CB650 "Parts Bin Special"

[andy120t]

...probably worth adding that my entire seat cost me under

[beermaker]

Loving this thread Andy, your project is looking really good!  I've just joined and am restoring a rusty chassis and lump and two boxes of bits into hopefully a shiny CB650 Nighthawk (was going to keep it original, but just seen a CB650 hardtail chop on ebay which has caught my fancy!) Feel very inspired by your articles and picked up some good tips along the way!  Please keep it coming!

Cheers
Philip

[andy120t]

Progress at last after 6 months of a new job and a tiny baby restricting my time in the cellar. I've now installed new head bearings & front wheel bearings & mounted the yokes & forks - piccies to follow over the weekend!

[andy120t]

...it's been an age since I posted, not least because my PC died and I lost all my piccies and my build log and my spreadsheet of costs. So I'm rather cross.

Brief update now - as I'm extra cross since I just wrote a long update then accidentally deleted it....grrr!

CB650 calipers are too deep for my spoked wheels so have sourced a set of GPz400R ones. Held my breath when they turned up as they are still deeper than I imagined but they are single piston only and don't appear to catch the spokes. I'm in the process of mounting them / making mounting plates so will soon see!

These will be combined with the master cylinder that came in my box of parts which is a CB one, although the reservoir on this is rather large and plastic & looks awful - so I'm thinking of sourcing an all alloy one. These appear to be shallower  but I don't know which bike they are off so if anyone knows please let me know.

I've also poached the wide handlebars from another bike - about 88cm wide & these look great, howeve they have a fairly shallow rise and foul the air top-up valve on the top of my forks. One of those 1980's technological advances (air-assist forks) that ended up going nowhere and are now causing me irritation! Thats all for the moment - piccies to follow once the camera works again!

[andy120t]

 A few piccies to summarise where I have got to.
New head bearings going in:



Sourced calipers from a GPZ400R :

[andy120t]

Last weekend it was finally warm for a while (unlike today!) so I headed to the shed & finally I got the engine back together - if you go back to the beginning of the thread you'll see that the rusted barrels were the a problem, now I have nice shiny ones in place.

I also put enought wiring in to prove the ignition worked - and found that I have sparks across two cylinders only. Need to fault find this weekend - but it seems to be either one side of the pick-ups or the connections feeding power to that side (I think). Coils are fine and swapping connections around indicated that both CDI's were OK.  ..But it was getting cold by then so I need to recheck everything again.

Piccies to follow when I get a minute, but the end seems to be in sight (at least in terms of having a runner - cosmetics will follow that). Once she's sparking I'll feel confident to source (ie spend money on...) some carbs (the ones I have don't fit - prbably going to go with GPz600 ones having read some threads on these on the US forum) and consumables - tyres, chain, sprockets, exhaust gaskets, brake pads. Then just need to wire in the horn and brake lights and it'll be MOT time!

Other minor parts I'm short of are the lower rear engine mounting bolt, points cover and the rubber grommets that hold the sidepanels in place - so if anyone has any spares of these please let me know.

[andy120t]

Last weekend it was still cold but everything sparked! So both sides of the pick-ups are working. Both CDI's, and the one coil & spark plug I've tested. Result!  I must just have been too cold to test properly the previous weekend.

I'm away this weekend so hope to have time to track down some carbs. I also need to test & wire in the starter relay & motor, but once those are all done here I'll just pop the carbs on and hopefully she'll fire up first time!

During the week I alo created a bespoke "parts-bin-special  manual" using the appropriate parts pages from various online sources, namely:
Cb550 frame & forks & swing-arm
CB400 wheels
Cb650 engine
FZR100 starter relay
GPZ400r front brakes
GPZ600r carbs

Quite please with it really! A very entertaining 'read' on the train home.

[andy120t]

... I need to post some piccies; but as an interim - 'bike is now out of the cellar and I spent the bank holiday weekend putting the engine in. I tried frame over engine but with the wheels attached & long handlebars this wasn't really working, so I then lifted it in & that worked a treat. Surprisingly easy for one person althought I had to remove the rocker covers. GPZ600 brakes are on but not really working - master cylinder is from a trail bike & may be a little small for the job so I plan to swop this out & put in the standard one to check that it all works properly & to get through an MOT.

