KDXRIDER.NET

Hello from Idaho. I have a 1981 KDX 400, I think, that I am currently working on. The VIN indicates it was made in 1981 and the motor has DX400 stamped on it. Seems weird since i thought the 1981 model was the KDX420 and the guy I bought it from said it a 400 with a 420 big bore kit on it, maybe an 80 model made in 81? I picked it up for $50, it hasn't been started in 20+ years and I hope to ride it this summer. Look forward to getting to know you all.

Welcome to kdxrider.

If you can post up a VIN and engine number, I may be able to help out.

KDX400 was supposed to be 1979 and 1980.

Well, some quick indicators are the rear suspension. The 400 had dual shocks, the 420 was the first with the uni-trak. I seem to remember that the bottoms ends of the motor were the same for the 400 and 420 which could account for the markings. Or it could be some one swapped motors in it's nearly 40 year life span! Can't beat the initial price that's for sure.

Nice find! Beats the heck out of my deal.
Welcome!
And good luck with your revival.


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I raced a 1979 KDX400 that belonged to a buddy of mine a couple of times. That thing was a beast!

$50 bucks. Wow what a buy. I would highly suggest not to try to kick it over yet untill pulling the head off and checking the rings and jug. I brought a bike recently where the bloke I brought it from had the bike sitting for years and tried to feed it some fuel and kick it over. The rings had seized against the bore and left deep grooves in the bore after trying to kick it over after all these years. Welcome to the site and good luck with the bike!

Sorry I haven't been back for a few days. Oh boy you all know your stuff. Bufftester - your are totally right it does have the unittak and the top end reveals it a 420, i did see the bottom end markings and mistook it for a 400. Huffnpuffer - great advice, I tend to get too excited and get ahead of myself. Which I did this time too. I have been working on it at nights and just got it started tonight. How do I post the video?

You would have to host a video elsewhere, then embed the link or post the link.

Good luck on the bike work.

Sweet mate. Good to see ya stepping back and thinking a bit. Some times we rush in and it bites back when ya finished and say I should have done this and not done that. Years of making mistakes. Keep us all updated on how ya builds going.