525 and maybe the 450's jetting problems

[Bonehead]

This is what I have found. The vent tube on the top right of the carb has a casting problem and is still solid. My new 525 would not run off choke. I made a big jet change and nothing changed. I took the vent hose off the top right and found it was still solid. I took a .078 drill and drilled it out and now it runs fine off choke.

I did change the main to a 185 and raised the needle one clip

 

[fremontguy]

Are you talking about the 2 hose fitting on the top right of carb near plastic pumper cover? 1 vent tube goes straight up and another comes out at 90deg. angle.

 

[Garyb]

Good work Bonehead

 

[Bonehead]

Yes fremontguy, it is the one that has a brass hose fitting on top and the casted one just under it. The casting was solid about 1/8" in.

 

[fremontguy]

I guess all is well with my 450 carb. Passage on the T fitting goes vertical up the side of carb, lower nipple(can I say that) is open.

 

[endoquest]

Hear, hear, just confirmed the problem with Bonehead. My 525E has the fitting drilled, it's an air intake vent, I think. It has to be drilled to the brass-fitted/vertical vent.
My bike runs GREAT (130 miles if test in woods and fire roads) with a 182 main and the needle at the 4th position (stock is 3rd). Elevation 0-2300 ft.
In my opinion, the stock jetting is closer than most people think. There are 7 clip positions on the needle and it's a LONG needle. Main should be a bit fatter and, ah heck!, why not fatten the pilot a notch too?!
Think of it this way, richen everything up one notch (main maybe two) and call it good.
Great job, Bonehead

 

[Garyb]

Hey Endo - does your 525 have a OBDVR like my 450 ?

 

[endoquest]

Uh oh, Garyb on an RFS. I'll have to switch classes next year!
Mine has an OBDVT, I believe, but I didn't confirm it when I had the needle out, silly me. What do you think of the boingers, Gary?
Bonehead's bike had an obvious problem, his headers were glowing red and his bike wouldn't even run. The stock jetting is lean but not THAT bad. Everyone should check the vent first and then start fattening. Like I said, mine runs great with a 182 and the needle in the fourth position from the top. I haven't fattened up the pilot but I'll try that soon. The bike starts right away also.

 

[angry jim]

Bonehead and Endo,
Are you guys planning on Reno this year? How the heck will I keep up on my little 200?

I'm making a b-line to the goat trails :thumb: .

 

[Bonehead]

Goat trails R us. I hope like h--- I can make it this year. I had a great time last year and hope to have the same this year As long as I dont loose a tranny 37 miles from home it should be a better one.

 

[Garyb]

I like the boingers Endo - I have resprung for my weight and this bike definately turns better than my 250. It seems to ride down a bit though, maybe because of the new top out springs. We are shut out of our riding areas because of the fire levels so I have not been able to get a final feeling for them. I did add 5mm preload to the fork and then replaced the 5mm with 2,5 mm after trying it. What was the outcome at the Washington enduro series ? Did you get the #1 plate ? The Devils Head race was awesome...tight trails.

 

[JC Soto]

Bonehead,

I have the same carburetor nighmare that you had. When the carb was stock, I was unable to run my bike without the choke on. I had to open the fuel screw 4 turns to get some idling going, but that just causes the needle to fall off (it's wrong). So I changed the pilot jet (slow idle jets) from 42 through 55, and it would still take about 3 turns of the fuel screw to get peak idling RPM's. So I took it apart down to the mid section of the carb and blew out all the circuits with compressed air and carb cleanner. When I disassembled the carb I did noticed that the midsection gasket was not seated properly. After this work the carb responded better to the 55 pilot jet. It only took 1 1/2 turns of the fuel screw to get peak RPM's (it is still wrong). This is a compromise, but I am not satisfied because these bike should run with a 42 or 45 pilot.

I did try other needles such as the EMN, and I am currently using an OBDVP on the #3 clip with a 170 main and stock air jets and exhaust. I live and ride at 8400' at about 80F and relatively dry air.

I did look for any clogged up vents, but I can close one at a time and blow through each one. This tells me that they are open.

