90's CB500 build


Been Around the Block
Not making a lot of progress as another build keeps on getting in the way.....

013 (2).JPG

But was lucky enough to come across an Africa twin hub on ebay....a rare item nowadays! It does mean I can have a twin disc spoked front wheel though and, as far as I can judge there'll be no clearance issues with the calipers. It was an easy fit as well....spindle size the same as Suzuki....a couple of spacers and its bang in the middle!

009 (2).JPG

Not so much stopping power at the rear though....a Transalp hub....using it mainly because I had one lying around feeling lonely....and because it looks the tiniest bit like a Manx hub! Had to make up a stop for the brake plate and a spacer but again an easy fit.....and chain line is dead on too....

006 (2).JPG



Been Around the Block
Finally came across a reasonably priced donor bike on ebay which should provide pretty much all the bits I need....

s-l1600 (23).jpg

Its a decent runner but one unwelcome surprise.....

011 (2).JPG

You often see that broken lug on CB500's.....usually caused by the bolt seizing in place and then people trying to hammer it out.... this one though caused, I suspect, by engine bars being mounted to it and coming off?
Not to worry....the motor will be getting a rebuild anyway so it can welded when its all apart!
So, onto the frame in the next few days.....this pic of a Paton is fairly close to what I have in mind....



Been Around the Block
So, onto the frame.....basically my plan is to make it in sections and then assemble them on the jig later
In the pic above you can see how they've used short lengths of tube at the top front and lower rear engine mounts, much like a Ducati frame....something I'll be copying.
In the past I've found its best to use longer than necessary bits of tube and only cut back to correct length after final welding....otherwise the weld tends to 'bite' into the edge and leave it looking a bit untidy.
The frame itself is going to be in 16g tubing but for these joints have decided on 10g.....

022 (2).JPG

It can be a bit tricky to weld the washer centrally to the tube so I screw them down to a piece of wood first....

023 (2).JPG


Been Around the Block
So, onto the first section....front downtubes.....

001 (3).JPG

I've spaced them out by 8mm either side to give enough clearance to fit the exhaust pipes....I hope
Next job is to cut the tubes where they attach to the headstock, any gaps that need filling with weld means distortion....something you don't want especially there!
So, I find a bit of tube with the same id as the headstock od...though here I had to slit it and widen it....then carefully tack it in place over the tubes, being careful to get it square and at the correct angle....


Then run a holesaw down inside the tube....with lots of lube!

004 (3).JPG

Which, if everything is set up right gives a really good fit....thats just a spare bit of tube for checking btw....not a really long headstock!

008 (3).JPG


Been Around the Block
With nothing better to do tonight I've been trying to add in links to other builds I've done here.....how do you do it properly please??


Been Around the Block
Next, on with the main top section of the frame....I know it looks like a bit of a concertina but will be addressing that later.....the idea is to make sure carbs, head etc are all easily accessible with the engine in the frame

014 (3).JPG

And then the first 2 sections assembled into the jig....and btw the reason they seem to be multiplying is that I always make a trial piece in cheap erw tube and then when I'm sure its right make a copy in proper stuff!

009 (3).JPG

And last job today....a trial fit to the motor!

012 (3).JPG


Been Around the Block
Oh....and a bit I forgot to mention.....adjustable lock stops....the strip and bolts there so I can clamp them in place before welding

004 (4).JPG


Been Around the Block
Next job is to add the diagonals that run from the lower rear engine mount back up to the top shock brackets....

014 (4).JPG

016 (2).JPG

That finishes getting all the main mounting points on the frame finished.....leaving just bracing tubes....and mounts for stuff like rad, coils, airbox etc

001 (5).JPG

So, out of the jig and see if everything fits together!

002 (3).JPG

Which it does....surprisingly! A couple of small problems....nothing too major and a stroke of luck with the carbs.....2mm clearance to the tps....
Swingarm mounts are just tacked in but the triangle where they sit will eventually be plated in both sides.

004 (5).JPG


Been Around the Block
Getting close with the frame now....a couple of detail pics....

002 (4).JPG

004 (6).JPG

005 (4).JPG

And a try out with some bodywork on.....and on its wheels. I got talked into seeing sense and now going for a rear disc though I think caliper mounting is going to be tricky....front wheel will be a 17" too....the one on there at present is a 19" borrowed from a Triumph Tiger!

009 (4).JPG


Been Around the Block
Thanks Steve, all the mounting points will be cut flush after welding and then fitted with rubber bungs....I'll be trying to resist the temptation to paint it gold though!


Been Around the Block
Not really sure Steve, am slightly tempted by a Ducati look...red bodywork....gold frame....but next week I'll probably be thinking something completely different!


Been Around the Block
Made an airbox today.....

009 (5).JPG

The slot is for a small panel filter....

011 (5).JPG

And some temporary rad mounts.....eventually there'll be a bit of a shroud there to direct air to both the rad and the air intake which will be just inside the tube marked 'R'!

014 (5).JPG


Been Around the Block
Headlight brackets made.....

001 (8).JPG

003 (5).JPG

And the nosecone mounted....

006 (7).JPG

Also, had a go at the tank....this one is just a mock up from scrap steel sheet....I taped the edges so I could fill it with water to measure the capacity....1.9 gallons.

005 (5).JPG

Was having a lot of trouble getting the shape right so it fitted under the grp cover....then it occurred to me to make another mould of the top of the tank and try it that way....

008 (6).JPG

Not exactly a perfect fit....wish I thought of that plan 2 or 3 hours earlier!!


Been Around the Block
Finished making the actual tank in ali but kept on looking at the way the tank cover overlapped the frame at the front....
In the end decided I couldn't live with it.....it won't take long to alter I thought.....3 days later and nearly a whole tin of filler....

004 (9).JPG

003 (6).JPG


Been Around the Block
Well.....bit of a long answer...originally I'd just planned to link the downtubes and main frame rails with tube a bit lower down
But there is a big cast lug on the front of the cylinder head that is unused on any of the 500 twins....no idea why its there at all
So at first I just made the triangular plate to give an extra engine mount to the sleeved holes in the downtubes which are also mounting points for rad and duct
I had some concerns that maybe the lug wasn't used because of differing expansion rates causing problems and was thinking I could always delete it later on if need be....but then thought no....its not as if its a pre unit Triumph!
With that decided I just added a stub of tube around the engine bolt and welded tube to that to brace the two
The other plus of doing it that way is when I finish weld it theres a good chance the headstock will distort one way or the other a bit....I'll have it checked and pulled straight if need be but by leaving the bolts out whilst that is done there'll be less stress involved.....


DTT Bike Of The Month Gallery

DTT Light or Dark

Top Bottom