biggest bore on a lambretta

[Supereibar]

Biggest bore on a lambretta.....

A Lambretta is a bore... or a very large hole... that I keep putting money into...but I luv'em!

AMEN TO THAT!

[CANbus]

nope wife reckons I'm the biggest bore, so I will get back in the garage then

[GP Kevo]

80 mm, from Worb5's sprinter, now in the hands of a SoCal Lambrettist hoping to break a world speed record.

[Adam_Winstone]

OK, old thread but I've just come across it... and it happens to be an issue still close to my heart.

My mind has played on this for a long time but I still keep coming back to needing a barrel with a thicker wall. Even if you plug the stud holes and bore out, you soon run out of bore wall. Little point of going beyond the bore wall and fitting an iron liner as you still need enough meat in the barrel to run the transfers down.

What we really need is a barrel that is just BIGGER, with thicker walls, bigger transfer casting and longer barrel for long stroke increase. I'd happily sacrifice a casing and have the mouth machined off and a bigger mouth welded on (as the Germans/Austrians used to do to convert small block casings before SIL 200s became readily available). The problem I keep coming back to is barrel... and I don't really want to change to a bike barrel

Adam

[dirtyhandslopez]

What about a mico-lite barrel the German man did a few years ago?

[DigDug]

OK, old thread but I've just come across it... and it happens to be an issue still close to my heart.

My mind has played on this for a long time but I still keep coming back to needing a barrel with a thicker wall. Even if you plug the stud holes and bore out, you soon run out of bore wall. Little point of going beyond the bore wall and fitting an iron liner as you still need enough meat in the barrel to run the transfers down.

What we really need is a barrel that is just BIGGER, with thicker walls, bigger transfer casting and longer barrel for long stroke increase. I'd happily sacrifice a casing and have the mouth machined off and a bigger mouth welded on (as the Germans/Austrians used to do to convert small block casings before SIL 200s became readily available). The problem I keep coming back to is barrel... and I don't really want to change to a bike barrel

Adam

Gratz on the oldest "zombie" thread revival I've ever seen.

Why the veto on a bike barrel as whatever barrel you use will not be a Lambretta item?

[Adam_Winstone]

I'm not really anti bike barrel, it's more about wanting to keep the Lambretta format and have inlet and exhaust in roughly the same/original positions so that lots of work is not required to get an inlet route and exhaust position sorted. Then there is also the fin size and configuration issue to address.

If you look at the inlet work (piston port from reed) and fin machining that was necessary for Stuart Owen's sprinter, let alone casing mouth work, you quickly see that fitting a bike barrel isn't easy. The ease isn't my concern, just that I'm not looking to end up with a bike barrelled engine, just a bigger Lambretta engine.

Adam

[Hey Jimi]

Long time lurker here. If we assume the inlet port is at 12 o'clock looking from the front . If we could twist the port layout clockwise to say 2 o'clock then more room for inlet re engine mounts and posibaly more exhaust clearance.
Cheers Jim

[Knowledge]

Adam,

I'm waiting for Harry Barlow (Pro-porting) to build my new engine. It will be a 277cc, with 76mm piston and 61mm stroke.

Harry has achieved these dimensions by re-casting the TS1 barrel to give space for the piston and transfers, but the next issue is the studs. Harry takes a (cheap) 150 casing, machines-off the crankcase mouth and welds-on a new CNC machined base-plate with stud-holes further apart and the base of the transfer ports in-situ. The 76mm pistons are excellent quality, and not too expensive. Harry can supply a billet head to suit the new stud spacings. Off the shelf TS1 exhausts should still fit, and known items like reed valves and manifolds can be used.

The 61mm crank features an over-size web (99 or 101mm??), but Harry is also supplying 62mm and 64mm stroke cranks with oversize webs.

What I want is an engine that makes about 22ftlbs. I am not too interested in the bhp, so if the bhp was just 22, I'd be a very happy bunny (a 22/22 engine has a certain ring).

So yes, it can be done.

[Adam_Winstone]

Yep, I've kept my eye on Harry's work, checking it out on line and at parts fairs, it certainly does look very good

This issue for me is that I wasn't necessarily looking for reed induction and I'd like some control over my port durations. TBH a standard TS1 225 with decent setup is perfectly fast enough for me, and well capable of running at the max rev ceiling that I would want to run it at... so I'm sure that Harry's would be more than enough performance for me.

Webs, crank, casing are all good developments.

Adam