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PX pep up

Last post 10-28-2014 09:59 PM by Lupine. 20 replies.
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  • 01-19-2012 05:05 PM

    PX pep up

    Well, the time has come (the walrus said) ...

    850km on Blackie* and a few things are clear.  It gets all squirrelly (or should that be it wiggles like a pissed possum?) above 80kmh, especially with any wind about or with any sort of agressive lean - soft tubed tyres are an obvious culprit (my mate's '63 TV175 has modern tubeless rubber and hangs on better in bends, so a 2011 PX150 should oughta beat that!), so it's new rims and modern tubeless rubber for a start.  A firmer bottom is always desirable (ohhhh, yesss), so better shock for a start. It runs out of puff around 80, drops to 70 on steep hills, and I've been listening to the Ace of Steve, so it's time for a few 'liberations' in gas flow to keep the strong bottom end but still improve breathing ....

    Now we're off to pep-up land and have (waiting fitment):

    Bitbubo rear shock (no Bitubo front available as yet)

    Tubeless rims and tyres (still debating between Hiedenau K61 and Michelin S1)

    SITO Plus pipe and re-jet (the full plug chop treament from a mechanic who knows)

    None of this should change Blackie's character, merely fix these particular shortcomings for city work.  I don't want to lose the light, nimble scoot with good low end urge so I shan't be heading down any radical path. The PX is still mostly a bit of nostaglic solo fun and any serious city riding / pillioning goes to the GTS (which is loving its new Bitubos front and rear).

     

    *yeah, yeah, hardly an imaginative name but it brings to mind the eager small dogs of my childhood, which the black PX seems to embody - not quite the quiet (or snarling) competence of a true cattle dog, but noisy and eager and happy and skittish all at the same time.

    Sydney / Vespa PX150 & GTS250ie / BMW R1200R
  • 01-21-2012 09:28 AM In reply to

    Re: PX pep up

    I got a terrific improvement in handling by fitting polyurethane bushes to the rear suspension, obtained from Claussstudios.com. The ones in the cross-bar were difficult to fit (i.e. getting the old rubber ones out), but well worth it. Felt like it was running on rails.

    There is an air-filter mod which I believe gives a bit more go. Haven't used it, but you should be able to google it, or look at the SCSC site. I think it involves drilling a small hole in the top of the box.

    Mike.

     

  • 01-21-2012 12:06 PM In reply to

    • jrevis
    • Top 75 Contributor
    • Joined on 05-18-2009
    • Gold Coast
    • Posts 387

    Re: PX pep up

    Mike Holland:

    I got a terrific improvement in handling by fitting polyurethane bushes to the rear suspension, obtained from Claussstudios.com. The ones in the cross-bar were difficult to fit (i.e. getting the old rubber ones out), but well worth it. Felt like it was running on rails.

    There is an air-filter mod which I believe gives a bit more go. Haven't used it, but you should be able to google it, or look at the SCSC site. I think it involves drilling a small hole in the top of the box.

    Mike.

     

     

    The air filter mod is just drilling a holes above the jets in the standard air filter.There is already a heart shaped indentation where the holes used to be.Or even easier just buy a new air filter from an earlier model and the holes are already there,just in case you want keep the original parts intact.It also gives you the peace of mind knowing you're not doing anything dodgy because thats just how the filters used to be before emission controls!

    PX200
    BMW g650gs
  • 01-23-2012 09:53 AM In reply to

    Re: PX pep up

    Mike Holland:
    I got a terrific improvement in handling by fitting polyurethane bushes to the rear suspension, obtained from Claussstudios.com. The ones in the cross-bar were difficult to fit (i.e. getting the old rubber ones out), but well worth it. Felt like it was running on rails.

    Mike - I've looked at those and asked about: my mechanic thinks the new Bitubo will solve the problem and the urethane bushes woud be overkill. Me, I tend to think that anything that hardens up the "hinge" in the middle of a scoot has to be an improvement. 

    Since the shock goes on this week, I'll see how the shock alone goes.  I have the new tubless rims coming as well, so want to changes seriatum - first shock, then wheels, then consider urethane bushes. 

    Also considering urethane engine mounts but the ones on the clausstudio site are PX200, which has different mounts to the PX150.

