Drilling holes in the air filter base. The real gen.

[inscootable]

Forgive me if I've broken protocol by opening a new thread on this subject. I'm seeking clarification, and not just for me.
My scooter is a 2005 PX125 Disc and at present it is absolutely standard. It's running well but if it could be improved at very low cost by fitting a filter with holes or drilling the existing filter, and with no downsides, that sounds good to me. I understand that it will need upjetting slightly even if this is the only mod.
So what would be the effect of this mod on an otherwise standard PX125 Disc, why are (were?) filters manufactured with and without the holes, and what possible disbenefits could there be? Presently my scoot has a BE5 , a 140 and a 96 main jet. I do have a 98 jet which I'm hoping will be sufficient for upjetting with just this mod. I have no plans to fit a sports exhaust or a big-bore kit at present. I've read everything I can find on this old chestnut and I'm not clear on it.
Some say it is a great little mod, some say it achieves nothing. I asked about it at a certain well-known scooter parts shop and was told that it would richen the mid-range but give no more power. The same fellow also told me that the mixture screw on my scoot would weaken the mixture when turned further out, and I don't think that's right. I guess parts suppliers want to sell kits and sports pipes so they're likely to say they're the only things that could give an increase in power.
So what really happens and why?
 

[mickingle]

Ill just add my experience having done this recently.

Mine is a 64 plate PX, I've swapped the cat exhaust for a sitoplus. Then a month later i swapped the air filter for a drilled one.
Main jet went from 96 to 98 for the exhaust, them up to 100 when i swapped the filter.

I can't tell you what it does without the exhaust being swapped, but i did notice a significant power increase by doing the air filter. It's certainly no faster , but it gets up to the required speed quicker and is better uphill. You can hear the difference in the rev's.

[inscootable]

Thanks for the replies. It sounds like a 98 (up from 96) would be enough for just the filter mod. On the Vespalabs graph their test of a PX2 with just the filter mod shows the power coming in much earlier and still being fractionally better at the top end.
www.vespalabs.org/Labs/Lab_Research/Dyno_Results/Air_Filter_Hole_and_Sito_Plus
They also upjetted just by 2 points for the filter mod. Is it everyone's experience that the filter mod gives squirtier performance through the gears but nothing on the maximum speed?

[rab]

it just makes your scoot quicker no top end gain without further mods

[sbwnik]

You'll not get any more speed without any capacity increase. What you will get is a 'stronger' engine that doesn't hate hills and headwinds as much, and is a little smoother to ride. A change of exhaust to a SIP Road or similar (BGM Big box etc) will help a little too. It's not about top speed, but about keeping the speed you have from dropping off.

[rab]

nik worded it a lot better than me there ill have to stop the quick fire reply's

[inscootable]

OK, it sounds like the best thing I can do is to get on and do it. Before I do I'm going to time the scoot from standing start, up the lane round the bend and upto the farm gate. Then I'll just fit the 98 jet and do the same test, then the drilled filter and test again. I'll let you know how I get on. It is of course impossible to operate a stopwatch and ride the thing simultaneously, but so long as I do the same routine each time then the effects of the mods should be obvious. The jet alone should slow it down, shouldn't it?

[rab]

with just the jet change you will either feel it bog down from what it was or feel nothing but the plug will change colour from not enough air to the mix.as soon as the filter is modded and on you will feel the difference and hear it. but i wouldn't up jet any further than 98 unless your coming off the standard pipe to a sip or something. some that are better in the know on the jetting may differ from me

[inscootable]

I have carried out the tests. From standing start to the farm gate up the lane and round the bend:
1. Standard. 55 secs
2. 98 jet. 55secs
3 98 jet and drilled filter 55secs.

The scooter felt no different with just the jet change. With the drilled filter it wouldn't tick over unless I held the throttle open a bit. I'll need to adjust the throttle stop screw. Subjectively it did feel as if the power was coming in a little earlier (on the run back), so that the scooter would be livelier than before with short shifting. I'm surprised it was no quicker on the test though. At present I'm a bit disappointed.

