Ive had this bike for almost a year and the pipe turned blue almost from the day i bought it. My question is my jetting off and its runing lean? If reading the plug makes a difference it almost looks a little to rich to me. I almost only ride tracks and always mixed 40:1 with maxima super M. Is the stock pipe made of cheap metal and would a after market pipe hold up from rocks better. The front of my pipe looks like the moon with all the rock dents in it. Thanks for any help.
08 250sx pipe turning blue?
Started by kevb312, May 16 2009 04:00 AM
12 replies to this topic
Posted 16 May 2009 - 04:00 AM
Ive had this bike for almost a year and the pipe turned blue almost from the day i bought it. My question is my jetting off and its runing lean? If reading the plug makes a difference it almost looks a little to rich to me. I almost only ride tracks and always mixed 40:1 with maxima super M. Is the stock pipe made of cheap metal and would a after market pipe hold up from rocks better. The front of my pipe looks like the moon with all the rock dents in it. Thanks for any help.
Posted 16 May 2009 - 10:57 AM
kevb312 said:
Ive had this bike for almost a year and the pipe turned blue almost from the day i bought it. My question is my jetting off and its runing lean? If reading the plug makes a difference it almost looks a little to rich to me. I almost only ride tracks and always mixed 40:1 with maxima super M. Is the stock pipe made of cheap metal and would a after market pipe hold up from rocks better. The front of my pipe looks like the moon with all the rock dents in it. Thanks for any help.
Yes the stocker is thin...I have heard guys on here last 2-10 months with the stocks before it is riddled too much. PC II is good and so is the FMF Gnarly...much more stout. I am still on my stock pipe the PO never used it so we will see how long it lasts me.
Posted 16 May 2009 - 04:06 PM
If the plug looks good then youre good to go. Turning the pipe blue just means youre riding it hard - sweet.
Posted 16 May 2009 - 04:53 PM
Thanks guys, all my buddys tell me its too lean but with 40hrs on it i think it would have blown by now. I dont wanna go with the gnarly because of the lack of topend. I was looking at the fatty or the sst. Does anyone know if i need an fmf silencer with the sst pipe? And are they made with thicker metal? Thanks for the help
Posted 16 May 2009 - 05:32 PM
kevb312 said:
Thanks guys, all my buddys tell me its too lean but with 40hrs on it i think it would have blown by now. I dont wanna go with the gnarly because of the lack of topend. I was looking at the fatty or the sst. Does anyone know if i need an fmf silencer with the sst pipe? And are they made with thicker metal? Thanks for the help
The best way to read the plug is by doing a plug chop...
Install a new plug into a warm engine.
Run the bike quickly up to wide open throttle in 3rd gear and then chop the throttle and kill the engine.
Pull the plug and examine the insulator.
You're looking for an even brown color.
Black soot and oil indicate a rich condition.
Light tan to white indicate a lean condition.
Sputtering down low can be corrected with the Air Screw. A good starting point is 1.5 turns out form all the way in.
Adjust idle after you have you've made changes to correct the lean or rich condition.
I have the stock pipe on my '08 300 XC-W...I also have an FMF fatty which is a little more durable than the stocker. The Fatty fits with the stock silencer. The SST will not work with the stock silencer without some trimming.
The Fatty is a good pipe. I just pulled it off and put the stocker back on because I bashed up the Fatty to the point where it needs to be fixed...again. Damn 2-stroke pipes...they get beat up eventually.:smirk:
Don't give up yet. It's worth the carb tinkering.
-Jay
Posted 20 June 2009 - 06:00 PM
anyone else on the blue pipe? mines turning bluish purple for the first couple inches out of the head. does it really mean anything or should i not worry about it? thanks
Posted 20 June 2009 - 06:29 PM
you guys with the blue pipes definitely need to work on your jetting . A 2 stroke shouldn't be running that hot .
Posted 22 June 2009 - 10:30 AM
Jays07WR450 said:
The best way to read the plug is by doing a plug chop...
