In my ongoing quest to get this thing running 100% again, I have another question.. (I know, taking a stab at this one day a month doesn't help but..)

My bike only idles with the idle speed screw turned all the way in, but only at around 800- 1000rpm. Stutters a bit off idle. Haven't run it on the road yet so I'm not sure of the behavior beyone garage throttle blips..

Also, It wouldn't start with the idle speed screw in, it had to be way out to start.

So something's not right with the .. slow air screw.? (screw w.spring behind the intake horn) damn the terminology, every place I check has different names for each of these things. anyway.. idle circuit is off somehow.



any initial thoughts? As of today, I've got a fresh battery and fresh gas in the tank, the carb has been completely cleaned... And damn this FCR35 is a total bitch to take out and put in.... mm clearance to the starter, mm clearance to the exhaust.

thanks for any thoughts guys. Gotta get it running reliably enough, then I'm sending it down to a shop.
~Steve

 

I'm going to try and help you the best I can, but someone else should confirm what I say here. The issue is with your pilot jet. I would take the jet out and blow some compressed air through it to make sure that it is clean and clear. After doing this, turn your fuel air screw approximately 720 degrees out from the carb(2.5 turns). It just sounds like something is clogged with your pilot jet. If you can rev the bike up and it sound normal, that's the only thing I can think of.

 

Thanks Jhoffy...

Well, it starts nice and easy (when hot) and runs well (as it always has) A slight stumble/miss around 4k, pulls hard up to 8k or so. Will pop once or twice on decel at around 6-7krpm.. Quickly settles right at around 1200 rpm idle. (with the idle speed screw all the way in)

We'll see how it starts tomorrow (when cold)

~Steve

 

Info for FCR35 carb, spec sheet from jerry @ FSW for a klx250s. He ran it on his personal bike before delivery.
Jetting for 350 kit (sea level altitude) in my signature.

 

Race gas, - thanks alot!!!!!

I have a sheet here, from the guy who sold me the bike a few yrs ago. Apparently, the FCR came from a KLX300. The sheet says "Stroker Jetting Specifications"
Here's what it says:
KLX300
1997-2002
300cc bore
35mm FCR

5000-6000' elevation
Pilot #48
OCDVR needle, 3rd clip from top
162 main
1.5 fuel screw out
air screw -
main air jet 200
Pilot air jet 1.25 out
plug stock or CR8VX

NOTES: Use hot start system, Remove airbox lid.


It ran fine when I got it as a 250, It still runs well, but not perfectly as a 340. I am at sea level or 100' up, (NJ) have a full KLX300 stock exhaust and my airbox lid is drilled / no snorkel. I have a hot start system installed. The previous owner lightened the flywheel.

Hard to start when cold, easy when hot, and my idle speed screw needs to be all the way in for a 1200 or so idle.. It runs very strong all the way up to WOT, with a pop or two if I chop the throttle closed. There is a slight stumble or miss if I hang around at 4000 rpm, nowhere else.
I'd like it to start easier from cold, and get rid of the stumble and pop if possible........



If anything stands out as the cause of the stumble, or my out of whack idle speed screw setting, exhaust pop.. then please let me know, I'll give it a shot. otherwise, I'm riding it down to someone with a dyno and pony up $$. I really want to know that this is running right.

thanks alot!!

~Steve
(And I see we're running the same exact tire setup. Parker DT-Awesome DOT tire!!)

 

The only thing that stands out is the 48 pilot jet. I'd try a 50 to start with since your altitude is close to sea level. To make your life easier dialing it in call for a FSW adjustable fuel screw (similar to the kouba fuel adjusting screw/whatever its called), that way your not pulling the carb to make the adjustment as you know it sits right over the starter making it impossible to get a screwdriver in there. The 162 main sounds a little optimistic, but if it works for your bike thats great.
Like everyone says make one change at a time, determine if it helped or not. Write it down for future reference. Good Luck

 

This FSW adjustable screw you speak of... where can I find one? Do you have a pic of on on the bike for me? Coz I cannot see where the space is to be able to fit something like that on the FCR on my bike as there is only a few mm clearance between the bottom of the carb and the starter motor. If there is a product that works though I want it!

 

I just called Jerry and asked for two of them. Left a message there might be another person asking for one. The room for adjustment is tight but a long pair of needle nose pliers does the trick. I had to dimple the FMF header to make room to fit the fcr...you can see the brass hex sitting above the rubber boot for the electrical wire on the starter. good luck

 

Revtor did original owner have to do the taffy mod? Look at Arctras' first pic it shows a black collar on the fuel pump rod, no rubber boot on the rod. I didn't have to install the taffy mod as it runs great w/o it. Read up on the taffy mod at Planetklx.com...

 

It's actually a BLUE collar To be honest, I have not played with it enough to get it working right. It's one of the things on my "to do" list for this carb. It's just taking it off and putting it back on is such a mission that I have been avoiding it