Ohh, Yes, he did...660 the easy(?) way

[Lastmile]

Right it works similar in a car tbi, but thats computer controled injection. The YZF carbs are carbs not computer controled injection... right? So what if the TPS was eliminated? What would it hurt.... could you use the YZF carbs w/o? Just curios. Because the head is better.... right? Would the carbs have to be so detuned would it even make it worth it?

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I don't think there is any real difference in the head, definately not in teh combustion chamber itself. But, the YZF intake ports are oval-ish, at least at the upstream end..which makes them larger, which in my opinion is detrimental to intake velocity.

from about when the first gen YZFs came out until about 2004, 600 intake ports got smaller and smaller(volume) and yet power went up. This tells me the manu's got seriously interested in charge velocity vs. raw flow....they haven't gone back to the large volume paradigm...tells me velocity is more important than huge static flow rates.

Would a port and polish bring the fzr up to the yzf head? Or does the ovalish shapes out do the fzr no matter what? Continuing that line of thinking, would a port and polished yzf head be too much static flow and not enough volocity?

[DonTZ125]

Static flow helps max power, IF your engine is capable of drawing in that much air in a single gulp. Like RR said, most 80s-90s intake tracts were oversized, killing velocity and seriously hurting mid-range and even top-end power. Also, the intake tract should be a little rough, to enhance turbulence and improve mixing of the charge. Polished intakes reduce turbulence enormously, leading to puddling and uncontrolled charge stratification (rich and lean zones). Polish your exhaust, by all means - it reduces heat transfer (reduced surface area) to the head and reduces coking. Leave the intake rough.

[Genesis]

This discussion is so interesting, and I learn so much, thank you:-)

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[cntryboy85]

i have both the YZF head and my factory head which would be better to use. i am just now seeing the difference in intake ports which would be great going for FI but not going to do that so..would the smaller intake ports on the factory head be better for this build. but if i do that i would need to modify the yzf head gasket right?

[cntryboy85]

If it works I have a set of rods I'd like to send you!

Any decent automotive machine shop will have a rod hone.

The one I used uses a rod hone that indexes off the big end so that the small end is perfectly aligned with it. And 'reads' the pin for sizing. They need to take approximatley .018" out radially to fit the YZF pins.

i took my rods and pins to a machine shop in florida and they said that .0400 had to come out. that they couldnt do it and they refered me to some one that could but i am looking at anywhere from 80-150 a rod to have it done. any advice? also with the valve lifters, tappets, buckets or whatever you know them as. they sit between the cam and the valve. can you use FZR's on the YZF head?

[reelrazor]

going price here is $50 per rod. buckets are interchangeable

[cntryboy85]

they should be able to just pop out of the head correct?

[reelrazor]

So. update.
18,000 miles on my 660
Stilll ride the pisss outa it and its holding hard to the build it was

[britx303]

So. update.
18,000 miles on my 660
Stilll ride the pisss outa it and its holding hard to the build it was

Nice!! Im finishing uo my 660 engine now. Was hoping to run it at daytona.....but its looking like I gotta hold out for a bit longer What carbs are you running?......just curious

[reelrazor]

I run theh stock FZR carbs with a factory pro jet kit

[britx303]

I run theh stock FZR carbs with a factory pro jet kit

Ahhh cool,thanks. Im already running that with the stock 600. Wasnt sure what to expect with the 660 and the stock carbs.Thanks

[reelrazor]

Should be a fine setup, take your time and get the carbs right

I THINK im running 125 mains,

37.5 pilots

midddle neeedles

[britx303]

Should be a fine setup, take your time and get the carbs right

I THINK im running 125 mains,

37.5 pilots

midddle neeedles

Ahhhh beat me to the next question on what mains you are running Im running K&N pods.......is that what you are using with this jetting?

[britx303]

Nevermind,I just went through and read the whole thread and see youre using the airbox. Got me a little concerned on which head to use now