Scooterotica

What affect would welding and widening the transfer ports on the crankcase, and opening up the base transfers on a std rb barrel.
Would it increse bhp, torque or both, or have no affect unless combined with other porting modifications?

cheers

Russ

IMO the Transfer area at the case is less than it is down the ports... so in effect its a possible restriction to fuel/air flow into the transfers at the bore... Any improvement in area at the case to equal or slightly better that of the barrel transfers, should be an improvement to flow... Which in theory would allow the cylinder to recieve a greater charge at probably mid to higher revs... With a slight lowering of primary compression which at lower revs might slightly affect power very low down... only my opinion & not cast in stone...

Have a look at any motorcycle two-stroke barrel. The transfer size at the base of the barrel is VAST compared to any Lambretta. There is clearly work to be done here, or else Mr Honda, Mr Aprilia and Mr Cagiva et al wouldn't bother, would they?

Or look at a T5. This isn't the LCGB site so I can spell Vespa properly
The T5 is a sports scooter which is why the same power was achieved from a 125 as for a 200 Lambrettas included. The transfers on them are very much like a bikes.

Well had them welded its a spanish 125 casing so ive had the stud holes welded as well, so i can redrill at 200 spacings then the mouth needs opening up
Next

What do you think?

I'm not a welder but there looks to be a lot more weld on those casings than when I have them done. I hope there isn't any distortion because of it.

Where are the main areas that would distort?

If enough localised heat is used without pre-heating the casing the spigot area can distort as can the mag flange area.
Like I say I'm no welder but the guy who does mine makes me break open the stud holes and grind out the threads before he welds them to prevent any voids.
Around the transfer area he lays succesive runs along the transfer I assume to prevent the case from overheating.
Someone who knows what they are talking about regards welding may well tell me I'm talking out of me arse

Diablo wrote:Someone who knows what they are talking about regards welding may well tell me I'm talking out of me arse

I have no f@@king idea about welding, but on the ones Sean has done, he builds in layers to avoid distortion. So either you're both talking out of your arses, or its just good advice.

Diablo wrote:If enough localised heat is used without pre-heating the casing the spigot area can distort as can the mag flange area.
Like I say I'm no welder but the guy who does mine makes me break open the stud holes and grind out the threads before he welds them to prevent any voids.
Around the transfer area he lays succesive runs along the transfer I assume to prevent the case from overheating.
Someone who knows what they are talking about regards welding may well tell me I'm talking out of me arse

No its common sense with alloy welding it has to be spotless and any voids not fully welded will cause problems later, probably cause a void that could later crack and further pourosity... Its been a while sinse I did any Alloy welding, but Tig was the prfered method for a quality weld... It can be done to a high degree with Mig, and Mig does offer less distortion as there is less heat input to the surrounding area, but a good pre heating is needed first....