After being K-less for about six weeks Low Flying Brick fired up again this afternoon. I've done the tappets (five out of eight needed replacing - one exhaust was down to 2 thou!!) and that's made a real difference to the sound of the engine. I also made a complete new wiring loom which was modified from the original diagram to suit the Honda switches; that's by far the most complex loom I've ever modified and built. I made a couple of errors (it does help to provide power from the starter relay to the rest of the bike for instance.... ) but nothing that was difficult to track down or fix.

One thing I discovered along the way: BMW seem to have used two different AMP connectors on the FICU at different times. I bought a secondhand '85 K100 wiring loom to strip for the FICU and ICU connectors (they're not available new from AMP) and assumed it was the same as my '83 one. Not so. The hooks on the nose of the plugs are slightly different shapes, the '85 one has two small locating strips molded on one side and the '83 one has a locating strip molded into the socket on the FICU. Three snips with the wire cutters later and the '85 plug now fits the '83 socket securely.

But! it's not quite finished yet. I still have to reassemble the bodywork and heat-soak the engine so that I can balance the throttle bodies again. It'll be done by next weekend - I hope! - then I can put the Bandit back into its obscure corner.

Nice work Dai. A big undertaking with the wiring loom, glad it worked out OK for you.

I was getting a little worried that your new found tin box license was going to usurp poor old LFB and she would become one of those projects....

Reading knowledgable posts like yours make me feel guilty and leaves me thinking I should be doing all those engine jobs like valve clearances, injector cleans and throttle body balancing....but everything seems to be running OK and I'm currently getting 5.2l per 100km on my commute and, yesterday even managed to get a personal best of 5.03l/100km (56mpg) when out riding over the Quantox, North Devon coast road and Exmoor - despite a lot of low gear work and a fast run home. 

Maybe I should get my donor bike engine and gearbox up on the work bench and use the time to get that refurbished instead.

fingers crossed it all comes together mate

Well it was alive. I took it out today to heat-soak the engine so I could set the throttle bodies up. The short ride went well and I'm quite happily sitting in my garage with the arse-end poking out of the door and the vacuum gauges on the throttle bodies when there's a god-awful grating noise from the engine and the overflow bottle starts making like a steam loco. Engine off in a hurry and it didn't take long to figure that the fan blades had jammed (probably something dropped in there) and the fan motor had burnt out.

A check on Motorworks' website showed secondhand fans at £75 each ( !!!) and new ones at double that price, so in forlorn hope I turned to ebay. I checked a couple of pages but nothing really doing; a couple in the US at reasonable prices but the shipping and tax is horrendous; a couple in the UK at almost the same price as Motorworks but not looking that great. I changed the search terms slightly and suddenly there was a nearly perfect three-row radiator and fan for £75 inc. P&P BIN. So I did   .

poor sod dai
but good to hear there is a recovery happening

wonders why you didn't look up the thin type 6.5 inch or whatever fans and make a adaptor ?  robmac posted the template for the mountings in here somewhere

cheers

I wanted to change the radiator on mine anyway because I managed to do a small amount of damage to it with a power hose (knocked out about 5% of the fins). Aaahhh - wanna bet I find bits of fin in the fan motor? Serves me right, if so.

[Edit] It seems I'm not guilty. I got the fan motor off and found that the negative brush was non-existant and the brush holder was cracked and rubbing on the commutator. The positive brush was still a good fifteen-twenty millimetres long, so the conclusion is that whatever jammed the negative brush had been there for a long time.

Or you could try this, Iv'e not tried yet but have been told they will fit a K.

http://www.ebay.co.uk/itm/271053572017?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Sometimes it's tempting to buy something just to see if you can make it fit, even if you don't need it!!!

Dai wrote:.... I also made a complete new wiring loom which was modified from the original diagram to suit the Honda switches; that's by far the most complex loom I've ever modified and built. ....

Would be great to get some additional information about how you went about this Dai. Which Honda switches did you use? What modifications were needed with the wiring etc.
Cheers

Good question! I'd had some experience of fuel-injected looms before (my Guzzi California 1100ie) so I was pretty sure that by the time I'd 'untangled' the original wiring diagram I was going to find that both the FICU and the ICU were on separate circuits and that was exactly what I found. I drew them out as separate diagrams and made them as individual sub-looms that plugged into the main loom. The original BMW loom obviously works but it's not logical in the fusing department (I did wonder if Mr. Honda had been talking to Mr. BMW because Honda stick fuses in the middle of the looms too, not near the power feed where everyone else does).

I had to use 1970s Honda switches because I needed the built-in clutch bracket on the leftside switch; the K100 handlebars are too narrow to take separate switches and levers. You can't use mid-Eighties onwards switches because Honda moved to CDI ignition which requires the killswitch to make to earth. The earlier switches break the power feed to the ignition system. You could always ride with one of the later killswitches in the permanently 'off' position...

Because the BMW self-cancelling system effectively requires three switches, you lose it but... None of my other bikes have self-cancelling indicators so I'm not going to miss it. This means replacing the original BMW flasher unit with any old 12-volt 4-way unit. Wiring wise, the existing black/blue wire in the righthand BMW switch moves across to the leftside Honda switch.

I was talking to ComberJohn about the cafe-racer crowd sticking with the standard BMW switches when a few relatively simple mods to the wiring loom means that they can use any handlebar switches and, more importantly, it opens up a whole world of new master cylinders too. I helped a Polish member on this forum (Piotr) do exactly that, so I guess it's about time I posted the end wiring diagram and the instructions to go with it.

