Malossi 221 set up

[modpx]

Hello guys, i have some questions for you. I am working on a Malossi 221. Can anyone of you tell me exactly what kind of modifications is worth to be done on the cylinder? What about enlarging the exahust port like in the worb 5 version? What does it give more? How much do you enlighten the piston exhaust port?
Thanks

[Rudi]

im not a modification expert but I do know that the right level of pressure, BETWEEN the two following points: 1 - the cylinder and 2- the end of the exhaust, is crucial to performance and Im not sure enlarging the exhaust port would increase performance...it may do the opposite by lowering exhaust pressure...

[modpx]

this type of job im talking about , im thinking of doing the same job to my cylinder , cutting the exhaust port up to the cylinder base and enlarging upwards the port right above

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[sbwnik]

Unless you know what you're doing, this could be an expensive experiment and learning curve.

[modpx]

Doesnt that give more power? I've done that already ;D i'll test it later this week,with lightened piston, Gran Sport gudgeon pin. i also ported the cases for that "new" transfer enlargement...

[sbwnik]

Hmm, so much for the theory that you only change one item at a time then....

[pxguru]

Have you changed your carb from the SI24/24? This carb isn't big enough for a tuned 221 and if the tuning is making it more powerful, you won't be able to get it rich enough to stop it heat seizing.
You are going to learn a lot very quickly!
Did you ever get your barrel set at the right height and the squish sorted?

[modpx]

Hi , yes i have a 26 SI by BGM fitted with the DRT float chamber cap, this one: www.sip-scootershop.com/en/products/float+chamber+cover+dellorto_128295t7 I would ike to keep the mixer.

I quit the Pinasco cause it just stops revving too early, and it starts screming on 4rth gear. The set up wasnt too bad after all, but Pinasco doesnt give much choises cause is pretty much like a standard Piaggio with just one port bigger and the head is calculated to have that super squish over 2mm. Either with central spark plug or the standard the music is always the same. Ok at the lower ranges gives you a great kick but that's all. Boring.

I guess you (guru) have experience with Malossi 221, have you ever tryed the Malossi head htsr, the one calculated by Malossi with the 0.85 squish? just one question: whats ur fav set up, 1.5mm at the base or 1mm base + 0.5 head or 0.5mm/1mm or 1mm/1mm etc..?

[pxguru]

The SI26/26 is still pretty small for a 221. Did you already buy a Malossi 210 kit?

There is no one set up for anything. I depends on what you need it to do. My favorite for a Malossi 221 is a 2mm base packer, the biggest ports you have ever seen and a custom head with 0.8 squish but for this not to blow up you need a 38mm carb ;D If you cant get enough fuel in it will burn to hot and seize.

Do you have someone who will grind out the ports?

[modpx]

Yeah i ported the cases by myself and i opened those ports like in the pic taken from SIP worb 5 cylinder approx 2mm each side and upwards. I asked if someone has ever done the same job but i got no answer.

What im asking now is what is the perfect packing for a 221 since i have a 210 cylinder. I can try all the combinations by myself of course but asking to someone who has had that cyinder before would help. You surely know Malossi suffers the lower ranges so by packing the head or the base is possible to adjust that. We had more or less the same conversation for Pinasco but in a completely different context. Malossi has made a head called HTSR (High Squish Tubulence Rating, the one with the o-ring) with a squish of approx 0.7/0.85mm calculated appositely on their piston head. That's the head i have in my kit. If you or others dont have experience with the same kit or cylinder head then nevermind.

[pxguru]

For those heads to work you will need to piston high in the barrel. 1.5 mm should be ok. You might need another thin gasket as well depending on your engine. Measure the squish when the head is tightened down to check you got it right.
I hope you measured how wide you were opening the exhaust port. You can only open a Malossi a few mm wider before it starts to eat piston rings!

let me know all the measurements (to 0.1mm) when you set the base height and I'll calculate what you should expect!
Main transfer to top of barrel
Exhaust port to top of barrel
top edge of piston to top of barrel (should be zero!!)
Squish mm

[modpx]

alright next i'm going to center the piston with the cylinder in order to match the ports perfectly (i enlightened the piston so i cut between the two little ports of the Malossi piston to make one out of them, plus other little works) then i'll take care of the packing. So you say 1.5mm at the base, like is normally suggested for longstrokes. Hmm ok... I tryed 0.5 down and 1 up and the result was a on/off Vespa: dead down and super torquey and revvy at the middle high range. If i could pull the gears a little more in the lower ranges i'll be satisfyed. But even like this is another Vespa compared to how it was before! Malox is another league. ;D I guess you're going to tell me the correct engine timing by using millimeters instead of grades, that will help as i dont have a protractor and i havent done that yet.

i didnt touch the inside of the barrel i just opened the transfer in the cylinder part that goes into the case and the corresponding transfer above so hopefully no rings will be eaten? The case is ported with all the enlarged transfers.

