What are the pros and cons of cast iron vs. aluminium barrel

[jonashford]

Alloy cylinder with iron sleeve

[Noplastic]

I recommend alloy, piston ported. Buy the latest Mugello 225. Rock solid and fast, nik-plated by Gilardoni (enough said). Don't save money on the crank. A finely balanced crank makes the difference at every level and it will turn useful also for future upgrades. That's my experience.

ps: Gori has a great reputation in Italy, he writes in a local (italian) forum, he's mostly for standard look old school tuning: 22Sh carb, original airbox, Gori cylinder kit & dedicated box pipe. They are quality kits but i doubt you can safely trash 'em around and be as fast as Mugellos with big carb and JL's.

[Burnside]

Nobody has mentioned the absolute ball ache of running in a cast iron cylinder.At least with an alloy cylinder you only need to run the piston rings in.

GT200 kit, cast iron cylinder. Running in is 1st 100 miles mix at 4% and take it easy, but use full throttle range, for next 250 miles. Hardly call that a balls ache.

[onthelam]

It makes a difference when a mechanical failure of a seal or, unwittingly ethanol laden fuel is included into the equation.

I'm in Thailand and fuel is ALL 10% ethanol, plus other limited availability with 20 and 85%.

Is ethanol per se over PURE petrol the problem or the unwitting use of excess ethanol thus leaning out the mixture?

If run all the time on 10% should be OK then?

For the non-believer the Gori kit comes with PHBH 30BS. Not saying I will use one, might ask someone to put a kit together for me. Want to use Avanti head for better cooling (ambient here about 30C) regardless of what I end up with. Just that the currency exchange makes Gori tempting and it should all be matched? I'm probably older than most and I will be riding in town(80 kph limit but some roads 100+) so really low and mid-range is better than absolute hi-end HP. Oh and a converted Li150.

[B-Race Tuning]

I'm not sure an Avanti head would be necessary just because it's 30*, at no time, once warmed up would your engine be running below 30*, it's air flow that cools (takes away heat) and I'd hope your engine will cope with 30* (that would be air temp, road surface temp could be over twice that, but you'd still be alright. The Avanti head will benefit your set up, and any advantage gained in cooling has to be a good thing. If set up for 10% ethanol then you should have no problem. Our problem is in the UK our fuel "should" be a max of 5%, but we (as a collective) believe there are instances when the % is greater and is not recognised or % content advertised at the pump by the fuel companies. If setting up for 10% ethanol then you'll find you will probably have to de-tune the optimum set-up, away from the advice of the manufacturer. This will be potentially expensive because you will be experimenting with set up. Expect to run lower corrected compression ratio, several degrees of extra retard on the timing, and an AFR of around 11.5/12.5 (ish). If you can get hold of Mr. G, on this site, he'd probably give you better pointers than anyone based in the UK as he's been/ going through it all now.
Oh, and while you are spec'ing you engine, try to have mid/ higher speed revs at around 7200+. Air flow has seemed to suffer below that in my experience, although it doesn,t seem to matter whether running standard sized flywheels or the AF size. Flywheel cowl face to fins distance is also critical, aim for as small a gap as you can. i.e. 0.5/ 1.0mm.
S

[B-Race Tuning]

Unless you build it to 10% you'll get detonation=massive heat at the wrong time=blow-up. It's not that it runs weak, it's the detonation. And if you build it to cope with 10% ethanol, expect 25-40% less design performance (estimate). Oh and to get through cranks quicker S

[onthelam]

We do have 100% petrol here but not every up-country station has it should I decide to venture outside the city. Maybe I could set up for 100% and ride slowly in the even of there being non available for 50kms or so. Sound like a leg shield glove box and an extra tank is the best bet. After all I won't be using that much fuel.

Just for info. http://www.eppo.go.th/retail_prices.php

[B-Race Tuning]

So for good juice, about 72 pence.(^^^ it's 4.53) If you can fit a long range/ second tank/ carry a can then set up for 95ron, 100%. I was under the impression you didn't have a choice, sorry. You're better off than us and although it costs 50% more (ish) a) well worth it b) better for every bit of your engine inc seals, carbs, aluminium, fuel tank lining, fuel pipe etc. etc. and c)build to full power set up (protect crank too).
S

[Noplastic]

[/quote] For the non-believer the Gori kit comes with PHBH 30BS [/quote]

Maybe earlier i didn't make myself clear. I told what type of tuning he's mostly popular for especially among people like you who likes riding between 80 to 100 kmh , possbily keeping the standard look and the original air box (read: Gori Sport kit). And that's a fact. But he is a pro tuner with an incredible experience so he obviously can make you go fast with anything you want.

Personally i wouldn't buy a iron racing kit with high compression head and a big carb (like the kit that you want ) with the addition of an Avanti head that wasn't designed for that kit. I prefer aluminum kits for certain type of performance but thats just my opinion.

[eden]

Cast iron all day long. the heat dispersion argument is old hat, what it actually means is that the ali barrel will warp to the right due to the fan blowing cooler air over the left side. Cast barrels are a lot more stable.
Cast iron barrels withstand being tuned and making power and more heat just as well as ali barrels.

Ali barrels are much cheaper to produce than cast iron barrels, the reason cars moved over to ali was to reduce weight to make MPG better, a Lambretta barrel is such a small % of the weight of the scooter that this loss in weight makes next to no difference at all.

Ive always ran cast iron and always will, I don't feel ive suffered from any loss in performance or reliability.

People moved away from cast iron with the inception of the TS1 barrel which came out at a time when 95% of the people riding and working on lambrettas didn't have much of a clue about setting up any kind of barrel, due to this cast iron got the reputation for being unreliable. Most people who turned to TS have never gone back to cast iron so they have an 80's skewed memory of cast barrels.

Another good reason to go for cast iron is that when you fly past people out on the road and they then ask "whats in that" you can say "its only an underdog cast iron barrel"




obviously i'd go for the GT not the gori!

As far as running in goes, ive posted all the miles of my latest cast iron barrel while its in its running in period, its been great fun