Modern Vespa

They never are!

It is good that I now have all tools for setting ignition timing right.

My standard problem with my short stroke cylinders.
After near 500 km after assembling them start to leak under head. Polini 75, 102 or Malossi 112 - its doesn't matter.
I tried to put only sealant, only gasket, sealant and gasket, torqued according to manual and torqued higher, sanding down head and cylinder.

Only with DR 102 I have no problems on my motor and on my friend's motor.

Same story again.

Today before going to work I started PK and it suddenly dies. Kicked again and nothing. No spark. So I took 50 Special and go to work. In the evening I changed CDI and all work again.

Also noticed that leak under cylinder head appears again And it is just after 200-250 km of riding.

Can anybody give some advice of how to fix it?

I'm guessing the cylinder head and cylinder aren't flat enough.

Had a Polini 102, it did around 300kms didn't leak, but had a soft seize because of a leaky exhaust manifold.

Agreed.

With a standard head, you're at the mercy of the quality of your mating surfaces. You can try lapping them with a thick sheet of glass and some wet-dry paper.

Color/coat the head & cylinder deck with machinist's blue or a sharpie, then give it a quick few swirls on the glass. You might be amazed at how unevenly it is wearing. If that's the case, you know what you need to do to fix it.

I like to use Permatex copper spray seal on my cylinder-to-head joints. It's sticky stuff, but works great to prevent leaks.

Next time you're shopping for a top end, look for one with an inset head like the BGM 177 for largeframe or the Quattrini M1L series. They almost NEVER leak because it's a better design. Makes getting squish correct super-easy, too.

Great tips guys, thanks!
Head was lapped, but I don't touched the cylinder.

I did not want to put a mudflap but was forced to. After a few rides after rain and just on a wet road, I found that the entire my back, helmet, back of the scooter and the seat were splattered with dirty water, mud and sand.

Few days ago original 42 years old seat spring said "enough" and went away. I have no any spare and wait delivery from Sip is too long.
Cos it is my daily rider I decide to try springs for bicycle seat. Pair cost only $2.5.
It was PITA to mount new springs and take near 2 hours before I find right way how to do it.
The result is overtaking all my waitings - seat become more stiff and comfy for me, less bounce. I never thought that this seat can be so good.

Just few photos.

Nice work on the springs!

Every time you post pictures, I want a PK a little more.

It'd be just the thing to put an M200 in...

Yes but not in this scoot. I'm thinking about Egig but when/if I got it it goes into my Special.

PK will stay with Malossi 112 for how long it can. It is very comfy daily rider with enough power to stay safe in city traffic and low fuel consumption.

When things goes wrong and I will be ready to make some upgrades I think that will be nothing outstanding but good old DR 130 or Polini. Or maybe VMC T-56

Love the transformation and also the setup of the engine!

I have some problem with carb. It is leaking. Again. Same story was when it was mounted on my 50 Special engine which have bit worn rotary pad and I thought that problem was in it. But this PK XL cases have really perfect rotary pad without any marks on it.

It is old original SHB 19.19 from ET3.
I changed all parts and gaskets except throttle slide and its cover.
Carb sits on manifold perfectly.
Fuel tap and fuel hose is ok.
Scooter runs without any issues, I really like how it works. Always starts from second kick, idles ok, after throttle blip get back to idle very quick.

Bottom of carb and air filter is too much wet as for me. Fuel even goes thru seams and drips on the ground.

So maybe anybody know where I need to look or it is just old carb which tired of it life?

I wipe this places every morning before I go to work. Then when work ends I need to wipe it again.

maybe the brass seat for the float needle is slightly damaged? I use a bamboo chopstick chucked up into an electric drill to burnish the brass seats in my carbs.

Thanks!
Tried your method few days ago. Also changed float needle to new one. And tried few old needles that I have. No luck.

So can't do nothing with leaking carb. And I decide to go for new SHBC 20L. I still not have it on hands but I'm curious what air filter is best to use?

Engine specs:
· Malossi 112cc case matched
· Mazzucchelli Super Competizione crank shaft
· LeoVince Secsys exhaust
· Original PK ignition

Malossi E3A


Polini


RAMAIR

This. It's leaking at the float needle, I 99% guarantee. Maybe check float height, too, and make sure it's not set too low.

