Scooterotica

Hi,
Several years ago I picked up a cheap 69 GP200 with a tuned 205 engine that needed some TLC. I have tidied it up a bit but the scoot is in need of a birthday.
I would like to keep the iron barrel, which has the following port timings (courtesy of a rebuild receipt):
Exhaust 181 deg, 45 mm wide
Transfers 121 deg
Inlet 152 deg.
These look like classic "stg4" ish figures.
It had a 25mm dellorto and clubman, but has had an expansion at some point. Crank is of unknown origin as yet: I suspect it is a 58mm stroke and 107mm rod. Once rolling the scoot is nice to ride, boggy off the line and could do with a bit more torque.
Currently running 30mm PWK and clubman.
I intend to rebore to 67.5m and run a BRace/JL3 curly......I quite fancy a 60mm crank but unsure of rod piston combinations that would work (racetour piston, standard rod, or longer rod, jap piston etc).

I was wondering if anyone could give me some pointers on possible set ups?

Thanks
Mark

If you read all the post on here you'll end up confused!

I'm aiming for a LPC, long stroked (60mm) long rodded (120) big eyed (18mm) Jap pistoned, Iron barreled, boost ported, centre squished, welded transfered, low primaried, 240 stump puller, A'la the popular 240 convesion back in the day and covered I believe in Dave Websters tuning manual?.

But might change that next week to a high HP 150 thats amazing on fuel, very quick off the mark and last more that one season of rallies. (depending on Mick Abbeys current project )

Nice answer and sums up the world we inhabit :biggrin:

I suppose what I am really asking is with the port timings currently on the 205 barrel do I have any other rod/piston combinations or would be it be easier to stick to "standard" 60mm crank and racetour piston?

Thanks,

If you download ScooterCentres excellent Lammy catalogue from their site it gives you all sorts of options for port timings etc. Aslo there are the port timings for a host of different kits so you can have a good idea of what you may achieve.
I'd say your port timings are a little more than stage 4 and would expect it to be a little revy with 181 deegrees exaust. Fitting a 60mm crank may well help with that if its a torquey motor your after.

And maybe a long rod to try and help with the torque a little....

Thanks Chaps, the catalogue is a wealth of information...more night time reading no doubt!

oakerz wrote:Thanks Chaps, the catalogue is a wealth of information...more night time reading no doubt!

I looked but couldn't find it on the site, got a link?

cheers

hello,

this my first post so I should have introduced myself. hope it is okay to hijack this thread. I do work for Scooter Center, doing some Lambretta things there and are happy to help out on answering the question:

the download link is here: http://scooter-center.com/scoweb/pages/ ... cid=614379.

the catalogue gives a basic overview about the Lambretta model history and parts that we do stock. But it is nearly three or four years old now, and the updated version of the catalogue is our ecommerce shop. we have some copies of the printed catalogue still available.

cheers philipp

Philipp wrote:hello,

this my first post so I should have introduced myself. hope it is okay to hijack this thread. I do work for Scooter Center, doing some Lambretta things there and are happy to help out on answering the question:

the download link is here: http://scooter-center.com/scoweb/pages/ ... cid=614379.

the catalogue gives a basic overview about the Lambretta model history and parts that we do stock. But it is nearly three or four years old now, and the updated version of the catalogue is our ecommerce shop. we have some copies of the printed catalogue still available.

cheers philipp

Cheers Phillip you are a star

eden wrote:If the engine was originally run with a standard 58mm stroke and you changed it to a 107mm roded 60mm stroke and base packed the barrel so the piston crown was in the same position in the barrel at TDC as it is with the 58mm stroke you timings would be:

exhaust 186
transfer 129
inlet 148


if you go with a 60mm stroke with 115mm rod you would require a piston with a 30mm deck height
if base packed as described above your timings would be:

exhaust 185
transfer 128
inlet 149.5

if you go with a 62mm stroke with 115mm rod you would require a piston with a 30mm deck height
if base packed as described above your timings would be:

exhaust 189
transfer 136
inlet 146

on all the above you could either lower the bottom of the inlet port or cut from the piston skirt inlet side to lengthen the inlet timing.
all timings are rounded up or down

Thanks for that Eden, exactly the kind data what I was looking for....
Looking at the Scooter Center list it would appear that the original port timings are similar to Honda 205 conv'..My limited knowledge suggests that the above timings would create a revvy motor...?
If using any of the above combinations could shortening the barrel at the base and and adding the correct packing plate for a 60mm stroke, as suggested, bring the port timings back to the original, yet provide some torque increase via the stroke increase?
I appreciate there is an easy route to follow to achieve my goals, but who wants an easy life...
Cheers
Mark