I am currently searching for a fcr 35 carb, and could use some info about the jetting. The carb would be going on a 09 klx250s modded with the basics - pipe filter free mods. Carb is off a drz350. Anyone have a baseline to start out with jetting wise? Thanks in advance.

 

I'm just guessing from what I have used with my FCR35 on my 300 and 331. For a 250, probably a 150 or 152 main and 50 or 52 on the pilot jet. I would start the needle on the 3rd clip. I think those settings would be a good base but may also change depending on what number/taper needle you have as well.

Hopefully someone that has an FCR35 on a 250 will chime in on there specs.

 

Can anyone experienced w/ the fcr 35 give a suggestion as to what number needle to run on the 250?

Thanks

 

here's my current setup @ 300cc's.(most numbers should be close to what I am running, I may have done some small changes that I forgot to write down) Fuel screw setting is around 1-1.5 for summer. I also had someones 250cc settings written down. All numbers were the same as my current ones with the exception of the fuel screw at .5 and the pilot air jet at .75 You may also not have a screw type adjustable air jet. It may have a fix jet that needs to be changed to alter size(like a main jet)
148 main
48 pilot
4th position on clip
f/s 2.5
200 main air jet
pilot air jet 1.5
OCDVR needle.

That setup is ridable, but no way in complete tune. I still have a bog down low when I really crack on it at very min rpms. There is also a lean spot around 1/8 throttle maybe a little more. I probably need to go with a different needle to richen it up a little more in that range. I have 3 tips of advice for you:

Tip 1- Give Dean a call at R&D and order one of his "flex jet" adjustable fuel screws. You need to cut a little bit off the bottom of the bowl where the fuel screw goes in, but you will get an adjustable fuel screw that you don't have to take the carb off the bike to adjust. Its like the idle adjust with the long flexible shaft.

Tip 2- Do the taffy mod with the collar or get a setup like this to limit the a/p squirt. I made this one for my bike.







Tip 3- get good at taking the carb on and off of the bike. You will be doing a lot of it until you get it dialed in.

 

Nice aluminum bracket your using with the adjuster. Sweet. I also noticed the clamp for your idle adjuster, since mine was missing.

The suggestion for the 'flex jet' is appreciated. Keywords 'ease of adjustment' for dialing it all in.

Thanks for the tips.

Can you post a pic of the entire carb so I can check intake bell lengths- airbox and intake sides. It appears that I may need different length ones.

 

RaceGass, I went through that process too with my FCR. The parts are available from Sudco, these are the items I purchased:

021-216A airbox adapter.
020-462 spigot (between carb and engine). ID mark 894

Note that these fit my Aus spec KLX, I believe US spec KLXs might have different sized airbox openings and different sized intake boots on the engine head.

My FCR is jetted:
58 pilot
145 main
OCDVR needle on 2nd clip.

I think it's a little rich, it certainly is at idle. I need to see if it needs a smaller pilot. I wonder also if it's a little lean above quarter throttle, it seems to run hotter than the CVK I had on prior. FWIW I've got a Bill Blue 331, no airbox lid, 300 header, FMF Powercore muffler.

Good luck


EDIT: After looking at the pic of your carb, it looks the way mine was prior to my meddling - short spigot and long airbox adapter. This will require you to grind the engine mount away at the frame. Using the spigot and adapter I listed above moves the carb back toward the airbox about 15mm, giving clearance from the frame. It's still tight, but better. I'll tell you now, the performance gain you'll get is well worth it.

 

My settings which worked very good with a 300 jug were 155 main, 52/55 pilot, OCDVR needle, 3rd clip, fuel screw out 1.5-2. In experimenting I dropped down as low as 150 on the main and 48 pilot, with different combinations in between and the above settings seems to work great. It is also very close to how FSW sets them up for the 300.

 

Thanks for all the jet specs. I am ordering the spigots for sure and a range of pilot jets 50-58 and the ocdvr needle. The mains look like the 2 strokes mains I already have. Going to go to a r/c hobby shop for the a/p rod stopper, or look for a drill bit stop for the taffey mod.

Is 1 second for the a/p squirt and 200 main air jet/1.5 pilot air jet a constant for all applications?

Muchos Gracias, Mike

 

1 sec is pretty universal for a/p squirt. I don't know about the main air jet. You may not have a screw for the pilot air jet, it may be just a brass jet that has to be changed for a different one to make adjustments(like a main jet). Some of the 35's didn't have the screw. Take the intake bell off and its under it.

Mike, Jerry custom machines the inlet or outlets(maybe both) for the 250s. I don't know if I would totaly trust the sudco numbers that kbekus gave you for the US spec 250s installation. I remember that the AUS. spec bikes had a different boot than ours.

If I were you I would give jerry a call and see what he would charge to go over the carb and set it up for the for the 250s. It might actually save you some money in the long run.

 

Here's some pics of the inlet and outlets I had on photobucket for some one else a whille ago. Hope they might be of some help.

I think the pilot air is on the left and main air on the right.