Upgrade to enjoy this feature!
Vital MX fantasy is free to play, but Premium users receive great benefits. Premium benefits include:
- View and download rider stats
- Pick trends
- Create a private league
- And more!
Only $10 for all 2026 SX, MX, and SMX series.
Well, NOT with that 'Gelding Tank' they cobbled together to try to get through the Dutch GP!
Watching some 500cc GP compilations and races the other day, it reminded me Thorpe Did Not like the 250 type frame on the SR.
He went back to the std type backbone frame, and Malin went onto the perimeter framed SR. Malin, liked the perimeter bike.
Quite a few riders built up perimeter framed KX's in the GPs, over the next few years. You'd see a mix of them under various riders, and sometimes them swapping types between GPs.
Billy Liles was on and off the 2 different frames, over, I think, a few seasons.
Eventually, the perimeter bikes seemed to dissapear, in the very later years of the 500, then the MX3 classes. Riders stuck with / returned to the std frames.
Not relating to the perimeter frames : A classic picture you can find is of Hakan Carlqvist gas torch welding his top shock / subframe mount in the pits. One of the 'trouble spots' the KX frame reinforcement kits address.
Interestingly, I just recently got the "No Regrets" DVD - long after having read the book by Dave Thorpe. He very briefly mentions an "Alloy" framed SR he tried in Japan. First time I have ever heard mention of it, and I never read about it, or saw any pictures of such a bike.
Great Book and DVD, by the way, but I do wish both had had more detail of his Kawasaki effort, and subsequently (semi) privateer efforts by him, with Cinti ( and others ) - Things like him lending some ex works / semi works 500 engines to a Brit privateer, and the bikes being stolen......
Wow, very good info, thanks for all the background. I wonder how many frame breakages they had?
Please note : I'm not implying that the perimeter frames were breaking. I daresay some did : 500s ( well, anything) pushed at GP / Pro pace certainly got / get a hammering : it's a hard life for whatever design / material used.
Just that, many tried them, some liked them, some didn't.
Just as some like AFs, and some don't.
Everyone has their 'druthers.
Hakan (hand me some bloody sunnies!) doing some metal melting :
And, Billy Liles circa 1991 at, I would think, a Dutch GP = Sand and a Big Tank - on a Perimeter framer :
Billy spent a Lot of years on the GP circuit, something, it seems, few Americans know.
He, like Gary Semics, could tell some pretty good stories about their careers. Gary has done so, on his website, and, I think here on Vital a while back. I wish he would publish his journey through MX, in a book.
The Shop
Luxon 4-Post Bar Mounts
$189.95 - $239.95
DeCal Works Huge Plastic Inventory of UFO and Polisport kits.
Free shipping: VITALMX
With the KX perimeter frame being as stable as it is, it seems more riders would’ve preferred it on the 500.
Keep in mind the standard KX500 frame was about as stable as you could possibly make a chassis. Getting them to turn was the challenge.
Can you imagine any top rider now whipping out the old acytelene and fix his frame in the pits lol
Håkan was a badass RIP
IIRC, another rider (non-factory) raced a perimeter-framed KX500 in 1990 (or 1991).
Jo Martens, I think.
Someone wrote 'April Fools' on the hastily welded tank extension.
Although it was a long time ago, from what I remember, it is a very valid point I never though about before and I agree, the 500 old frame was "as stable as you could possibly make a chassis" (but still flexible, even a bit too much as it was possible to feel the frame working with so much torque). It was even better than the 250 yz, and in comparison with a kx 125 frame, the perimeter was also the most stable of its class but could still do some head shakes. The old kx frame would not do that even at high speed, it was inspiring confidence, and honestly it was still turning on a dime as you just had to open the throtle to pivot with the rear. I think with the production rule and the US being a big market with lots of eyes on it particularly with sx, from the late 80's and 90s the bikes were more made for sx, for tight corners, jumps, more compliants but a lot less for high speed tracks (in term of offset, longer swingarms and lower rear). That said, I absolutely love the look of the updated 500 as in the pictures. That may means "the ultimate 2 stroke for mx (real mx tracks and not outdoor sx)" could very well be a bike from the 80's with updated suspensions and brakes.
I remember with mine when you were on the throttle it just wanted to stand up and go straight, you really had to point and shoot in the corners and use wheelspin to keep the bike turning if you got on it early. Trying to lay the bike down into a rut and roll on the throttle was not something I could get it to do, but I knew nothing about bike setup at the time either.
