FXR front end upgrade

**Buddha#81:Me** · 10th January 2009, 09:15

Ive already converteted the rear to GSX250 so the next project was to further improve handling. I've been (along with most MotoFXR owners) keeping an eye out for a GSXR/GSX250 front ends. Well one snuck under the Trademe radar and its out of a 250 Katana which after my reserch is the same. The big gain is from 33mm - 38mm forks, wider front wheel (slicks run better profile) and bigger brakes (not that the MotoFXR's has any issues there)

Now reports are that they bolt staight in, no mods nothing. We'll see and I've manage to score the complete front end including brakes, bars and the front wheel. If its as easy as reports its only going to take 20 minutes or so I'll be changing the oil to 20wt and using the exsisting braded brake line.

Anyone need a complete FXR front end. Forks (new seals and 20wt oil), caliper, master cyl, tripple clamps and stem, clip ons and wheel (slight ding, never bothered me in 3 seasons of racing) $250ish plus freight.

**F5 Dave** · 12th January 2009, 10:06

What? No radial callipers?

**Pumba** · 12th January 2009, 11:40

Is the photo the FXR or Katana front end? (im pretty sure its still the FXR but my eyes could be deciving me)

and what size frount wheel do they run out of curiosity?

**Buddha#81:Me** · 12th January 2009, 12:59

Originally Posted by Pumba

Is the photo the FXR or Katana front end? (im pretty sure its still the FXR but my eyes could be deciving me)

and what size frount wheel do they run out of curiosity?

That still the FXR front end (for sale). The Kat front end turned up today and its a 3" wide wheel, this may be an oversight, but free for tyres.

**Pumba** · 12th January 2009, 14:25

Yea, thought the front was a 3.00 not a 2.50

**F5 Dave** · 12th January 2009, 14:34

So to run 125 type tyres you can get away with a 2.15 frnt & a 3.00 rear but ideally 2.5 frnt & 3.5" rear.

A 3" front would be 'a bit out there'.

**Sully60** · 12th January 2009, 14:52

Originally Posted by F5 Dave

So to run 125 type tyres you can get away with a 2.15 frnt & a 3.00 rear but ideally 2.5 frnt & 3.5" rear.

A 3" front would be 'a bit out there'.

2.15 fronts are the way to go. 2.5's make the 90 width slick look like a rear tyre profile i.e. too 'flat' across the crown.

Yeah. I've run a three before and the ideal size is a 110/70-17 which limits you to running road legal race tyres like Super Corsa's or Racetecs (if that size is actually available here, check with Forbes & Davies) Still fuggen heaps of grip but hard to find second hand in any usable condition and new they virtually cost the same as a 120/70 anyway.

I ran a 120/70-17 Superbike slick on the front of the 'Sled before the skinny wheel conversion and grip and steering wise it was ok but that was with a 4" rim with a 125/70-17 on the back. Me suspects you could end up with funny handling characteristics with skinny rears and wider fronts.

**F5 Dave** · 12th January 2009, 16:30

Yeah hard to know with slicks, but Dunlops are quite triangular. They come in 90 & 95 sizes. My fronts on 2.15" don't go to the edge, maybe I don't lean very far. Think I've used both 90 & 95.
Old RS - '91 etc used a 2.15". Newer RS use a 2.5" so running 95s should be sweet.

**Buddha#81:Me** · 12th January 2009, 17:52

Originally Posted by Sully60

I ran a 120/70-17 Superbike slick on the front of the 'Sled before the skinny wheel conversion and grip and steering wise it was ok but that was with a 4" rim with a 125/70-17 on the back. Me suspects you could end up with funny handling characteristics with skinny rears and wider fronts.

I've done the 3" conversion to the rear, how would 125 rear and 115 fronts go?

**Sully60** · 12th January 2009, 18:41

Originally Posted by Buddha#81

I've done the 3" conversion to the rear, how would 125 rear and 115 fronts go?

Are the 115 fronts Bridgestone or Yoki front slicks? If so, you could be ok. It's really a suck it and see thing bacause all sizes on the tyres are nominal and one brands 115 is could be wider or flatter on the rim than the others 125.

**Buddha#81:Me** · 13th January 2009, 16:41

Originally Posted by Sully60

Are the 115 fronts Bridgestone or Yoki front slicks? If so, you could be ok. It's really a suck it and see thing bacause all sizes on the tyres are nominal and one brands 115 is could be wider or flatter on the rim than the others 125.

3" rims front and rear with 115 front and 125 rear both dunlop......be ok?

**F5 Dave** · 13th January 2009, 16:43

I wouldn't run the 125 on the rear with only 3", but could try it & see what it looks like.

**Buddha#81:Me** · 13th January 2009, 16:56

Originally Posted by F5 Dave

I wouldn't run the 125 on the rear with only 3", but could try it & see what it looks like.

looks ok on this http://www.dropbears.com/u/utilities/tyrerim.htm . Plenty of free 120's around?

**Sully60** · 13th January 2009, 17:03

Originally Posted by Buddha#81

looks ok on this http://www.dropbears.com/u/utilities/tyrerim.htm . Plenty of free 120's around?

That list seems to be for crossply's based on the sizes I saw. Radials run more vertical sidewalls than crossies so need wider rims.

I'd give the tyres you have a go and see what happens, I imagine you'd end up with a flat looking front and a pointy rear. Have you consisdered running the same size tyre at both ends?