2 stroke builds

Draxxus · Dec 10, 2013

Thinking of building an older kx 500 , would have to make a custom fit kit due to the traditional forks. This might be really beneficial because it would eliminate the chance of bending chrome tubes . Not positive but should be easy enough to modify some swing arm fit kit pieces or fab some custom ones to mount the kit itself. The other nice parts of this option is the low purchase cost 1000-3000 and that nice comfy couch of a seat.

The other build I've been thinking of, is putting a 300 sx kit on my xcw 250. Giving me the benefit of electric start with low weight and it's already outfitted with fastway pegs , soft seat and other standard goodies . It should be pretty comparable power to my current crf 450. The kit is only 800$. Come summer I can swap the little black boxs and power valve springs.

Both builds would get a smart carb if they live up to the hype.

What would you do given the choice ?

Might have to build both .....

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Uncle si · Dec 10, 2013

I just built up a kx500 and I love it. I know of one with three year's use that is well loved by the owner.

backcountrysnowbikes · Dec 10, 2013

2 strokes seem to be the way to go.

The kx is working for you Seth.
Lots more power?

tomk · Dec 11, 2013

I just built a kit for an 86 kx 500, just left the shop!

1dn5up · Dec 11, 2013

there was a 500 in a aluminum frame for sale is squmish a few weeks ago on craiglist for pretty cheep may wana see if you can find it

JimBridger · Dec 11, 2013

I lol!!!!

http://www.ksl.com/index.php?nid=218&ad=27945369&cat=236&s_cid=S0001

Uncle si · Dec 11, 2013

backcountrysnowbikes said:
2 strokes seem to be the way to go.

The kx is working for you Seth.
Lots more power?

She does have power. I am having a hard time getting it to the ground with the dust on crust snow. I am really happy with how well it runs. It chugs pretty well without stalling, too. I am really looking forward to getting familliar with the machine.

if it spins the track easily in good snow, I will probably step up to a bigger track -I am eyeballing 144×2.5".

Bigred1 · Dec 13, 2013

Anyone building KX500s find a way to put a thermostat in yet?

dhdey · Dec 13, 2013

Bigred1 said:
Anyone building KX500s find a way to put a thermostat in yet?

you could put a single in single out inbetween the rads and drill a decent size hole in it for a bypass. in theory when its cold would be restricted enough to keep engine temps up on cold days and should be enough flow to open in on the trail/setup snow days. also use a sheet a plastic inbetween rad and rad louvers that you can slide in and out depending on temps

Bigred1 · Dec 14, 2013

Ill try that and see if it works. the first radiator may never let enough hot water up there before it overheats but its worth a try.

portgrinder · Dec 14, 2013

Bigred1 said:
Anyone building KX500s find a way to put a thermostat in yet?

Don't need one. Its a myth.

I run no t-stat on my kx500af and temps are 120-140F in all conditions. Would actually like to get it colder.

mtn-doo · Dec 14, 2013

portgrinder said:
Don't need one. Its a myth.

I run no t-stat on my kx500af and temps are 120-140F in all conditions. Would actually like to get it colder.

Yep, I think 120ish would be ideal.

ravenous · Dec 14, 2013

Hey Portgrinder. Thats interesting.Maybe I wasted a bunch of time on my
T-stat. Where and how are you taking your temp reading?

dhdey · Dec 14, 2013

portgrinder said:
Don't need one. Its a myth.

I run no t-stat on my kx500af and temps are 120-140F in all conditions. Would actually like to get it colder.

have a hard time beleving that. on powdery days my cr500 with one rad would not stay over 100.

dhdey · Dec 14, 2013

Bigred1 said:
Ill try that and see if it works. the first radiator may never let enough hot water up there before it overheats but its worth a try.

thats why you drill it. it will work and it will keep you temps more consistant

Bigred1 · Dec 14, 2013

dhdey said:
thats why you drill it. it will work and it will keep you temps more consistant

I will have the bike finally running tomorrow and see how warm it stays for a couple rides, then decide what to do from there.
So far your idea seems to be the only thing that can work with the limited space.

summitboy · Dec 15, 2013

I think the KX and the CR are different beasts when it comes to temps etc. my CR will barely get to 110F in the powder. On the trail it can get warm goin up the trail. I have seen 180F. Even if you see 120F at the top of the head with no stats you are still getting a cooler temp at the bottom. You will have some shock cooling for sure. Im not a big fan of the holes in the stats with a bypass. I think thermobob has the right idea with sealed stats and bypass. Will know very soon !

DieselTwitch · Dec 15, 2013

I think you might do good with a 2T in the powder but in the tress you're going to trench bad!!!

portgrinder · Dec 15, 2013

ravenous said:
Hey Portgrinder. Thats interesting.Maybe I wasted a bunch of time on my
T-stat. Where and how are you taking your temp reading?

Right out of the head with one of those in line sensors everyone sells these days

Trees, powder, trail doesn't matter. Stays nice and even.

I run no t-stat on everything. Be surprised how much better it all works. I think they cause 1/2 the problems they try to solve with open/closing too quickly.

If I ever need to adjust temps I use restrictions inside the rad hoses. Use a smaller piece of pipe shoved inside ect. Fine tune till you got it nailed.

summitboy · Dec 15, 2013

DieselTwitch said:
I think you might do good with a 2T in the powder but in the tress you're going to trench bad!!!

Why do you figure that ? My 500 is a rocket in the trees ! Gets up on the snow fast and doesn't get stuck LOL. Almost two fast in the trees in 3rd on the pipe ha ha.

I think the trick with the tstats is proper bypass which almost no one has. You need constant temps whether its a 2 or a 4. I agree that single in out stats do open and close to fast and add to shock cooling. Also I have been thinking about the pressure a fair bit as well.

I see some guys who have used the Thermobob in the 4 stroke app, have gone from unstable temps (big fluctuations) to perfect stable temps moving only a few degrees. The guys running the KTM stats with bypass seem to have issues and end up plugging the bypass off.

Portgrinder it seems like yours is the only 2T that I have seen that runs nice and warm without stats so far. The nice thing about the 2 stroke is they can take the cooler temps. I know some ice racers that ran no stats and ended up cold seizing some engines on 2T 500's because they had no stats. They do move faster though. Maybe I'll yank the stats for my next trip and see what happens. Would be interesting. I think having perfect jetting and a clean intake is probably more important than temps. Unless your a 4 stroke LOL

2 stroke builds

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