Topic: CB650 Cafe Racer Project

[luke3696]

HI EVERYONE; NEW TO THIS TYPE OF FORUM BUT THOUGHT I'D JOIN IN WITH UPDATES OF MY PROJECT IN THE HOPE THAT IF I RUN INTO ANY PROBLEMS YOU GUYS CAN HELP ME OUT, AND YOU NEVER KNOW I MIGHT BE ABLE TO HELP SOME OF YOU GUYS OUT?
I'VE BEEN WATCHING THE CAFE RACER SERIES ON DISCOVERY AND HAVE ALWAYS WANTED AN OLD BRITISH RACER TYPE BIKE.
I OWN A GSXR1000 K3 SO DON'T NEED ANYTHING FOR SPEED BUT FANCIED SOMETHING FOR A MORE LEISURELY RIDING PACE DURING THE SUMMER.
SO I SET ABOUT LOOKING FOR AN OLD JAP AIRCOOLED BIKE.
SAW A FEW ON EBAY BUT THEY WERE GOING FOR SILLY BIDS AND AS I WANTED TO CHOP IT UP AND RENOVATE IT I DIDN'T WANT TO SPEND ALOT.
I FELL LUCKY ON A 1980 CB650Z FOR £200 LOCAL TO ME, IT RAN HAD A FEW NEW BITS AND WAS A BARGAIN SO I SNAPPED IT UP.

[luke3696]

AS YOU CAN SEE FROM THE BELOW PIC THERE WAS A BIT OF DAMAGE TO THE LOWER HEADSTOCK.
I MANAGED TO SOURCE SOME TUBING JUST SLIGHTLY TOO SMALL, CUT IT TO THE RIGHT LENGTH HEATED IT UP SO IT EXPANDED A LITTLE AND HA,,ERED IT OVER THE OLD HEADSTOCK COVERING THE DAMAGE. I WILL MIG WELD THIS LATER TO SEAL IT AND ADD TWO BOLTS TO ACT AS STOPS FOR THE YOKES. THE LOWER HEADRACE WAS IN TACT SO LUCKILY THE DAMAGE HADN'T AFFECTED THE STEERING.

[luke3696]

DIDN'T LIKE THE LOOK OF THE STANDARD CB650 TANK, TOO SQUARE AND FLAT SO MANAGED TO GET ANOTHER BARGAIN FROM EBAY, A CX500 TANK, DENT FREE.
THIS TANK HAS MORE SHAPE TO IT.
HAD TO EXTEND THE MOUNTING FRONT RUBBERS AND WELD A BRACKET TO SECURE THE REAR TO GET IT TO SIT HORIZONTAL WITH THE SEAT.
THE BACK OF THE FRAME HAS BEEN CUT OFF JUST BEHIND THE SHOCK MOUNTINGS, SEAT BRACKETS WELDED TO SUPPORT A SEAT UNIT I GOT FROM EBAY (AGAIN) FROM A FIRM IN BRIXHAM.
I ALSO MANAGED TO FIND A SET OF FORKS AND WHEELS FROM A 1978 CB400F. THE SPOKED WHEELS MAKE THE BIKE MORE CLASSIC LOOKING AND ALTHOUGH THEY ARE ONLY 33MM INSTEAD OF 35MM 650 FORKS WITH A SECOND HAND CB400 YOKE FIT PERFECTLY.

IVE ALSO BEGAN MOUNTING THE REARSETS, THEY ARE OFF MY GSXR1000, THEY ARE A LITTLE LOWER THAN THESTANDARD PEGS BUT A GOOD 3 INCHES FURTHER BACK, WITHN THE ACE RACE STYLE BARS THEY THE GIVE IT THE RACEY FEEL I'M AFTER.

I'M HOPING TO MOUNT THE BATTERY AND ELECTRICS UNDER THE SEAT UNIT (BATTERY WILL HAVE TO SIT AT A SLIGHT ANGLE) ANY TIPS FOR THIS GREATLY APPRECIATED!

THE FRAME WILL BE EXTENDED AGAIN WITH A PIECE OF BENT TUBING TO THE SHAPE OF THE SEAT UNIT TO MOUNT THE REAR LIGHT ON.
DON'T WHETHER TO MOUNT REG PLATE ON THIS OR TO SIT IT AT THE SIDE THE RIGHT HAND SHOCK?

