Hi folks I'm Howard from Manchester UK. Can anyone tell me what the size would be on the main jet on my untouched 2007 model vespa PX 125 carburetor? I've just bought a Sito plus exhaust and will be fitting it this weekend and replacing the standard main jet for a larger one. Any help would be great, thanks!
thats after 87 and only upto 1990 for the dellorto sime its a 2007 if im right the last of the older px was made in 06 which would also make an 07 within that bracket. then lml made them untill vespa re started the build line
Thanks Rab and sime66, very helpful info. I think I will drill the air filter and see how that goes, will drilling a hole change the colour of the spark plug when ran in? I've had Vespa's for years, I had a T5 before this PX and it ran like a dream, it was really quick, thats the reason I bought the Sito plus because I've heard it's based on a T5 exhaust. I had to sell my T5 ia while back when I was out of work. The PX I have now I've just got back on the road after being sorn for 2 years and I'd forgot how much I loved to ride it. I've started to try and do most of my own repairs now and servicing because the last time I had it in a scooter shop they were very rough I.E chewed nuts the odd scratch on body work etc, I've had to change all the nuts and bolts for stainless steel ones, the bike looking good the next purchase will be FA Italia polished aluminium alloy rims. I'm a novice at the moment but I'm learning quick especially with help from you guys which is much appreciated. Cheers guys!
I didn’t post when I first saw this question because I thought the best thing for Howi to do was to check the carb himself, rather than make any assumptions. I still do. I posted later because I was concerned about your 117 jet advice. I still am.
But perhaps I need putting right; I’ve always taken the SIP table to be ‘from’ dates, after 1987, rather than the only year they were relevant. In what way has a 125cc engine and carb materially changed between 1989 and 2007 to change the standard jetting from 96 to 117?
As a guide to my thinking was my own (kitted 150 – 177): - When I got it the 20.20 drilled carb had a 106 jet. - I upjetted to 108 when I fitted the Sito+ - I changed the carb to a 24.24, and then settled on a 116. - I’ve since changed to a SIP Road 2 and ended up with a 120, though I may go back down a bit.
I don’t mind which of us is right, I only posted because your 117 main jet on a standard 125 concerned me. All jet sizes and upjetting advice for exhausts is only a guide anyway, and needs setting up for the individual scooter (plug chopping – yes, to your plug colour question Howi), but I think standard(ish) for a 125 is 96.
Howi, you want to get your hands dirty; why not go and have a look at what is there…………
I would say that you’ll end up going up a few for the Sito+, and a bit more for the drilling (if you do that, which is worthwhile), and end up about 102-104 (as a guide only).
i agree take your jet out and let us know. if the main jet is original to the carb and it is a dellorto 20/20 carb as its may not be any of these. i don't mind if im wrong i only go on what i learn and what ive been told but put us out of our misery and get ye carb lid off then one of us can look do our im right dance lol
Exhaust fitted and got rid of the secondary air system fully. Still not had time to look at the main jet yet, I will strip it down after work tomorrow and let you know the size. The exhaust sounds nice though I give it a quick go up and down my street. Had a look at the spark plug before hand and it didn't have that nice orangy colour, hopefully when I sort the jet and drill the air filter it should be good. I will replace the spark plug for a new one. What would be the best stuff to clean the air filter? or should I buy a new one? Oh by the way I couldn't get the exhaust to fit dead snug up to the engine pipe it's very close though about 1 or 2 mil away if that, that's the closest the Sito plus would let me get it and I used a lot of brute force. Sorry to waffle, I'll keep you posted Cheers Howard.
That’s a 2 year old Sito+ that didn’t fit very well, and was shoved in anyway by a lazy mechanic, who didn’t bother to tell me about the problem, which is one of the shabby jobs he did that made me decide to now do all my own work!
That’s my personal experience. If you have read that you’ll see a couple of things you could do to prevent it happening to you.
