Scooterotica

Hi all,

Noting that DT's SIL Tuning on a Budget feature in Scootering found it necessary to dramatically increase the size of the main jet when swapping to a remote filter, has anyone had a bike dyno'ed after fitting one of the BGM high-flow filters and/or air box? I realise that the change of airhose also has a big influence so I'm wondering how much of the main jet increase is down to a free-er flowing filter, the airbox and/or the airhose (airhose remaining constant when using the big-bore airbox?

Anyone had such a setup dyno'ed? We could 'talk' theory all day but what I want to know about is figures!

Cheers,

Adam

I'm guessing that's a 'no' then?

Keith Hudson of the Luton club has, he built a rapido for afandy and andy wanted to use the 22mm and the bgm filter and air box.
I'm not 100% sure but I think Keith said it flowed too well and caused him to change to a 30mm phbh.
Dyno carried out by Jb

Thanks for the reply.

Funnily enough, my thoughts are that mine is flowing so well that I'm half tempted to try a 28mm PHBH , however, that would totally go away from the standard carb use that I'must looking for.

Adam

Adam,

This is not completely relevant i know, but i had a Dave Webster stage 4 steel barrel where i upjetted the standard Delly 22 to a 128 and then 130 main jet, completely removing the air filter and it really flew along as opposed to when i left the paper filter in the bow.

I was going to try the BGM one but it seemed to go so well with nought in the box. I literally just took out the filter altogether and silcone sealed the hole where the bolt passes though.

Hi Strummer,

Currently the bike in question is running pretty well and doesn't seem a mile off, with me having done some testing already. I'm keen to see what a dyno might suggest for jetting / set up.

Bearing in mind how many people are looking for a semi-standard look but with a little more performance, I'm a little surprised that there is so little info about!.

Adam

I have the high flow but not fitted it yet. I was told by mb that it's designed for 26mm carb max.

The carb that I'm currently running with it is a reamed 22-24mm and that flows like a good-un. I initially ran it with the modified airbox but traditional paper filter (new so as little restriction as it could be) and the difference in pickup from low revs, by changing to the BGM mesh filter, is instantly noticeable.

Considering that the Vespa tuning features in Scootering suggest that many people are wanting the big-bore version of the standard PX carb, I'd have thought that there would be similar interest/demand for a free'er flowing Lambretta option, with dyno figures to back it up. Perhaps this is the way ahead, although I'm pretty sure that dyno tests confirm that there is more to be gained from changing to bigger/more modern carbs and different filtration options.

Adam

I cant offer any dyno results but can only comment on some of the experiments i did with a 28phbh through the airbox,my motor is a reed converted mugello 225 with a bgm clubman,id converted the airbox to something similar to the bgm wide neck box,used the bgm high flow filter and through a few modifications married the carb too a std 22mm airhose,without any extra holes in the box and the swan neck removed inside i can say the motor performed well,it was only on a decent run the problem became aparant!
The induction noise resonated through my bones it seemed even with ear plugs in,i asked the guys i was riding with did my bike seem loud and they said no,but they wernt sitting on top of the airscoop.it was cured using a remote filter.

^... I run a number of motor configurations on remote filters, however, I'm really looking to see what can be done through a modified airbox this time around. Indeed, this is not the first time that I've run any manner of reamed carbs or big carbs through modified airboxes, however, I've not had a bike dyno'ed with a modified airbox so would really like to see some figures to know how science/measurables might back up previous 'seat of the pants' experience.

Surely someone must have dyno'ed a bigger carb through a modified airbox?!

Thanks,

Adam