There's not a lot of room but I found a nice pleated paper hot rod filter designed for old 2 barrel carbs was just the right size to fit on the 20L carb lip.

Or use my method: filters are overrated.

How I can do it on SHB 19.19 ?

Does that polini filter fit in a PK? I have one that i discovered is V range only. it hits the frame at the side on the PK.

It fits. Two my mates successfully use it on their PK for several years.
On the other side Malossi E3A(on the photo above) is hitting the frame when I ride with pillion. To be honest - I am 99 kg and pillion near 90 kg

It's not carb-specific. You remove the float bowl and check that the float sits level when it's all the way down. If it's off, you bend the tab under the needle to adjust it.

There are tons of videos about how to check and do it.

I understand about what you say, and I done this for my PHBL carb.
But on the SHB there's nothing to bend - tab under the needle is plastic.

I waited very long for new glove box door. The handmade lock mount by previous owner is totally broke and I rode some time with door holding on the scotch tape.

For sure I can't paint new door to match old colour of scoot. So I asked my bride to draw something on it.

This is Petrykivka painting - a traditional Ukrainian decorative painting style, the earliest known examples of this style date from the 18th century, but it continues to thrive and develop as a modern art form.
It turns not bad in my opinion.

And I put new lock barrel and complete button kit.

You can also see on photos that I mounted right mirror and luggage rack.

Ahh. Then I don't know what to do. Find a float with a metal tab?

Today evening I have some free time and decide to mount SHBC 20 carb.
But as always there appears some troubles.

When I take off 19.19 carb I noticed that air filter hits few times on the frame.


And it pops out from the mounting


Also insert was pop out from it place and deformed a bit.


I always wondering how rubber bellow holds on the 20 manifold.
Today I got answer on my question. Manifold have the border for which the bellow is attached perfectly.


So I put the Ramair filter and put carb in. The frame chewed up the filter so much that it seems when I open throttle carb sucking it in and engine stalls.
Then I removed air filter and start engine again.

Then it turns that jetting is too lean - 45 idle jet and 99 main.
Put 50 idle and all become better. But this is the biggest idle jet I have. Hope it will be enough.
I have also 100, 102 and 105 main jets and hope that it will be enough too.

I tried to ride a bit and was impressed how good punch new carb give! But I thereis no place to ride fast enough to try it on 3rd and 4th gears. I also need to shorten throttle cable and outer. And I want to try put Polini air filter but I was borrow it for my friend and get it back only tomorrow.
I have no time for all of this and hope I can sort all tomorrow.

I noticed that mixture screw on SHBC 20 have thinner tip than on the SHB 19.19.
Is this means that I need to turn it out more than 1.5 turns to get similar effect?

Mate seems you loosed some text

Lol dont know where my comments went.
I was admiring the art work on the door, you have a very talented lady there.

Thanks mate. I told her your words and she is happy now)

Finally I collect all parts to install centre stand. Stand and it brackets was powder coated. I was want to put on MRP luggage brackets but it turns out that its needs to modify a bit to correspond holes in frame. I also have no such long bolts so I left this for other time.



Maybe front wheel bit higher than it must be but it not worries me. Stand was worn so it was welded 2cm longer. But I did not consider that the boots would add more height.


At first I want to keep the side stand. But due to it was for PX and reworked for PK it turned out that it interferes with the сentre stand. Not a significant sacrifice.

And of course main stand was not main add-on.
Yesterday I put Polini air box on carb. And changed main jet to 105. Too rich. Went down to 102. Bit better but still rich.
I need go to the meeting and have no time to change jet again so I went as is - 50 idle jet and 102 main. It was too rich, revs up weakly and I accelerate to 80 km/h difficulty.

Today I took air box off and rode again. It was night and day. But I don't want to ride without any air filter or at least air box.

So I decide to make additional hole in the air box. Works much better but I rode not too much. Tomorrow will tell me more. I think I maybe need to down main jet to 100 or even 99. Or add one more hole to air box. And try 48 idle jet seems also worth.


Pity but noticed that air box still touching the frame.

make sure you have a drain hole near the bottom of that, mine used to load up with fuel. i had a kind of larger amount of spitback from the carb though.

Great tip! I was thinking about the same but also want add a hose routed out of frame.

control the mess - nice idea to add the hose

Easy to add another hole, you can always seal hole up later if you want.