A3 Porting (warning Tomo content ahead)

So lets start this off right, no biturdos, no 60mph Jersey bikes (lets face it Southern Ohio is the new Jersey) here

Ok, so I've got a beautiful Golden Bullet, and I'm debating what to do with it, now I've kitted lots of A3's, I used Puch brash bushings back in the day and love the A3 Airsal, but I'm thinking about keeping the stock cylinder this time around, because when is the last time you saw someone using one?

So I'm thinking of doing one of two things, port the shit out of the A3 cylinder? I mean they have lots of meat, and they are cast iron so I can go pretty big, BUT, man those fins are tiny! Is cooling gonna be an issue? Here is my second thought, use the stock A3 piston, but run a Magnum cylinder/head, the angled exhaust should line up so I dont have to get to tricky with headers, then port the shit out of it and let the big ol fins do their thing?

As for carb, Im just gonna be lazy and get an MLM intake, I'll run either a 15 sha, or maybe a 15 Amal

Now onto the pipe, Im thinking about trying out an end bleed estoril? Or maybe a Homeot, if I'm trying to get this thing moving, Im gonna need some RPM's

Thoughts, tips, experience? lets here it

Re: A3 Porting (warning Tomo content ahead)

If you port the stock jug then you would want to add a bit more carb and a goodly pipe, retard the timing so the pipe does all of the work for the motor and keeps the temperature down. Jet two numbers below 4 stroking with the engine fully heat soaked, that will also help. Drilling fins with a #30 bit will increase the surface area and add to the cooling, just dont go overboard with the number of holes because if you take out too much material it decreases the cooling capacity. Always run goodly oil.

Re: A3 Porting (warning Tomo content ahead)

Jeremy Homser /

I put a Magnum cylinder and head on my A3. I only had to open up the stud holes to fit over the tomos m7 studs. I used the A3 piston too. It worked but the tomos piston i used has just a little too much play in the mag cylinder. I think I'm going to order the Puch piston with a 10 pin that treats has

Re: A3 Porting (warning Tomo content ahead)

> Jeremy Homser Wrote:

> -------------------------------------------------------

> I put a Magnum cylinder and head on my A3. I only had to open up the

> stud holes to fit over the tomos m7 studs. I used the A3 piston too. It

> worked but the tomos piston i used has just a little too much play in

> the mag cylinder. I think I'm going to order the Puch piston with a 10

> pin that treats has

hmmm thats some good information, I think I'll just stick with the A3 cylinder then

Rebel, ya I am going to use a larger carb and a pipe

Re: A3 Porting (warning Tomo content ahead)

Baron Von Hamilton /

I ported one for my neighbor. I raised the exhaust 2mm and went 1.5-2mm on each side. Lowered intake about 1mm and matched it to intake. Ran the 14:12 and I put a techno bullet on it. It was a solid 45. I was shocked how quick it was.

I would gut the stock pipe and see how that does before going aftermarket.

Re: A3 Porting (warning Tomo content ahead)

> Baron Von Hamilton Wrote:

> -------------------------------------------------------

> I ported one for my neighbor. I raised the exhaust 2mm and went 1.5-2mm

> on each side. Lowered intake about 1mm and matched it to intake. Ran

> the 14:12 and I put a techno bullet on it. It was a solid 45. I was

> shocked how quick it was.

>

> I would gut the stock pipe and see how that does before going

> aftermarket.

'back in the day' i built a whole mess of these, they run great, even with stock pipe and an encarwi, its not too hard to hit 40.

the other trick i did back in the day was to put a window in the A3 (10mm) piston and run it in an A35 Jug, you gotta get the intake manifold, carb, head, etc from the A35 but its a great cheap way to go. plus you are using a3 clutches so you can pound on them pretty good without exploding them.

Re: A3 Porting (warning Tomo content ahead)

Baron Von Hamilton /

Using the A3 piston in a A35 jug is a great idea! I’ll have to remember that one.

Re: A3 Porting (warning Tomo content ahead)

> Graham Motzing Wrote:

> -------------------------------------------------------

> > Baron Von Hamilton Wrote:

> > -------------------------------------------------------

> > I ported one for my neighbor. I raised the exhaust 2mm and went

> 1.5-2mm

> > on each side. Lowered intake about 1mm and matched it to intake. Ran

> > the 14:12 and I put a techno bullet on it. It was a solid 45. I was

> > shocked how quick it was.

> >

> > I would gut the stock pipe and see how that does before going

> > aftermarket.

>

> 'back in the day' i built a whole mess of these, they run great, even

> with stock pipe and an encarwi, its not too hard to hit 40.

