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Author Topic: 1990 KX500 SF conversion, few Q's  (Read 198 times)
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Joined: 02.13.17
Posts: 5

« on: March 11, 2018, 08:13:23 AM »

So I have been collecting KTM parts for a while and recently purchased a 1990 KX500.
Will be building this bike for next year ice racing season.
-2014 KTM (frame, swingarm, subframe)
-2013 KTM shock
-2016 KTM 4CS forks
-2008 KTM triple clamps

KX500 plan (items not purchased)
-44 mm Lectron carb
-AJ FMF pipe,
-Prox basket/inner hub
-new intake (does a person go Rad Valve/Vforce 3/stock?)
I'm sure I read somewhere the Vforce3 didn't fit correctly, but Im not sure
-Wossner piston
-Ported and Polished

Kickstart is very worn, buy new KX500 or will some other KX/KXF be a better fit?
Decompression required?

Thanks for your input

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Joined: 01.14.15
Posts: 1,794

Goliath Returning from Battle

« Reply #1 on: March 11, 2018, 11:02:16 AM »

Sounds like a fun project.  Sandblaster is building a 2016 KTM conversion as well.  It seems like it is pretty straightforward if you start with a 450.  Here is a link to the thread if you want to look through it. 


It seems like most guys use the stock 500 kickstarter.  In fact, there have been a couple of KTM/KX 500 conversions on the site that used the stock kicker without issue.  As for the compression release, I would highly recommend it anyway.  It makes kicking the big 500 a lot easier.  Larry Weichmann on this site does a really nice job.  Here is a link to his thread:


Perhaps I have a dirt bike addiction?

03 KX 250/88 KX 525 - Goliath
2017 KX250F/2004 KX250 - Project Back Burner
04 KX 250 - Lunchbox's Bike
05 KX 125/144
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Joined: 02.13.17
Posts: 5

« Reply #2 on: March 11, 2018, 05:24:53 PM »

Thanks for the intel.
Just bought a pipe and silencer from AJ waggner (Flea-bay).
Plan on doing a bike tear down this week.

The frame is a 350, so I know it's not a drop in. I do have a 08 300 frame here that I plan on using the frame rails like the 2016 250 conversion above. (that green frame is sweet)

I have done 2 CR500 AL conversion for myself and built another for friend. I always wanted a KX500 again here I am, all in at this point.
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« Reply #3 on: March 11, 2018, 05:33:38 PM »

I'll be watching your build.
The best bang for you intake buck is a V-Force 2, not the 3's and definitely NOT a Rad valve smiley

On the kick lever parts, I would buy new if I had the option but I do have some used one's in my K5's..
In the very least, get a new return and thrust spring for it.

Even on a stock engine I run a decomp head.
It's easier on me and it's easier on the components.

What do you plan on doing for your engine?

The four stroke engine: That's one stroke for producing power and three for wearing the engine out.
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Joined: 02.13.17
Posts: 5

« Reply #4 on: March 11, 2018, 07:51:54 PM »

where does one buy a Vforce 2?
New kicker will be placed on my OEM list

Plan for the engine right now is:
-Stock bore
-Port and Polish
-Re-shape the head + decomp
I need a hard pulling mid to top power engine.

I will be looking for someone to do the porting and head mods.
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