Best tune I've gotten so far.

[xtreme762]

11:1 Wiseco .040" over, stage 2 HC, K&N, and stock exhaust w/ titanium wrap.

After break in I decided to pull the plug and see how it looked. Running a mix of 100LL and no-ethanol 93.

http://imageshack.us/a/img856/6351/imag0084am.jpg

It's got OEM equivalent jets, 175m - 38p - 2.5t on screw. I realize it's running a little lean. I'm waiting on actual Keihin jets to get here to richen it up a bit.

The power difference is night and day, especially when you get into it. The stage 2 HC kicks in and RIPS! As far as the HC "Tick", it's no where to be found. I have valve lash at the recommended specs that are provided with the cam, and not a tick to be heard until it gets to operating temp.. Then you can very faintly hear a tick that sounds somewhat like fuel injectors on a car engine.

No complaints here!

[duneslider]

I am looking to do a little power increase on my 400. I am trying to decide if I want to spend the money for a hi comp piston. Did you have your cylinder honed or anything when you did the piston, or just put a new piston in?

I don't know that you need the race gas? I think you would be okay with 93 octane?

I am just hesitant to drop too much money on the 400ex for negligible results.

Did the cam and 11:1 seem like a big increase? I just want to keep up with the 450's and raptors a little better at the dunes.

[Zakradu398]

Originally posted by duneslider
I am looking to do a little power increase on my 400. I am trying to decide if I want to spend the money for a hi comp piston. Did you have your cylinder honed or anything when you did the piston, or just put a new piston in?

I don't know that you need the race gas? I think you would be okay with 93 octane?

I am just hesitant to drop too much money on the 400ex for negligible results.

Did the cam and 11:1 seem like a big increase? I just want to keep up with the 450's and raptors a little better at the dunes.

I went from completely stock internals to 86mm (406-407cc) 11:1 Wiseco Piston and Stage 2 HotCam. It was a very nice increase in power compared to stock.

You could put a new piston in with just a hone but I personally would only do it on a cylinder that has <5 hours on it since the last rebore..

Also 11:1 compression with no timing advance is the highest you will want to go on 93, some people go higher but I don't advise it. 12:1 and higher comp you will want 100 octane at the least and heavy duty head studs.

[riley1374]

What jetting are you running. You and I have almost the same mods. I am trying to squeeze every bit of HP out of this combo. I am currently running 170 main, 40 pilot, and needle moved 1 from stock.

[xtreme762]

Originally posted by riley1374
What jetting are you running. You and I have almost the same mods. I am trying to squeeze every bit of HP out of this combo. I am currently running 170 main, 40 pilot, and needle moved 1 from stock.

Right now it's got a 175m and 42p(changed from 38p). But as you can see, it's to lean for this mixture. I changed the plug to the cold plug and it helped a little at the top. The 42p jet also helped a lot with low end. I thought maybe a 40 would do it. But I don't think it will. I have one, just haven't tried it yet.

I have 180, 185, 190, 195, and 200 on the way. I'm gonna start with the 200, and work my way down. Once I get it in the ball park, I'll order 1/2 size jets to get it right on. Remember these are Keihin OEM equivalent jets, not dynojet, or actual Keihin.

I also went ahead and put (2) 1/2" holes in the baffle of the silencer to lower the back pressure a bit until I get my HMF slip[ on. The high comp. piston creates more back pressure, so I don't see it hurting anything. I haven't felt a decrease, or for that matter an increase, in power modding the silencer.

[riley1374]

Yeah I am using those jets also. That is good to hear. I am going to keep upping my jets as well. Every couple of jets I go up, it keeps unleashing more power. Your air lid is off right?

[xtreme762]

Yeah, air lid off, and I don't actually have a K&N. It's a spectra or whatever those are that you can get at Autozone fairly cheap. Just as good IMO.

[riley1374]

Awesome, keep us posted what you end up with. I am going to order some jets also. I thought I would be too rich at 170, but I guess we keep going and see what we end up with. Already runs awesome and psyched with the extra power.

[xtreme762]

Right on!

I started out with a 175m, and thought it would be way to rich. I was completely surprised when it was lean. Especially without having a slip on.

[riley1374]

Guess I will try 180 and 190 and see where we get. Gotta find some jets.

[riley1374]

Also, did you move your needle?

[xtreme762]

The needle's in the third slot. I didn't move it because I really don't want to dig that far into the carb. unless I absolutely have to.

[xtreme762]

OK, I put a 200m in this thing. Topend is great now! The down side is now for some reason on occasion, when I hit the throttle, it bogs down.

It seems really lean but with no cracking or popping. I'm only at 550ft, so I don't understand how a 200m is even feasible. I'm thinking I may have a vacuum leak between the carb. and the head. I'm gonna take the intake off and see what's going on.

The spark plug looks nearly new even after riding for several hours, except for black soot around the ground(bottom of the threads).

I just can't see this mix of fuel running this clean. So, I've got to still be lean, or have a major vacuum leak. It's got plenty of power, and gets better with every bigger jet. But doesn't seem to be getting any richer.

Suggestions?

[riley1374]

I bet your lean on the needle. Try moving to 4th spot. I bet that cleans it up.

[xtreme762]

Yeah, I'm gonna go ahead and do that while I got this thing apart. It seems to be mid range, so the needle makes since.

I'll keep ya posted.

[riley1374]

Sounds good bro. Hey quick question... Do you remember how the throttle cable was routed? Is it under that white plastic shield or over? Had some binding issues when i put it back together, but seems like it only happens when the motor starts getting warm. If i shut it off and restart the cable is fine until it starts running hot again.

[xtreme762]

It goes over, if you look at it, there is a slot on top for it by the bars.

[riley1374]

Thanks man. Going pit riding tonight and dont want issues.

[xtreme762]

Well, I moved the needle to the 4th slot, and it really made it rich. So I changed the pilot jet to a 40, and started my way down the main jet scale. Right now it's at 180m, 40p, and 2.5t, and still just a tad rich. But running WAAYYY better.

The rear end now droops 2 or so inches when you rev it. Before it would hardly move an inch.

She's gettin' dialed in slowly but surely. I'm thinkin if I put the hot plug back in it. It might put me where I need to be.


Be safe tonight