>

> the other trick i did back in the day was to put a window in the A3

> (10mm) piston and run it in an A35 Jug, you gotta get the intake

> manifold, carb, head, etc from the A35 but its a great cheap way to go.

> plus you are using a3 clutches so you can pound on them pretty good

> without exploding them.

Ive dont that a few times too, it is fun! But I'm going to keep that stock A3 cylinder, I mean when is the last time you went to a rally and saw someone rocking the stock cylinder!

Re: A3 Porting (warning Tomo content ahead)

Baron Von Hamilton /

^^^ I am all for that! would be cool to see it blasting people.

We have a real shitty puch in the club that is 50/50 bike. It has a shittttt biturbo but blasts bikes with kits all day. It pisses them off quite nicely.

But were talking about Tomos here. Would be rad to see a 50/50 A3. I think it is very doable with 15:15 SHA or even better a bored out 14:12. And some creative porting.

Re: A3 Porting (warning Tomo content ahead)

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Re: A3 Porting (warning Tomo content ahead)

Baron Von Hamilton /

> Toledo Riot Wrote:

> -------------------------------------------------------

> So lets start this off right, no biturdos, no 60mph Jersey bikes (lets

> face it Southern Ohio is the new Jersey)

No jersey bikes.....

Re: A3 Porting (warning Tomo content ahead)

Baron Von Hamilton /

03B55A61-ED78-406D-AFE7-3AA9F2E7249F.png

Hummmmm. A3 with A35 head?

Kinda wish I had an A3 lying around so I can do this too.

This one is on CL for 200 but I don’t want to drive 2hrs to get a Tomos.

Re: A3 Porting (warning Tomo content ahead)

> Baron Von Hamilton Wrote:

> -------------------------------------------------------

> >

> Hummmmm. A3 with A35 head?

>

> Kinda wish I had an A3 lying around so I can do this too.

>

> This one is on CL for 200 but I don’t want to drive 2hrs to get a Tomos.

Due I'll send you a3 cylinders if you wanna play along! Just use some puch piston or maybe an a35 piston and toss it on whatever tomo motor you have laying around

Re: A3 Porting (warning Tomo content ahead)

Baron Von Hamilton /

> Toledo Riot Wrote:

> -------------------------------------------------------

> > Baron Von Hamilton Wrote:

> > -------------------------------------------------------

> > >

> > Hummmmm. A3 with A35 head?

> >

> > Kinda wish I had an A3 lying around so I can do this too.

> >

> > This one is on CL for 200 but I don’t want to drive 2hrs to get a

> Tomos.

>

> Due I'll send you a3 cylinders if you wanna play along! Just use some

> puch piston or maybe an a35 piston and toss it on whatever tomo motor

> you have laying around

Thanks! Andy your the kind of guy that would give someone the shirt off your back. I appreciate it!

But the problem is I have 0 Tomos anything.....like maybe a headlight. I 99:9% of the time can’t stand Tomos stuff. But this has me excited. I know a guy in Charlotte who is a collecter. He let us have a rally at his shop. He has a A3 golden bullet collecting dust. I am going to ask him if I can “borrow” it and make it run. (Which it doesn’t) .....soooo humm. Why not make it run fast. I’ll have to see how this pans out.

Re: A3 Porting (warning Tomo content ahead)

Tobias Doesn't Care (ง •̀_•́)ง /

Came in to thank you for tagging tomo content appropriately.

Re: A3 Porting (warning Tomo content ahead)

do tomophobic macho bro still say 'No Tomo' after they make a thinly veild tomos comment seeking attention?

its ok guys, this is a tomos safe space, we're not gonna out you, but you should probably put some kind of 4 loko can silencer on that biturbo if you don't want to be a victim of hate crimes.

Re: A3 Porting (warning Tomo content ahead)

> Tobias Doesn't Care (ง •̀_•́)ง Wrote:

> -------------------------------------------------------

> Came in to thank you for tagging tomo content appropriately.

I do what I can

Grahm I live in Ohio, land of the 60mph 2 grand cl tomo’s I can only live in the environment provided

Re: A3 Porting (warning Tomo content ahead)

Baron Von Hamilton /

CCF3647F-5590-4E81-9202-A84D445D74E3.jpeg

Alright! I got one so I can play along! This is a strong running bike. This is one of the guys in the clubs girlfriends fathers bikes. Glad I am going to start with a decent bike.

Re: A3 Porting (warning Tomo content ahead)

Baron Von Hamilton /

Andy I am going to hit you up for a cylinder so I can port it ahead of time before I grab the bike.

