Topic: Sportbike Front On CB500 Help

[stealthy]

I hate to post questions, but trust me, I have done much research and cant really find any clear, definitive answers to my questions. So, anyone that has experience or the knowledge, please please chime in. I have a 73 CB500. The front fork seals are bad, and need to replace. However, this winter I plan to strip the bike down, hard tail it, and run a 21" wire wheel up front, 16" or 18" 5.5" wide wire wheel on the back. I would like to do a sportbike front end, but cant seem to find what will work, or what I need to do in order to complete this task. Any insight is much appreciated, thanks in advance!


Anyway, here she is. Just got her a few days ago, and is all stock basically.

[GoatBaSS]

Home page has a Faq section page 9? has a list of fork sizes. I would start there.

[fevah]

Hit this guy up, hes got GSXR 600 forks on a CB350 i think
http://dotheton.com/index.php?topic=6710.0

[Beans]

Funnyjimmy did the conversion you can look for his build thread.   

[CrashBar]

http://forums.sohc4.net/index.php?topic=27159.0

[Geeto67]

if you are going to a 21" wheel, Why not go get a modern dirt bike front end? All the modern dirt bikes have upside down forks and 21" wheels with some pretty trick looking brake setups. It seems it would be easier to get the triple trees to work with a cb neck than trying to figure out what forks work with what brakes work with what wheels. If it were me I woud get a set of cb500 trees and a cr250 set of trees and figure out a way to make the stem from one fit another - usually this requires a fair amount of machine work and welding.

I think a cr250 front end would look hawt. I mean this is all for looks anyway right there is no real advantge I can see otherwise to what you are doing.

BTW, you didn't happen to ask this same exact question on caferacer.net recently (under the name Kent)?

[Flying J]

http://forums.sohc4.net/index.php?topic=34836.0

[stealthy]

Thanks guys, I'm on it....hopefully find what I'm looking for.

No, I didnt post this on cafe race, nor am I "kent"

[HavocTurbo]

I'll agree. Easiest way I have found is to find a front end and remove the stem. Then either find a way to mount yours in the new trees... or have a machine shop make one that fits both the bike and the trees.

By far the easiest way of doing a full custom job. All you need is a lathe.

I've done several over the years for both cruisers and sport bikes. After you do a few it's pretty easy to look at and figure out what's needed.

if you are going to a 21" wheel, Why not go get a modern dirt bike front end? All the modern dirt bikes have upside down forks and 21" wheels with some pretty trick looking brake setups. It seems it would be easier to get the triple trees to work with a cb neck than trying to figure out what forks work with what brakes work with what wheels. If it were me I woud get a set of cb500 trees and a cr250 set of trees and figure out a way to make the stem from one fit another - usually this requires a fair amount of machine work and welding.

I think a cr250 front end would look hawt. I mean this is all for looks anyway right there is no real advantge I can see otherwise to what you are doing.

BTW, you didn't happen to ask this same exact question on caferacer.net recently (under the name Kent)?

[Beans]

Can't a cb750 tripple fit a 500?  If so theirs a guy on the forum who mounted a set of cb900 forks to a cb750 tripple.  It can be done its just some fab work and time.  But acr250 fork would look sick but might be to long enless u shorten them because I know my cr250 forks on my 02 are pretty long.

[Flying J]

there is no direct swap for these bikes. Just find a front end you like and go to work figuring out what to do to make it work. All the front end swaps i have seen needed fabrication. usually you need to build a custom triple tree stem from what i have seen. Why do you want a sport bike front end on a hard tail? Why not get some harley forks and put them on. i know people make springers fit all the time.  Anyway thats what i got, still curious as to why you want the sporty forks?

[stealthy]

you guys are bringing up a new concern to me....the inverted front and 21" wire wheel...

granted i dont know much about this stuff, but is this feasable? the reason for the swap is cosmetic, i dont care about the brakes or that kind of thing. i just like the clean look of the inverted forks. what do you think

[HavocTurbo]

No problems other than different sizes for different applications.

Same as with any fork.

[bigsherm]

I fit a CBR954 front end on my '78 CB750K.  The CBR stem was the same diameter as the CB750, but not long enough!  I was about to get the CBR stem lengthened, until I found another member who was abandoning his front end swap and already had the stem made.

I used 18 inch rims from Buchanan's on the stock hubs.  3.5" front, 5.5" rear.  I had adapters made to fit the huge CBR954 rotors on the stock front hub.  The CBR front axle was so much bigger than the CB750 that the bearings had to be very small to fit the CB hub on the CBR axle, so I used two bearings on each side of the front hub, for a total of four front bearings.  Works great.  The front end swap was completely worth it; the brakes are awesome.

