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78 50 special - 85 honda aero - 62 125cc honda c102
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Location: KCMO
 
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78 50 special - 85 honda aero - 62 125cc honda c102
Joined: UTC
Posts: 16
Location: KCMO
UTC quote
finally starting to get down to brass tacks on parts to order for my small frame build and am needing some advice on the rest of the setup.

here is what i have:
78' 50 special
malossi 135
cylinder induction reed kit
ETS crank

NEEDING
Ignition (maybe stock ETS, dont think i can fund a vespatronic, but has to fit large taper crank)
exhaust (thinking PM40 or hammerzombie 2.0 if i can pick either one up for a decent price second hand)
carb (thinking mikuni 24, possibly kehin since all my hondas use kehin carbs i dont have to worry about jets)
capability to run signals and the sort (keeps the local fuzz off my back)

I am looking for this scoot to be a daily driver for work, but with enough power to push 50+ easily on a short stretch of highway (less than a mile) that i have to go down on my way to work. I still want enough low end torque that i can pull away easily in stop and go city traffic.
I am debating just going with a polini snail exhaust for the time being with a mild port job, but the way i look at it, i have already taken way to long to pull together parts so i might as well go all out and take my time with the build and do it right the first time.

I would love to go with a vespatronic kit for the ignition but 400+ USD is more than i would like to spend on the ignition. If i can track down an ETS ignition, it should do just fine on a non-race bike right? The problem is finding even an ETS flywheel here in the states is proving to be a lengthy endeavor.

any pointers on which way i should go with the build?
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hammer pipe is going to require a way ported malossi to work right
and a 28mm carb min

upjet the stock carb with a uni pod performance air filter
electronic ignition
hav Al lighten and balance the stock flywheel as that shall make the bike go a lot better.
static timing @ 17 BTDC is fine for now
you can make it variable with gadgets like the KyTronik Smart Booster
porting and transfer minimal work is good but not needed yet

50mph is what these rides do anyway so your already there

my pals who race told me to get the VSP race instead of the Hammer or other pipes since it works better anyway. You do have to loose the battery area if you have one.
OP
UTC

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78 50 special - 85 honda aero - 62 125cc honda c102
Joined: UTC
Posts: 16
Location: KCMO
 
Member
78 50 special - 85 honda aero - 62 125cc honda c102
Joined: UTC
Posts: 16
Location: KCMO
UTC quote
i dont think the stock 16/16 carb is giong to flow enough to feed 135 cc, so with purchase of a new carb, i might as well buy something like a mikuni 24.
I would have to purchase said flywheel and ignition, once i go and spend the money on a stock large taper electronic ignition, i could have just saved a few more pay checks and purchased an aftermarket variable ignition right from the get go.
my biggest concern is the exhaust however, i want it to be streetable with out being "peaky" in its powerband, and would like to keep a decent amount of low end torque to handle traffic. If a polini snail is the best choice than so be it, but if there is a better option in the 3-400 mark i am willing to entertain ideas.
loosing the battery tray is no big deal as i already cut it out due to rust and knowing that it would probably need to end up being gone for exhaust anyways.
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ok
I thought you might have a 19/19 already

my pals with up jetted stock carbs (19/19's) & running stock top ends and only a leo vince pipe get to 55mph fast which is enough for them. Static timing set to 18 BTDC most of the time.

16/16 is such a toy when compared to anything else as you know even the 19/19 so you are correct.

I was just trying to save you some cash for this build and get you a balanced engine.

There are 19/19 carbs out there for cheap since once a rider starts the tuning fun they ditch the stock carb around the same time they go for other performance parts like nicer pipe or ignition parts for reliability all of which you know. A uprated stock clutch works just fine to a little above this tune too.

I can find you a 19/19 fast (and other used mid level parts to keep your cost down) if you want or put you together with many people with hordes of used parts in the NW.

PM me if you want contact info

there is a issue getting a vespatronic be fore you need it for cooling needs
what happens with this ignition is that it at 1st advances the timing curve (hotter and more power), holds it at the advanced # until 4000 rom then starts a retard curve as is shown in the following picture:

green line
External inline image provided by member with no explanatory text

If you set a vespatronic on a stock engine that can't reach 8000+ rpms then your engine shall run hot and kill itself fast. if you change the idle set point to a lower BTDC# you can get by but this not worth you cash output. All depends on your goals. All depends on the max rpm your engine can get to since by that time (and a little before) it has to be below 18 BTDC.

here is an old exhaust writeup. it might help you a little:
http://www.down-and-forward.de/auspufftest_1.html

happy shopping

ww

ps - my malossi kit was not usable right out of the box
it had a squish above 3mm

here some info from a Tuner in CA
"from the Paisans forum:

"Making your Polini/Malossi 130cc kit fast...!!

At the request of some of you dudes i will try and explain how to make your smallframe Malossi or Polini kit fly.

