SS180 tuning options?

[Terrible Taff]

My ss engine has a gs160 crankshaft, converted with ss180 rod so 12v conversion was possible. Runs really nice btw.

I got an extra SS180 barrel with the scoot and I am trying to work out what my options for more power are.

It looks to me that I could proberbly rebore my spare barrel and use a more modern piston. I`m not too smart when it comes to the nitty gritty of port timings and not quite sure how far I can take the barrel, or what the bore to piston clearence should be.

To me it seems that I could actualy use a px200 piston (Iv`e also been looking at Wisco pistons), and I think I read something about someone doing just that on MB`s old website.

Does someone remember, or know someone who has done it, who can pass on some info to me?

I havn`t done any work on vespa`s for years and i`m maybe a complete idiot as to the differences between a barrel and a modern piston not made for piston induction.

I`m thinking that I could modify and fit a Sip Road to make a good tourer. If it goes tits up, I can revert to what I already have.

Hi there Fux

I am working on a SS180 cylinder that has been bored to 66.5mm giving 208.4cc & has had some basic tuning work done to the piston crown to advance the transfer & exhaust timings, as the standard piston set up masks the ports at BDC by approx 3.0mm.

The PX200 piston that was used had the rear port welded up, but had a lot of distortion plus when cleaning up the welded area of the piston the previous owner had not done a good job of it! At present with the old piston the bore clearance is 0.010" & should be nearer 0.003"!

The modified piston crown is similar to the way the stage 2 lami pistons were modified in the 1960's with the area that matches the transfers & exhauxt ports had been filed down by 2.5mm. Not the best way to advance the port timings as the squish is not at a constant depth.

I am at present reworking the bored SS180 cylinder with a new welded up PX200 piston. Which I have now modified to improve the fuel flow through the piston & Cylinder ports. Also the head has been reprofiled to suit the new piston unit @ 67.0mm.

When finished I will have a costing for doing this conversion for those interested.

[Fux]

Am I interested?? Look at my number plate.

[Mel K]

The SS engine is unreliable to start with, and with the shortage in spares and non existent tuning options I would leave it as is and tune something with potential instead.

Ss, unreliable ? That's not my experience of one, had one back in the day that I thrashed off road all summer and the only ever problem was a broken cruciform, easily fixed and bullet proof again.?

Also Fux, I'd think twice about messing with it if it's running nice and is nice to ride, keep your Lammy for tuning. Just my opinion.

[Fux]

Also Fux, I'd think twice about messing with it if it's running nice and is nice to ride, keep your Lammy for tuning. Just my opinion.

I`m not looking to tune the arse out of it (I dont think the gears would cope), just need it to get me to the rallys without causing a traffic jam..... like I said before, if it goes tits up, I`ll revert to what I have now but i`m pretty sure it will be fine.

The lammy is sold. It scarred the crap out of me in the end

[victor]

Also Fux, I'd think twice about messing with it if it's running nice and is nice to ride, keep your Lammy for tuning. Just my opinion.

I`m not looking to tune the arse out of it (I dont think the gears would cope), just need it to get me to the rallys without causing a traffic jam..... like I said before, if it goes tits up, I`ll revert to what I have now but i`m pretty sure it will be fine.

The lammy is sold. It scarred the crap out of me in the end

My standard SS easily kept up with the traffic and standard PX200's going to rallies. Bottomed out the speedo at indicated 120kph+ (probably 105-110 true speed).

When it was not seizing that is.

From scooterlounge:

The S.S. was fast for its day, and is still reasonably fast today. It can safely keep up with traffic in terms of acceleration and top speed. Flaws include poor 6 volt lighting and on early models, a distressing tendency to seize when not jetted correctly.

Boring out the cylinder in my experience will not increase top speed since it wont rev higher, but it will give a little bit more torque.

The problems involved, besides having to ruin a truly unique and impossible to find cylinder, do not justify this small increase.

If you want speed go for a tuned PX200 engine.

[/5 pence]

[Fux]

Top speed is fine. Normal speed limits on the roads I use are 80km/h.

We do, on the other hand have a few hills in Norway.

Its pulling power i`m looking for.

What would putting on a Sip road and an upjett do?

Iv`e already got hold of a couple of extra cylinders, so that to me isnt an issue. Keeping my gs original motor on the other hand is.

[Terrible Taff]

Am I interested?? Look at my number plate.

Hi Rob

Thanks for your enquiry regarding my Taffspeed SS180 to 210 Conversion.
I should have the present cylinder kit I am working on sorted by the end of next week & the final conversion cost could be close to £550-£600!

The cost of welding up the PX200 piston is £45.00 then there is a choice of pistons on the market which vary in price the OEM being £68.62 & pattern £40.68.

Back in the late 1960’s Piaggio had supplied Douglas Vespa a few SS180 conversion 200cc cylinders for the Avon Valley Scooter Club some of whose members worked at Douglas Vespa in Bristol & were riding in events in the IOM scooter week events. I managed to get hold of one for my brother Terry & we fitted it on his V90 framed SS180 engine & forks in 1975.

The conversion consists of the following work to be done;
Rebore the cylinder to 66.5mm,
Machine top of the cylinder,
Alter porting in the cylinder,
Chamfer port edges & final hone to cylinder bore,
Make an alloy cylinder packplate,
Reprofile the cylinder head & check volume,
Spark Plug BR8ES
Spec sheet & fitting instructions:- Ign. timing etc

As this is the first one I have done for many years, I am doing the above work on a time basis @ £40.00 per hour.

At the moment I have spent approximately 8 hours doing the conversion work but have the head still to machine up & check compression volumes & squish clearances.

I have also done similar to the GS160 motor using the SS180 piston for Paul Casey in Croydon a few years back.

Note! Before you send me your cylinder & head, please measure the depth the piston sits at TDC below the cylinder to head gasket face as I need this dimension to work the porting mods & the amount to machine off the top of the cylinder as I do not have an engine unit to jig up on!

Best regards