Anybody changed jetting on a Z250 for just airbox cover removal or modded with vents/holes. I am wanting to leave stock exhaust as is. Is the general rule go up one size per mod? Is stock main a 125? With cover removed and better flowing air filter maybe a 135?
Help if you can. Thanks

 

Bump

Anybody?

 

If you remove your lid your going to have to jet up.

 

I need the same info, NO change in the Exhaust, Just the lid off or Vented.

Like what size Jet, "PLEASE".

I have to order them and I only want to do it once.

I was planning on getting the next 2 sizes, Is that enough?

 

In the Jan. Dirt Wheels, they removed the airbox lid and added the White Bros. E2 exhaust and changed the main to a 150 with stock needle. I am guessing 135 - 140 with just the airbox lid removed. I am not in a big hurry to change mine, but when I do I will post size and results. I am sure the Dynojet jet kit instructions would give the info we need, but like I have found in the past a "jet kit" is not really needed, just one proper sized jet and a small drill bit. $3.00 vs. $50

 

Aren't there going to be problems with mud/dirt with airbox lid removed? Will there be much improvement with the stock exhaust?

 

I went to the Dynojet website, to the Z250 jet kit instructions. Of course their jet sizes do not correspond to the Mikuni sizes, but it is all there if anybody knew the "conversion factor".

There kit includes a new needle and has one remove the factory main jet cup and discard.

My experience has found that proper jetting will add more response/power to a 4-stroke than a pipe. But the combo of both is great. But, I would have gotten a Z400 if I was serious. I just want a little more snap than a stock machine.

As to mud getting into an open airbox, you would have to get in about 2 feet of it, which I don't plan on doing, and the filter is still in there. I run through the regular puddles and stream crossings but leave the mudding to the big boys.

 

Where can you buy an off the shelf jet kit and sport filter all sorted and ready to go which will show good results without changing the pipe? I'm like you, don't want to do major mods just a bit more go. Will probably consider opening up the filte raousing rather than removing totally.

 

If your worried about water in the air filter, get a K & N and an Outer Wears wrapper (water resistant). I believe they have a kit with the filter adaptor/filter/wrap/jets??
If your going to go place where there is deep water/mud crossings leave the cover on .

 

The www.rockymountainatv.com site has the K&N jet kit and filters. They also have Uni or Twin-air filters for the Z250 also. For whatever reason the K&N kit is a good bit cheaper than the Dynojet kit. I have always heard they are the same kit, just different packaging.