Winter Mods - RB carb and head?

[D_Moen]

Seems like the riding season is done here in the Okanagan, so the bike is shiny'ed up and stored away for the winter. Over the summer I did some basic stuff like sorting out the jetting and tossing the airbox lid, installing some stiffer fork springs and doing the "shim stack mod".

I got an absolute steal on this bike that I'm OK with dropping a little dough on it over the winter. I'm thinking of sending the carb and head down to RB Designs for thier modifications and getting a steering damper. Are the RB mods good bang for the buck? My bike has the FMF torque pipe on it, would this pose a problem at all?

Thanks for your input!

 

[hart125]

just depends on the riding you do. If i was you I would leave that thing alone! its setup good for fun woods and slow speed enduro. I'm sure its a torque monster,, if you were doing a lot more high speed enduro racing or fast trails you could make some changes but Id just go with a different bike then. I know you can get better top end out of it but then you will want to do something about the suspension. that pipe won't work well with the rb bored carb either because that opens up the top end and the pipe won't breath well on top revs.
theres a lot of fork flex for a damper to work well so you need a fork brace or a kx conversion front forks, I wouldn't do that either. the best bang for the buck has been done on that bike IMHO

 

[know_fear]

Ron's mods for the PWK carb include 4 basic alterations.
1 Larger bore size.
2 Install divider plate, notch jet screen.
3 Clean up pilot circuit.
4 Lean out slide cutaway.
It's true that with the torque pipe you may not feel the full benefit of the larger bore but the other 3 changes allow you to more easily tune the carb for max torque right from idle.
If you're not afraid of getting into jetting, do it. The wider powerband will be amazing. Throw on a rev pipe and it'll scream as well.

 

[karlp]

I've got both done, head and carb.
Well worth it, best running two stroke I've ever had.

Biggest bang for the buck: head work only, c'mon it's only $45 US.

I don't think Ron ships international, though.

 

[D_Moen]

Maybey I'll just work on getting the jetting cleaned up a bit more. After a ride on a pal's KTM 300 I see myself headed in that direction in the not too distant future. The green meenie will make a great second bike for my kids!

What I really want is a cleaner pull from the bottom end. I am running a 42 slow jet, 145 main with the clip on the needle in the second from top position, I have no idea if this is the stock needle or not, I assume so as the bike came to me with the factory tires on it! Most of my riding is in pretty steep, rocky, rooty terrain so I am usually riding in 1-3rd gears. My plug is black and slightly oily when I pull it out generally. I run 40:1 mix. In the summer I run the air screw about 3 turns out to get decent throttle response.

Should I try a smaller L/S jet and/or change the needle?

Thanks!

 

[John Harris]

Smaller L/S jet will do wonders for you. Do this first, then the needle if you like. John

 

[stevewr450f]

I would highly recommend using Ron Black. Get him to modify the carb and port your head. You will be amazed at what that engine can do. He has done work on my 2 kdxs and they both turned out great. I had had 2 friends ride my bike - they both have 250 2 smokes. We all agree that the modified KDX do as well if not better than the 250 2 smokers. One was KTM the other RM. The KDX after getting modified will get pulling so down low that its very difficult to stall and makes great traction.

The other mod you will want to eventually do is get some USD forks. Makes a huge difference. This is a good website but more info available at KDXRider.net

Good luck.