TV 200 barrel re build

[wibblethorpe]

Winter project is a First version TV 200 top end re Build..... the barrel is currently on 66.0 mm ...thinking about re- bore possibly to 225. The thing is I never like to deviate from the original 20mm carb & at most would fit a factory sx150/gp exhaust. I've got my eye on the short crown wossner 70mm/ tv116 crank... it's running on the TVs 200 g/box... any advice on the pro's & cons of set up appreciated.

[St George]

Keep it standard'ish other wise you will have multiply tuning problems, new carbs etc. Been there

[wibblethorpe]

Not really talking about tuning. Just how many CC's would a standard (20mmcarb/standard exhaust) run ok with. I'm not interested in getting too far from a factory 200 blueprint.. Just wondering what the extra cc's would give.

[missing lynx]

the problem with the first tv200 barrels is they have a very wide exhaust port causing the rings to snag when hot the tv200 gearbox needs a torque'y engine to enable it to pull enough in 3rd to get the most out of 4th on mine I spent most time round town in 3rd

[steve c]

go 66.6 or 66.4mm piston, fit a rapido if you want 225.
regards
steve

[Warkton Tornado No.1]

Rapido is a good route to go if you want to gain more grunt, as is long stroking of any barrel. That’s the compromise I did to an SX that I wanted to keep looking 60/70’s state of tune, but I wanted to use a VHB 30 from the outset. The gearing is 19 x 46 Pacemaker (same as TV200) & could probably pull higher.

However, if you insist on boring the TV barrel, you will gain a less wide exhaust port based on the bore, so could argue that reliability should be better.

In either case, unless you particularly wish to use the Wossner (or Kawasaki H2 re-pegged piston) the Suzuki TS250 is very suitable for the purpose though you need to bear in mind that they have an Ø18 mm gudgeon pin, but that is not a massive obstacle IMHO.

When it comes to carburettor choice, though, if you must retain the SH family look, then the SH22 was supposed to be bore-able up to Ø25 mm but I wouldn’t recommend it. You could consider the option of the SH24 which Rimini Lambretta has been using on some of their rebuilds for some time. There comes a point, though where the standard/modified air filter will cause issues, notably the engine over-heating as I found in my early days of half-arsed 'tuning'

Modification of any Lambretta to increase performance has to take into account the whole package, particularly the inlet & exhaust, to obtain any viable gains. Retaining a standard exhaust will be the major restriction, of that I am certain Why else did the firms such as Ancillotti & Royspeed start manufacturing exhausts in the Sixties if there wasn't good reason?