CR500AF or KTM300XC...?

[ravenous]

Right on Rush! I dont think my kx is for everyone either.
My friend Lonespin rides a 2013 450 sx with a 2014 LT.
It is awesome and capable of everything he wants it
to do.I cant find any fault with the way that thing goes.
All bikes are fun and no bike is perfect.

 

[partypete]

I built a cr500af that I used for one ride at the end of the season before I put tires back on. I have a 40mm smart carb that I can't go full throttle, still working on getting the right needle. But even at 3/4 throttle it had more juice than the several kx450s I've rode and my crf450 that dropped a valve earlier this year with a fresh top end haha.
I never wired up my carb heater and didn't have and carb ice. That was only one ride and it was warm out. If I were to do it again I would deffinitly get a decomp head, man these things have a lot of compression with a fresh motor lol!

 

[summitboy]

What do u mean u can't go full throttle on the Smarty ? The needle really has nothing to do with top end. Maybe up to 3/4 throttle only. If u go full throttle does it cut out after a bit ? Maybe ur running out of fuel. Float level ?

I also second the decompressor ! The name mentioned earlier as well as Adam Millar from Millar Racing does a sweet job in Canada. Also his TWIRP porting is the bomb in the 500 realm ! Awesome and knowledgable guy ! He builds serious torque monster 500 motors !

 

[partypete]

Yeah Corey and I have been trying to get it worked out. I've adjusted the float to the point it doesn't stop fueling lol and tried new needles and they all make a step in the positive direction just havent got it right yet.
Yeah I got my porting and a reed cage made by Adam Miller too. Good stuff I haven't rode anything that compares yet... Well for the first 3/4 throttle. I think I'm going to send my head back and have it decomped whenever I do my first top end.

 

[n16ht5]

I can say after one ride on my CR250 I wouldn't even consider a 4 stroke for a Snowbike. Valves don't like banging the rev limiter for five minutes straight. If I find a good deal on a 500 I am jumping on it

 

[partypete]

Ya it only took 4 good rides to turn my 450 engine into shrapnel, not cool. I think one of those 345 esr cylinder kits for the yz with a stroker crank would be the ticket for a 2 stroke snow bike.

 

[capulin overdrive]

Sounds like you're in good hands there going with the 300.

 

[summitboy]

Wow thats strange for sure. Tell us more about this bike ? Adam told
me there was a guy he knew with this issue. Have u tried putting the stock carb on it to see if the issue goes away ? Could it be electrical or fuel related ? The Smarty just pull whatever fuel it needs. Weird

Also which needle are using and at what clicker. Im on a stock 80 at 70 clicks. I started with a 76 but after finding my issue with the adjuster vibrating to full rich i slowly worked back to the 80. You can get some deto at 3/4 throttle and i use fuel builder or a little race to get the octane slightly higher so it doesn't deto.

 

[partypete]

Well it's got a billet 40mm so maybe I should have gone with a 38mm. I have a service Honda ignition and everything seams to spark and grounded well. I've tried switching fuel lines and tank vents/gas cap didn't do anything. I haven't tried putting the stock carb on yet but I might try it if this next needle doesn't help.
But every time we make a change it seems to help. Like changing the float level helped a little bit, shortened the rod by about a 1/4 in and that helped a ton. Not I'm supposed to have a richer shorter rod to try and hopefully that does the trick. O yeah I started with a 76 rod and I think my last one was a 74 but don't quote me on that and I've tried all clicks lol seemed to work best the richer I went until it was waaaay to rich.
.

 

[summitboy]

Id try the stock carb and rule out the ignition and other things first. Cant see why you have to go so rich even for the 40mm. When u say shorten the rod do u mean with the adjuster or actually cutting the rod ? Why the 40mm ?

 

[partypete]

Yeah I'll try this new rod if that doesn't fix it I'm going try the stock carb. Yeah Corey sent me a rod that was about 1/4" shorter which made the biggest improvement. I went with a 40 because it was all they had when I decided to go away from the cast version.

 

[summitboy]

I would try it before the new rod shows up. Im seriously thinking its not the Smarty. Id be looking at that SH ignition first. I sent mine back lol. At least you can rule some things out instead of chasing your tail with rods. At WOT the needle really doesnt affect WOT. The carb gives whatever the engine wants signal wise. I have never even heard of this problem before to be honest.

 

[partypete]

Lol why did you send your ignition back? Idk man it might be it will run full throttle in first gear when there is not much load on the motor.