    Mike Holland:
      There is an air-filter mod which I believe gives a bit more go. Haven't used it, but you should be able to google it, or look at the SCSC site. I think it involves drilling a small hole in the top of the box.

     

    jrevis:
    The air filter mod is just drilling a holes above the jets in the standard air filter.There is already a heart shaped indentation where the holes used to be. Or even easier just buy a new air filter from an earlier model and the holes are already there,just in case you want keep the original parts intact.It also gives you the peace of mind knowing you're not doing anything dodgy because that's just how the filters used to be before emission controls!
     

    Thanks - I'll ask!! It can't hurt, methinks.  Since this exhaust tuning will involve the "plug chop" route, I think I'd want any upstream airflow mods done before the plug chop diagnosis, to ensure the jetting suits the whole "new" gasflow.  I am very keen to keep low end tractability (hence SITO Plus) so don't want mods that only give me "top" end.

     

    Sydney / Vespa PX150 & GTS250ie / BMW R1200R
  • 01-23-2012 03:02 PM In reply to

    Re: PX pep up

  • 01-24-2012 09:30 AM In reply to

    Re: PX pep up

    pyrah:
     

    Thanks

    I've read a lot of the pros / cons of the plug chop method on ModernVespa (the not-so-modern forum) and while I couldn't hope to do it myself, my mechanic makes a good case for it as part of tuning / re-jetting to get the pipe and gasflow right.  His line is that every PX motor / carb / pipe is a bit different and the SITO set-up will benefit from individualised jetting.

    I will be talking to him this morning and will mention the EGT route, and the unleaded fuel issue, as hear his take on it.

    He's not charging a motza, so it's worth the experiment - methinks.  We're only talking SITO not Gianelli or any of the outlandish UK racing pipes. I want a slightly (and only slightly) better top end without loosing the PX' great low end tractability. So worst case, I go back to stock or some standardised SITO jet ... and  anyway, even if I crash a piston, on a 2T single that's hardly the end of the world.

    Sydney / Vespa PX150 & GTS250ie / BMW R1200R
  • 01-25-2012 03:26 PM In reply to

    • hank
    • Top 100 Contributor
    • Joined on 12-01-2010
    • Posts 281

    Re: PX pep up

     you wont overheat a prange by going sito plus

     

    itll just make more noise

    i cant explain myself im afraid sir, because im not myself you see
  • 01-25-2012 04:11 PM In reply to

    Re: PX pep up

     I had Bitubos front and back on my PX200 for years before I fitted the Claussstudios bushes, and while the Bitubos were excellent, the bushes still made a good improvement. Definitely not overkill.

    Mike

  • 01-29-2012 11:20 AM In reply to

    • dean0
    • Not Ranked
    • Joined on 01-10-2011
    • Brisbane
    • Posts 9

    Re: PX pep up

    An alternative to sito plus is the Sip Road for about $20? more.  Search MV for discussions, I'm pretty happy with mine.  Sip's airfilters come already drilled.  Sip have a real talent for stuffing up my orders, so recommendations are not unreserved.

    Peter

     

    Fuelly
  • 01-29-2012 04:08 PM In reply to

    • hank
    • Top 100 Contributor
    • Joined on 12-01-2010
    • Posts 281

    Re: PX pep up

     aahhh so they are, peter

    i cant explain myself im afraid sir, because im not myself you see
  • 01-31-2012 12:41 PM In reply to

    PX Pep-us progress

    Stage one is done

    - SITO plus on plus upjet, up plug and airbox drilling

    - tyres (Pirelli SL26 3.5 tubless) and rims (FA Italia 2.5-10)

    - Bitubo shock

    Still with shop for a bit of settling in and one more plug chop to confirm tuning.

    Compromised on tyres - I really wanted 100/90 but was convinced mainly on the downside of shimming out the wheels.  I didn't want to lose steering / turn in precision (such as it is) and since most of the 100/90s have no bigger a contact patch than a 3.5, I guess I didn't really give up much.  I do wonder what slimmer sidewalls and less flex would've given me, but maybe on the next set I'll think again.  I'm unconvinced the Pirelli SL 26 are the best available option in a 3.5, but choices were very limited .. more research for next time there, too. They should be a vast improvement on the tubed Michelin S83, but let's see how they ride.