WILL HAVE TO GET SOME LONGER SHOCKS AS WELL, AS MY 15 STONE FRAME WONT LEAVE MUCH ROOM FOR ABSORBING THE BUMPS LOOKING AT THE GAP PRESENTLY BETWEEN THE REAR TYRE AND SEAT UNIT.

ANYWAY LOTS TO DO AND FABRICATE, I HAVE REBUILT HALF A DOZEN OR SO JAP BIKES BEFORE OVER THE YEARS BUT THE LAST METAL FABRICATION I DID WAS 24 YEARS AGO IN O LEVEL METAL WORK! SO WATCH THIS SPACE.
MUST ALSO KEEP A TAB ON WHAT PARTS ARE FROM WHICH MODELS, CB650 FRAME AND ENGINE, CB400F WHEELS FORKS AND YOKES, CX500 FUEL TANK!

[Pinhead]

I'm very interested in your project; I'm working on a '79 CB650Z. Could you post pics of your brake pedal rearset? I've found that the shifter side is easy but the brake side is more troublesome.

Would you want to part with the original tank?

[luke3696]

WELL; BEEN BUSY AGAIN GRABBING THE ODD HOUR WORKING ON THE BIKE WHEN I CAN!
HAD TO BEND THE CX500 TANK BRACKET DOWN TO GET IT TO FIT SO IT LAY LEVEL WITH THE FRAME AND SEAT UNIT, WELDED A BRACKET ONTO THE FRAME AND A NUT AT THE BACK OF THAT SO THE TANK JUST FITS ONTO THE RUBBERS AT THE FRONT AND ONE BOLT SECURES IT AT THE REAR.

I'VE THEN EXTENDED THE SEAT PAN TO COVER THE TANK BRACKET. THIS WILL BE SHAPED WITH SEAT FOAM AND A BLACK LEATHER COVER OVER THE NEXT COUPLE OF WEEKS.
I'VE DROPPED A PIECE OF TUBING OFF TO A PIPE BENDERS WHO ARE GOIN TO SHAPE IT FOR ME TO FINISH OFF THE BACK OF THE FRAME,

I PURCHASED A LUCAS REPLICA REAR STOP/ TAIL LAMP WHICH WILL PROTRUDE FROM THE SEAT UNIT WHEN THIS PIPE IS WELDED TO THE FRAME.

[luke3696]

Got headlight today so did a rough mock up.
Put the engine back in the frame so I can get te gear linkage sort and see the correct height that the bike will sit at.
I've started the battery mount under the seat unit, I'm a bit concerned as to the clearance between this and the rear tyre so might gfo for some longer shocks. I've seen some 405mm ones but theyre arent the eye to fork versions so might need some modding.
Starting to get a feel for the look of the bike now, just waiting for the rear frame tubing to come back from the tube benders so I can mount that and then sort the rear light.
Then it will be a frame strip down, grind down all the unwanted tabs and brackets and off to the powder coaters.

[rickyracer]

Nice work so far, the headrace work was excellent i probably would of been looking for a new frame! keep up the great job.

[MasterChief750]

are you going to be using a sealed battery? with that angle i would be worried about dumping electrolyte

[luke3696]

Yes I will be using a sealed battery, apparently is does them no harm to be angled or even flat.

A few more picks attached; Overcame the rear brake linkage by converting it to a cable link instaed of the steel rod. Will still give adjustment so should be okay. The gear linkage married up well with a simple 6mm stainless rod threaded at each end and a rose joint each end.

The rear light I have mocked up using an angled cut piece of rubber and a stainless washer held in place by a 28mm circlip, this should give me easy access to remove the light should I need to change the bulb.

Going to go for 405mm eye to eye shocks to give me the clearance I nee at the back end as at present only have about 50mm, with the linger shocks this should increase to 100mm.

Hopefully will be picking up rear tubing bent to shape for rear of frame under seat, once this is welded in place I should be ready to strip the frame down grind off any lugs and try and smooth it out rwady for powder coating.

[wannabridin]

Good work so far!  Thank goodness you figure out how to turn caps lock off, my ears were ringing from all the YELLING!!!  Haha

[luke3696]

Bit more fabrication done this week as got the bent tube for the rear subframe. Got to mount a plate under this to mount the electrics on.
Also got the 405mm shocks so mounted those after re doing the shock mounts, they had to be moved down slightly and made longer as the only shocks I could get without paying silly money were eye to eye, They seem to fit fine and I now have plenty of clearance.
Hopefully not too far now from stripping frame down giving it a good grind and smooth over before off to the powder coaters.