A bit of warning: You can really fuck up your barrel/cases and ultimately your wallet if you do any of this stuff incorrectly. Never ported before? Then the following is probably going to be way too advanced for you and best left to someone with experience. I assume no responsibility if you ruin your shit.

To make the Polini fly i recommend the following: Get the proper head (the malossi comes with one), intake, carb, gearing and pipe setup. In the case of my buddy's Polini PK we went with the MMW head, new 24 mm polini reed intake, TM 28, standard Primi primary with short 4th and Stoffi's Race pipe.

PORT TIMING
Note: Before and After I alter any barrel I fit it to the cases and check port timings. The way malossi and polini set these barrels up out of the box is a not suitable for expansion chamber exhausts. This is a brief explanation of how you optimize a barrel to work in conjunction with the other items like exhausts and carbs.

Note regarding the polini reed valve: I port the shit out of the cases and also remove the sealing pad when using a reed intake. Thus With this type of intake you do not have to take the crank timing into account. Reed valve intakes are my preferred way to modify these engines. If you want to keep the rotary valve intact then i would strongly urge you to use the Malossi with direct reed induction or brush up on your maths as you will need to factor in the duration of the crank opening on top of the transfer and exhaust timings.

Now, To get the timings to work with a true expansion chamber exhaust it is well documented that you need to run higher port timings to allow the pipe to work as it was designed too. A good rule of thumb is anything above a minimum of 120* transfer and 180* exhaust timings. I also like 30* of blowdown. Anyway use a packer (For the polini i machine a packer out of 2.5mm aluminum sheet and make a couple of gaskets in various thicknesses) and or gaskets to raise the barrel to get the transfers to 122*(+/- 2*). I then measure the exhaust which should be around 170* give or take 5*. I then advance the exhaust timing to 183* (+/- 2*) and mark it with a sharpie. I check and verify that mark at least three times to ensure it's where i want it. A STRONG WORD OF CAUTION as with most things like this... If you go too far with porting ONCE IT'S GONE IT'S GONE. Once i have that mark setup i scribe a line and optimize the exhaust port shape. I like to open the exhaust port up to achieve a safe yet good performing 67% or 68% of piston diameter. What's an optimized shape you ask? well lets just say i learned the hard way and by trial and error. I cant give all my secrets away. Just think of a nice radius with a flat style top.

MODDING THE BARREL TRANSFERS
Looking at the bottom of the polini barrel you will notice that the casting has two indentations that do not allow the transfers to be opened up to their full potential. I machine 3 to 3.5mm off the bottom of the barrel thus removing the bullshit indentations allowing the transfers to be open up 1/3 larger than stock. The malossi barrel is ready to go here so port away. NOTE: I rarely have to modify the direction of the polini transfers since they are nicely cast in the correct direction. The malossi's need a little work here but that will be for a later class

PORTING THE CASES FOR POLINI INTAKE AND NEW TRANSFERS.
There's no point in doing the above if your intake cant flow enough fuel. I like to port the case intake open approximately 1/3 bigger than stock completely removing the sealing pad. In every occasion that i have done this i have blown through the lower wall of the cases close to the entrance of the crankcase. There's just no getting around it... you will blow through if you port it correctly. Anyway I've had the hole welded up and used JB weld. and after some odd warping to the gasket sealing surfaces from welding i exclusively use JB in this area.

Then i match the transfers to that case... typically you need to add some weld to the primary side of the cases to keep from blowing through but i have also gotten by without welding. A word of caution. I have opened the transfers too much on the barrel causing a lack of sealing surface from barrel to case. if you make this mistake A touch of JB works well in this situation as well.

SETTING THE SQUISH
OK so you have your all of your porting and port timings set... you're ready to go right? NOPE! You need to set the squish. On a 125cc setup like this i like to run 1mm to 1.3mm of squish. In order to get a polini/malossi barrel to do this you will have to deck the top of it. I measure the squish with solder or plastigauge and then remove the amount from the top of the barrel to provide the correct distance. example: Measured distance minus desired squish equals amount needed to me removed from top of barrel. Remember that if you try to alter the squish by altering the base gasket you will screw up your port timings so this is why I remove it from the top. If you fuck up here and take too much material you can salvage it by adding a head gasket

Anyway if you do all this correctly and your pipe is of good design (EG: Hammerzombie, PM40, Stoffis ROAD, RACE or CURLY or FRANZ) you will have a fire breathing smally. These mods however will not do much of anything for the kidney or the polini EVO type pipes.

Another note of caution: If done properly this formula will produce a very powerful little engine. IT WILL REVEAL all the weak parts in your engine like cruciforms, transmissions and clutches. it's better to start with all new bits from the get go."
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small frame and a lammy
Joined: UTC
Posts: 19
Location: Santa Cruz
 
Member
small frame and a lammy
Joined: UTC
Posts: 19
Location: Santa Cruz
UTC quote
VSP race is a killer pipe if you want to do less cutting the VSP road is also very nice.
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