[rab]

it wont make it go faster you need to go further with mods for that what you've done is get a stronger pull and better hill climb speeds. now take off your side panel and adjust the tick over until it stays running on its own. if you want it to go faster get your hand in your pocket and buy a bigger head and a pipe and a carb untill then >>> (refer to what nik said)

[inscootable]

Yes, I realise the tickover is no problem - I just ran out of time as we were going out! I was all set to fit the DR180 kit until I rang my insurance broker JMI (part of Carole Nash) and they wanted to more than double the premium so I thought I'd leave it until next year.

[mickymidas]

I think you are getting slightly confused between "speed" and "power"

The filter mod WONT make the scooter any faster.......

It WILL keep the power on for longer on hills and into headwinds so NOT slowing you down as much , and in effect getting you where you want to go quicker....So making the overall journey faster


I think

[sbwnik]

Find a long hill and repeat the experiment.

[inscootable]

No Mickeymidas, I'm not confusing speed and power. What I had expected is that if there was more power even in the mid-range, the scooter would get off the line a bit quicker and pull out of the bend a bit quicker and so cover the distance a little quicker.
I can't repeat the experiment as I have only one filter (now with holes).
I've got it to tick over. It needed maybe 2 further turns in! I've had a ride out on it and it does feel gutsier in the mid-range with a deeper sound if I'm not kidding myself. It feels as if it'll get up to speed now with less revving.
The test I gave it would mostly have had it revving quite high so wasn't perhaps the best I could have devised.
The only other thing I've noticed is less 4-stroking on the overrun, but that could be due to a slightly lower tickover.

[henri]

if declaring kitting a scoot to in,sewer,ants dump carol nash ,there 1 of best for classic un modded scoots n try bennets ,there better set up for kitted/modifyed scoots ,for example mates lamb chop all declared ,no bodywork left,longer raked forks,upped in cc an with race pipe ,diff bars an seats ,basically totally diff from standard ,bennets drop down menus wouldnt cover it an a phone call got a quote for bout 30 quid more than nash wanted for a standard scoot of equivalent value ,
on bennets website if mods are simple n less than 3 types you do it by drop downs that cover everything simply , h

[inscootable]

OK let's get it clear what I understood from the contributions of other more experienced (in Vespa terms) posters. I did not expect a gain at the top end so no faster in terms of top speed. I did expect more mid-range torque which means more power at a given engine speed but not a higher maximum power output. With more mid-range torque I would expect some improvement in acceleration which is what I meant by quicker. I think the acceleration has improved when using a lower rev. limit, that is short-shifting, but the test I gave it to the farm gate kept the revs too high most of the time for that to be apparent, so wasn't a very useful test. I thank those posters on this thread who have increased my understanding. 

[rab]

i know its confusing when your learning fella and some times posts can be worded wrong confusing it even more. once you get her out on the open road and with a few hills then you will see the difference. if you upgrade the exhaust it will improve performance more for you ie a bit nippier and smoother running beyond that dig out the dr and up the main to at least a 110 or 112 if your on a 20 mill carb for still decent fuel consumption. if economy isn't a factor get a 24 mill carb

[inscootable]

Thanks rab, I'll see how things go with it and I'm presuming a 'plug chop' is simply an examination of the plug colour after a ride, which I shall be doing. One issue I've noticed when joining a forum is that there are some people out there who've been on a particular forum for a while who assume that a 'newbie' is generally inexperienced and wet behind the ears. Having owned and repaired, modified and maintained approaching 200 cars, motorcycles, scooters and mopeds from 49cc to 5751cc over the last 44 years I'm not either of those things. I merely lack specific experience of Vespa motor scooters, but I'm learning. I'm particularly interested in technical explanations of how things work, and I still don't fully understand the workings of the Dellorto 20/20 with regard to the jet stack and the filter!

