'71 CB450 Front end Upgrade to EX250 ?'s

Chris L.

Active Member
I have seen several threads and posts about guys upgrading their cb450's to Ninja EX 250 front ends. I am currently working on a hard tail 71 CB450( YOu can see my build here http://www.dotheton.com/forum/index.php?topic=40854.0) I asked the question there as well, I figured I would ask here as it seems to be a better place for the question. If its not ok to have this thread, please delete it.

I know that both front axles of the EX and the CB are the same size. My question is what needs to be done with the wheel bearings if anything? Can anyone shed some light on this process? I know I can get the bearings for the neck but I am just unsure about the front axle as I want to use the original wire spoked '71 CB wheel. I wanted to make sure I have the process down before I shelled out the 200.00 for a complete front end.

Any help or insight is greatly appreciated.

Thanks

Chris
 
The Ninja EX250 axle came in today. It fits perfect into the front wheel. It looks like the only mods I will need are some wheel spacers to line it up on the EX axle as the EX axle is longer than the CB450 original axle. THe EX axle is smooth and doesn't seem to have any steps in it. I am guessing it will just the same bearings as the CB axle did? Thoughts?

I guess I will pull the trigger and get a EX front end.... wish me luck!!!!

Here is a pic of them side by side.

CB450 is on the left EX250 on the right

IMG_0905.jpg
 
Same bearings / axle size makes things a fair bit easier.

Still, you are going to need custom spacers to centre the CB wheel inside the EX forks (judging from the longer axle the EX front looks wider than the CB), and probably a mounting bracket / adaptor for the caliper.

Not sure if you're going to run a front fender, but it will have to be custom as well. And the steering stops may need to be fabbed up to suit.

Other than that, piece of cake ;)
 
Hmm...thanks for being the guinea pig. I have a cb450 and was wondering about fork swaps. Im subscribing to this one! Looks like its guna be fairly straighforward. How's the steering stem guna work out?
 
hillsy said:
Same bearings / axle size makes things a fair bit easier.

Still, you are going to need custom spacers to centre the CB wheel inside the EX forks (judging from the longer axle the EX front looks wider than the CB), and probably a mounting bracket / adaptor for the caliper.

Not sure if you're going to run a front fender, but it will have to be custom as well. And the steering stops may need to be fabbed up to suit.

Other than that, piece of cake ;)

Thank you for the reply, I was wondering if anyone was into this thread.

I was going to use the ex calipers and the a new disc. I had read that most disks will bolts up to the CB hub after you remove the rivets?? We shall see

What is the best metal to make the spacers out of, I was think aluminum, would be good? I don't have a great lathe to do one, is there a good source for someone to make em?

No front fender, but I may toy around with one if I think it looks better....


teddpage said:
Hmm...thanks for being the guinea pig. I have a cb450 and was wondering about fork swaps. Im subscribing to this one! Looks like its guna be fairly straighforward. How's the steering stem guna work out?

Thanks, I hope it works out ok, from what I read it seems to be a easy swap but there isn't a step by step, I will document the entire process hopeful this well help you and others with not making those costly mistakes?

It seems that the stems are very close. The EX may be a touch taller, so I may have to use a spacer there as well.

I hope your CB450 build is going well. I will take a look at your thread.

Thanks for the feed back and replies.
 
As for spacers, im sure you could have a machine shop turn you some for pretty cheap.
As for no front fender, you will want to run something up front, either a fender bracket or fork brace. Running no brace/bracket on the forks can cause some funky handling if one fork tube moves a little different from the other.
 
Chris L. said:
I had read that most disks will bolts up to the CB hub after you remove the rivets??

Whoa - no way. There's a gazillion different sized discs / mounting holes / carrier ID's / offsets between each brand / model of bike, so that's simply not correct.

There probably is a combination of disc and caliper that will work on a CB wheel in EX forks, but I don't know what that is.
 
teddpage said:
Hmm...thanks for being the guinea pig. I have a cb450 and was wondering about fork swaps. Im subscribing to this one! Looks like its guna be fairly straighforward. How's the steering stem guna work out?

I would do Katana 600/750 forks, 41mm
Ninja 250 has a real ugly top yoke and steering stem is completely different top to Honda (I got some 250 Ninja forks for 360)
 
Sorry for being so vague about the disc that will work, I have read that a 320mm front disc will work...

What bikes ran 320 mm discs? Does the EX250 run a 320mm?

One of my concerns is making the bracket for the caliper. I do not have the means to fab one. Not sure if all this work is worth it for a hard tail? If I was going to use the EX250 rim I would be a lot better off but the look would not be that great for this hard tail??? I really want to use the stock spoke rim
 
EX front disc is 260mm diameter, so you won't be able to slot a 320mm disc onto an EX caliper and fork without an adapter to space the caliper out.