GPZ600 carbs slotted straight on and by the end of the long weekend all 4 cylinders were firing. - I had to piggyback fuel from my Triumph using a long fuel pipe so had a few concerns about the 650 going up in flames and taking my Triumph out too - however in the end it all went smoothly. Only problem is that it's not running fully on it's own, just firing,  so the plan is now to clean the plugs, juggle the choke a bit more and try again. Also, I'm currently trying to run it without exhausts so I'm not sure if putting those on would help it run.

I also wired in the brake lights & horn so I have the MOT minimum in place for electrics.

Aside from that - I need tyres; chain & sprockets; two disc bolts and a few odd nuts & bolts and a number plate. Cosmetically, it's a little untidy but I want it running and MOT'd and then I'll move on to how it looks.

One final concern is that now it's all together the chain may not line up with the 400 sprocket/wheel hub, so I need to assess that this weekend & see if it needs solving - either with spacers behind the sprocket or alternatively I may go the need a 550 wheel route. Don't want to buy tyres until I've made that decisions.

[andy120t]

Managed to get quite a bit done over the last few weekend.
GPz carbs on . Original loom on the bike and plugged in. It seemed to be firing but it wasn

[K2-K6]

That's come a long way andy120t, and much work to get it there.

Be interesting to see how it runs on the gpz carbs, I guess they should easily flow enough to let it make good power.

Thanks for taking the time to post for us to see as it's interesting to see something different come together, looks quite flat-trackish.

Don't know if you are aware that if you want copper washers to seal well it's best to soften them first by heating to red hot and dropping into cold water. this should give you the best chance of working with the threads you have left.

let us know how the mot pans out and also what it's like to ride.

[matthewmosse]

Looking good, and an interesting thread, right up my street, keeping to a budget and making a good workable machine from odds and sods. Great result though a bit shiny (I prefer rust on my bikes) does look like it will be very sweet when finished.

[andy120t]

Thanks for the comments!

..no MOT yesterday..exhaust isn't yet silenced / sealed - bought a silencer but now need to find a collar to fit it with as the diameter is a couple of mm more than my header pipe.

Sealed the engine - tried anealing the copper washer in the oven but couldn't get the temp. high enough...they have to get to 6/700 degrees to turn red. Anyway, I hand-filed a bolt to the exact length of the hole in then engine and that gave me enough grip to seal using the existing washer. Very pleased that there'll be no helicoiling for now.

Drilled & fitted the numberplate & stuck a reflector on. Plate is legal, back-end of th ebike is skinny with a very skinny tyre so it all looks faintly ridiculous. Will need to source a smaller version for other occasions.

Chain & sprockets on & aligned using the spacers I had in place already so pleased with that.

Two final probs. Fuel tap seems to be missing a brass pipe (where the fuel line mounts). It has a single one and a thredaded hole for a second. Petrol is coming out of both which is a bit of a pain. Any ideas where I can source a spare for this?..Anyone have a spare one lying around?

Engine won't run fully. I still had the plug leads on the wrong cylinders so after a few huge backfires I reviewed the wiring diagram and finally got this right. Now it runs on full choke only but dies the moment I touch th throttle..not sure if this is a grubby carb problem or related to me using CV/diapraghm carbs rather than mechanical ones...Will do some online research on this, but any thoughts on this please let me know.

.....So, no MOT yet!

[K2-K6]

The carbs should be able to run that motor, some are even using bike CV carbs on car engines for example so they should be able to be configured to get it going. and I'd guess at the original demands being not that far off what you need to at least get some half sensible response from it.

Assume they are all in good order i.e. clean clear and minty with good diaphram sealing?

Fuel pipe, can you use anythng from a car spares shop as they sometimes have copper of varying sizes available.

[andy120t]

My worry was that there might be a need to have a vacuum pipe linked to the fuel tank. However, the carbs are filling with fuel and as I understand it the vacuum element of the carb. is primarily related to raising / lowering the needle; rather than drawing fuel down.

So, with the 'bike running the carbs should work. Since they aren't, I'm assuming that the jets may be blocked so need to give them a good flush through with carb cleaner as a first step.

[K2-K6]

Usually the vacuum pipe to the fuel tank is only to turn the fuel supply on and off by using a small diaphram operated valve inside the tap.

If the tap hasn't got this then it should just be gravity flow when it's switched on.