Regarding Main jet, I had a good read around on this forum and many other places before initially posting the table showing a 96 main jet; and again on Sunday evening, and I have no reason to doubt that a 96 main is standard. I found the same answer over and over again, but I really only got involved to make sure you weren’t given odd information, and wasted your time and money. I'm pretty new, and only give advice if I'm pretty certain of it, or add to it that I'm not certain, or that others may disagree. Other than that, I don’t need to score points; that isn’t what this forum is for, so that’s the extent of my contribution on that subject. I added mine purely because I saw something that looked wrong to me. You’ll check it and upjet for the job(s) you’re doing, which is sensible. I will look out for your answer though, because it may be something I’m not understanding properly.
Equal care should be taken giving and receiving information here.
I cleaned my air filter with petrol, seemed sensible enough to me. Be aware that if it’s cruddy, a good clean will lean your mix too, but you’ll be taking care of that properly when you plug chop after exhaust and drilling of filter though.
Bloody hell mate that sounded like a right nightmare getting that exhaust off, I'm going to keep a close eye on mine. what did you think of the sito plus, did you rate it before it started giving you problems? Nice 1 Sime for all the information it's been a massive help to me and is much appreciated, I'll be sorting my carb and air filter tomorrow now, it's been a tough day a work and I'm going to chill tonight, I'll keep you informed when complete Take care Bud Howard.
You’ll have seen I was repeatedly told to use copper grease when I was looking into this after it happened. Of this I am absolutely certain: - If you didn’t use copper grease on the bolt, take it out, grease it up with copper grease and put it back; not maybe, just do it – you’ve seen why. - Also highly recommended is regularly loosening and retightening the bolt, just enough to keep it free-moving. Don’t overtighten it to keep the exhaust secure; torque it properly. If the geometry is poor, deal with it.
What happened with mine was that it was a poor fit (geometry between exhaust stub and swing arm hole, just poorly made; not uncommon for Sito+). As a result of that it kept slipping off the stub. As a result of that the w*nker who fitted it, just kept tightening both ends when I was too green to know any better. This put a big force on the bolt, which sheared. Double trouble; it had seized in the arm, and it had no head. Yes it was a nightmare. Worse than that was that it was avoidable.
In its day the Sito+ was generally thought of as best of it’s type for our silly little scoots; you will see until recently that it was recommended on this forum too. When I put it on my 177, 2 years ago, with the correct upjetting, it was a good improvement. I have since gone on to a SIP Road 2; I already knew it was now regarded as better, and as you know, I ended up chopping my Sito+ off anyway. There is another new exhaust, that may be better still, but I don’t deal with the importer/UK stockist of those for my own reasons, so won’t mention that one. The last I heard their data was vague anyway; I plan not to need to know for a good few years now.
Scootering did a comparison of exhausts for PX125 – 180 in July 2013, but you’ve bought yours now anyway, so too late.
The SIP Road 2 is also an improvement on my scooter, especially now with the 24.24 carb.
I don’t wish these sort of problems on you, but it certainly makes you learn quickly. Especially if you get the generally excellent advice on here, much of which is already here in old threads, and covering the nightmares and mistakes made by others so maybe you don’t have to.
Hi guys, finally finished the up-jetting, drilled the air holes in the air filter body and did the plug chops ending up with a nice brown colour and a vast improvement in performance and sound, it feels like a new bike again. With the help from you's I found it a lot less complicated than I thought it would and yes the MAIN JET was a 96 and I ended up changing it to a 100 and it responds well to that. Thanks to everyone who shared there advice Cheers! Howard :-)
All: I was reading this at the weekend looking for some recommendations for main jet size now that I've fitted a Sito+ and saw the comments around bolts fusing etc due to lack of copper grease, so first chance I got it was straight down to the hardware store, bought some copper grease, whipped off the Sito+ (which was only fitted a fortnight ago and came off nice and easy, thankfully!), greased up the bolts and refitted it. Glad I found you guys; I suspect I've saved myself a lot of trouble further down the line, so many thanks. I've drilled out the air filter, which made a lot more swarf than I expected and was a bugger to clean out. I've seen several different posts recommending different main jet sizes. Most seem to recommend a 98 or a 100, so I've ordered a 99 for my first try; we'll see how that goes.