Does this seem like a nice kit to have? (see link below) The auction says "Genuine" Mikuni main jets...

If I swap the main jets, do I have to do anything with the secondary jets? (Sorry for the n00b question, I'm a carb n00b.)

Ebay listing for jet kit

 

Well they sell for generally 2-5 dollars each depending on which one it is. Have you verified that these are the ones to fit your carbs as there are many different sizes/shapes.

see what I mean:
http://www.factorypro.com/products/jets.html

If you are just going up a size on the main jet you should not need to change the pilot jets. Normally you would also shim the needle height accordingly as well.

Tuning carbs is a trial and error process. If you havent altered anything on the exhaust or intake you may end up doing more damage than good.

Also after tuning the carbs, you would probably wanna make sure they are synch'd.

What are you trying to accomplish?

Steven

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by _Cyclone_ &raquo;</TD></TR><TR><TD CLASS="quote">

Does this seem like a nice kit to have? (see link below) The auction says "Genuine" Mikuni main jets...

If I swap the main jets, do I have to do anything with the secondary jets? (Sorry for the n00b question, I'm a carb n00b.)

Ebay listing for jet kit</TD></TR></TABLE>

These are jets for a two stroke. Looks like the std range for the TZ250, exactly the same kit as I have. All of them are main jets and are mostly used for racing to set-up how rich/lean you run due to air density.

You do not want to play with them, they have the ablility even when fitted to the right bike to screw it up. What bike are you running and why do you need such a large range?

 

It's for an 88 Yamaha RZ350 YPVS (2 stroke) I don't really need a large range, I just want to jet the carbs properly for my setup, which is: 0.080 bored over (maintenance reasons, don't ask), expansion chambers and individual K&N's. I may add larger reeds at some point, or have the head milled to add some more compression. I just want to put the right amount of fuel into the engine and not lean out, because that's how my buddy blew the last YPVS engine. Blew a hole the size of a silver dollar through one of the pistons. These engines are so simple, a monkey could rebuild them, but it's still a pain in the *** and not a good way to learn about carbs.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by _Cyclone_ &raquo;</TD></TR><TR><TD CLASS="quote">It's for an 88 Yamaha RZ350 YPVS (2 stroke) I don't really need a large range, I just want to jet the carbs properly for my setup, which is: 0.080 bored over (maintenance reasons, don't ask), expansion chambers and individual K&N's. I may add larger reeds at some point, or have the head milled to add some more compression. I just want to put the right amount of fuel into the engine and not lean out, because that's how my buddy blew the last YPVS engine. Blew a hole the size of a silver dollar through one of the pistons. These engines are so simple, a monkey could rebuild them, but it's still a pain in the *** and not a good way to learn about carbs.</TD></TR></TABLE>

Right first thing to do is throw the K&N's away, they are shxt. Get a std airbox back on there and do some research on what filter to run inside it. You may benefit from drilling it but I would check it out. With the K&N's the midraneg will be all over the place. Having the head 'milled' is nothing to do with compression, you are dealing with squish. With pump fuel less than 0.8 could detonate, and if its cold it is worse. Race 2 strokes look around 0.6mm or so. As for head volumes leave them stock. Get the barrels tuned, decent pipes and go about 5 jets rich and plug chop it. Reeds, well you can stuff them but depends how far you want to go. I have seen 70HP 350's but they ran TZ pistons, clutches, etc.

Two strokes are simple, until they go bang and chuck you down the road