I started stripping down the carbs yesterday and unfortunately found that 3+4's needle tops were snapped, tried drilling them out and using stud extractor but this just cracked the casting.
Oh well back onto E-bay I found some CB750 F1 carbs at a bargain price so hopefully should be able to get a bank of 4 between all 8.

[popssss]

Nice project. I'm working on the CB550 your bike is a better conversion to a cafe.
Being in England, wouldn't it have been easier to get a Triumph to convert?

Ive been looking at the 2011 Thruxton, and I really like it, they're about $8900 (~5500 quid) how about there?

[luke3696]

Frame off to the soda blasters, swinging arm wheel hubs and rims and other bits off to powder coaters, so I started on ther engine,
It was immediately apparent that the engine had not been apart for many years as four of the cylinder head studs snapped very easily,
Buggar!!
With a bit of brute force manage to get the cylinder head off, had to drill one of the studs out as the bolt head had rounded off but managed this without causing any damage to the head, then after several hours of careful coaxing with a rubber mallet managed to get the barrels off to reaveal the broken studs.
As shown in the picture three of the studs had snapped leaving only millimetres showing above the crankcase, I bought a 'Laser' stud extractor which is like a drill chuck which tightens on the stud as you turn it anticlockwise. It was only £20 and did the job easily, I did heat the studs up first to try and break the thread.
So the engine is all apart ready for soda blasting, wheels have gone off for building, seat unit should be ready soon and as I write this the frame is drying after several coats of etch primer and satin black metal paint.
The engine appears in pretty good condition, I will probably replace the main shell bearings as the cases are apart and a couple do show a bit of wear, with the bronze showing through.
I'm looking forward to having a nice clean rolling chassis to work on in the next couple of weeks so I can begin the engine rebuild and the electrics,

[luke3696]

Update;
Soz haven't been on in a while;
Slow progress made but the big stuff done now!
Wheel hubs and rims powder coated in satin black and laced with stainless spokes, really happy how they turned out.
Seat unit recovered with more than the 5mm of foam the original unit came with, also sprayed gloss black and laquered.
engine soda blasted then sprayed with high temp engine paint, side covers and a few other bits all polished and sparkling!
Things to do;
Engine rebuild, got all the gaskets seals and new shell bearings ready to go.
Carbs need a strip down, clean and rebuild before fitting.
Fuel tank needs paint, can't decide on a light silver with some side decals or a bright Ducati red??
Electrics need a complete overhaul as relocating battery and electrical units under seat hump.
Need to get front brake caliper, probably go for a Honda Fireblade unit as its the only effective brake on the bike so I want it to be effective!
Gonna go with just a speedo, seen one 60mm diameter with built in warning lights so prob go for that to keep things clean up front,
Still undecided how to mount rear number plate so that needs sorting, as do indicators and exhaust mount.

[scunny]

nice looking project. for the number plate, I just turned mine into a chain guard.

[luke3696]

Cheers Scunny,

Don't think I'd get away with that in UK legally but might put it in the same place,
Wouldn't be able to curve it tho.

Regards

Steve.

[luke3696]

Engine sprayed, rebuilt with new seals gaskets and main bearings.

Engine back in frame and side race number plates powder coated and stickererd up.

Starting to get that classic race look I'm after,

Fuel tank to be painted, exhaust and carbs to be cleaned and then fitted.
Then the big job of the electrics!!

Wish me luck.

[luke3696]

Hi all,
Finally got the loom on and got the bike started after several nights of scratching my head until I traced the reason it wouldn't start down to a break in the wire between the right hand coil and spark amplifier!
Anyway got it going now, lots of smoke from the exhaust wrap,
I've posted a clip on you tube of it running

CB650 Cafe racer first startup

Does anyone know what the occasional phut noise is?
It seems to be a backfire back out though the carbs?
Be grateful if anyone can give me a clue, could be down to timing or carbs not being balanced yet?

Regards

Luke3696

[scunny]

bikes looking good. that "phut" sound at the carbs could be due to having no restriction at the carb throat. have you done a plug chop ?

[luke3696]

Cheers Scunny,
The carbs haven't been balanced yet so mixtures could be a bit off, I have got cone filters to put on too,
What do you mean by a plug chop?

Luke3696

[KB02]

Does anyone know what the occasional phut noise is?

...could be down to timing or carbs not being balanced yet?

Yes.


Did you also notice how the idle varied in speed a little bit? That is also an indicator that the carbs are out of sync.