I have a 180 tire on the back and it barely fits in the stock swingarm with a little grinding.  I made my own offset sprockets by ordering 630 sprockets and removing material from the inboard side with a grinder.  The chain clears the tire by the smallest possible margin, and I used a non-o-ring motocross chain so it would be as thin as possible.

Sorry for the crappy cell phone pic.

Sherm

[stealthy]

Man, thanks everyone....This is my first bike and I think this front end swap is just too much for me. Maybe on the next bike, but I think I'll just rebuild my stock front end and just go with that...

[Toxic]

Wise move, some of the guys posting on this forum have incredible skill and talent.

Sometimes they can make anything seem easy. 

[Flying J]

if you want that chopper front end you can always find some longer forks tubes

[Retro Rocket]

I have a Gsxr 1100K model front end and the steering stems were the same diameter as the Honda one, so it was a straight press the suzuki one out and replace it with the honda one....very easy conversion.


Mick

[stealthy]

ffjmoore - i dont want longer forks, in fact i dont want/care the brakes, just the inverted forks


retro rocket - what bike do you have? cb750? probably different from my cb500....and when you said "it was a straight press in/out" what do you mean?

[Beans]

retro rocket - what bike do you have? cb750? probably different from my cb500....and when you said "it was a straight press in/out" what do you mean?

I think he is talking about the steering stem.  Ive seen some like the busa forks you press the busa forks out and out ur cb forks in.

[Retro Rocket]

ffjmoore - i dont want longer forks, in fact i dont want/care the brakes, just the inverted forks


retro rocket - what bike do you have? cb750? probably different from my cb500....and when you said "it was a straight press in/out" what do you mean?

Sorry i should have said it was a 750 but that shouldn't matter as it wouldn't be too hard to get a 750 stem if they are different. I meant you press the steering stem out of your 750 triple clamps and have it pressed into the 1100 front end....simple.

Mick

[HavocTurbo]

Arent the CB500 Stems welded in to the lower trees? I know my old 750 one was.

A front end swap isn't all that hard. Just takes careful measurements and time. Well money helps too lol.

First things first.... those of us who have done it (I do it quite often for customers) can walk you through it.

No better time than now to get your bike how you want it.

[stealthy]

retro rocket - so you are saying i need the gsxr1100 specifically, or are there other options i can search for? and when you did your swap, thats literally all you did, swap the steering stems and thats it?


beans - busa front is the same way as the gsxr1100 that retro rocket mentioned?


havocturbo - if they are in fact welded, how big of a problem is that? you are right, i should build the bike how i want it. i just dont want to bite off more than i can chew, nor do i want to spend a ton of money on it right now. if the gsxr1100 front is pretty much just swapping out the stems (which i still dont even know what they are--looked for a diagram but no luck), then thats what i'll look for. but if i have to go to a shop for more extensive work to be done then i am going to have to unfortunately pass.


thank you everyone for the help so far. when looking for parts, what exactly do i need to look for, just the forks, triple trees and steering stems? if thats all, at that point, what will i need to do as far as brakes and a wheel/hub? thanks for being patient with me and helping out a new (but learning) enthusiast!

[HavocTurbo]

Since you want an inverted front with a 21" wire wheel my suggestion would be to get a dirt bike style front end.

Seriously long forks and they fit a 21 front easily.

No way will my GSXR750 fit a 21" wheel. Even in stock form.

First things first.... find a front end that you WANT. Looks and all that are great but it has to have a 21 front right? So start there. What bikes carry inverted forks with 21 wheels?

Most likely an enduro of some sort or a full out dirt bike. Maybe an older YZ250? 2-stroke version?

Once you find the forks and triple tree you like you have the stem pressed out of the lower tree.

That part looks like this.... with no forks in it. (Sorry cant do pics now at work)

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Then you take the measurements from your EXISTING stem from your 500. Again... found in the same place in the neck.

Then go to a machine or fabrication shop with a good lathe operator. Tell them you need a new stem machined with the mounting dimensions of the new front end.... but the overall dimensions of the 500 stem.

Presto change-o they cut a new stem on the lathe and you are done. All you need to do is press the new stem in the NEW lower triple clamp.

You can use the original 500 bearings (should probably upgrade to tapered bearings at this point anyway) on your new stem. No custom bearings needed.

So now with you new striple trees and forks.... anything that applies to your new front end (in this case a YZ250) can be bolted on (I.E. 21" wheel and brakes, etc.) without too much trouble.

[Retro Rocket]

retro rocket - so you are saying i need the gsxr1100 specifically, or are there other options i can search for? and when you did your swap, thats literally all you did, swap the steering stems and thats it?

There are many front ends that you can match, i am going to use 90 CBR front on my "F" model. There are heaps of guys on here that have used different fronts, Kawasaki, Honda , Suzuki. Yes, my front end swap was that easy although i had a guy that specialises in modding bikes do it for me.

Mick