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Building another FZ17

Posted: Sat Sep 03, 2016 8:10 am
by tabond
I'm headed out for our last race of the year with our FZ17, and I'm picking up a YZF750 motor for this winter's race project. I was recently reading some threads on "poor-man's OW-01" and am doing some planning.

I have a 91 FZR1000 donor motor that I'm thinking of robbing the head off of and swapping it onto the YZF block for the bigger porting.

Obviously I'd do all my clearance checking, but my thought would be to use the YZF750 cam in the 1000 head.

Nuts?

Re: Building another FZ17

Posted: Sun Sep 04, 2016 1:12 pm
by sickle44
Nope, Higher duration and lift and supposedly a little lighter.... wouldn't hold a candle to that though... doing it myself

Re: Building another FZ17

Posted: Fri Sep 09, 2016 2:30 am
by spook
Apparently the YZF750 head is the same pattern as an extremely rare and expensive kit part for the OW01. They cost about $10,000 dollars back in the day. I have an article somewhere stating this, it was an interview with one of the Willing brothers, Warren here in Australia. (he was Kenny Roberts Jr's world title Crew Chief).

The YZF750 is an evolution of the OW01, it makes sense that Yamaha incorporated the best tech they had for that engine. Bigger valves don't always mean bigger performance.

A Michael says, better profile, and a heap lighter... probably 50%. The exup cams are almost solid lumps of steel, whereas the OW01, YZF750 and YZF1000 are much lighter, which means less drive train wear and hp losses, as well as less reciprocating mass Cheers.

Re: Building another FZ17

Posted: Wed Sep 14, 2016 6:23 am
by tabond
The drive behind swapping the 1K head onto the YZF750 block is rules based. The YZF750 engine as-is is illegal in our vintage rule. But with the 1K head installed it's a OW01 replica, as the lower end of the YZF is identical other than the expensive lightened parts. Vintage racing is more often about rules that it is about performance, so this is my "work around" to obtain the more desirable bore/stroke relationship of the OW without finding and then having to maintain an actual OW01 mill.

Re: Building another FZ17

Posted: Mon Oct 10, 2016 10:58 am
by tabond
I've obtained a YZF750 frame for this project. I'm wondering if anyone knows if the actual shock length is the same from the 1K to the YZF? I have an early Ohkins from a 1K that would make a decent start point for the build, but with nothing to compare to I'm not sure it will work. I know there's an R6 style upper clevice on the YZF. Is there a modern swap-in that works in the YZF chassis if this one won't work?

Re: Building another FZ17

Posted: Mon Oct 10, 2016 5:10 pm
by sickle44
I think they are interchangeable but as far as stock lengths, sorry, I cannot remember. I thought there might have been a 10mm difference, height changes and handling made customizable by use of linkage of course. Sorry I'm not more definitive than that.


Michael

Re: Building another FZ17

Posted: Mon Oct 10, 2016 6:38 pm
by tabond
On the smaller bikes (400/600) the '08+ R6 shock is a very simple but not quite direct swap. I'm wondering if the R1 or something would be a swap to the YZF

Re: Building another FZ17

Posted: Mon Oct 10, 2016 6:48 pm
by sickle44
when they went to the 1st gen R1 in 98, they really changed the entire machine, so while there are things that stay the same from years 89-95, even 96, 97, when the R1 came, everything changed and the R7 was pretty much a race machine only with very few machines ever reaching the streets. While we can fit the R1 brakes to our machines, the familiarity stops pretty much there without any major fabrication and mods. Of course, anything can be done depending on how deep your pockets are. I suppose really, it depends on how badly you want to make something work as my motto has always been you can do whatever you put your mind too. Using the 750's frame will already see you dropping a good chunk of weight from the 1K just to let you know and it didn't sound like you were using the heavy front end as well, change the wheels out and you've solved most of the 1K's porkiness.

Re: Building another FZ17

Posted: Mon Oct 10, 2016 8:22 pm
by tabond
Again, we have some very specific rules when it comes to builds. It has to look the part. The YZF frame looks enough like the OW01 frame to work, and so does the 99-02 R6 front end (43mm max station diameter allowed) which is what I used on the first FZ project. I'll swap the YZF swingarm for the 1K swingarm, and it's enough OW01 to be considered "like build".

Re: Building another FZ17

Posted: Fri Jan 13, 2017 12:29 pm
by tabond
So I have most of the pieces in place now to start this winter's build. I'll post some pics as I go, but the plan is fairly simple. Basically if I downgrade a YZF750 far enough it becomes an OW01 replica making it eligible for our vintage racing rules.

The formula:
YZF750 main frame
91 FZR1000 swingarm and wheel
Custom KYB shock
Complete 99-02 R6 front end
YZF750 lower end/mid block
91 FZR1000 head
91 FZR1000 EXUP header
Custom high mid-pipe/can
OW01 bodywork
YZF750 tank
39mm FCR's

I'm toying with the idea of converting to the 99-02 R6 rear wheel as well. Have to measure bearings to see if a simple bearing swap is available. This build will be used mainly for endurance racing so it'll retain the charging system. I also like the idea of keeping the EXUP for that as well.