Dai wrote:Sometimes it's tempting to buy something just to see if you can make it fit, even if you don't need it!!!

That is the cooling fan I'm using on the Big Block. It works a charm.

The reason I'm using a slim type is because it clears the 44mm stainless steel intake elbows the 38mm TBs are at the end of. The original fan motor is so very long in the proboscus. This replacement clears and is spread nicely across the (three row) width and breadth of the
rad-yator.

Dai wrote:.....

Because the BMW self-cancelling system effectively requires three switches, you lose it but... None of my other bikes have self-cancelling indicators so I'm not going to miss it. This means replacing the original BMW flasher unit with any old 12-volt 4-way unit. Wiring wise, the existing black/blue wire in the righthand BMW switch moves across to the leftside Honda switch.

I was talking to ComberJohn about the cafe-racer crowd sticking with the standard BMW switches when a few relatively simple mods to the wiring loom means that they can use any handlebar switches and, more importantly, it opens up a whole world of new master cylinders too. I helped a Polish member on this forum (Piotr) do exactly that, so I guess it's about time I posted the end wiring diagram and the instructions to go with it.

Interesting. This is why I'd like to change switches to something more workable. My master cylinder is on the way out. Also, with some help, I'm building a new microcontroller to replace the flasher unit so I have greater control over how they work and how they cancel. I'm not sure how this is going to interact with the K switches but figured I'd need som wiring modification somewhere and probably different switches. I like your idea of modularising the loom.
Any additional info and pics would be helpful. Thanks

I have removed the BMW indicator system on the Chookie and replaced it with Yamaha switches on both sides including the throttle twist grip and clutch mount.

ungaas wrote:Or you could try this, Iv'e not tried yet but have been told they will fit a K.

http://www.ebay.co.uk/itm/271053572017?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

yes been tried ...and works ...with a higher flow of air through the system ...and ...less current as well .

RicK G wrote:I have removed the BMW indicator system on the Chookie and replaced it with Yamaha switches on both sides including the throttle twist grip and clutch mount.

I knew I couldn't be the only one!  Define 'Yamaha switches' Rick - early metal ones with the choke lever under the lefthand one or later ones with the lever rotating around the handlebars? I ended up mounting a Yamaha FZR 750 choke lever under the Honda CB125 switch because of the space problem with the narrow bars.

Most switches these days seem to come out of the Domino SpA factory in Italy. The external moldings are slightly different depending on which motorcycle manufacturer they're bound for (and the wire colours are different too, obviously), but the guts of the switches are frequently interchangeable. As an example, I had a lefthand unit with 'Triumph' boldy molded into it but that one had no flash/passing switch. I also had a broken lefthand unit from a Suzuki SV1000 with the flash switch. All I had to do to get the Suzuki flash switch into the Triumph unit was to open up the Triumph molding with a Stanley knife and screw the Suzuki switch in. The mounting boss was already there and in comparing the moldings, it was quite obvious that the internal 'fixings' were from the same mold.

They are the later type with the rotating choke lever and came directly fron the Hoo Flung Muc Chinese crappy switch company. They were $25 for the pair so I got 2 pairs and pulled one set apart and they seem to be fairly good. I also bought a bag full of connectors in various sizes for almost nothing. I think there are 120 plugs and sockets of varying sizes with pins for $38 landed here when all I could find here was about $4-6 each.
I also went to the auto wreckers and got 2 complete harnesses for $20 and got just about every colour in the book plus heaps more.  All I had to get was brown for the earths.

You might be suprised, then, to know that Hoo Flung Muc have just opened on the NYSE, the Footsie and Euronext, are rated just below Alibaba in net worth and have purchased Rolls Royce, Lear and are negotiating on Apple. They started as a pig iron smelterer in Sum Win All's backyard back in 2011. Investigations show no link to the Chinese Gubmint. And, the air quality is good to excellent.
:suspect:

I think you are becoming a tad cynical as you age Daz. If you try hard you may become as cynical as me but I have learned one thing from being so cynical and that is that I am no where cynical enough.

I don't use cynicism as a refuge, but it's good to visit the island once in a while.

The replacement radiator and fan arrived on Friday and I was bitterly disappointed. The fan had one missing brush, one broken brush and was seized solid. The three-row radiator however was in excellent condition and having emailed the seller, we're negotiating a partial refund. Meanwhile, I've ordered one of those unversal fan-thingies which is probably what I should have done originally.

Well, it's finally back on the road. The nice clean three-row radiator I was so pleased with? It leaked. Both it and the fan are going back to the vendor tomorrow. In his favour, unless you knew what you were looking at inside the fan the damage there wouldn't have been obvious and you'd only find a leaky radiator when filling it. At this point I'm only going to be out of pocket by the cost of the postage - sh!t happens, so what.

I also checked and reset five out of the eight valve clearances; the result is that LFB no longer has the dreaded diesel knock. Taking Rick's advice and advancing the timing by four degrees does seem to have made a difference to the pickup (over and above what I'd expect from fixing the valve clearances). Not a huge amount, but combine that with the K1100 carb bodies and there's a very non-K punch at about 4300rpm. Again, not huge but noticeable. The Brembo 34/40 Goldlines on the front are doing a lovely job of slowing the whole thing up.

Finally I can put some more miles on it...

Well Dai feel free to put more miles heading down this direction......!

Great to see you back on the road.