CR500AF or KTM300XC...?

[Wundah]

Trying to sort out what bike I should try to use next winter and I'm interested in getting all the opinions out there. I rode a 06 CRF450X this winter without a ton of mods on my UFO kit but just need to find a setup that can get better track speed and keep up with my buddy on his highly modded ktm300 and TS kit. I'm considering selling the motor out of the 450 and doing the CR500 engine swap but not sure. From all the reading i've done the 450 should have been plenty fast but I was either WOT and hitting the limiter or not going fast enough (gearing I know) so I just want to find a way to straight up haul *** and have fun. I'm in it to win it and want to make a sick setup but just wanted to see what you folks were thinking. Cheers

 

[Wundah]

KTM300XC it is

Pretty stoked to say that I just talked to MtnDoo and got in the queue to have him do a full mod on the 2013 300xc that I just picked up...good times are going to be had on this beast for sure! Build updates to follow

 

[dhdey]

my basically stock steelie cr500 beats FI 450's and my buddies KTM 300SX with ease

 

[thejean]

What are the downsides to a big 500? I hear they can be a bugger to start. Any others?

 

[Uncle si]

Get a bigger track, you are spinning that short track too much.

Climbing, My tired KX450f with a 146x2.5 spanked a UFO equipped new KTM 450sxf with a more talented rider.

I mean to say a real paddling.

 

[Wheel House Motorsports]

functionally, the UFO kit is not as well suited for deeper snow compared to a TS kit. it is designed to have more of a bike feel. your gonna need a good power advantage on the ufo to hang with a ts in the deep due to that idea. not that the UFO is bad, its just not designed to operate as well in deep snow, but have better suspension feel, which the TS is not great at IMO.

 

[Rush44]

What are the downsides to a big 500? I hear they can be a bugger to start. Any others?

Vibes are also much higher. And they are simply just more temperamental. My bike you pretty much put fuel in it, change the oil, push the button and go. I would love to have a big 2 stroke for some days, but I wouldn't want it to be my daily driver. Kinda like the classic muscle car in the garage.

 

[tomk]

Vibes are also much higher. And they are simply just more temperamental. My bike you pretty much put fuel in it, change the oil, push the button and go. I would love to have a big 2 stroke for some days, but I wouldn't want it to be my daily driver. Kinda like the classic muscle car in the garage.

the 500s are so big they are kind of indestructible, and from my experience with mine at least. for the last 2 yrs jetting seems very forgiving, I have the pwk39mm I have been running the same jets all year from -10f up to high 20s with the same jets. now its up around 40f and its starting to gargle pretty good so I am going to the garage now to drop the needle and lower the main. vibes are not bad unless you are on hard pack holding it wfo for a long time. pick up a set of those fancy bars and ur good to go. I like that it lugs around in any gear, from barely moving in 1st gear to lugging on the trail in low- mid 5th at 50mph.

 

[mtn-doo]

Vibes are also much higher. And they are simply just more temperamental. My bike you pretty much put fuel in it, change the oil, push the button and go. I would love to have a big 2 stroke for some days, but I wouldn't want it to be my daily driver. Kinda like the classic muscle car in the garage.

Vibes are a rumor to most folks. Few have ever personally ridden a 500CC two stroke snow bike, much less spent a whole season on one. Vibes are not an issue. You don't even notice unless you concisely try to evaluate it. Yes, they are virtually indestructible. No oil to change, no valves, cam chain timing, etc. etc. etc. Fill it with gas and go. No oil to change when you get home. After about 3 years, you can rebuild it in the back of your truck with two wrenches, one screw driver, and a set of pliers for about $150 bucks. All of the best snowmobiles run these engines for a reason.

The down side is refinement with the big 500's. The 300 is up-to-date and super sweet. If we could get a modern/refined two stroke bike engine , like the refinements in the snowmobile engines, it would be awesome. There are projects in the oven. Time will tell

 

[Rush44]

I've rode a steel frame CR500 and the vibes was the biggest thing I noticed. The snow was a little more setup that day, but it was very noticeable. The bike had a smart carb and it was still fiddle fiddle fiddle almost every stop. The issue was carb icing even with heat and a jacket. The owner said he was getting a thumper for next season because he just wanted to gas and go. He also broke 2 kick starters by late February.

Ausman's buddy that came over with his smartcarb 300 for the day was also fiddle fiddle fiddle. It had power, did everything we did, but still was temperamental. Carb heat, carb jacket, and even hand warmers in the jacket and it still didn't run right. Several times during the day he mentioned how he just couldn't get it running right and he was going to get rid of it if he could.

The only big 500 or 300 I've seen that didn't have a problem when I rode with it was mtn-doos and he still broke a kick starter once that I can recall. And that just speaks to his attention to detail in the build.... I don't think I could ever reproduce that quality independently.

For shop idiots like myself the 450 thumpers have an advantage. I can just go buy what I need and slap on the rest pretty easily. Just my preference. If you have the ability to build one up right it would probably be great.... but there are people like me who can't. That is who my opinions will help the most.

 

[portgrinder]

I wouldn't go any less than a 500 again. Don't think it would be much fun.

From what I can see they're pretty easy to deal with. If you ride a dirtbike with any proficiency, the vibration is not a big issue.

Largest pain was carb icing. That's Std on any bike though. Coolant lines wrapped around the carb fixed that.

They are kinda tough to start. Just have to learn how to kick it. Put a primer on it too.