I wonder if squish would be better with a puch Magnum head or a A35 head.

Re: A3 Porting (warning Tomo content ahead)

Baron Von Hamilton /

Wham bam boom.

I get back from the beach and there is a super greasy box wating for me!

Thanks Andy. Should have a port map and game plan by the end of the week. This week is fucking busy for me. Wish I had more time to mess with it!

Re: A3 Porting (warning Tomo content ahead)

> Baron Von Hamilton Wrote:

> -------------------------------------------------------

> Wham bam boom.

>

> I get back from the beach and there is a super greasy box wating for me!

>

> Thanks Andy. Should have a port map and game plan by the end of the

> week. This week is fucking busy for me. Wish I had more time to mess

> with it!

Woooo glad it got to you! I’m going to play with mine on Wednesday! A55 port map hereeee I come

Re: A3 Porting (warning Tomo content ahead)

I'd start at an a55 map, then take it to 175° exhaust, widen & oval about 2mm each side. 25 blowdown, 150° intake. stock a3 piston matched & modded to match the a55, transfers cleaned matched and opened up on top and bottom as much as possible and matched on the case, intake opening to at least 17mm.

probably start around 16deg BTDC timing, taller gearing. find or mod pipe for topend.

I'm also talking out of my butts, but that's the fastest 50 portmap I've managed and it'd fosho haul lots of butts on a 2 speed.

Re: A3 Porting (warning Tomo content ahead)

Baron Von Hamilton /

095677CD-D22A-4248-9084-73AF89499E5B.jpeg

Just so happens I have an A55 cylinder to port also.....

Re: A3 Porting (warning Tomo content ahead)

So I have an overbored a3 cylinder....stock is 38mm I’m at 38.5mm so that’s like 51cc’s lol I’m already cheating! I might start playing with it tomorrow

While I do have a55 cylinders laying around, I just wanna use the stock a3 cylinder, gonna put an a55 base gasket on it and go to town!

Re: A3 Porting (warning Tomo content ahead)

Baron Von Hamilton /

> Toledo Riot Wrote:

> -------------------------------------------------------

> So I have an overbored a3 cylinder....stock is 38mm I’m at 38.5mm so

> that’s like 51cc’s lol I’m already cheating! I might start playing with

> it tomorrow

>

> While I do have a55 cylinders laying around, I just wanna use the stock

> a3 cylinder, gonna put an a55 base gasket on it and go to town!

Oh I am doing A3 cylinder for sure! A55 is for another dudes bike. I picked it up yesterday. I am going to measure ports and such.

51CCs huh hahah.

I think I am going to start messing next week unless I get some time with weekend.

Re: A3 Porting (warning Tomo content ahead)

the thing bout the a55 though is I think alotta it's performance also comes through the humongous transfers, which is gonna be a lot harder to replicate with a dremel and an a3, vs copying just the portmap

Re: A3 Porting (warning Tomo content ahead)

not trying to shit on the idea, I ust wanna bring up that concern so we think about it and can either address or dismiss it.

Re: A3 Porting (warning Tomo content ahead)

Baron Von Hamilton /

I am curious to compare the two. Idk have the A3 bottom end to seee how much surface area I can cut out of the transfers without creating to thin of a mating area.

I plan on exploring doing bost ports like in the Athena 70cc puch and drill holes in the piston to match.

Along with typical porting mods and piston modifications all just thoughts till I can dig in.

Re: A3 Porting (warning Tomo content ahead)

So I used an a55 airsal base gasket to make my ports, it was REAL close to being a55 size, I had to drop the top of a transfer anhair tonget it to fit, but it’s close, opened the top of the intake to 15.75mm, and the neck at 15mm, I matched the exhaust port to the pipe I’ll be using, and opened the ports in the cylinder by 2mm on either side so the ring posts don’t catch, also took out a ton of meat on the exhaust, we’ll see how it runs!

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Re: A3 Porting (warning Tomo content ahead)

i never saw much gain out of making the a3 transfer ports bigger, of course i wasn't ever building shit to go 50. 40 mph was fucking fast in 2007. 45 with a biturbo and you blasted most kitted bikes (still do?) the one cylinder i ported the shit out of the transfers wasn't a whole lot faster than ones i didn't.

the few A55's i've messed with, the top speed never seemed that much better on them but they have way better torque. i've always stayed pretty conservative on them too, max about 165 on the exhaust, i was scared to loose torque going above that but it would be fun to try, especially now that those cylinders are becoming more common and cheaper.

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