I thought it was overdue that we gave you a detailed report on our shop Targa Twin 250cc engine.
Too much work and too little time means that this report is over 1 year late. This in a way is better, as we can give a real over view of this amazing piece of engineering, so, on we go, I hope you enjoy the article and find it illuminating.

Targa Twin 250cc (MPS engine no3)
1, Mileage covered
2, Fuel economy
3, Top speed
4, Cruising speed
5, Tyres fitted, tyre pressures
6, Carburetion
7, Furthest distance travelled

1, Mileage covered (from 0 miles) 4532 miles/7004 kms.

2, Fuel economy
Unleaded fuel 95 octane was used 90% of the time, super unleaded 98 octane was used when I could fully unlock my wallet. Only Rock Oil Synthesis 2 was used at a mixing ratio of 3% adjusted to 4% on long, very fast journeys. 55.4 mpg was achieved, mainly ridden on fast dual carriageways and motorways, which is what this engine was designed for.

3, Top and cruising speeds,
Before we go any further I would like to confirm that these figures are taken from a satellite navigation system. Top speed (as G.P.S) 84.54 mph (136 kph) cruising speed 65mph (105 kph). The cruising speed may not sound that fast, but it is the speed I found most comfortable, as above this you use too much fuel and concentration is harder. Most quick scooters will cruise at this speed, anyone who cruises much above these speeds has an amazing piece of kit,or, has just been shunted up the arse by a very large, very fast lorry.

4,Servicing
Not a lot, having stripped the engine when new to check tolerances and measure components, I had total faith in the unit.
Gearbox oil was change at the following intervals:
100 miles (161 kms)
500 miles (805 kms)
1000 miles (1609 kms)
2000 miles (3218 kms)
3000 miles (4828 kms)
4000 miles ( 6436 kms)
I know this may sound a little over the top, but, I have always done these short mileage oil changes. However I have had very few clutch failures or gearbox problems over the past thirty odd years of riding Lambretta scooters.
No other servicing was carried except for one cable adjustment session and checking the plugs at 100 and 500 miles. There will be a full service this winter if I have time, I think the filters will definitely need a clean.

5, Tyres
Front tyre Continental Navigator 350-10
Rear tyre Continental Navigator 350-10
Front tyre pressure 19p.s.i
Rear tyre pressure 30 p.s.i
Both tyres filled with Puncture Safe solution, no punctures during the running of the Twin. No damage to the tyres when inspected at 3000 miles (4828kms) Both speed rated to 81mph (130 kmp)

6, Carburetion.
On this engine we have always used 26mm fixed jetting PHBH Dell Orto carburettors. I found on test engines that power jet type carburettors needed too much adjustment over a variety of conditions. With an engine of this type (and cost) you should not have to alter your carburetion when changing form town to motorway riding. Any way I settled on the following setup:

Main jets 103 changed to 101 at 2000 miles for better fuel economy
Pilot jets 55
Choke jets 60
Needles x7
Needle position 1 1/2 from top notch setting
Slides 40
Float valves 250
Mixture screws one and a half turns out from fully closed.

7, Furthest distance travelled in one go. Manchester to Killarney ( Euro Lambretta 2011) total round journey 687 miles (1105 kms)

Finally
I hope that you find the information interesting, and was worthwhile reading. At least it kept you off some social network site, or stopped you watching Strictly Come X factor or other such crap. At the time of writing we are testing different carburettor types, and some new high compression cylinder heads. If and when I have time I will report on the results, for now, Ta Ra

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