Fwiw my 88 kx250 probably cornered better than my 95 kx125. So I would bet the standard frame turned quite a bit better than the perimeter.
How did the early 90's Kawi 125/250's handle? I preferred the Honda and Zooks handling. Headshake but carved like a scalpel
You had to be a bad, bad man to ride a 500cc 2-stroke fast on a gnarly track! Thorpe was one of the GP guys who was really good at it.
Thorpe was the rider MXA called the "World's Fastest Novice" right?
I know the 95 was sooo good at everything but the middle of the turn. Like the poster mentioned before, it had a tendency to stand up in the turn. But it was something I could live with. My ‘91 Suzuki (250) was better everywhere though.
It was mentioned later in the video that Thorpe started to like the perimeter frame.
The standard 500 frame was like riding a very fast lounge chair, so I can only think they were searching for a bit more rigidity and sharpness from the perimeter frame.
I can see why some would like that and others wouldn’t be so keen, especially on a chewed out 500 GP track!
I’ve always wondered what Thorpe did to piss off MXA. That whole deal was just to much high school/mean girl drama..
Pit Row
As I wrote, plenty of riders tried the perimeter frame, quite a few went to and fro with them, and yes, Jo Martens was one of them.
And, as I wrote, they pretty much disappeared in the later years of the 500 and MX3 class.
You also had a few ( but far less) riders trying AF CRs. Most notably Stefan Everts winning Namur.
Rob " The Fish " Herlings, I think, persisted with the AF, on the RJW ( I think ) Team. But, after that, to the end, the std CR500 chassis was what was predominantly out there. The early AF frames were Not an improvement on the steel chassis. I made around 5 or 6 conversions of the 97 / 98 AFs ( they were Very easy to do ) virtually right after the 250s came out, and within a short time the blokes, other than 1 ( he's still got it, as a garage queen ), went back to the std frames.
There's a lot to be said for a well built, well developed steel backbone and cradled frame, tied together with a Big , Boofy engine...... and CRs don't have the weak points that KX500s had. Don't shoot me - I love the KX500s, but they did have some problems, and you can still buy reinforcement kits for them. I've repaired / reinforced quite a few since '88.
George's Jobe and his riders, with his Belgacom Team, including Billy Liles, had the integral Tank / Subframe ( I think ) and sidecover set up, somewhat akin to the CTI Carbon Fibre set up that Jacky Vimond used on a CR for just a few GPs, in '89(?). I've pictures of that I can put up when I get back to my Workshop desktop, if people are interested.
it was not their only mean spirited dumb ass comment over the years,
Here's a pretty cool look at the '91 SRs. I remember hanging out at the Team Kawasaki HQ in Bourne End as a kid.
Definitely interested 👍
The late Andrew McFarlane holeshot (with Byrner in tow) and lead the first 20 mins of the 2000 Australian GP on a locally built perimeter frame KX500. No one internationally had heard of the Aussie lads before that moment.
Nice one!
I appreciate the backstory on these bikes. The look good 😊
They were good times. My mate was the son of the local Kawasaki dealer which was just a few miles from Bourne End so I got to hang there quite a bit and get free parts for my KX 250. My mate just took them off the shelves and put them on his dad's tab.
We got to go with the team to a British Championship race one time. I remember Malin passing DT in both races on the same off-camber straight to go 1-1. He went faster than I thought was possible.
The duct taping of Malins mouth was a crack up, even with it being well before his MXGP commentary years. I would surmise he was quite the motor mouth even then. He's the best in the business.
I 've always wondered if there were any experimentation / options used with the early Bolt in Shock Tower KX ( well, the SR's, I don't doubt they had options) Perimeter frames. I can't recall anything being offered as an aftermarket item for production bikes.
Of the many types of frames that KTM experimented with, I remember at least one with a bolt on shock tower.
I made the effort to have a bolt on lower shock mount on my swingarm when I did my PDS conversion to my CRE. I made several mounts, for different ride heights and ( for very slight differences in) leverage ratios to try. It was a useful thing.
Johan Boonen?
Yup, he's seen hurling them about a fair few times in various GP videos .
My memory is worse than I thought ;-)
Post a reply to: Dave Thorpe’s ‘90 KX500