Tomos A55 carb selection

ben henderson /

Feb 10, 2019 10:38PM

Thanks to help on here I now know my bike has the A55

It came with a old dellorto 14:12P carb...so I bought a new one to go on it thinking

the bike had the A35.

Currently the bike starts easy, idles good, is a big sluggish in the mid range but slowly builds up speed and will reach 36mph. To my knowledge, the only mod is the biturbo pipe.

A new A55 PHVA carb costs too much for me.

Would the Dellorto 15:15 be any better than what I have now?

Any info on what the numbers mean?

I have yet to try putting a bigger jet in the current carb, but I do intend to do that.

But Im wondering if the current carb can allow as much air/fuel as either of the

2 other carb options?

Re: Tomos A55 carb selection

pat splat /

ggspeed

Feb 10, 2019 10:54PM

the stock phva is pricier because it is better, what air filter? what main jet? r u using now?

Re: Tomos A55 carb selection

ben henderson /

benhonda OP

Feb 10, 2019 11:03PM

> pat splat Wrote:

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

> the stock phva is pricier because it is better, what air filter? what

> main jet? r u using now?

large cone filter, whatever the stock jet is that came in the 14/12P carb

Re: Tomos A55 carb selection

pat splat /

ggspeed

Feb 10, 2019 11:13PM

wanna say unmessed w stock is a 52, just read yr other post . w a pipe and the cone id say 55 to 62. in the meantime u could raise your needle n see if that helps.

Re: Tomos A55 carb selection

pat splat /

ggspeed

Feb 10, 2019 11:17PM

it is easier to stick to one post, avoids confusion.

Re: Tomos A55 carb selection

Aaron Blair /

aaronb

Feb 11, 2019 09:16AM

like dude said, one thready is betty...

anyway, you never tuned your carb... you should really do that......yeas a 15.15 will increase powah. but get your title first...

also, you diddnt tune that del 14,12....that is a 1 jet carb(ithink)... a phbg has 3, and like the Sha, does not come pre setup for your bike.wayyy more complicated than the carb you already have to tune...

if you really want a the carb it came with, you have an amazing opportunity here, a community of dumbasses that think mopeds are awesome...why look for a new phva? look for a used one w/intake that actually came off of a stock a55...youll be much closer

Re: Tomos A55 carb selection

Brandon Weiss (Detective brandon to you) /

mopedallday

Feb 11, 2019 12:49PM

Whats going on here? You say that you have the stock 14/12 jet in your 14 phva? That doesnt make sense, the jets are not interchangeable, the phva takes 6mm jets, the SHA take 5mm.

You cannot just slap a 14/12 or 15/15 SHA onto the A55, the intake will not accept it. You would need to craft a spigot so the SHA can be held by the rubber intake coupler.

You should thoroughly clean and tune the PHVA 14 you have instead, its a fantastic carb. Stock cylinder with the 14phva and the stock unmodified airbox and a biturbo should land you around 57-58 main jet. With a metal mesh air filter, somewhere around 62-65, no air filter at all somewhere around 68 In my experience

Re: Tomos A55 carb selection

ben henderson /

benhonda OP

Feb 11, 2019 05:51PM

> Brandon Weiss (Detective brandon to you) Wrote:

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

> Whats going on here? You say that you have the stock 14/12 jet in your

> 14 phva? That doesnt make sense, the jets are not interchangeable, the

> phva takes 6mm jets, the SHA take 5mm.

>

> You cannot just slap a 14/12 or 15/15 SHA onto the A55, the intake will

> not accept it. You would need to craft a spigot so the SHA can be held

> by the rubber intake coupler.

>

> You should thoroughly clean and tune the PHVA 14 you have instead, its a

> fantastic carb. Stock cylinder with the 14phva and the stock unmodified

> airbox and a biturbo should land you around 57-58 main jet. With a

> metal mesh air filter, somewhere around 62-65, no air filter at all

> somewhere around 68 In my experience

sorry, i was saying that I have a 14/12 sha with the stock jet in it.

The bike came with a homemade intake and had a 14/12 sha on it when I bought it, so I bought a new 14/12 sha to get it running.

I didn't even know until just a couple days ago that I have a A55

I was reading about modding the slide on the SHA carbs to help lean out the midrange...which is where mine seems to be sluggish.

If I cover the half the air intake with tape the midrange becomes more sluggish but the top end feels a bit better. So I think it is running a bit rich in the midrange and lean on the top end. I'm hoping to mod the slide and put in a larger jet to get more power.

When I have a day where the weather is good I plan to do some plug chops at half and full throttle to see if my assumptions are true...then mod the slide/change jet size accordingly.

