My O3 Z400 is completely stock except for a K&N filter and outerwear. I have gone up only one jet size to a 132.8. For maximum benefit from the filter should I jet bigger? It runs fine but some have said I should have gone a lot bigger??????? Thanks.

 

It really depends alot on altitude and temperature and add ons but generally speaking yes it seems a little on the small side - dont forget the mixture screw and maybe the needle as well ?
As you still have the stock exhaust you arent really achieving much anyway as what goes in must still come out just as fast !!

 

The biggest difference will be noticed when you remove the cover from the air box (perminently). For that you will need to go up to a 140 to a 142 Mikuni jet. The difference is that big!!! Remember, dynajet main jets run considerably smaller per number then Mikuni jets, they are not the same. I bought the Dynajet kit and ended up not being able to use any of the jets, the largest being a 155. I only used the needle so I spent 70.00 for a friggin needle. A dyanjet 160 would be in the ballpark but I recommend buying Mikuni jets from the dealer.
I have a W/B e-series with a K-N filter setup with the cover removed and I run a 148 Mikuni main jet. Below 1500 foot elevation, this thing absolutely rips. It never backfires or loads up.

 

A DynaJet 160 for a stock bike with a K&N Filter & no lid? No way!!!

I have a UNI Filter, No Lid/Outerwear cover, & a Full Yoshimura Pipe, and I only have a DynaJet 155, However I did need to get a 25 Mikuni Pilot Jet to stop Backfireing on the low end, and dieing on decell. I am at 0 elevation.

-ThaChad

 

What ever works for ya I guess. The 155 d/j caused a top end stumble (no, not the rev limiter) on mine thats why I went back to mikuni sizes and the 148. I was able to adjust the pilot screw to tune the idle/ part throttle mixture, no jet needed there. Suz must have changed something between 03 and 04

 

Well You have a Different pipe than I so that could make up the difference... My Team Suzuki / Yoshimura Pipe has the smallest TEC-kit tip installed, so it probably doesn't flow as much as yours, if I took the insert tip out, I am sure i'd have to rejet..

But suzukisusie's bike looks to be stock atleast from the signature, so the jetting for a Stock bike with just a better flowing air filter, and no lid wouldn't be anywhere near our jetting. [img]i/expressions/face-icon-small-wink.gif[/img]

p.s. What are "laserlights"?

-ThaChad

 

Chad,
You are correct on that one. Since my last post I rejetted a neighbor kids Z400 to run without the airbox lid. He already had a Yosh pipe and he still had the stock 130 jet in his, he said it ran good that way. The pipe doesn't make a very big difference at all. I also learned that the stock air filter element is quite a bit more restrictive then the K&N. When I did mine I put the pipe and modified the airbox with the K&N all at the same time then jetted accordingly. When jetting the neighbors z I found that the main should be more in the range of 148 Dynajet jet when the stock air element is retained. That is a big difference in power output, more air at the correct ratio = more power.

The laser lights are small round lights like you see so much of these days on buggies and quads. They run 35 watt bulbes and mount to the top of the steering stem on a plate which doubles as the bar clamps. The light bracket also houses the warning lights and key switch. Very cool addition especially at night where you can direct your light with your bars. The wife would not ride at night without them.

 

[quote]
Originally posted by: JSsDS
Chad,
When jetting the neighbors z I found that the main should be more in the range of 148 Dynajet jet when the stock air element is retained. [quote]


Is that with the air lid on or off?
I just did a K&N filter,no snorkel, no lid & jetted to a 142.5 mikuni main.
I have a Billet exhaust end cap, so there is only a little flow change in the exhaust(there is more than I though, the stock 7/8" end cap 'VS' the 2 3/4 hole is huge)
I ride at around 0-500 feet in the winter months. When it warms up I ride from 500-6000 feet. I'm sure i'll have to lean it when it starts to get hot out.....

 

Thats with the lid removed and the stock foam filter in place. As mentioned the K&N breaths much better then the stock element so jetting will need to be richerwhen the K&N is installed. 142.5 sounds a bit lean but again, your pipe may make the difference. My setup as described in my signature runs perfect with a 148.5 Mikuni jet.
If you can hold the throttle wide open without the engine missing and/or backfiring (before the rev limiter), you should be ok.

 

I have gotten a kick out of all you guys and your jetting advice but you all have pipes and I have done nothing except add the K&N filter plus Outerwear. I just wondered if I needed to rejet for only that modification. As I mentioned in my first message, I am running one size above stock - a 132.8 which is probably nothing. I am hoping that Suzuki comes out with a new and improved EFI Z400 soooooooooon! Probably won't happen though. Thanks for all your good intentions but my quad is nothing like any of yours.