YZF front end into 92.3 FZR 1000

sbutler · Post by **sbutler** » Thu Dec 18, 2008 5:37 am

OK guys I need to know if anyone has done this mod & what do I need ??
I want to use the whole lot, triple clamps, forks, brakes. The lot.
I know a lot of people put 1000 motors into 750 because of the handling advantage. But what are the advantages??
The 750 is near as I can see the same frame. It has a better 6 piston callipers, & comp & rebound adjustments. F&R But other than that, there isnt much difference So I was gonna put the YZF front end in the FZR..Help please.

Post by **FZRDude** » Thu Dec 18, 2008 10:28 am

First off it is going to be way undersprung. Then there's the steering stem.

Oh, ditch the 6-pot calipers and put some R1 Blue/Gold dot calipers on there.

Yoniboi · Post by **Yoniboi** » Thu Dec 18, 2008 4:01 pm

The YZF frame's shorter and has a steeper head angle. It's not the same.

Undersprung doesn't matter 'cos you were gonna put new springs, oil and seals in there anyway,

I think there are issues with the steering lock. Do a search, it has been discussed before.

Best of luck.
John

sbutler · Post by **sbutler** » Thu Dec 18, 2008 5:36 pm

Yoniboi wrote:The YZF frame's shorter and has a steeper head angle. It's not the same.

Undersprung doesn't matter 'cos you were gonna put new springs, oil and seals in there anyway,
I think there are issues with the steering lock. Do a search, it has been discussed before.

Best of luck.
John

Ive mesured all over both bikes & they are the same.
Axle to axle the FZR is 10mm shorter. Depending on chain adjustment.
Swing arm to pivot is the same .
Front axle to pivot is the same.
Rear axle to pivot is the same.
The only thing I can find that is shoter is the fork legs. They are 35mm shorter on the YZF.?????
So I cant see how there is that much of an advantage in swapping motors.
Ill cant find anything on a search. I might be looking in the wrong places.
Any help would be great.

Im gonna have a go at the frontend change first & see what happends.

Yoniboi · Post by **Yoniboi** » Fri Dec 19, 2008 12:33 pm

I'm flabbergasted (must be 20 years since I used that word)!

That's what comes from opening my mouth without having measured them myself!!!

Of course swingarm pivot to rear axle is the same, (hardly interesting making it longer, and considering the crank cases are the same they couldn't make it shorter). The general swingarm pivot to cylinders figures are gonna be the same too for the same reason, but i was sure the head stock was shortened, and the rake reduced.

The (1994) Spondon FZR is 3cm shorter from the cylinder mount to the headstock, and the fork is visibly more vertical. (And it uses a GSXR fork which is 3cm shorter than the FZR unit). BIG radiator/ front wheel clearance issure, but lots of fun and easily fixed by chopping the back end of the mudguard off.

I just always assumed the YZF had done pretty much the same mods, I mean, they work, and it's not rocket science.

Oh well.
JOhn

sbutler · Post by **sbutler** » Wed Dec 24, 2008 11:48 pm

Well another thing I have found is the FZR has [as we have set it with 155mm DBs] 25.5 deg head angle. The YZF has 24 deg standard. So we need to get the rake a little steeper. I will do that by getting the frame bent by a pro frame straigtner.

PS::I have done another mesurement & beleive it or not! the forks are the same lenth??

So its on with the show.

chengsr · Post by **chengsr** » Thu Dec 25, 2008 2:39 pm

That is insane, buy your self an Attack triple and order it with a FZR stem and play with the insert to accomplish the proper rake.

sbutler · Post by **sbutler** » Thu Dec 25, 2008 4:01 pm

chengsr wrote:That is insane, buy your self an Attack triple and order it with a FZR stem and play with the insert to accomplish the proper rake.

Why is it insane?? When guys crash & bend their frames, you get them pulled back into shape. This is the same, only in reverse. To get 1 deg less rake, you only need 10mm at the fork ends/axle. So the tweek is tiny at the stem. Its called thinking outside the square.
If I had the money for clamps, I would get some addjustable ones made. But I havent got that sort of money. They are big bucks over here!

Anyway did some weight last night, very interesting what I found.
The FZR was
88kg at the front. [with no race glass]
107kg at the rear.
200kg all up

The YZF was [road trim]
99kg at the front.
101 kg at the rear.
200kg all up.

