Build thread - KX500B1 Supermoto

[derek badger]

Excuse the vagueness to the early part of the build, it was started 11 years ago and I'm only just picking where I left off about 9 years back.

So, what do you do when you're un-married no kids and an IT contractor on a stupid hourly rate? You spend your money buying stupid s**t on eBay and getting drunk. The rest of your wages you waste on rent and bills...

In the garage was an RMX250 enduro bike, a GPZ600, a Ducati 900ss and an old aircooled '80 YZ465 in Supermoto trim. The YZ and the GPZ got finished and sold and I ended up picking up a non-running '85 KX500 on eBay as my next project. It turned out to be worse than I imagined. It was a dog. A tired old abused s**tty dog. It got worse as I stripped it down too, cracked frame, broken mounts, knackered rads, leaking tank and some sort of wooden peg where a mixture screw should have been in the carb body. It had clearly had a hard life and was owned by someone with no mechanical sympathy.















And so the strip down began...

[derek badger]

The bike got a jetwash, all the crappy old body work was removed complete with hideous 90's decals. The wheels were binned a) they were going to be replaced with 17's and b) I was going to change the rear from drum to disk. Although I prefer the look of spoked wheels the plan was to go for cast wheels off a small sportsbike to save a few quid.



I bought 25kg of grit and gave the frame a shotblast in the garden and then a good run over with a flap disk before welding the broken lugs back on and repairing the crack in one of the lower frame rails. It then had a coat of primer and a couple of coats of gloss black. Non standard, but then the whole bike was going to end up that way.





I removed the engine and stripped the top end down. It had seized, at least once, and there was play in the conrod/crank so it went off to my mechanic for a rebuild.

[derek badger]

I managed to pick up some parts over the next couple of months - NOS for the engine, a desert tank to improve mileage, side panels, seat cover etc. and start putting things together. The mechanic stripped the engine down and it was pretty f**ked, I told him to fit it in when he had time as I wasn't in a hurry for it and I knew how busy he was.





Can't remember what was going on in my life at the time but it was about 6 months before I contacted my mechanic again and he'd only got the bottom end rebuilt. I was happy to finish the top end off myself so took it home and re-assembled it.





While it was on the bench I contacted a firm about a lighting coil, they didn't make one but said if I posted them the old stator plate they could make one up for it. So it was done and I could run light later if I wanted. The engine then had all orifices masked up and together with the repaired original exhaust pipe they a couple of coats of high temp black paint. In hindsight I probably shouldn't have painted over the engine bolts, but never mind.

[derek badger]

The forks were all of the following - bent, pitted and leaking what rancid fluid was left in there. I picked up a set of KLD650 forks, partially to keep the original-ish look (USD's would seem out of place in my opinion), partially as they were from a dual-sport model but mainly as they came up cheap. They got stripped, seals replaced, new fork oil and green gaiters fitted. The yokes needed a small sleeve for the lower bearing but they were the right stem height so they got cleaned and painted black.







The shock got cleaned up, the spring painted and then reassembled. It probably needs a rebuild or a replacement but I'll deal with that later.

[derek badger]

I made up some new engine plates from ally plate and fitted the engine to the frame. I'd fitted the tank and an enduro headlight/numberboard and refitted the shock and swingarm. I presume I cleaned this up and changed the needle rollers in the linkages but I can't find any pictures.







Hmm, seems the GPZ is still in the garage at this point. Told you my memory is a bit hazy... The rad brackets are straightened and/or new ones fabricated and the coolant system is bolted back on. No idea why that cone filter is on there I've got a massive ram-air style foam filter to fit somewhere in the workshop.

[derek badger]

I've now got a set of 17" wheels and some part worn tyres so the bike is at least manoeuvrable around the garage. I can't for the life of me remember what they're off, (the front it a Honda but running reverse so the brake disc is on the correct side). They both need spacers making up but the bearing have been changed to match the axle diameters.









With bodywork and wheels fitted it's starting to look a bit like a bike again...

[derek badger]

It's now June 2006 and I was a member of a was a small-ish online community for SM riders in my local area. We'd been invited to a show at Beaulieu Motorcycle World so I needed to get the KX into at least a rolling chassis and then with the combined technical ability of a dozen SM riders we could probably finish the wiring and get it fired up on the stand. That was the plan anyway.





Coil, HT lead, plug and/or plug cap are all potential issues to the lack of spark. But the kickstart return spring dies and nobody fancies trying to bump starting a half litre two-stroke single at this point so we get drunk and I borrow an XR650 for the track session the next day.

[derek badger]

All change. The GF and I buy a house and it needs some work. Well, it needs a lot of work. New kitchen, bathroom, carpets, decorating, landscaping. The full monty and I'm no longer freelancing so all my money is being sunk into the more important project. It's got a garage, but it's not attached to the house and it's not got electricity. Over the next 7 years the KX500 gradually disappears at the back of the garage behind other bikes, boxes of bike parts etc.



House is finished around 2009, maybe time to take a look at that kick start return spring? No, time to plan a wedding... We get married 2011 have a couple of nice holidays then 2014 our son is born...2015 our daughter is born. I still have faith that I'll get round to it though and continue to pick up bits now and then. I find a load of NOS front sprockets in various sizes. They get slung in a box and added to the pile of crap that is my garage.

[derek badger]

Dec 2015. We sell the house and buy one with a bigger kitchen, a garden for the kids and a garage attached to the house with power. The missus is pregnant again and we've got the builders in to extend the house a bit - new porch, playroom for the kids and an additional toilet. While they are doing this I get them to add another 4 power sockets to the garage. 10 years of hoarding parts, tools and workshop equipment is about to come to fruition.





This is how it's stands presently, these are the last photos of any real progress I took back in 2007.















So, things to do.

Fix kick start return.
Sort ignition.
Get engine running.
Spacers for wheels.
Sprocket alignment.
Brakes - front and rear mounting brackets, rear m/c, pedal and torque arm.
Get MOT done on frame number.
Contact Kawasaki UK to get letter stating year of production.
Get age-related registration number from DVLA.

So with baby #3 due November the plan is to have the engine out and on the bench by September. But I'll probably be revisiting this thread in another 10 years knowing what I'm like...

[derek badger]

Just found a complete kickstart return mech on eBay. The seller is away, and them I'm on holiday for a week so it should be waiting for me when I get back to work at the end of the month.

[sandblaster]

Wow!!
At least you still have it and have made some nice progress.
It's amazing how life gets in the way of what is really important 
Keep up the good work!

[Foxx4Beaver]

that is a bad a$$ bike!
post up some vids if you ever get time!

[LukeG]

I'm with fox, I want to see that thing being ridden in anger.

[derek badger]

So today I had a spare hour so I took the body work off and made a start on getting the engine out. Strangely enough the kick-start seemed to be working but I'll still be opening her up to check the mechanism. The replacement part arrived and is in good condition.



I'd honestly forgotten how huge that barrel looks!


The boy comes to give me a hand.


Massive carb...


Coolant was in good nick, no change in colour and no indication of corrosion. Good news as it's been sat for so many years.

[Abbott]

awesome build Derek! definitely keeping an eye on this one. I have a 1985 KX500 as well that I am converting into a "superbike". ducati 748 front end and using a CBR300R rear wheel.

Question for you if you have gotten to this point yet...how did you adjust the offset for the rear sprocket to line up with the front sprocket on the outputshaft?