[rab]

i see plug chops as more a tuners thing ie track bikes but some will dig there heals in and say its a must. ive never done one and never will as i personally don't see the need if the plug colour is right and scoot is running fine then there is no need to get so technical. i understand were your coming from with the newbie ive repaired cars for years built bikes from boxes of parts as a hobby since i was 12 but i have to say vespas are by there very nature a different ball game god knows why but they are. im still am on a learning curve after 12 months of owning mine and re building the bugger i still need the mixed and good help you get on here and also get to pass my knowledge.for jet stacks and filters id ask Henri you will get an essay for a reply but that guy is normally bang on the money with jetting and you will understand it at the end of reading. carb wise and main jet wise is dependent on what you use your scoot for and want. i stick with 20/20 as mines for commuting with varied speeds upto 60mph for work and back and keeps it economical other wise id be on a 24 mill carb.Again for what im running quite a few will say it should be on a 24 mill. my scoot is good running proof that its more than happy and fine on a 20 mill with a 112 main jet and filter mod

[inscootable]

With a 112 main jet you must have done a few mods! I've been out on a long ride this morning which included a long flat-out ride up the mostly dead straight A15, followed by country lanes, then Scunthorpe and more country roads back home. About 55 miles all told. It ran faultlessly. It seems smoother, sweeter and no longer has the slightly flat feel that made me think it was running lean. A plug check before the off showed a better colour after the last time I rode it which wasn't far and lots of stopping and starting; if anything it looked a bit rich as you might expect. Haven't rechecked yet. So what is a plug chop if it isn't just checking the colour?

[Robjack]

Oct 1, 2014 14:36:26 GMT inscootable said:

So what is a plug chop if it isn't just checking the colour?

To do it properly, you need to cut away the threaded end (hence chop) and see the colour at the base of the insulator. Most just take a look at the general colour at the end they can see. Also you need to kill the engine while the main jet is being used, ie at wide open throttle and when it's thoroughly warmed up. You can do it in third but when I've done it I've found a quiet long stretch and got it flat out in fourth then switch off, pull the clutch and coast to a stop. Then take the plug out.

[inscootable]

Thanks. I don't think I need bother with all that with my basically bog standard motor! I'm looking out for a PX200 to add to the stable, rather than messing about too much with the 125.

[henri]

Aaahh my spidey senses are tingling ,somebody say my name , thanks for the creds rab , an yes i'm a "wordy beggar" but tho the questions might be short i'm not ,in words of height ,
right as youve declared "dirty hands" inscootable i dont have to use baby talk , what people call the stack is a main jet stuck into a atomiser with a air correcter jet on top ,the larger of 2 brass jets under filter on carb top ,smaller 1 is ya pilot jet ,ok, the heart shaped indent on filter base sits directly over these when assembled , with air flow coming over a lip from main filter space ,the idea of drilling is to remove the heart shape giving a larger path/cross section for air an a more direct route .
an as rab says a full-chop destroys the plug ,most on here when saying chop mean what robjack describes an just look for general colour , on a standard thats what i do ,its all the state of tune needs , if ya wanna go further sime66 has posted a full plug colour chop chart showing what ya can read from diff bits of plug ,but even when tuning (a bad habit i use to have that seems to be re-occuring)mostly i went on general colour/seat of pants type stuff.
ive been trying to think of another carb i could compare the 20/20 delly too you might already know ,but with almost same years an easily same amount/varyiation of experience cant think of one , as rab says vespa's are similar n totally unlike at same time,sounds imposs but piaggio have there very own way of doing stuff ,an come from a aero background ,closest i can think of is early webers ,an they aint that close ,
but as robjack says even just checkin colour needs to be done mid ride ,as the slow/idling n stopping at end will darken/richen the colour n not tell ya wat ya want to know , an burnin ya fingers twice is usual/mandatory/reccomended, H

[inscootable]

gazpx, I've not been on here'til now so missed you invite to , was it Scunthorpe? How often do you gather and where?
Henri, thanks for your explanation. It feels right now. I'll check the plug again before I next ride.