SuperMoto Junkie banner

KTM SXF to Supermoto

178K views 661 replies 47 participants last post by  rrrr1rob  
#1 ·
Hi Guys, picked up this 2008 SXF 505 to turn into supermoto. I know it's not the ideal base for a SM given the 4-speed transmission, and I really would have preferred the fuel injected newer models with suspension linkage, but the price was right. $2500 and I've been wanting a KTM project to play with anyway. :D



 
#3 ·
Well, I've applied for the title and it's all insured and registered for the road, but I think this first year maybe I will just convert it for supermoto (racing), and then over the next winter, worry about the wire harness and stator + lighting. Still have some other projects in the air.
Going to powdercoat the frame orange like the factory edition, and throw some orange accessories at it. Haha, not exactly breaking the mold with that idea, but I do like how they look done up like that. :)
 
#5 ·
Ah yea!

Nice grab rob, looks like a good candidate for a supermoto build! 505's are hard to come by (aleast around me), and I don't think you will have much of an issue swapping the four speed for an EXC tranny. As long as you have the magic button that's the important thing!

Once you drink the orange kool-aid you wont go back, believe me! I use to be a Honda guy now I currently have two KTM's, a Husaberg, and one Honda.

Definitely subscribed, if this turns out anything like your other builds I know it will be good! :thumbup:
 
#6 ·
Thanks for the kind words! I hope this doesn't disappoint, but I had to promise myself that I wouldn't get quite as fanatical about this build as the crf450, CR500SM, or the CR500 MX. There should be less custom fabrication at least. I'm gonna try to refrain from replacing every bolt like some of the others just so I can throw more $ towards the higher dollar items. Whereas I've decided to keep all the other bikes, I have to fund this one as I go.
If you, or anyone else has ideas for me, though, please throw them at me. I'm new to the orange so this is a learning process for me! But I'm excited :D
 
#8 ·
You've got a great looking bike there mate. But I'd go with a different coloured frame. The 450SX I'm converting atm had an orange frame and it makes it look very garish, particularly with orange plastics. Then there's the fact that most aftermarket 'bling' for KTM's is orange and the orange frame makes it all look a bit tacky.

I sprayed my frame 'aluminium' colour until I can afford to get the orange PC stripped and it really does wonders for it. Sets all the anodised stuff off well. I'm considering going with a black frame though eventually.

Anyway, that's just my opinion and after reading your previous builds, I'm sure this one will be awesome aswell. Can't wait to see it unravel.
 
#9 ·
Anybody know what transmissions swap in? and if I can add a "just-in-case" kickstarter? Just curious mostly. I've ordered a shorai battery, so that should have pretty good reserve capacity anyway. My husky doesn't currently have the kickstart lever, but that fires up a little bit quicker. Going to have to check the valves on this sooner than later.
It looks like I will replace the clutch, piston & rings, and waterpump as preventative maintenance. Well, actually the waterpump leaks a little now, so I know that needs attention.
 
#11 ·
Well that doesn't sound that fun, haha. Any opinion if the 4-speed is acceptable as is?
 
#12 ·
for track you can get away with it, for street that would be a definite no in my opinion but I guess it all depends what you're used to.

about the e-start, the only thing that can make these bikes a bitch to start is if you soup up the motor in way that compression skyrockets and the starter can barely turn over the motor (more powerful battery could still fix that I guess), or if there's some wear and tear on the audodecompression mechanism. this used to be a problem on some of the older bikes '07 through '09, on more recent bikes not so much and you can drop in a cam from those bikes if it becomes a problem on yours.

other attention points on these engines. oil bypass valve spring and the oilpumps which are made out of plastic, '07 and '08 had some problems with those but upgraded parts are available out of the more recent year motors. even so if you order parts for your bike now you'll get the upgraded parts either way, old ones are no longer available. the pumps as well as the bypass springs are vital to maintain oil pressure (duh), but on these bikes you need to keep an eye on both. the pumps can and will wear out because of the material they're made of. the bypass spring needs to measure within a certain length (thought it was 38,5 mm) to do it's job, if it doesn't that means it lost tension. the valve will open at a lower pressure when it's not supposed and the engine can suffer damage. usually the head is the part that goes first, marked by seized camshafts and worn guides. it's even recommended you shim the bypass valve spring even if it measures within spec, 1 mm shim should suffice.

on the 505 you also need to keep en extra eye on the barrel and piston, more specifically the piston rings, those tend to wear rather fast.

last but not least, stock camchain tensioner is junk, replace it with either a dirt tricks automatic tensioner (I run them on all my KTM's and some friend's bikes) or fit a manual one and block off the oil feed to the tensioner port, in which case it's recommended you shim the spring by 2 mm's to cope with the rise in oil pressure caused by blocking off the port.
 
