Lambretta small block Port Maps

[johnny650]

I tried my hand at producing a port map of my 200cc small block cylinder before fitting it and as it turned out quite well I thought that it might be useful to someone else.
It could prove a useful starting point for porting other small block cylinders perhaps?

I'd be interested to see your small block port maps or hear any observations or opinions on the porting of this cylinder . This cylinder was part of an Indian cylinder kit I purchased several years ago so I have no information about it unfortunately.


After much faffing about with bits of paper, scissors and sellotape without success I applied a bit of commonsense and devised an easy foolproof method.
Using 2*Pi*R to find the internal circumference of the cylinder so a 66mm bore gives approx 207mm and the cylinder is 128mm high so cut a piece of paper 207mm x 128mm and join together the short sides with a narrow strip of sellotape to form a cylinder with perfect fit ...simples
175cc cylinder bore 62mm = 194.8mm
186cc cylinder bore 64mm = 201.1mm

Why not have a go with your spare barrels

200cc original port map by John, on Flickr

[johnny650]

nothing much to do today so I thought I'd amuse myself with doing another port map.
I've searched the web but not found a single small block port map anywhere.
Not sure if these are going to be helpful to anyone as despite several hundred views there hasn't been any feedback ?

At least it might give someone a starting point for porting from stock or guaging how much porting work has already been carried out on an unknown barrel.

Problem is I have no idea of the vintage or manufacture of this cylinder

TV 175cc port map by John, on Flickr

[YAMLAM]

Page Not Found
this is what i get from your link/photos
Oops! Looks like you followed a bad link.

If you think this is a problem with Flickr, please tell us.

Here's a link to the home page.

[johnny650]

sorry yamlam there wasn't a single response to my posts so I assumed there was no interest so when I accidently deleted the images from my Flickr account the other day I didn't bother to upload them again.
What is your interest may I ask ?

[hendy]

I was interested

[drunkmunkey6969]

I've searched the web but not found a single small block port map anywhere.

RB20 here...I’m sure BGM195 and a few others are on here somewhere too?

viewtopic.php?f=7&t=490&sid=ac58d1acc8d ... 1e3b4c3b6d

[drunkmunkey6969]

This was the RB200 specific thread: viewtopic.php?f=7&t=296&hilit=portmap

[drunkmunkey6969]

This was the OPs original map:

[johnny650]

This was the RB200 specific thread: viewtopic.php?f=7&t=296&hilit=portmap

yes I did see that RB20 but that is a special cylinder with reed valve not a standard ci small block 150 or 175cc barrel that has been bored to 195 or a lined aluminum Indian barrel .

Thanks for re-posting my image I'll reload my 175cc port map when I get a spare minute

[johnny650]

185cc port map done tonight . Thought I would add it to the others in case it is of any interest to someone.


Lambretta 185cc Port Map by John, on Flickr