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Series 3 Standard Engine ignition timing?

Technical help for Series one, two and three Lambrettas. Models include the Li, Li Special, TV, SX, GP, Serveta and API/SIL models

Series 3 Standard Engine ignition timing?

Postby Littlewheels » Thu Sep 04, 2025 9:01 pm

I've been running my newly rebuilt engine with the ignition timing set at 19deg using E5 petrol. It runs ok but on longer rides it gets really hot and I'm worried it may seize :roll:
It's a TV175 with standard head, barrel, piston, and standard 20mm carb. On the main jet i've gone up 1 size to 107 as the barrel has been bored out to 181cc. Oh and it's running on a standard 6 pole points ignition system.
Any help greatly appreciated 8-)
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Re: Series 3 Standard Engine ignition timing?

Postby hullygully » Fri Sep 05, 2025 9:11 am

is it a TV or GP crank bud?
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Re: Series 3 Standard Engine ignition timing?

Postby Adam_Winstone » Fri Sep 05, 2025 10:46 am

Any doubts, reset to 17 degrees and it should run cooler.

Over-boring will have bumped up compression slightly, which normally requires ignition advance to be reduced. Modern fuels burn hotter, which requires ignition advance to be reduced.

Standard T5s, in the days of better non-E fuel, ran something like 15 degrees btdc so please don't think of 17 being in any way extreme!

FYI - A pal took his reliable Euro Lambretta iron 175 to a dealer to have his seals replaced and the dealer mentioned that he had "corrected" the 17 static timing to 19 degrees. The result of this 'correction' was that he seized it solid on the Newbury bypass, nearly missing the Euro! Piston replaced and timing put back to 17 dbtdc and it didn't miss another beat. On the return leg he covered 430 miles in a single day.
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Re: Series 3 Standard Engine ignition timing?

Postby Littlewheels » Sun Sep 07, 2025 3:40 pm

Thanks Adam, I've now set it to 17deg and fitted a 8 spark plug instead of a 7 which may also help. Will ride it to Wolly and see what happens, about 130miles and report back 8-)
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Re: Series 3 Standard Engine ignition timing?

Postby Adam_Winstone » Sun Sep 07, 2025 5:20 pm

Good luck, I hope that all goes well and you enjoy the rally.
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