry Barlow to suit a Suzuki TS185 piston and TV175 length con rod.

Stokie wrote:If you're interested I can take the measurements from the port map I made of my SR190 barrel which has been tuned by Harry Barlow to suit a Suzuki TS185 piston and TV175 length con rod.

thanks that might be handy soon but at the moment i am trying the first standard li150 in the webster manual with standard rod
cheers

What tools are you using to cut through cast iron?

johnd wrote:What tools are you using to cut through cast iron?

hello johnd i am using houshold electric drill with differant shape rotary burrs then dremell with sanding discs

Adam_Winstone wrote:But he does give you % of bore details for exhaust port width in the porting chapters, which then needs to be applied to any piston/bore diameter that you port.

You'll find that most people today will suggest that you can go wider with decent modern rings, however, you then get into a debate about port shape and how many miles you should expect out of a kit before it drops a ring and knackers itself! Dyno figures always show a power increase from wider ports... then again, many people waiting on the hard shoulder might think differently.

Good question... no simple answer

Adam

PS - I might be thinking of a different 2-stroke tuning bible (certainly does) but I think Dave does make comment in the tuning chapter.

hi adam has it got something to do with position of ring pegs in the piston
cheers john

41.6 is a loverly number

I've always followed the rule(from bell's book) of 62-65% of the bore. He also says some take the width up to 71%, but that ring wear becomes unacceptable at that level. I always shoot for 65% for intake and exhaust and it always works. Appears to be safe, but probably not the maximum

Muppet wrote:41.6 is a loverly number

i assume you meen 41.6mm wide but that is probably on a larger cylinder
i am using a 57mm bore and -65%=19.95 then take away the 19.95 from 57=37.05 is this right or completly wrong