Z400 smoked me???

[prnstr4life]

I was out riding with some friends...kfx/Z400's and we were on an old road and I was wide open in 5th and one on a Z400 just blew by me like i was on a 250ex.

he just has a Yoshi pipe without jetting.

I have hmf slip on, 170 jet, no airbox lid(aluminum airbox)

I think my big iRazr tires might be part of the problem...too big for me

is my practically new machine crap or are they really quick??

[Scro]

It's all in the gearing. If a 300ex is geared right, it could out run a 450 in top speed.

[PowerJunkie]

Originally posted by bama450r
It's all in the gearing. If a 300ex is geared right, it could out run a 450 in top speed.

if you had a mile to get to that speed

[Scro]

Yea, but he was talking about just wide open speed.

Just remember, it's not all about speed. It's how you get to that speed that really matters;)

[miller821]

Yep, its just a tad faster on top end, but it does make a difference when your topped out.

[prnstr4life]

comsidering these are the only mods and he was about 2 quad lengths behind and then pulled like a SOB. Kinda depressing

[hauck400ex]

a z/kfx with similar mods will beat an ex... i have an ex with a cam, piston, full system, jetted, etc. and my buddy has a kfx with a full system and jetted and we are pretty even but my bike has more bottom end and will always pull ahead

[400exrider09]

sounds like u need 2 learn how 2 go through the gears

[coryatver]

Make sure your throttle is adjusted and your carb is opening the whole way. The z400 is faster but it shouldn't blow by you like your on a 250ex. Also like you said your bigger tires might not be letting the motor pull any more gear

[hauck400ex]

go through the gears? They have more power, I love my ex, but a z/kfx has more power... dohc, different gearing, higher rev, its just a faster bike if you go with similar mods

[Wheelie]

You're jetted way too rich on the main circuit. Drop down to a 155 or 158 and try again.

Too rich on the main circuit will make top end performance suffer.

[crazycd1]

I have a z400 and my bro has a 400ex, jetting is the key here, I am not much faster then his!

I also worked on my jetting alot, and I find most people on here are too rich, I am running leaner jetting then most with similar mods and still very tan on the plug! Top end will suffer with to big of a jet, even if its close enough to run good still!

[prnstr4life]

the instructions for the jet kit said 170 for pipe with airbox lid removed. I havent pulled the plug yet to check how it looks.

It may be the jet and my big rear tires...

[Wheelie]

Trust me, try a smaller main.

With my slip on, K&N Filter, no choke and a massive hole in my airbox lid I ran a 40pj and 155main at sea level to about 3000ft.

It ran great. Most people run thier machines way too rich.

FYI--I'm running a 178main right now with the mods listed below, and it's too rich. I'm dropping down to a 175 or 172 after the engine is fully broke in.

[crazycd1]

Exactly, I am much leaner then HMF calls for!

[prnstr4life]

Good call....Guess I will throw in one in the 150's

[flauge]

Originally posted by prnstr4life
Good call....Guess I will throw in one in the 150's What kind of jet kit is it? Sounds like a dynojet kit b/c u said u have a 170 for a pipe and no lid... Remember the DJ size and Keihin size is different...

[prnstr4life]

ahh I forgot about that size difference. since I installed a dynojet 170 what is the Keihin size??

[flauge]

http://www.exriders.com/vbb/showthread.php?s=&threadid=210561&highlight=dynojet+Keihin
Hope this helps :)

[prnstr4life]

According to the number difference i should put in a 160-165 jet in sound right then???

[Wheelie]

IMO a 160 still sounds rich.

Try it, if it runs better, you know that leaning it out is the right direction.

[prnstr4life]

i think i have a 155 in the kit. i will probably go with that.

how far out should i go on the mixture screw? 2.5/3 turns?

[prnstr4life]

I installed a 155 and went like 3 turns out on screw and seems to run fnie but the headpipe got warm quick. i dont remember how quick it got warm before.



any ideas?

[flauge]

When i put my jet kit on a while back, I put the stock pipe back on and tried a dj165. It was dead on i think, it ran perfect...A dj160 or 165 will be about right for ya i beleive.....

[Wheelie]

The headpipe will get warm, that's normal. Run it for awhile w/the 155 in it, and race the Z400 again.

Personally I jet with a combination of seat of the pants feel, quality of throttle response throughout the range, and plug reading.

[jsmith2232]

I had a setup like yers and ran a 146 dynojet and it ran awesome that's equivelant to a kehien 165.

[prnstr4life]

I have a DJ 165 not Keihin 165. I am gonna go for a ride tonight...

[jsmith2232]

A dj 165 is alot bigger then a kehien 165, I'll bet youre gonna be running way too rich still on wide open throttle. I would be around 146-150 dynojet or 160-165 kehien for your setup.

[prnstr4life]

I just took it for a ride down some trails i can kinda get wide open on and then went down the road and opened her up and dont seem any different. IDK if my but would notice it though...seems to pull up the same but i guess ill go to a 150 and see what we got. I am assuming it should be more powerful with the correct mixture?? How far should i turn the screw out?

[THE EXMAN 400]

it depends on the rider too! if you can't go through the gears fast enough you will get beat. the z400 are fast. what were you racing a 8th of a mile or quarter of a mile?

[prnstr4life]

I was already wide open in 5th and he was behind me from when we came off the trail and he just wizzed by like i was nothing...

I havent rejetted yet...i am thinkin if just goin with a 426/440 kit

[jsmith2232]

Is he running stock gearing or is he geared for speed. Last summer my buddy had a z400 with k&n and slipon yosh, I had my 400 ex with just a K&n full fmf exhaust and revbox and he gps'ed out at 69.4 and my ex gps'ed out at 69.2 with stock gearing on both.