At this point I have no idea on how to proceed, so any hints will be deeply appreciated. Thanks, JC

 

[endoquest]

Sorry everybody, it looks like the problem has NOT been solved yet. Boneheads bike is running hyper-lean again so the vent orifice(although defective) was not the real problem. We're thinking that it slowly allowed fuel back into the float bowl so the bike ran good for a little while after a long shut down. It might have something to do with the throttle position sensor too.
BH is going to check the float bowl level and if that doesn't work he's going to take the carb off his '00 520. That will tell us if it's the carb at all or not, could be ignition. Sorry about the premature solution. We will find the gremlin!
Angry Jim, I have been invited to New Zealand in Feb. If I don't go there I'm definitely up for Reno again. In the mean time, Jawbone Spanksgiving is right around the corner!
Gary, I like both ends of the bike so far. I still need to spend more time to break in the springs but it's really close. I have a slight mid-stroke harshness in the forks but I think I can sort it out with clickers and oil, valving seems good. I'm using all of my travel already and I'm at the stock compression setting. What a great bike out of the crate.
In the NMA enduro series, I cooked my rear brake about thirty miles into the last enduro and had to dnf, losing the championship in the process because my two closest competitors also dropped out. I'm bummed. Still might try to hit a D-36 enduro in October. Sounds like the Devils Head was good, alot of people snivelling about how hard it was. :whiner:

 

[Bonehead]

Sorry guys I thought I had this in the bag but not to be. I got home tonight, started the 525 and the same thing as befor so now I'm stumped.

This is what I have done.
Checked float bowl (Looks like the book)
Put the carb off my 00 520 0n the 525 (runs better but still lean)
Unplugged throttle position wires, ran it (slower throttle response)
Ran with wires connected (better response)

Could it be timing?

JC Soto I'm at sea level to 2000' 70F 80% humidity. You would think it would be rich at 8400' I think this is going back for the thirty day warranty and you know all they are going to do is put a 60 idle jet in it and say it's ok and it's not. This thing is going to be broke in on the airlift without ever riding it!

 

[JC Soto]

Bonehead,

I think Endoquest might be onto something about the throttle position sensor. I am currently on my 4th carburetor disassembly! This time I am bringing all the parts to work and cleanning it on a clean bench and checking the jet holes with a boroscope.

I tested the bike this weekend on dirt and asphalt to characterize its behavior. I ran my bike with the 55 pilot jet (PJ), DVP #3, 170 main jet (MJ), stock exhaust, 1 turn on the slow air screw, and stock main air jet. From 0 to 1/8 throttle, the bike felt fuel starved. It hesitated and misfired. When accelerated from 0 to 1/3 the bike accelerated predictably. It probably can be leaned out a bit through this range. From mid to WOT the bike is snappy and responsive.

Eventhough I am using a 55 PJ, the bike is hesitating at 1/8 throttle and the RPM's tend to increase when the bike gets hot. This makes me believe that there is not enough fuel going through the slow/idling circuit in the carb, why?

I did re-check the vent holes and I am positive that they are open. I also measured the float level at work using a comparator and they are set at 8.6mm. I will report the results of my next reassembly and setup. JC

 

[JC Soto]

Forgot to add that I have the pump squirt set at 1 second and the fuel screw at 1 3/4 turns with the 55 PJ. Should I try the 58 PJ? JC

 

[endoquest]

JC, my bike (525EXC) runs just fine with the stock 42 pilot, a little lean but very rideable. Something must be wrong in the slow idle/choke/pilot system. Check very carefully for blockage in any of those jets. It's GOT to be some sort of anomaly. My idea about the throttle position sensor is just a guess as well as the ignition itself. Maybe we should start looking at the numbers on our ignitions to see if there are differences. Keep us posted. Bonehead and I are leading a large torture ride this weekend and his bike needs to run well.

 

[JC Soto]

Endoquest,

I been closely inspecting the carb today, and the only anomaly that I could observe was in the mid section of the carb. After removing the midsection of the carb body and then remove the part that sits on the mid section (needle guide/slide alignment feature? Any body know what this part is called?) there is a small hole that is supposed to align with the PJ hole. These two parts did not align. I also observed that on this third piece, the through hole (.039" dia) was not fully centered on the casting feature. The drilled hole came out of the side of a boss feature. I imagine that this does not help the PJ flow because the exit orifice is half on the top of the boss, and half on the side. It also seemed to have some flashing on it. This is the tini hole that sprays into the carb throat. I used gage pins to measure the initial diameter (.039") and increased it to a 0.042" hole. I meticulously removed all the glue on the casing and gaskets and I am ready to install. The other thing I noticed is that the lower and upper body of the carb do not have particularly flat mating surfaces. As a matter of fact they seem somewhat warped! I guess that is why they need rubber gaskets to cover their tolerance manufacturing errors... Is it possible that I could have a vacuum leak from these mating surfaces?

