Posts
414
Joined
8/11/2016
Location
Eugene, OR
US
Edited Date/Time
1/1/2021 4:24am
So, here it is in the back of the truck and headed 4 hours home...
I have never tried this conversion before so we will see what happens.. :-)
I have never tried this conversion before so we will see what happens.. :-)
No... I will not be using my SM for a donor Lol...
The Shop
Now get to work?
Looking forward to seeing it finished.
That was easy enough..
I have a set of 11 KX450F forks but I'm looking at something else right now...
Schools still out on that for now..
Pit Row
The pumpkin came from Grantspass OR..
A guy on Facebook had it for sale.
I eventually ended up buying two and shipping one to Canada...
Someone gave me the heads up on the first pumpkin on Facebook... but I can't remember who.. I thought he was in the US.
If it was you, Thanks! Lol
We are being very careful to remove as little material as possible.
These tubes are thin and we don't want to weaken them and more then required..
keep an eye on the counter shaft sprocket location vs the swing arm pivoit bolt. You want the counter shaft
to be a little bit below the swing arm piviot bolt... )
You've made things so much harder for yourself.
I did such a conversion last year, and I just removed the tubing part of the cradle and made a whole new cradle to go from the cast plates, and then up to (the necessarily higher point to clear the exhaust) downtube.
All it took was less than $60 AUD of 1 1/4" 4130, and the 2 bends to each side of the cradle. I also put in 2 diagonals from the linkage mount / frame cross over much like you'd see on most steel frames.
I always set the Counter Shaft center of any 'hybrid' I make at the same height as the original engine (well, unless it's too bloody high as std, when you factor in the huge torque of a 500 2t) .Too many people end up placing that center too high, just to make 'ancillaries' easier to accommodate, but it's a great way to really, really stuff up your suspension and handling.
The Center of the CS and SA Pivot Center is dictated by the engine (but you can get fancy with offset case inserts for the SA pivot bolt to go through) , but I've found usually less than 5mm difference, as designers had long since learned that as small a distance as possible was the go.
I hope it works out for you - my mate that I did the KX500 / 16 SXF Hybrid for loves it, and it was an easy job to do. Being steel, with far smaller frame sections, makes things far simpler than an AF.
But, you missed something really important... but it will be made very clear over the next few days...
Things may not be as they appear to be...
I also appreciate your insight on alignments.
A lot of thought went into this, so stay tuned I think you'll be happy with my results..
One of the things I may not have mentioned is that these frame rails are really thin so great care was taken to not grind off any more material then was absolutely necessary...
Jason at JT Engine Works and I are working on this project together as we have the spare time.
Jason is a CR500 and KX500 specialist and works out of my shop.
He builds all types of dirt bike engines and chassis.
Here is a few engine builds he has done..
Bultaco Pursang 125
1989 CR250
KX500 bottom end with custom made 2 piece clutch cover
Couple of KX500's
Here is a couple of pics of his Championship winning CR500 build
This thing is insane..
Needless to say I am very happy to have him helping out on this build..
As I said, it was a very easy job making a new cradle, and, using round, 1 1/4" 4130 made it cheap, and a hell of a lot stronger for a vibratory old 500 2t - and that's what they are, no matter how well built / balanced an engine is, when compared to a counter balanced 4t. KTMs have become utterly minimalistic, in their pursuit of light weight. And that means you need to be bloody careful.
As you said, the KTM cradles are very thin, and quite small in size. And their shape doesn't compensate for those two points.
I wish you well with your build, but you can get 4130 easily, and finding a tube bender is not hard, even in the back of whoop whoop. But, I've been building frames for over 4 decades now, so material procurement , bending, mitreing , machining and welding is an every day thing for me.
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