Any advice welcome

[Stevepshipley]

I've recently got more time on my hands and am a bit more confident with engines etc. one of my scooters is a Spanish LI 150, early model (66). It was running a muggelo 186 with 26mm delorto and 42mm AF clubman. Nice ride and goes well. Recently though my mates are leaving me behind so I've been fiddling a bit. I've changed the front sprocket to a 16 tooth, gearbox is the early one without the 3rd gear gap. I'm quite pleased with this but wondered what else to do to get a bit more? Before I touched it it would do 63 mph (gps) at 7100 rpm (sip speedo). It's been pretty windy but now I'm getting 65 mph at 6700rpm first test run.
Do you think it would pull a 17 tooth sprocket? Or should I look at expansion exhaust? I would have fancied a bgm clubman but they're not available, so was considering a jl3.

Any thoughts/advice? Bigger carb and expansion or try another change to gearing?
Thanks chaps

[Wee Mark]

Hey Steve

Depending on choice you should get a decent gain from an expansion but as ever with these things, its got to suit your riding style and what you use the machine for. I run a Rapido Classic 225, Li 150 Box and 30ml PHBH and have used both revy(JL4) & Torquey(B-Race Stealth) and also AF Clubman and the scoot went well with all of them but both the expansions just gave the engine just that bit extra either way, in saying that I have not used any of the recent batch of Clubman style(big down pipe) so cannot comment on them. You can good results without further gearing change.

hope this offers a little help
Cheers
Mark

[Eden]

you talking Lambretta speedo speeds here?

[Rich Oswald]

If you are getting 65mph gps Steve then that's pretty good for 186 Mugello. Don't think you are gonna get much more without changing to a 30mm carb, expansion and a bit of porting work,

Rich'

[Stevepshipley]

Cheers Rich, Mark,
Yep GPS figs, I think on balance now it's a much better ride with 16 46 and tbh 65 is fast enough. I'll think about a bigger carb and expansion pipe but just changing the front sprocket is a it of a transformation really.

[hullygully]

for the sake of a couple more mph, its not worth changing to a bigger carb, expansion box, etc......

[johnnyXS]

also it has been very windy lately which at those sort of speeds into a headwind will make a tremendous difference in terms of drag and the power required to maintain that speed. If you were to look at a graph showing speed plotted against power required you'd find there is a very steep rise around 55mph upwards due to overcoming air resistance.

Your best and cheapest option is to look for ways of reducing weight and drag which could be worth 3-5mph at 65mph and cost nothing.
Remove unecessary stuff from the scoot like unused racks . Consider carrying a airstop canister instead of a spare wheel and tyre
Wear tighter cloathes that flap less and hunker down to create a more aerodynamic shape.
Maybe a short racing screen might actually reduce turbulance I don't know. I'd try all these things first as they cost nothing .
This is supposing that your scoot is already in perfect tune with the optimum advance etc . You might sneak a few mph by increasing your advance by a degree or two and by switching to fully snthetic oil and reducing the mixture to 2% which will give you a richer mixture.


To be frank I can't see the point in screaming everywhere at 6000rpm+ 70mph+ on a 50 year old scooter but then i don't travel 100's of motorway miles attending UK and Euro rallys

[Captain Pugwash]

To estimate my speed I use wagon speed when we're slow touring just keeping pace with the wagons 52-55 then coach speed when we're moving a little quicker keeping up with most coaches 60-65 then if your overtaking coaches on motorway's usually around 65mph or more.
75mph or more tends to get you out into the third lane a little more than is comfortable. Left Hand hovering over the clutch just incase

Less strain and to get me there quick enough I prefer coach speed

SatNav is accurate but it under reads on hills both up and down.

[Eden]

Yes... 55 is boring...65 is comfortable.. 75 is stressful 85 is asking to blow up no mater how much bhp you have.

[Markpm]

Totally agree with Eden
55 is pretty tedious but at 65 my scoot seems to find a sweet spot,vibrations almost gone etc
i can't do 85 so couldn't possibly comment

[Stevepshipley]

Tbh the scooter just feels much improved with just the front sprocket change. Cruising at a genuine 60 which I think it will now do is comfortable for me. I don't feel like I'm ragging the arse off it. I'll wait final judgement till I'm out with my nemesis (186 mugello, 30mm mikuni and bgm clubman), for a final decision

Thanks for your input, very much appreciated. Good fun tinkering init