[modpx]

i forgot to mention that the on/off vespa result was before all the works ive done on the malossi. it was pretty much plug and play at that time so it's not so relevant as a test. But still..

[super150]

Jesus…this conversation is way over my head! I give up even trying to understand :0)

[modpx]

@guru: alright these are the measures:

Main transfer-top of the barrel: 47mm
Exhaust-top of the barrel 34mm
squish approx: 0.75, lets say between 0.7 and 0.8

the piston measure with 0,.5 at the base is Zero, i mean he upper piston ring is still inside the barrel at the very edge of it. i think i cant pack less than that or it'll come out of the barrel. but i havent tryed. Let me know.

[pxguru]

Why do you think the top ring will come out of the barrel?

Can you post a picture of the piston at the top of the barrel? With a 60mm crank you need 1.5mm base packer (+/- a bit) to get the piston to zero deck at TDC.

If the barrel is too low it will be all torque and no power!

If you get the piston at TDC sorted the port timing is perfect ;D

[modpx]

what do you think about 1mm down and 1mm up? this way i should get the right compromise torque/power with a squish of 1.3mm...

[pxguru]

1mm top and 1mm bottom, is too many mm and too boring for me.

1.5mm on the bottom and 0mm top and get the head skimmed to set the squish at 0.8 Then you will have plenty of bottom end without losing power!

The higher you set the barrel the longer the transfer ports are open, more fuel gets in and a bigger bang. As with all things two stroke it's not so simple; the longer the transfers are open the more time for the new charge to get sucked out by the exhaust. There is a balance and 1.5mm is the most power without porting a Malossi barrel.

Once the head is skimmed you can use different thickness head gaskets in the future if you ever want to put the metal back or adjust the squish!

[modpx]

right, i could finally made a few tests and the 1.5mm at the base w/o head gaskets i have to say was the best! with 1mm down and 1 up it was de-compressed, not revving so fast and not much torque either (the worse) with 0.5mm down and 1mm up huge torque at the middle high ranges but dead at the lower and not much fast at revving too. With 1.5mm and the 0.8 standard Malossi squish w/o head gasket instead has a great torque but revs much faster than with any other set up! A real beast! Havent tryed the top speed yet but easily gets over 100/105 in third gear! And it doesnt scream! It just loves to rev! Thanks Guru for the tips, now i just have to keep t cool and for once being able to finish the running in properly without seizing it!

[linoldi]

Hi I bought Malossi 221 mhr kit and MAZZUCCHELLI log stroke crankshaft for my Vespa PX200E. Now I am wondering if this will work with my original 24/24 dellorto carburator? I also have Sip Road 2.0 and 128 main jet. Timing wil be set on 18 tdc. Could something go wrong?

[pxguru]

What stage are you at? Is it still in boxes or assembled already?
SIP road is not an ideal choice for that but hopefully a 128 main jet will be way too small. It will run well on a 24/24 but only if set up properly. It would run fastest on a 30mm carb.
What type of riding do you want to do with the scooter? How important is the autolube to you? Buying an MHR and a race crank, I would guess you are looking for it to go as fast as possible.
Something can always go wrong but with experience it happens less and less

[linoldi]

Feb 22, 2016 12:11:03 GMT pxguru said:

What stage are you at? Is it still in boxes or assembled already?
SIP road is not an ideal choice for that but hopefully a 128 main jet will be way too small. It will run well on a 24/24 but only if set up properly. It would run fastest on a 30mm carb.
What type of riding do you want to do with the scooter? How important is the autolube to you? Buying an MHR and a race crank, I would guess you are looking for it to go as fast as possible.
Something can always go wrong but with experience it happens less and less

I already assembled all the parts. Bigger jett is not a problem I have a whole box of them. At this moment I just want it running with this components. I'm more of a torque guy (wheelies:)). How should I set up my carb? Which one would you recommend? I think that autolube is not an option.

Read more: vespa.proboards.com/thread/3199/malossi-221-set#ixzz44OWEdc9z