gs450 shim under bucket conversion

[herbie 1964]

  Hi guys, I'm going to race a 450,fitted with 500 pistons in a aircolled 500 class in uk. On researching cams its been siad that if you fit race cams you need to do a shim under bucket conversion, has anyone done this? & if so what buckets/shims were used, any info greatly received!!
also has anyone put a gs500 front end in a 450 frame? do the yokes go staright in?? would be nice!!

cheers Mark.

[burning1]

I haven't done the conversion, but I have researched it. You'll need to buy the shim-under buckets, the shim-under valve spring retainers, and obviously, the shims. Kibblewhite & Ape Race Parts sell the retainers. Kibblewhite, Ape, and MTC sell buckets (MTC advertises their buckets as being for the 1100, but the 1100 doesn't use buckets. I'm pretty certain it's a typo.)

You can buy low lift cams that can use the stock shim over buckets, but I'd probably go the full race route. Install the buckets, retainers, shims, race springs, and race cams. Dyno the engine, set the rev limit to whatever makes sense based on the dyno results.

[burning1]

I don't know if the front ends are compatible, BTW. Would start by comparing part numbers for the steering stems, axles, etc... to see if the parts are similar/the same. If the class allows unlimited suspension mods, I'd suggest doing a full front end conversion; $$ spent on suspension tend to pay off better than $$ spent on engine.

[herbie 1964]

class allows mods that "look" period ( pre 81) so has to have right way up forks 37mm max, 2 psiton calpiers, just about get away with floating discs!!
Idea is to put 500 yokes into 450 frame, use 500 forks spindle/caliper disc, but fit onto wire wheel!!
just need to know how easy the yokes go into frame,as the rest is do -able!!

cheers Mark.

[Rhoekahr]

I don't know if the front ends are compatible, BTW. Would start by comparing part numbers for the steering stems, axles, etc... to see if the parts are similar/the same. If the class allows unlimited suspension mods, I'd suggest doing a full front end conversion; $$ spent on suspension tend to pay off better than $$ spent on engine.

I have a GS450 that I've made into a cafe racer. When I started the build, I had a 91 GS500 sitting next to. I started eyeballing it and thinking about what I could take off. It should fit. I remember looking into the parts on bike bandit and comparing. If memory serves, it works.

I imagine you have a set of GS500 forks, but what I wanted to do was but a set from a GS550M. Twin discs, anti-dive, and a stouter tube. The thing I liked about that option was that it didn't change the front tire size.

By the way, what wheels were you thinking of using? I've always wondered what the adverse side effects would be if you used a smaller tire diameter for the bike's geometry.

[wera90ex]

Hi guys, I'm going to race a 450,fitted with 500 pistons in a aircolled 500 class in uk. On researching cams its been siad that if you fit race cams you need to do a shim under bucket conversion, has anyone done this? & if so what buckets/shims were used, any info greatly received!!
also has anyone put a gs500 front end in a 450 frame? do the yokes go staright in?? would be nice!!

cheers Mark.

Hey Herbie, Sorry for the slow response, I don't get on here that much. Been racing a 450 for some time,25 yrs, and have done the race cam thing. If your using more than a .400" lift cam you have to use shim under. Anything under .400" lift you should be OK with shim over. Don't forget to degree the cams. Put cam lobe centers at 107 degrees.
   Also, a bolt-on is a GR 650 head. Use the 500 head and base gasket. You can use the 650 cams too. Just replace the 650 cam sprockets with the 450 sprockets.
   The 500 front end won't bolt on with the 500 steering stem.  It's easier to use a 89 GSXR750 front end. 3-way adjustable much nicer front end. Haven't tried it yet but I think an SV 1st gen front end might work too. RG

[wera90ex]

 One more thing, Not sure what carbs came on a UK 450 but  the early US ones were terrible. I used GS 500 carb's til I got my 37mm Kiehin cr specials. Big difference!

[werase643]

88-89 gsxr forks are 43mm....so no on them  SV are 41mm

[wera90ex]

88-89 gsxr forks are 43mm....so no on them  SV are 41mm

SE, Don't know what you mean?

[werase643]

class allows mods that "look" period ( pre 81) so has to have right way up forks 37mm max, 2 psiton calpiers, just about get away with floating discs!!