cams/ cams/ cams

[FZRRDRZ]

I’m looking at a valve adjustment in the near future and while I'll be in there anyway (and while I have some 600 cams in a box somewhere) I’ve been thinking about cam swaps.

So… Looking for information from anyone that’s put something a little more aggressive into the 400… I’d really like to know what performance results they experienced.

Any info/ opinions will do (and be much appreciated) but in particular, I’d like to know how the stock 600 cams perform in there (‘cause I already got ‘em). It seems a stock 400 intake/ 600 exhaust is the preferred setup (and I've heard a YZF600 will fit but I haven’t researched the difference between it and the FZR600 profiles). I’ve also heard people have swapped them both, or experimented with intakes as exhaust, etc.

Anyone?... It seems to be a mod people have gotten a good deal of success from but I haven't had a chance to talk to anyone about it.

Thanks,
John

[Evilchicken0]

Have a look at Kent Cams website in the UK they'll have info on fast road and race profiles.
One thing though, you may need stronger springs with the more aggressive profiles

[reelrazor]

all I've heard about using other than stock OEM cams is using an intake on the exhaust.

Megacycle cams makes no distinction between 400 and 600 cams. I have their 276x5 (discontinued grind) cams, and perf springs with Ti retainers in my 660 build

[FZRRDRZ]

I figured something may need to be done to the springs and was wondering what people who used the 600's did (although the swap from 400 to 600 is not all that radical). Did they run the 400 springs/ can you use the 600 springs in the 400/ did they get new springs?

At one point, I also seemed to hear a lot about OEM 600 intakes as the 400 exhaust... lately I seem to be digging up a lot of ex. for ex. swaps.

I got the following info here: https://groups.google.com/forum/#!topic ... _B2sLhmth4 (but maybe this guy more accurately should have written "FZR600 intake as exhaust"-- the way it looks to me is 600 ex. as new 400 ex. though.

"Get the Cosworth pistons, they are the hot setup. I am getting 72.4 bhp
from my race 400 and most of the engine internals are stock or modified
stock. Use the stock 400 intake cam and an FZR600 exhaust cam. I did not
degree mine and the thing runs great. Also, use the Keihin FCR 33's,
start jetting around 115 mains. Use a D+D pipe, I recommend nothing else.
DO NOT use the "race kit" CDI box. The stock valve springs will not take
the extra 2000 revs for very long."

[reelrazor]

ehh, the 600 springs aren't gonna be any better than the 400.

Honestly, I don't believe there is any lift/duration difference between 400 and 600

Here's the stock cam specs for the 600, you should at least be able calculate lift from this info.

[FZRRDRZ]

Thanks...

The difference seems to be this: FZR400 exhaust cam has a lift of (roughly) .2874—FZR600 intake lift is .3070.

So the 600 in. in the 400 ex. seems to be marginally better (tomorrow I’ll measure duration on the 600… I can’t on the 400 as I have no 400 cam available)

The lift is on the mild side but interestingly, I just checked Meacam’s catalog and they have a cam set for the 400/600 (grind 276x1/ there tamest offering) with a lift on the ex. of .308. The difference between this and the OEM 600 cam is that the 600’s provide the 400 90.3 percent of what Megacam is offering here on ex. Not a bad place to experement from I think.

They say: designed for use with stock pistons/ best short course road race cam/ provides better acceleration, mid-range and some top-end.

WebCam seems to offer 3 individual camshafts to use as you please. They sell a .309 for the 400/600 that they say is designed for street/ road race applications and that stock springs are okay.

[Evilchicken0]

Here have a look at these
http://www.kentcams.com/product-manufac ... aha/m/FZR/

One thing that gets done to the 3TJ race engines is the crankshaft oil mod. The 400 is smaller than the 600 (4JH) so they get drill out threaded and the 600 "jet" (not sure of the right word) is fitted.

[FZRRDRZ]

The 600's intake duration is 272deg. @40deg.-- At 50deg. it was something like 266. (I used 40 just 'cause that's how Megacycle does it.)

It's longer then any after-market cams I've seen offered, which isn't to say "better" of course because different durations serve different rider needs.

I'll go check out Kent cams now... thanks for the link

John

[FZRRDRZ]

Opened up my engine-- jeez, do those intakes get tight...

FZR400 EX. cam: duration @40 is 273deg. / @50, 267deg.

If people are swapping out 400 ex. cams for 600 intakes they must be in it for the lift ‘cause the duration is near identical.

[FZRRDRZ]

Trying a straight swap for the time being—600 in. as 400 in./ 600 ex. as 400 ex. (I'll move ‘em around next week to different configurations... I’m not bothered opening up the top a few times to experiment.)

First, they fit no problem (’89 600s into a ‘90 400 clear everything/ I’m trying to clean up a few hot debates I’ve seen elsewhere.)

The duration on both bikes, on both cams, is nearly the same but the 600’s provide a taller lift. The following changes are not profound but immediately noticeable.

The bike has a smoother power deliver/ not as peaky as my 400 was at high RPMs. (I'm not sure what this is attributable to... maybe the ramp/ flank portion of the 600 cam profile has more of a radius then the 400?)

The bike feels as if it has more juice at the top end of the rev range. I want to say it “absolutely has more power” (because I absolutely think so) but with no mechanical HP testing I’ll leave it as a “feeling”.

It seems an immediate improvement to the 400 as a street bike… of course; this is dependant on what a rider is after.