    I'm waiting on Bitubo for the PX150 front shock - not available yet.

    Clausstudios (et al) poly mounts don't seem to be available for the PX125/150 ...

    Sydney / Vespa PX150 & GTS250ie / BMW R1200R
  • 01-31-2012 11:58 PM In reply to

    Re: PX Pep-us progress

    Michelin S1 tyres are a longer lasting , wet road proven and sticker alternative that has been much favoured in Blighty for many a year now.

  • 02-02-2012 02:42 PM In reply to

    Re: PX Pep-up progress

    declanmagee:

    Michelin S1 tyres are a longer lasting , wet road proven and sticker alternative ...

     

    Maybe so - and (genuine) thanks for mentioning it -  but S1 is hard to get in 3.5 from my supplier from some reason (yes, I realise they may be getting better margins on Pirelli, but base on a long chat with them, I don't think so). 

    Personally, I don't like Michelin moto tyres as a rule: that's a matter of taste, but has held true over a wide range of bikes from a Ducati 900SS (1982) through a few BMWs (K100RT to F650CS) and now shows itself in the S83.  My experience is that Michelins give little or no warning before they lose grip altogether ... whereas Metzelers (for example) seem to be engineered to 'slip' a bit bfore they give way altogether.  Plus I like the way Metzelers (in general) feel: is a consistent grip, side to side, that I like.  Pirellis (even though they've the same parent) don't have quite this feel, but in general I prefer them to Michelins.  Other folk on the same bikes with the same general riding style may well prefer Michelins - I really think tyres ultimately come down to personal taste as to how you like a tyre to feel in you own riding ...

    Anyway, the SL 26s are cheap enough to experiement with.  If I hate 'em, I'll take them off and try the Michelin S1.  Or maybe the Heidenau K61.  Or maybe ....

     ... anyway, thanks for taking the trouble to mention the S1.  It's always good to hear other opionions.

    Sydney / Vespa PX150 & GTS250ie / BMW R1200R
  • 02-02-2012 09:21 PM In reply to

    • hank
    • Top 100 Contributor
    • Joined on 12-01-2010
    • Posts 281

    Re: PX Pep-up progress

     i remember the 26ers as pretty good you can really throw them about

    had them on my first px ,,, and i saw it the other day spoke to the owner hes had it for 12 years now,,,,,,,,,,,,, dunno what tyres it has now 

     

     

    i cant explain myself im afraid sir, because im not myself you see
  • 02-06-2012 10:03 AM In reply to

    PX is now peppy!

    Hooo - weee! Collected my PX150 ("Blackie") on Saturday mornng and spent much of the day zipping about, mostly two-up.

    It's transformed!

    Motor

    The SITO Plus / re-jet / hotter plug / freer intake has made a marked improvement to midrange urge, without losing the low-end urge that makes teh PX so tractable.  It would pull through much more quickly to 80kmh two-up on level ground - previously it would lose urge from 70kmh, solo.  Hills are still a big ask above 70kmh two up - but I didn't expect a miracle and I don't really use the PX for fast two up riding ... have the GTS for that (around town).  I feel I've still got the PX character I like, and now even more of it.

    Ride 

    Tyres first. The nice surprise is that the SL26 3.5s are just fine. A reasonable amount of spirited riding saw my "chicken strips" down to about 1cm each side, whereas on the S83s I was skipping on the edge of the tread. Of course, I wasn't about to test the edge of the envelope with Ms Delectable aboard! I should get right to the edge of the SL26s with a bt of solo fun.  More to the point, the stiffer sidewalls and even 'feel' of a good tubeless tyre makes the PX feel more planted to road - it's lost the jittery feel of the tubed S83s. 

    Rear Bitubo shock plus new bushing (firmer - think it's urethane but not 100% sure) has made the back end both more planted and more compliant.  The PX has lost a lot of the "hinge in the middle" feel, and it tracks a lot more predictably through corners where it used to wallow.

    Sound

    Nice and crisp!  The Sito Plus (plus the better intake flow) has a bit more snap / bite on overrun, and noticeably louder but still not offensive.  Well, It's a lot quieter than the Lammie series II I was riding with!

    Sydney / Vespa PX150 & GTS250ie / BMW R1200R
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