You are pretty much in custom build territory with this. If I were you I'd use your existing CB disc and get an adapter made up to space the EX caliper to suit it (or any 2 piston caliper really).

Although, there are better front ends to use with neater top clamps (like PJ has suggested).
 
hillsy said:
EX front disc is 260mm diameter, so you won't be able to slot a 320mm disc onto an EX caliper and fork without an adapter to space the caliper out.

You are pretty much in custom build territory with this. If I were you I'd use your existing CB disc and get an adapter made up to space the EX caliper to suit it (or any 2 piston caliper really).

Although, there are better front ends to use with neater top clamps (like PJ has suggested).

Great points!!! Hmm, I wonder if the ex250 disc would match up? Does anyone have one they can look at?

I am all about other front ends, hell I just want something that works. I need to see what size the front axles are on the front ends PJ recommended as I want to use the cb450 wheel. That is why I went with the EX250

Sigh, man its so hard when you don't have a ton of parts at your disposal to check fit and try something else. :mad:
 
I wanted to add I know the ex250 won't bolt right up but it has been done by taking out the rivets on the CB450 disc and the rotor will mount to those holes? Can anyone verify this?
 
This is an EX disc:

DBFSGPX688_dim.jpg


OK - it's an aftermarket wave pattern, but the important thing is that it is a one piece unit that solid mounts to the EX wheel spokes (or outer hub). Your CB disc has a carrier that bolts to the hub. Whether you can take the rivets out of your CB disc and mount this....I don't know.
 
Just had a look at your build thread - looks like your CB disc carrier has about 10 rivets as opposed to 6 bolts on the EX so it ain't gonna work.
 
I did it with a 95 EX500 front end and a honda wheel off of a CB360 (on my CL350). In an amazing stroke of luck the holes lined right up with the rivets ob the carrier. In fact, the only odd thing I had to piece together were the proper steering stem bearings. Other then that I used the EX500 top and bottom yokes, axle, and speed drive. It worked out great. I skipped the fender and got a fork brace for it.
 
Ah, should add that I also had to get the EX500 speedo drive boss and swap it for the Honda one that came on the wheel.
 
Chris L. said:
One of my concerns is making the bracket for the caliper. I do not have the means to fab one.

If you have a hacksaw, files and a power drill, you have the means to make brackets.
A vice is handy but you can use a woodworking clamp or a vice grips to hold plate
I made caliper brackets from 5/8" alloy plate for my XS650 with minimal equipment, used a 3" flap wheel to smooth everything out The hole in plate was there when I bought it
KatanaBrakesonXS650Right.jpg
 
djelliott said:
I did it with a 95 EX500 front end and a honda wheel off of a CB360 (on my CL350). In an amazing stroke of luck the holes lined right up with the rivets ob the carrier. In fact, the only odd thing I had to piece together were the proper steering stem bearings. Other then that I used the EX500 top and bottom yokes, axle, and speed drive. It worked out great. I skipped the fender and got a fork brace for it.

djelliott said:
Ah, should add that I also had to get the EX500 speedo drive boss and swap it for the Honda one that came on the wheel.

Dj thank you so much for positing on my thread. Your thread is the reason I was trying to tackle this upgrade. I have read and read your thread and watched your video over and over. I think I will go ahead and give it a shot. I was hoping you would stop in to share your experiences. I know it can be done, I just need to stop being a pussy and go for it.

You used the EX brake bracket right? I see that the speedo drive helped you line it all up? How did you make your spacers for the wheel to line up on the other side?

Thanks again for stoping by. I really appreciate your help
 
crazypj said:
If you have a hacksaw, files and a power drill, you have the means to make brackets.
A vice is handy but you can use a woodworking clamp or a vice grips to hold plate
I made caliper brackets from 5/8" alloy plate for my XS650 with minimal equipment, used a 3" flap wheel to smooth everything out The hole in plate was there when I bought it

PJ,

Thanks for positing that. I have a full tool shop just no mill :mad:, I've always wanted a mill I need to get one, oh well one day. .. Its great to see that it can be done with what I have. I may be picking your brain once I get there if you don't mind? Thanks again for all of the help

Chris
 
hillsy said:
This is an EX disc:

DBFSGPX688_dim.jpg


OK - it's an aftermarket wave pattern, but the important thing is that it is a one piece unit that solid mounts to the EX wheel spokes (or outer hub). Your CB disc has a carrier that bolts to the hub. Whether you can take the rivets out of your CB disc and mount this....I don't know.

Thanks for the picture as a reference Hill! I think it will mate up, I just need to get one in and see. They are not that expensive, I will get one off ebay tonight and let you guys know..
So far I know the axle will work, lets see if the disc will???
 
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