I will take some pictures and document this work. If this rebuild works out, I can sned you the photos and explain better what I did. Keep you posted. JC

 

[JC Soto]

OK, I am back to square one! The carb rebuild did nothing for me. I installed a 48PJ with a OCEMN on #3, 165MJ, and stock air jets. Started the bike and it would not idle. I had to turn out the fuel screw about 4 to 5 turns! I replaced the pilot jet with a 55 and got away with 2 1/2 turns on the fuel screw. This is worse than before! At this point I am baffled... I am sending my carburetor back to the dealer and requesting them to either fixing it or replacing it under warranty! After putting more than 40 hours on this project I am ready to give up. Any suggestions? JC

 

[Katoum]

:ugg: Ater first break in ride on 450EXC European version (factory street legal kit)
it started to back fire when throttle closed and would not idle at all. Inspection revealed that the Idle mixture screw had fallen right out of carb. Prior to this happening bike idled perfect but no idea how many turn out it was. Replaced screw with one off dealers showroom, (great dealer) and at 11/2 turns it ran really lean, it was 31/2 turns before idle returned to previous smooth idle, however I could see it was already starting to vibrate out of carb, not enough spring tension. Changed from 42 to 48 pilot jet and it still took a little more than 3 turns out to obtain proper idle. This has me wondering if there is something else going on. Previous post went up to a 55 and still did not help. Has anyone else checked there fuel screw, at 3 turns it will vibrate out. The 03 carb is different design than 02 as pump is now housed internally, and fuel screw is visable from bottom side of carb, 02 was recessed in float, and hard to tell how many turns as custom made screwdriver and much patients due to lack of space between starter and float. Anymore findings or solutions, please post. Thanks :thumb:

 

[Motopainter]

I was thinking of selling my 02 CRF450 and buying a more enduro woods ready 03 KTM 525 or ?????

 

[flyinfinn]

if you have the time check the exhaust pipe. My friend bought in '99 new ktm 250 exc (street legal) and in stock condition it ran very bad. there were some junk in his silencer and in "headpipe" too. removing those helped a lot. but i'm just quessing...

 

[drehwurm]

Servus,

Lets try it a different way - maybe this checklist can offer a little help in pinpointing the problem.

A 55 pilot or 3 1/2 turns on the pilot screw is a clear sign for a problem - no matter how you put it! It seems obvious that we have a lean situation mostly affecting the pilot circuit here. Lean means too little fuel or too much air.

Too little fuel:

1) clogged pilot circuit: as the problem seems to affect more people, there may be a problem from production on some carbs!

2) as needles and pilot jets have been changed to no avail , only the needle jet (aka main nozzle or emulsion tube) could be the culprit. If too small (due to whatever reason) symptoms are the same like a wrong (too big aka lean) needle root diameter, which can cause exactely the problems described here.

Too much air:

3) maybe not a carb problem at all! Did anyone switch carbs to verify?

4) air leak: carb boot, carb housing, choke circuit, ...

5) pilot air jet: has not been mentioned so far. The PAJ is located beneath the intake bell just beside the main air jet. If not the corret size (should be a 100) or maybe missing at all (!!!) symptoms are like described.


Michael

 

[endoquest]

Cheeze whiz fellas, I don't know what to say. My first impression is that after all that work, maybe it isn't your carb. What a bummer. Try calling a bunch of dealers to find out if they've gotten similar complaints. A list is available on the KTM website. Maybe one of them can shed some light on your problem.
There is no doubt that this year's models are lean in stock setup, probably due to the 50-state emissions, but your situation is severe. Sit down and make some calls. I'll call some industry contacts here and see what I can find.
BTW, Boneheads bike ran fairly well this weekend, still lean but not "grenade" material. I changed my pilot to a 45, kept the needle in the 4th position down and kept the main at a 182, it runs great, really great.

 

[Katoum]

Rode 60 miles of fast and tight fire road today, and no complaints with the way the bike ran at all, carburated fine, with no apparent flat (lean) spots. Used Canadian 94 octane Cheveron which left the pipe a medium gray color. I placed a blob of silicone over mixture screw to prevent it from backing out of carb. I've heard that the bottom portion of needle may be to lean affecting pilot setting. I will be taking carb down again to make a note of all part numbers for needle, main, air primary and secondary so as to see if there any changes from my Euro, Australian spec to that of the American model, but my hunch from parts manual is that they are pretty much the same. I will post my finding, and maybe we will be able to solve the 3-4 turns out on the fuel screw problem. I would like to hear from other 450/525 owners how many turns out there fuel screw was as to form a concensus as to whether all the bikes are being sent out the factory this way.