Modern Vespa

Hi Guys,
Query-has anyone ever removed and cleaned the secondary air system (SAS) filter? It's a small curved sponge, located in a housing down by the water pump. As I will be draining and flushing the coolant, I am toying with the idea of attempting this procedure. It's recommended to do it every 2 years in the workshop manual and I would imagine it has never been done on my GT125.
There is a procedure in the workshop manual which I could follow, but I'm wondering if there is anyone out there who has actually done this ? and more importantly, is it worth the hassle ??
thanks in advance,
Frank

Yes, I cleaned both of mine not too long ago. It is kind of tricky to get the flywheel cover off and on but it isn't really difficult. If you need any tips let me know.

Hi Hachi,
thanks for the reply, I think I saw your posts on the topic but I didn't see a resolution. I'd gratefully accept any tips or lessons you might have learned.
I'll have the exhaust off and will be draining the cooling system so I said I may attempt this.
Is it essential to remove the flywheel cover? it looks like one could access the black plastic cover that holds the filter in place with the cover in place?

iirc, the sas filters are only accessible by removing the flywheel cover. It was time consuming. I think the hardest part was removing and re installing the sas valve. Oh, by the way, there are two sas filters.

two of them ?
where is the second one ? The only one I have seen in the manual is a small curved foam one located on that flywheel housing ? if the second one is also on that flywheel cover then I guess it's not a big problem

also,
what was tricky about removing the SAS valve? just the access to the mounting screws or something else? it looks pretty tight in the pictures

iirc, they are both inside the flywheel cover. The two mounting screws at the top of the sas valve are difficult to thread in and out. I used a number two phillips in a small socket wrench to do this. I could only turn them a small amount at a time. The space is very limited.

Good enough
Thanks for the tips. I think I'll give this a try as I'll be doing the other work anyhow with the exhaust and coolant, and at least I'll know then if has been done. I'll keep an eye out for the SAS pump screws and will let you know how I get on. I'll post a few photos for the next soul.

red arrow sas filter. green arrows ????????

I was going to ask that question and you beat me to it. My misgivings were directed towards whether or not one needs to overhaul the flywheel or just undoing the screws of the cover and replacing the filter would sufice. Thanks for the thread.

Edited for title mispelling.

Hi Max,
I still have not attempted this so apologies that I cannot shed any more light on it. I have too many other jobs going on at the moment with the exhaust, transmission, etc. I had a quick look and it does look like one could pop off the cover of the filter by undoing the 3 screws holding it and examining the filter. I don't think there would be a need to totally disassemble the water pump/flywheel cover, only if one wanted to check out the SECOND filter contained in the housing. I would do a hassle vs reward analysis and wonder of the benefits ??

P.S. I followed your GTS coolant change thread, popped off the bottom hose, drained the coolant and filled with new coolant. However, the system only took one litre but the system apparently has a 2 litre capacity. Am I missing something ??

Hi Folks,
Well here I am, 3 years later and after much procrastination, this weekend I finally removed and cleaned the SAS filter !!
I have to say that once I got into it, it's not massively difficult but it is time consuming-allow 4 hours at least. I used the workshop manual which can be a bit unclear at times, but I took a few photos:
The full exhaust/muffler would have to be removed for this.
1. Disconnect the coolant hoses and drain the system.
2. Unplug the black electrical connection at the top of the flywheel cover.
3.Disconnect the small 9mm black tube called the depression pipe in the manual.
4. The SAS valve is connected to the head of the engine by a hard metal pipe, via a rubber coupler at the SAS valve itself. The manual says to disconnect this coupler by removing the clamp, but next time I wouldn't bother. At the head of the engine, disconnect the metal pipe from the header by removing the 2 bolts (10mm spanner). You will need to get under the bike for this.
5. Take off the bolts holding on the flywheel cover and it should come right off, with the hard metal pipe attached.
5. Now you can access the plastic housing for the air filter

continued:
so the process was a bit of a pain but I'm glad I did it as it had obviously never been done before. The OEM filter was pretty crappy and there was also a dead beetle in the housing !! Will it improve performance? we'll see....
The manual recommends doing it every 2 years but I think you'd be mad to do it that often- every 5 years would be loads. or, if like me, the bike is 10 years old and you suspect that it has never been done.
The filter replacements are about EUR3 each so it's pretty cheap.
Like I said, take your time and it will be OK. trickiest parts were to line up the locator pins with the water pump, and removing the clamp from the rubber coupler on the SAS valve- what a pain. replaced it with a stainless steel jubilee clip.
All done now and TBH I'm glad I did it- another job off the list !!
later.

Mine was toast. Totally gone and just little bits were left.We just used a piece of foam that was similar. Was a PIA to get in there.

Inchvale this is a great narrative with great pics. I am starring the thread right now. Job well done. Weren't you sursprised by how long the two screws of the valve were? I had to use a very mini screw driver and lots of patience.It's like the engineers of th Reed valve did not get the memo from the ones of the rest of SAS. It's nuts!!!

Hi Max,
thanks for the kind words. it only took me 3 years to actually do it !!
Glad you enjoyed the thread and hopefully the photos might help somebody else on here who is thinking of attempting this.
The Screws are very long alright, but as I had the whole unit off, it's wasn't an issues for me. I think it's easier to just unbolt it from the engine head, and then remove the flywheel cover itself to allow full access to the SAS. Trying to do it in situ, given the space limitations, would be a massive PITA I would imagine.
thanks again,
Frank