#13 ·
Thanks for all that ^^ Will hopefully start posting some actual pics soon.
 
#14 ·
Any thoughts on handguards? I'm thinking Racetech or Circuit... but they are not as available in the states as say Cycra and Zeta, both of which I'm currently using. Side note, the Zetas seem to fit better (than the Cycras) due to the articulating knuckle, however I feel this might sacrifice a little rigidity in impact absorption? Have yet to ground test either, haha. Can I get the Racetechs in the US or do I have to order them from Europe? :headscrat
 
#16 ·
Picking up a few smaller items for the project
SMR front fender



SMR fork guards. Hope they fit

 
#18 ·
FLU Designs seat cover. More on this later when I actually install it.



Some KTM orange radiator protectors





Ordered these Renthal grips and then came across the KTM ones ready to be mounted with handguards. Yea, they were double the price, but I thought they were cool.



Scar gas cap vent. Looks good, though I'm still tempted to order the one from KTM



Hammerhead Desings brake and shift pedals. I went with the CNC shift lever, but the forged brake lever. I was real impressed with the strength of the forged brake lever on my CR500AF motocross build.

 
#20 ·
CV4 31 Lb. (?) radiator cap



Here's the interesting part. 31 Lb.



...but wait...29 Lb.! I want my 2 extra Lbs, haha.

 
#21 ·
and some blue CV4 radiator hoses.

 
#22 ·
New Shorai battery. Currently I'm using both the Lithium batteries from Ballistic and Antigravity and I've been EXTREMELY happy with both. This time around, thought I'd try out the Shorai because the case size and shape seems closest to the original battery.
LFX14L2-BS12. 210 CCA @ 1.46 Lbs.
versus the original (YTX)4L-BS 50 CCA @ 2.9 Lbs.,
the next size up with the larger battery box (YTX)5L-BS 70 CCA @ 3.5 Lbs. and
the YTZ7S, 130 CCA @ 4.6Lbs
Seems like money well spent to me.



Here it is next to the 4L-BS that came out of it and the YTZ7S that came out of the Husky.

 
#23 ·
Biggest purchase for the project so far.
Hinson BTL Slipper Clutch, Hinson Clutch Basket, and Hinson Clutch Cover. Have new clutch plates/ springs awaiting also.

 
#24 · (Edited)
Being a bling-whore and drinking the orange Kool-aid. Bad kombo, Kids. It leads to this...



Also, picked up another throttle tube. This has the end that removes for handguards.

 
#26 ·
Thanks! ^^ I hope it turns out good. :D
 
#27 ·
Got my title in the mail today. Still waiting on my custom license plate. As far as paperwork goes, it's all street-ready :arsenal
At this point, I'm not planning on putting all the street gear (lighting, wire harness, stator etc.) on it. Maybe over next winter, who knows?
 
#28 ·
Got new Leo Vince Exhaust. Just went with the SS header, Ti can/ Carbon end cap combo. $300 shipped. Naturally I wanted the Ti header cuz they look so purdy after some heat cycles and I was leaning towards Akrapovic or FMF, but I saved hundreds $$ going with this. If I change my mind though, the Leo will be going up for sale.

 
#29 ·
Plan on powdercoating frame and swingarm. I need some input on a chain guide and skid plate, with pix preferably. I would like to do all the fab work before the powdercoating, i.e. any required welding mounts etc. I will need a upper chain guide for an inspection sticker down the road. Plan is dual purpose with bike- track and street, that is :)
What works, what doesn't? Put on a 530 EXC chain guard? or perhaps one from a 2014 500 EXC? Maybe it uses the same one? I haven't looked yet. How about one off a 690 SMC? Those cover more area, but are in excess of what I need for a sticker.
Also I would like a quick release skid plate, but I haven't found anything for the 505 SXF yet? Has anybody used one off another bike that fits or would with a little work or maybe found one that is available? Leaning towards plastic rather than carbon, as it's not likely to stay pretty and glossy.
 
#31 ·
The 500 EXC chain guard bolts right on. :D Possible I may have to notch it to clear a 160 tire though. That's fine, I just wanted something for down the road so I can put it on the street.



KTM catch can



some frame "protection" decals
 
#32 ·
I did end up getting the KTM gas cap vent



as well as some Renthal Fatbars