Re: Tomos A55 carb selection

Saabsonettguy . /

saabsonettguy

Feb 11, 2019 07:40PM

I think the main question is, what are your plans? Although the SHA isn't the best carb, it'll still run and should support you up to the low 40's. A small phbg would allow more adjustment and would probably run better but would be kind of unnessicary if you're just going to putt around at 30.

Re: Tomos A55 carb selection

ben henderson /

benhonda OP

Feb 12, 2019 07:24PM

> Saabsonettguy . Wrote:

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

> I think the main question is, what are your plans? Although the SHA

> isn't the best carb, it'll still run and should support you up to the

> low 40's. A small phbg would allow more adjustment and would probably

> run better but would be kind of unnessicary if you're just going to putt

> around at 30.

currently I would like better acceleration and to hit 40mph. As it is now, acceleration can be a bit sluggish and it tops out at 36mph. Again, not bad for a 50cc carrying a fat guy who has no business being on a moped. But it would be nice to say it can hit 40.

I just got the Vin # problem sorted out...got insurance on it (NC requires it) and tomorrow will go and register it.

Re: Tomos A55 carb selection

ben henderson /

benhonda OP

Feb 25, 2019 11:45PM

I have a 15/15 SHA carb on the way

But since the set of jets I bought arrived first I threw them in the 14/12p sha carb

Midrange is still slow but top speed is now 40mph.

I notice after I shut the bike off and let it sit for a few, some fuel comes out the air

filter onto the floor. Between that and the slow acceleration I think I may have

jetted it too high. Right now it has a 72 in it.

I will play around with jet size more once the 15/15 sha carb arrives.

Re: Tomos A55 carb selection

Aaron Blair /

aaronb

Feb 26, 2019 08:12AM

jetting affects the amount of fuel metered into the engine while there is air flowing through the venturi. the carb leaking after sitting has nada to do with jetting, either the float is stuck or the float needle isnt sealing. that could also happen from leaving your petcock on after parking the bike..tap the bowl with a screwdriver handle and see if the leak stopps.

when you say mid range is slow what exactly do you mean? this is a mostly stock moped.... is the bike running smoothly in the mid range? breaking up? you should hear a smooth increase in rpm, no choppyness.

i think your on the right track. im not sure but 72 seems rich to me.

Re: Tomos A55 carb selection

ben henderson /

benhonda OP

Feb 26, 2019 10:33AM

> Aaron Blair Wrote:

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

> jetting affects the amount of fuel metered into the engine while there

> is air flowing through the venturi. the carb leaking after sitting has

> nada to do with jetting, either the float is stuck or the float needle

> isnt sealing. that could also happen from leaving your petcock on after

> parking the bike..tap the bowl with a screwdriver handle and see if the

> leak stopps.

>

> when you say mid range is slow what exactly do you mean? this is a

> mostly stock moped.... is the bike running smoothly in the mid range?

> breaking up? you should hear a smooth increase in rpm, no choppyness.

>

> i think your on the right track. im not sure but 72 seems rich to me.

it is a A55 engine, with custom intake, running a SHA carb/cone filter and a biturbo pipe. So kinda a mismatched carb and lightly modded.

The RPMS climb smoothly, no choppiness, but the rpms don't climb as fast as I think they should.

I have 2 tomos bikes right now, this one with A55 and another with basically stock A35 (only mod is a cone filter) The A35 is faster off the line, and pulls ahead by 100-150 feet before the higher speed of my A55 allows it to catch up and then past the A35. The A35 has a top speed of 33-35mph. If I could tune the A55 to have the same performance off the line but keep the 40mph top speed that would be awesome.

I haven't looked to see if the A35 bike just has different gearing. And it is possible that with the SHA carb and custom, longer intake pipe that the A55 will never run as well at lower RPMs as it would if it had the stock PHVA carb and intake.

Re: Tomos A55 carb selection

pat splat /

ggspeed

Feb 26, 2019 07:15PM

u might look into clutch springs, cut the og ones or buy some stiffer.

Re: Tomos A55 carb selection

Juel . /

rawllerlx

Sep 07, 2021 09:53PM

I just got a dellorto 15.15 sha, and ur righy cant just slap it on. What parts do i need from treatland to fix this issue

Re: Tomos A55 carb selection

Kevin Bishop /

kevers

Sep 09, 2021 02:55PM

60 jet max stock w pipe

72 with a kit n pipe

Re: Tomos A55 carb selection

pat splat /

ggspeed

Sep 09, 2021 10:12PM

> Juel . Wrote:

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

> I just got a dellorto 15.15 sha, and ur righy cant just slap it on. What

> parts do i need from treatland to fix this issue

https://www.doscycles.com/search?q=Sha+adapter

Re: Tomos A55 carb selection

Jesse Stephenson /

Go to branch

jesses

Sep 09, 2021 10:56PM

Best carb for tomos A55 is the 17.5 PHVA, anything else and you are blowing it.

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