Tomos A55 Jetting Suggestions

mike sweet /

Jun 15, 2018 12:41PM

Good morning all

Recently bought a 2008 Tomos Targa sight unseen. When I first started digging into it, I realized it ran like crap, but better with the choke on.

I did all the usual things like clean the carb, check for air leaks (fixed a pretty major air leak between the cylinder and head)

OK here is the real question. Carb has the stock 55 jet in it (dont remember the idle jet but Im reasonably sure it's stock also), but it came with a UNI pod filter. It seems like people are upjetting to 58 on even a stock air box so I'm certain its running lean, and can confirm it runs better if I cover the air filter side of the carb with my hand the right amount.

So what jet sizes are people running with a uni pod filter? What about with air filter and exhaust? I saw moped division sells a filter/jets kit for a55 so I will probably shoot them a message, too.

Thanks

Re: Tomos A55 Jetting Suggestions

mike sweet /

deweysmopeds OP

Jun 15, 2018 12:43PM

Dellorto PHVA carb too*

Re: Tomos A55 Jetting Suggestions

Brandon Weiss (Detective brandon to you) /

mopedallday

Jun 15, 2018 01:49PM

Uni filter and a pipe should be about 63-65 jet.

Although, foam and metal mesh filters get oil soaked and do not flow right after some time.

You could also run without an air filter if you arent riding on gravel roads or sand, then you'd need about a 67-68 jet.

If you're scared of running with no air filter, just cut the rubber elephant trunk off of the airbox mount, and take out the internal foam filter and grate out of the airbox, by removing the 3 screws to get inside. You dont need it, there is virtually zero chance of any dirt getting into your carb, as all the dust will get caught by all the internal surfaces coated in 2 stroke oil by the carb blowback...that is, if any dirt get in tge airbox in the first place, which is almost impossible.

Re: Tomos A55 Jetting Suggestions

mike sweet /

deweysmopeds OP

Jun 15, 2018 03:14PM

Sweet thanks for your response. As of now, I dont have a pipe so I'm gonna just be running the stock exhaust. The bike also didn't come with the stock airbox.

So based on your calculations i think I should order a 62 and 64 jet? I figure 62 would be about right with the filter, and if its too rich then no filter should work with either the 62 or the 64.

What about the pilot/idle jet, though? As of now I can get a little action if I rev it out, but of course it's too lean. The pilot jet is definitely way too lean. It doesn't want to idle at all without the choke on.

Thanks again

Re: Tomos A55 Jetting Suggestions

Brandon Weiss (Detective brandon to you) /

mopedallday

Jun 16, 2018 11:19PM

idle jet you can increase to 30 if you want, stock is 25 i think. Get a 60's range of jets, even, not odd.

Re: Tomos A55 Jetting Suggestions

mike sweet /

deweysmopeds OP

Jun 17, 2018 01:52AM

60s range of jets is the plan. Think im gonna go ahead and order the Tecno exhaust for it too. Idle is the primary concern right now, so hopefully the 30 idle jet solves that. It wont idle whatsoever without the choke on. Idle screw all the way in, air/fuel screw in all the way as well. More evidence idle is too lean.

If I kick it over and pull the throttle wide open, then I can get it to take off and actually run half way decent (I have a bit of the air intake side of the carb taped off behind the filter to restrict air flow a little)

Re: Tomos A55 Jetting Suggestions

frank dadog /

weenman

Jun 17, 2018 04:34AM

> mike sweet Wrote:

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

> 60s range of jets is the plan. Think im gonna go ahead and order the

> Tecno exhaust for it too. Idle is the primary concern right now, so

> hopefully the 30 idle jet solves that. It wont idle whatsoever without

> the choke on. Idle screw all the way in, air/fuel screw in all the way

> as well. More evidence idle is too lean.

>

> If I kick it over and pull the throttle wide open, then I can get it to

> take off and actually run half way decent (I have a bit of the air

> intake side of the carb taped off behind the filter to restrict air flow

> a little)

I'm not sure replacing the idle jet is going to solve the problem you're describing. By all means change the idle jet but I have a feeling there's something else going on. In my experience poor idling is more to do with carb adjustment/gaskets, electrical or transmission/brake issues than the jet itself.

60's jets into 70's will serve you well. I think I'm running a 68 right now with a Technigas, foam filter and porting. Hope to use the 70's soon as well.

Re: Tomos A55 Jetting Suggestions

Brandon Weiss (Detective brandon to you) /

mopedallday

Jun 17, 2018 12:12PM

Bullet pipe is a decent budget pipe, but honestly in my experience it leaves alot to be desired. The estoril sidebleed for the a55 is amazing. I ran a biturbo with the a55 airsal kit, topped out at 42 with 26x24 gearing. Swapped to the estoril sidebleed, saw 5mph increase and better power all around with no other changes.

Re: Tomos A55 Jetting Suggestions

pat splat /

ggspeed

Jun 17, 2018 03:24PM

u can richen the low end w your needle height. and adjust your throttle slide till it idles. i always forget which way is richen and lean on that screw.

Re: Tomos A55 Jetting Suggestions

Chris Straub /

straubzilla

Jun 17, 2018 10:31PM

If the screw is on the air filter side (relative to the venturi,) it meters air (in=richer, out=leaner.) If the screw is on the intake side, it meters fuel (in=leaner, out=richer.) So on a phva, the screw richens the fuel mix if screwed in, and out=leaner fuel mix.

> pat splat Wrote:

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

> u can richen the low end w your needle height. and adjust your throttle

> slide till it idles. i always forget which way is richen and lean on

> that screw.

Re: Tomos A55 Jetting Suggestions

pat splat /

ggspeed

Jun 17, 2018 11:00PM

^that way

Re: Tomos A55 Jetting Suggestions

Harris Brancazio /

harris_bran

Mar 28, 2019 01:38PM

anyone have jetting suggestions for a biturbo pipe with 70 cc head and phva 17.5 tomos a55?

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