Propper jetting with after market exhaust

I have a 14mm phba deltoro carb on my A55 running a 58 main jet and I don't feel that it is enough with the pipe my bike came with. I bought it second hand and am just not sure what the proper jetting should be with the pipe that the previous owner has on it. Any suggestions in the right direction would be great. Thanks

IMG_20181212_171148358.jpg

Re: Propper jetting with after market exhaust

Ought to be pretty close. The pipe doesn't warrant a huge jet change. Filter restriction change will have a bigger effect on jetting. You should be able to gauge by feel at how the bike responds to throttle input in the full throttle threshold and how the power feels when it's there. Sound also plays a part and the bike will tell you if it is lacking in power when the note from the intake is not crisp and clean.

A plug chop is the simpler way to check on it.

Re: Propper jetting with after market exhaust

Brandon Weiss (Detective brandon to you) /

A55 stock cylinder/stock carb/pipe no airbox will need low to mid 60's main jetting in my experience

Re: Propper jetting with after market exhaust

Brandon has it right. In my 2007 tomos st iam running, stock carb, aftermarket pipe, mesh filter and it takes a 64 main jet. It seems happy like that

Re: Propper jetting with after market exhaust

Find a stock airbox and you're gonna be perfect. Tomos run better with the airbox, just gotta cut the bend off the snorkel tube.

Re: Propper jetting with after market exhaust

I can give you mine if you like. But your gonna restrict your setup. Stock airbox with stock pipe. otherwise pod filter and upjet.

Re: Propper jetting with after market exhaust

A stock airbox really cleans up the low end and takes away that annoying intake howl. No restricting happening if you cut the tip off the snorkel tube at a 45* angle, you actually get quite a lot more velocity becuase of that tube.

Re: Propper jetting with after market exhaust

Overpriced Parts /

With a 58 jet with bullet pipe and stock airbox, on a heavy a55 tomos revival bike, 27x24 gears and 200lb rider the best I could get was 38-39 mph with moderate take off,

With a 64 jet (middle clip position on needle), stock airbox removed and a large metal mesh filter (13$), speed is around 44 mph on flat with more power throughout the range including low-end,

(if your at sea level and warm climate a 62 jet may work better)

Reed induction cylinders like a35 a little restriction is ok it seems but air restriction on intake on a 55 tomos piston port cylinder (and puch pp cylinders too) can decrease power and shorten powerband/ability to rev out,

You have to tune carb/change the needle clip position (possible air screw idle jet changes depending on elevation) when you pitch stock air-box not just main jet,

If you have clean crisp jetting throughout the range you’ll make good power throughout the range with no loss of low end, if not you will go slower on top end or have flat spots throughout the power band

Video shows Over 350lb pounds combined heavy bike and rider in a strong headwind, unported cylinder and cheap bullet pipe, cheap metal mesh filter 64 jet, stock idle jet, air screw set correctly 27x24 gears and untuned clutches:

I do this set up on several lighter a55 bikes like sprint with lighter riders and they go mid to upper 40s mph on the flat,

Re: Propper jetting with after market exhaust

Ken at sea level you need to upjet, at altitude you downjet. Thinner=smaller jet. Also you typically base your opinions off of one experience you've had. Don't get me wrong, its not that I doubt your tuing abilities, but you are so closed minded and stubborn I feel like you dont always know the best way.

Re: Propper jetting with after market exhaust

Jack Rutherford /

Damn really? that seems like some pretty good info to me. And "sea level" was not his only contingency on jetting.(edited)

Re: Propper jetting with after market exhaust

I set my A55 exactly as ken states and i went from 35mph to 40mph. I re-geared to 27-24 and got up to 44mph. Iam running stock top end, estoril sidebleed, stock carb jetted to 64 main jet and metal mesh filter. It barley broke 30 with the stock intake and estoril pipe.

Re: Propper jetting with after market exhaust

> Daniel '' Wrote:

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

> Ken at sea level you need to upjet, at altitude you downjet.

> Thinner=smaller jet. Also you typically base your opinions off of one

> experience you've had. Don't get me wrong, its not that I doubt your

> tuing abilities, but you are so closed minded and stubborn I feel like

> you dont always know the best way.

I totally concur 150%

Re: Propper jetting with after market exhaust

You guys cant jet obviously if you were only hitting 30. I was getting up to the rev limiter a bone stock tomos with a biturbo. Y'all flacid when it comes to tomos tuning because an a55 tomos goes almost 40 with just a 22t rear sprocket...

Re: Propper jetting with after market exhaust

so the 57 jetting should do just fine?

Re: Propper jetting with after market exhaust

I would go 60ish and work up or down from there based on the feel and sound of the engine.

« Go to Topic — end of thread

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account