Scooterotica

I've always used a ratio of 62% of the bore diameter, measuring straight across the port. A 70mm 225 will be a sensible 43.4mm wide.
I believe 65% size refers to around the bore.
Others may stand me corrected.

I measure mine around the bore, which allows for easy measurement from pencil rubbings that are laid flat.

Eden wrote:

Twinny wrote: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

be careful when using the dw tuning manual, i haven't looked at all of the stated measurements in there but i know for sure that the ones for the h2 240 are incorrect.

see a few posts down in this topic
http://scooterotica.org/forum/viewtopic ... 5&start=22

thanks for the info everybody
eden do you know if the suzuki 190 is right in the webster manual, just waiting for barell to come back from being bored then going to have a go on that
150 barell nearly ready should be fitting that the weekend

Skokie posted his Harry Barlow cylinders measurements on my thread

http://scooterotica.org/forum/viewtopic.php?t=25324

Hope that helps.

Sorry for OT but I'm getting increasingly interested in this manual - where can I find it...?

johnd wrote:Skokie posted his Harry Barlow cylinders measurements on my thread

http://scooterotica.org/forum/viewtopic.php?t=25324

Hope that helps.

thanks johnd but i am using 107 rod and barrel has had 5mm off bottom and 2mm off top so going to be differant i think
cheers john

I had a 190 done by Dave in the 80's and it was done as the manual suggests re port timings although I would suggest slightly smaller inlet timing as they tend to get lots of blowback at lower revs. I used a TV 175 cylinder as the transfers are larger with first a PHBH 30 then an Amal mk2 powerjet which helped with the blowback a bit. Dave suggested an LI 150 box which liked to rev with an early Fresco ,then one of his pipes. Don't forget to shorten the piston skirt before you start porting

victor wrote:Sorry for OT but I'm getting increasingly interested in this manual - where can I find it...?

here

wack 63 wrote:I had a 190 done by Dave in the 80's and it was done as the manual suggests re port timings although I would suggest slightly smaller inlet timing as they tend to get lots of blowback at lower revs. I used a TV 175 cylinder as the transfers are larger with first a PHBH 30 then an Amal mk2 powerjet which helped with the blowback a bit. Dave suggested an LI 150 box which liked to rev with an early Fresco ,then one of his pipes. Don't forget to shorten the piston skirt before you start porting

thanks wack 63 will get barrel back measure it all up and get back on here
cheers john

got barrel back today after being bored to 64mm, made a port map as is, do you lay map out and measure or do you reverse map into cylinder shape and measure
cheers