LukeG's 1990 KX250 period 6 road racing motardbuild

[Sandblaster]

Hello, my name is Luke!
And I have a problem! For some silly reason I decided to restore a 1990 KX250 and make it into a period 6 road racing motard. Sandblaster is a bad influence, I believe he goes by a few other aliases, K5saveslives and he has a given name somewhere out there.
This is my plan for my bike, I have also started a thread about it on KX Riders:
93 cylinder, bored to 72mm, ported, new power valves
92 KX 250 crank, this is the year they went to the 72mm stroke as opposed to the 70mm stroke of the 90. I have the cranks side by side and except for the stroke they are the same
91 KDX 250 transmission, the wider spread of gears will give me plenty of top speed without sacrificing low speed. 15/44 gearing will be a starting point. I need to be able to do more than 100mph
I have a FMF fatty pipe and I have also bought a PSI pipe. Not sure which one I will use I will have to try them both. As for the silencer, probably a PC or a DEP only because that's what I can get
I have a 4 piston FTE brake caliper or a 6 piston Beringer brake caliper to use I need to get more clarification on the rules before deciding which brakes to run
Suspension has been rebuilt and setup for motard
Frame needs a few welding repairs and then it will be powder coated green.
My other bike is a DRZ 400 motard, which has been modified to the hills as well. I have three sets of 17 inch wheels I can use with a 4.25, 4.5 and 5 inch rear. Trouble is the rear KX hub is 5mm narrower than the RMZ wheels I have between the sprocket and rotor inside faces. That makes two of the wheel sets hard to fit. The 4.5 rear is built for a DRZ, but they are RAD hubs with bolt on carriers so I can buy carriers to suit the KX
Need to get some 13mm offset triples made, I have a set of 06 KX450F titanium footpegs to go on. This will take some modifying to get on but I belive the end result will be worth it.

I'm a toolmaker by trade and have access to plenty of machines to make stuff as its required. I just need time and money.
Thanks for your time.

Luke

[Sandblaster]

LukeG

I finally thought it was a good time to share what I have been up to with my 250 since I joined. I bough a 1990 KX250 from my father in-laws neighbour which had been parked for about 8 years. It was sitting in a little garden shed getting full sun on it every day. The forks were absolutely cactus, the outer tube on the uppers was starting to oxidise and corrode, they were coming apart as if they were cast iron. Anyway here's how the bike looked when I brought it home.

oem-cycle.com 1990 kx250 supermoto build 101.jpg (225.23 KiB) Viewed 10518 times

oem-cycle.com 1990 kx250 supermoto build 102.jpg (176.22 KiB) Viewed 10518 times

My plans for the bike are to make it into a road racing motard so I can use it in period 6 historic racing. I already have a DRZ 400 that I raced until on of the crank bearings let go mid race. Everyting on the bike must be period correct so I needed a decent set of forks to go on it. Ebay scan and found a nice pair in the UK. Took the newer forks and the shock to the local suspension guy and asked him to do what he could with them to make them better for road racing.

Things like this are always a nice thing to find!

oem-cycle.com 1990 kx250 supermoto build 103.jpg (192.88 KiB) Viewed 10518 times

I tore the bike down as best I could, half the bolts were rusted or the threads stripped. The top end actually looked pretty good but there was no coolant or oil in the thing and the crank seals looked well past their use by date.

oem-cycle.com 1990 kx250 supermoto build 104.jpg (249.58 KiB) Viewed 10518 times

[Sandblaster]

oem-cycle.com 1990 kx250 supermoto build 105.jpg (156.27 KiB) Viewed 10518 times

oem-cycle.com 1990 kx250 supermoto build 106.jpg (220.64 KiB) Viewed 10518 times

oem-cycle.com 1990 kx250 supermoto build 107.jpg (198.16 KiB) Viewed 10518 times

oem-cycle.com 1990 kx250 supermoto build 108.jpg (205.75 KiB) Viewed 10518 times

[Sandblaster]

oem-cycle.com 1990 kx250 supermoto build 109.jpg (228.26 KiB) Viewed 10518 times

oem-cycle.com 1990 kx250 supermoto build 110.jpg (227.89 KiB) Viewed 10518 times

oem-cycle.com 1990 kx250 supermoto build 111.jpg (189.62 KiB) Viewed 10518 times

LukeG

I plan on getting the frame, sub-frame and shock mounts powder coated but I need to make a new mounting tab for the radiator and get a few holes in the bottom of the frame repaired before that happens. The engine has been completely stripped and I am off to get the cases repaired and vapour blasted some time this week. The engine looks like it has had a hard but loved life. The PO just putted around on it through the bush. What happened before that I don't know. All I know is the main bearing holes in the cases have steel bushes in them, there is some weld repairs in places and there was about 1/8 of an inch of sealant between every mating surface.
I will do some more updates tomorrow.

[Sandblaster]

LukeG

Can anyone please tell me the colour Kawasaki painted the swing arm back in 1990? I want to make it look original from a distance, I know it's grey but what shade, mines too scratched up and worn out to get a decent sample to colour match.

[Sandblaster]

Here is a pic of a 1990 kx250

1990 KAWASAKI 250 PICTURE ID.jpg (158.97 KiB) Viewed 10518 times

I will see if I can find more info on the swing arm color..

[Sandblaster]

Here is a pic of a slightly used 1990 kx250 swingarm

1990 KAWASAKI 250 SWINGARM PICTURE ID.jpg (476.77 KiB) Viewed 10518 times

[Sandblaster]

It just so happens I still have this swingarm.
I will see if I can figure out what color this is..
I might be able to get some paint samples and compare

1990 KAWASAKI 250 SWINGARM color ID.jpg (37.39 KiB) Viewed 10518 times

[LukeG]

I went to a local paint supply shop on Friday and spent nearly an hour going through colours to find one that matches. I found one that looks very close, it's an auto paint so it will have a little bit of metallic in it. Getting the swing arm soda blasted Monday and will be undertaking an hour and a half drive to get the engine vapour blasted next week.
I found some new side power valves for the 90 cylinder on eBay which arrived very quickly from the UK. The side ones for the 93 are obsolete but they are the same size through to 02, just the cut outs are a different size. I will add a photo later to show.

[Sandblaster]

That's good to know.
I can't wait to see how much you need to mod the side valves.
A lot of guys will probably need that info as more valves get discontinued.