CB450 Tracker


Been Around the Block
Long time lurker, first time poster...

Picked up a CB450 from a mate for free with the idea of turning it into a street tracker. I built an RD350 racer last year that turned out OK, so this is being built for my brother. His only request was that it be fitted with pillion footrests and a long enough seat to fit his girlfriend's behind on behind...


It was pretty weathered externally, but turned over freely with good compression.


The outer covers were a bit knocked around so we found another CB450 on Gumtree for $210 that was incomplete and had been seized at some stage. The frame was in good condition so we decided to use that and keep the other one complete for the mock-up stage.

I had a set of YZ250 Excel hubs that I bought for my race bike years ago, so they have been donated to the project. I ordered 19"x2.75" Sun rims and S/S spoke from Buchanan's and laced them onto the hubs...



..and fitted them up with some DOT approved Shinko flat track tyres.


I started the frame mods by pulling the steering head back a couple of degrees to 25 to give it a tracker stance.


Obviously the bigger diameter wheels and pulling the steering head back has affected the trail and the wheelbase, so I plotted it out on AutoCAD to work out the new values for swinging arm length and fork offset. I made a new square section swinging arm that will bring the wheelbase to 55"-56". It still needs to be gusseted at the front and the shock mounts installed but it is OK for the mock-up.


I also made all the hardware for the back wheel adjusters but still have to make an axle for it.


I ordered a big hunk of 6160 aluminium that arrived a couple of days ago so I will start making the triple trees tomorrow night.

Please excuse the photo's, they are a mix of camera and phone and I have had a hell of a time trying to post them on here, so I will try and correct that for any future shots.


Been Around the Block
Made some progress today. I finished making the back axle out of 4140, but still need to mill a couple of flats on the end for the wrench. I have a really old indexing head that weighs a ton, so I'll wait until I have a few jobs to do before I wrestle it up onto the mill bed.


Started boring the holes for the triple trees on the mill,


got them to size and then cut the bar in half (which turned out to be a big job), and tried them for size - all good. I'll set them back up in the mill and finish the thickness, profile, slots and retaining screw holes.


I'm using the original CB450 stem with All Balls tapered roller races, just have to make a threaded insert and weld it in the top as I will make a S/S bolt instead of using the existing chrome nut. I'm giving it 0.0015" of interference so that it fits up nice and tight with the aid of my press and judicious application of heat.

After looking for a long time I picked up a perfect set of R6 forks from eBay for $150, pretty happy about that. They came with an axle which I will be able to modify to suit the YZ wheel.

I'm still trying to decide whether to use an R6 or YZ caliper on the front. The rear will be YZ and in the interests of uniformity, I will probably use the YZ one. Either way I have to make up fork or disc adaptors, so that's not really a deciding factor. The bike will be considerably lighter than it was from the factory, and I don't plan on doing anything to the motor aside from a rebuild, Mikuni carbs and a free flowing exhaust, so it shouldn't be too hard to pull up. I'd appreciate any thoughts on why I should pick one over the other.


Coast to Coast
Make an adapter for a 320mm rotor and use the r6 caliper. Reasoning: supermoto guys upgrade to a larger rotor and 4 pot calipers to improve brake feel and fade. Although if you already have the yz caliper it would do fine, just might not "feel" as good, which is subjective.


Been Around the Block
Rat_ranger said:
Make an adapter for a 320mm rotor and use the r6 caliper. Reasoning: supermoto guys upgrade to a larger rotor and 4 pot calipers to improve brake feel and fade. Although if you already have the yz caliper it would do fine, just might not "feel" as good, which is subjective.

Good advice, thank you.


Been Around the Block
Thanks Guys...

Got the triples profiled finally. I ended up with 55mm of offset which equates to around 95mm of trail when it's all assembled, which should be pretty good I think.

This is the lower one and the two holes in the bottom are for the steering stops which will just be a couple of cap screws that will locate against the existing frame lug.


This is the upper one and the two holes in it are for the handlebar clamps. I am going to use Maico rubbers on the clamps to try and reduce the vibration that these CB450's are rumoured to have...


The forks assembled to check the fit. The steering stem will get pressed in and then I can install them and get on with making the handlebar clamps.


I bought an Acewell tacho from Dime City Cycles (what a great bunch of guys to deal with there) so I'll make up a mounting bracket for it once the handlebar clamps are finished - it will attach to the front of the top tree


Apologies again for the varying size and quality of the photos - not too sure what's going on there but I'll try and get some uniformity with them (I hope)...


Been Around the Block
Well, spent the whole day in the shed today as it was drizzling outside. Good way to spend a Saturday in my book.
I got the handlebar clamps and the tacho bracket all finished. Both fiddly jobs but turned out OK I think.





Starting to look almost like a bike now.


The next thing will be to get the bottom end of the engine in so I can set the back wheel spacing to get the chain line right. Once that's done I can offset the rim if it needs it and then make a rear caliper bracket. I bought some Cannondale calipers at Mid Ohio a few years ago for $5 each, so I'll probably fit one of them up. I bought a WR250 rear brake complete but the caliper is a bit ratty so I'll probably just end up using the master cylinder and brake pedal linkage. All good fun....


Been Around the Block
Made some new aluminium rear footrest brackets to replace the pressed steel ones that are standard.
Cut the old ones off and cleaned up the welds.
Made up some little brackets and tacked them in place on the frame

Started going through all the parts to see what else I needed and out of the three alternator covers I have there is not a single good one. All of them have gear lever scrapes on them - I honestly don't know what is wrong with someone that doesn't notice (or care) about the gear lever gouging the cover.
In fear of buying another one with the same problem I made a new one out of some spare alloy plate I had laying around. It was only 10mm thick so I made a removable outer cover which fixed the width problem and also allows the timing marks to be accessed without removing the whole cover. Removing the whole cover with the bike on the sidestand usually results in oil dripping out, so I won't have that problem any more. One advantage of it being thinner is less chance of the gear lever going anywhere near it lol..

Making a rod for my own back with all these alloy bits and pieces that will all require a lot of rubbing, buffing and polishing ::)


Been Around the Block
1fasgsxr said:
Closest I could find to a WOW !

Haha, thanks.

Made some alloy front and rear engine plates and roughly bolted the bottom half of the engine in to sort out the chain alignment.
I had an old sprocket and chain laying around so I fitted them up. With the chain lined up and the left hand spacer in place the wheel is offset around 8mm to the right hand side so I just adjusted the spokes and pulled it over into the centre, so all good now. I don't think it will be an issue but I will pull the tyre off and make sure that there are no spoke ends poking out through the nipples.
I'm having trouble sourcing a 520 16T countershaft sprocket for this motor. XL500 sprockets are very close but the spline minor diameter is 22mm as opposed to the CB450's 21mm. Not sure it would be a problem but I would like to get the correct fitting one. Anyone have any experience with this?


New Member
Thats one helluva lucky brother!!! If the intitial work is anything to go buy it will be an absolute weapon when finished....


Been Around the Block
JB56 said:
Thats one helluva lucky brother!!! If the intitial work is anything to go buy it will be an absolute weapon when finished....

Oh, don't you worry, he'll pay.. :)


Over 1,000 Posts
I had my 520 sprockets made at Rebel Gears. I don't know if you are in the states, but if so I would give them a try.


Been Around the Block
1fasgsxr said:
I had my 520 sprockets made at Rebel Gears. I don't know if you are in the states, but if so I would give them a try.

Thanks for the tip. I'm in Australia but heading to NC soon for work so I'll follow that up.

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