So I will need to get the weight bias towards the front a little.
I will get a friend to manufacture a alloy front & rear subframe. That should help. Plus with the shorter rake, that should get it a little closer?
Any suggestions guys?

chengsr · Post by **chengsr** » Thu Dec 25, 2008 10:33 pm

I still think it’s crazy to deliberately change the geometry of the frame, either way something to consider, by raising the rear end up by ways of changing dog bone you can shorten the wheelbase in shift the weight forward and vise versa. I got my adjustable tree make for around 700 USD and I like the fact that it’s easy to change the geometry and not mess with the frame and the bike handles as good as my R1 with a 2 inches higher on the rear end and 1 degreed offset on the front.

sbutler · Post by **sbutler** » Thu Dec 25, 2008 11:42 pm

Already raised the rear over 2 in with 155mm dog bones. Ive lowered the front by 10mm pushing the forks through the triple clamps, all of which got the rake down from over 26deg to around 25 deg. So Im running out of options.
$700 US is now over $1100 Australian.
Darn the world econmic crisis!
The aussie dollar was as high as 98c US 6 month ago.

I can say it did sharpin the handling a great deal. But Its still to slow in the change of direction/esses. Its very stable, but tends to understeer on the tighter tracks/corners.
I need to get the rake down to around 24deg to make it really sharp.
I can carry the same or better mid corner speed as the GSXRs & YZFs on wide open/flowing corners. but as soon as it gets tight they simply climb on me again.

PS:: I had both bikes to bits today. You cant just do a front end swap. The YZF has a totally different lower tripple clamp, steering stem, fork diameter, axle size, steering hear bearings, almost everything is different.
So its back to plan B. Work with the FZR frontend & see how we go.

hotcam · Post by **hotcam** » Fri Dec 26, 2008 4:50 am

But Its still to slow in the change of direction/esses.

I don't know how difficult it is to fit lighter wheels off a modern
GSXR or R1 or etc, but if you did that would lighten the change
of direction quite a lot... there are probably quite a few folks on this
board who have done that.

sbutler · Post by **sbutler** » Fri Dec 26, 2008 6:17 am

hotcam wrote:
But Its still to slow in the change of direction/esses.
I don't know how difficult it is to fit lighter wheels off a modern
GSXR or R1 or etc, but if you did that would lighten the change
of direction quite a lot... there are probably quite a few folks on this
board who have done that.

You might be right Cam, but I think Im attacking this from the wrong direction.
In the 87 Castrol 6 hour they were getting around Oran pk on an FZR1000 in 1.17s with road tyres. So I figure, I need to spend more time on the bike riding the thing. Its been almost 20 years since I last raced, & I think I am the limiting factor, not the bike.

Yes the track was in a lot better condition back then, & they were top shelf A grade riders, Doohan, Magee, Dowson etc. So what Ive decided to do is sell the YZF, its to good a bike to rat all the good bits off, just to inflate my ego. Any gains in times will be down to me rather than the bike. If at some stage my times stop improving, then I will look at the bike for improvment. So if you know anyone that is looking for a very well maintained & looked after 95 YZF750 its up for sale!!!

This bike is a credit to it owner for the way he has looked after it.
Ive sorted the suspension, serviced the engine, serviced the steering head bearings. It has new pads F&R, new chain & sprockets, etc & is a pleasure to ride.

hotcam · Post by **hotcam** » Fri Dec 26, 2008 6:36 am

I've always thought that best improvement in lap times per dollar comes
from spending dollars on the rider, not the bike. In my case, perhaps
a gym membership :ha

but that doesn't mean we can't tinker with our bikes as well...
I will let you know if I find anyone who is after a bike like that, because
that one you have looks really fine.
How much $, or haven't you decided yet?

sbutler · Post by **sbutler** » Fri Dec 26, 2008 6:33 pm

hotcam wrote:I've always thought that best improvement in lap times per dollar comes
from spending dollars on the rider, not the bike.
I will let you know if I find anyone who is after a bike like that, because
that one you have looks really fine.
How much $, or haven't you decided yet?

Well the rider is the limiting fator in this case!!

I think its worth about $4800 Australian, or there abouts..
There are about half a dozen on bikesales, they start at $4000 & go to $6500. So I dont think thats an unrealistic figure, concidering the condition.