 

[thejean]

I've talked about a 500 with some motocross buddies and then steered away when they mentioned the starting difficulties. Would be even worse when flooded I imagine. I agree with both Rush and Mtn-doo, 500 would be awesome but for me, I want simplicity. I envied how the last time I went out sled guys were just pulling the cord and ripping it up. I was messing with carb icing, starter issues, stuff vibrating off the bike, etc. Just plain annoying. I think I will definitely miss the playfulness of the 300 in the trees when I go to the 450 though.

 

[powdermuncher]

As soon as they come out with a direct injected 2 stroke I will be the first to get one --- the carbed stuff just does not do it in the snow.

If we could just get Rotax to put a gearbox on that 600 direct injected sled motor that would be sweet .

 

[kell8071]

I wouldn't go any less than a 500 again. Don't think it would be much fun.

From what I can see they're pretty easy to deal with. If you ride a dirtbike with any proficiency, the vibration is not a big issue.

Largest pain was carb icing. That's Std on any bike though. Coolant lines wrapped around the carb fixed that.

They are kinda tough to start. Just have to learn how to kick it. Put a primer on it too.

Anyone tried the decompression valve that is installed in the cylinder head?

I just picked up an aluminum framed CR500 for next winters bike and want to learn from others experiences to save me down time!

Kell

 

[eskimojoe77]

decompression valve

I have a decompression valve installed in my cr500af head and it makes a big difference. I can kickstart it with thin soled shoes. It's a great mod.

 

[ravenous]

The decompressor in the head is a must. Larry Weichmann does a beautiful job
of these. My kx 500 starts like a 125. Easy 1 or 2 kicks.I only think about
vibration when someone asks about it. I guess it might vibrate a bit, but I just havent noticed. Total non-issue. Temperamental? I dont think so. What do you mean, Rush? I had the jetting on my pwk dialed by Dec. and havent touched it since.Koso egt says Im safe and happy.Only other special mods
are tunnel mounted heat exchanger with thermo bob and temp gauge and carb heat.1 full trouble free season on my kx! Yeah!
I love it and highly recommend it.

 

[M5-]

I'm really thinking long and hard about doing up a dedicated 500 snowbike specially since my 4 stroker just blew up again. I am not convinced that the 4 strokes can last at the rpms we are using them at. Last season wasn't too bad as I was just learning but this year my bike saw a LOT of high rpm riding while climbing and such, apparently too much.

What I am thinking is I will pick up a KTM cro mo frame and graft in a 500 either a CR or KX. The KTM frame should be easier to work with than either a CR250f or KX alu frame, I can do the alu welding and fab easy enough but the KTM frame won't need any major mods and may vibrate less. This way I will also be able to use my fuel tank, seat and other parts and just quickly swap them over for winter.

So which motor is the question CR or KX. I have a line on a 2001 KX500. Opinions?

M5

 

[Gros Chien]

Could you tell me more about the Thermo-Bob tunnel heat exchanger, pics,,, and link where to buy, please!

The decompressor in the head is a must. Larry Weichmann does a beautiful job
of these. My kx 500 starts like a 125. Easy 1 or 2 kicks.I only think about
vibration when someone asks about it. I guess it might vibrate a bit, but I just havent noticed. Total non-issue. Temperamental? I dont think so. What do you mean, Rush? I had the jetting on my pwk dialed by Dec. and havent touched it since.Koso egt says Im safe and happy.Only other special mods
are tunnel mounted heat exchanger with thermo bob and temp gauge and carb heat.1 full trouble free season on my kx! Yeah!
I love it and highly recommend it.

 

[Rush44]

Temperamental? I dont think so. What do you mean, Rush?

I am only reporting on my personal observations. At no point have I ever said I owned a 500 smoker all I have said, and you can read my comments carefully, is that these are the things I have seen. I am totally not against the 500 at all... I would love to have one as my "take out on these certain day" bikes. You guys are all going to have your preferences and I have mine. I am not the only person who feels the way I do and I am not bashing those who like the smokers. The smokers have more power and the power characteristics are actually more conducive to snowbiking than the thumpers.

If someone is going to fork over their hard earned dollars on a bike they should know the advantages and disadvantages to the bike they are considering. I've owned Yamaha, Kawasaki, and KTM all in the last 3 years and each has it's own advantages and disadvantages. Every bike does. My responses have been in regards to thejean's original question "What are the downsides to a big 500?". Had he asked "What are the advantages" the answers would have been different.

I will amend my previous statement of mtn-doo being the only smoker I've seen that didn't require SOME fiddling during the day. Once Summitboy got his metering rod settled out at the truck his 500 ran like a beast all day long. Both mtn-doo and Summitboy put serious refinements into their bikes and take tremendous pride in the builds. You would be lucky to have something they previously owned.

 

[dhdey]

on my cr500 i used copper tube around carb for heat and solved that problem, jetting has been a non issue. starting isnt too bad once you learn the technique, never broke a kick starter and rode close to 100hrs this winter. but will get the decompression mod for starting in akward positions. vibrations were annoying at first but go used to it. rubber mounted the bar clamps and put silicon and lead shot in the bars and it helped. not changing oil after every ride is a big plus in my books. cheap rebuilds too. seems like if you ride a thumper and ride it hard watch your hours or you may get stranded with a grenaded motor. i will say the FI thumpers are easier to get setup up.