tk22 carb jets

Hi

I have a stock engine 81 gpz550 that I have bought a 4 into 1 yoshimura straight pipe (with a bit of baffle at the end)

the Tk22mm carbs have 94 main jet and 32 pilot jet on stock airbox.

would I have to go up some jet sizes or could I manage to tune the air screws to adjust for the change?

side note, do exhaust gaskets need to be made out of copper? or would something like these work?

rover.ebay.com/rover/0/0/0?mpre=https%3A...2Fitm%2F163290174154


Any insight would be great thanks

You might get away with just shimming the needles a tiny bit and adjusting the airscrews inward a little. But usually you will have to up size the main and/or pilot a bit.

If it had a normal street baffle, that is not super loud, then you might even get away with no jetting changes other than maybe an airscrew adjustment.

it does have a baffle, how good I'm not sure. will have to see when I get it.

is adjusting the needle necessary? I have found 95 main jets, if air screw tuning doesn't work I was going to go try for those.

next size up from 95 seems to be 100... is that too much of a jump?

It depends on what you are mainly concerned with. If fuel economy is an important concern, then very careful needle shimming is usually a must. If not, then there are other formulas that will work pretty well. For best running overall, under the widest range of temperatures, you will want to run a bit richer than you would for maximum power. For that, you can leave the needle alone and compensate with richer jets.

Jets R us should have a Keihin jet in between 95 and 100. Use type 99101-393.
It appears they have knockoff jets at half price too.
www.jetsrus.com/a_jets_by_carburetor_typ...ain_round_28-xxx.htm

You can also use Dynojet mains.

These 3 types of jets all use the convention of the size being hundredths of mm for the orifice diameter, but the jets are constructed differently so the same numbers don't necessarily flow the same, though I found they were not extremely different.

You may have already seen this page on Tk22 jets.
s3.amazonaws.com/gpzweb/TK22mainPage/TK2...22jetsAndDrills.html

Will update when the pipes come in. The keihin jets look to flow the best based on the charts, will probably get a set of those if I need to up a jet size or two.

sidenote: I've been seeing a lot of threads about block off plates for the smog hoses, is this something done to prevent exhaust popping when eliminating the airbox?
Something I have to do too? or because i'm keeping the airbox I can disregard this?

It is generally done for esthetic reasons. It also provides a bit more room for changing plugs and makes cam cover removal and installation easier. It also removes a couple of pounds of dead weight.

When you pull the smog covers, leave the reed-valve assembly inside. They like to break when removed. They are the seal to prevent air leaks, so you need them in there.

Ape makes some nice block-off plates.

I'll leave them alone for now,

Happen to know the header pipe torque specs for the 8 bolts? The service manual I have leaves the torque specs for those blank for some reason

Pipe came in, very excited. or course it came with exhaust gaskets after I bought some. (also torque specs came with it)

There are these 8 half circle pieces I'm confused about. they aren't mentioned in the installation directions, but they are listed in the part page that comes with it. my Japanese is not the best but I think they are "control collars"? anyone know what these are for?


edit: O these go on the headers and under the clamp things to hold the headers on don't they...

Yes. I haven't seen any collars like that before, but that is most likely what they are.

Well, I think everything was going to smoothly, fate had to throw me a curve ball.

Was getting everything tightened down and POP, broke an exhaust stud. will be ordering a new one asap. The 6mmx27mm ones on Z1 should work right? (also these collars are hell to work with)

anyone know how I'm supposed to get a torque wrench in there to work? I can only reach the outer nuts on 1 and 4....

Also here's a picture of a bee that somehow got trapped on my old headers lol poor bee

Caleator wrote:
anyone know how I'm supposed to get a torque wrench in there to work? I can only reach the outer nuts on 1 and 4....
Also here's a picture of a bee that somehow got trapped on my old headers lol poor bee

It´s not a bee it´s a wasp. Your M6 nuts should only torque by hand (tangible) (10 Nm) and a used Header gasket will never seal again like a new one.