-Jay
-Jay
Plug chops are actually pretty useless these days due to additives in modern fuels.
The proper way to jet a 2 stroke is to use what is called the "Wet Line Method". Basically involves pulling the expansion chamber and measuring the distance the 'wet line' is from the piston. If the wet line is too far from the piston the engine is rich. Too short however indicates to lean.
Look it up on ktmtalk in the 2 stroke forum if you don't know what it is.
Posted 22 June 2009 - 12:49 PM
PSD_Sun said:
The proper way to jet a 2 stroke is to use what is called the "Wet Line Method". Basically involves pulling the expansion chamber and measuring the distance the 'wet line' is from the piston. If the wet line is too far from the piston the engine is rich. Too short however indicates to lean.
Look it up on ktmtalk in the 2 stroke forum if you don't know what it is.
Look it up on ktmtalk in the 2 stroke forum if you don't know what it is.
Can´t find it at ktmtalk but would like to know more about it. Do you have a link or more info?
Posted 22 June 2009 - 02:29 PM
Dread said:
Can´t find it at ktmtalk but would like to know more about it. Do you have a link or more info?
http://ktmtalk.com/i...showtopic=41083
Posted 17 May 2011 - 03:41 PM
OK - all of you guessing on this need an education!
Pipe turning blue is from one of two things!
1. un-burned fuel burning off in the pipe from a rich condition.
2. Running wide open (long hill climbs) for 90 seconds or more!
Neither of these will damage a motor!
The pipe running hot from un-burned fuel burning off in the expansion chamber does NOT mean the engine is running hot.
Even perfectly jetted bikes will turn a pipe blue if run wide open long enough. If you take a propane torch and heat your pipe for 10 seconds it will not do much, take the same torch and hold it there for 90 seconds and it will be glowing red/white! Same thing with your engine. What do you think is coming out for exhaust??? A FREAKIN TORCH!!!!!
Now for the rest of you and your jetting guesses and opinions!
The only bit i have read here that was somewhat accurate was the plug color/ throttle chop. GREAT way to see if you MAIN jet is close or not at wide open throttle. This has nothing to do with any other throttle position.
Jetting sequence:
start from wide open throttle and work backwards.
wide open throttle is the main jet only.
Get 4 new plugs
run it wide open through all gears, pull in clutch and kill engine with stop switch. Pull out your plug and check the color. you are looking for a light to medium chocolate brown. If the plug is to light increase the size of the main jet. If plug is to dark decrease the size of the main jet. Repeat until proper color is reached.
Now we are going to work on the proper idle/quarter throttle position.
First get the bike to idle the best you can.
The bike should idle clean and at a normal low rpm.
If it doesnt, adjust the air mixture screw in to 1/2 turn out from seated, if it runs better and your throttle response is perfect your idle/pilot jet is too lean. Increase the size one jet size. Turn air screw out to 1 1/4 - 1 1/2 out. Then find where the throttle has the cleanest response from 1 1/4 out to 2 turns out.
If the bike runs better at 2 1/2 to 3 turns out you are to rich, decrease the pilot jet one size. Then turn air screw out to 1 1/4 - 1 1/2 out. Then find where the throttle has the cleanest response from 1 1/4 out to 2 turns out.
Now for the mid-range throttle 1/4 to 3/4 - this is adjusted by the carb slide needle clip position. MOST STOCK NEEDLES WILL NEVER PERFORM PERFECT OR WELL! JD needles are great! They always have the right taper!
If you hit the throttle and the power completely falls on its face then comes on strong you have a lean condition. Move your e-clip on your needle down one position, this raises the needle up and gives more fuel delivery at that throttle position. Repeat if nesessary.
If you hit the throttle and it accelorates but is choppy and studders you have a rich condition and you need to move your e-clip up on the needle thus dropping the needle down. This will deliver less fuel at that throttle position. Reapeat if nessesary.
Just a Note - KTM's have the worst stock needles out of all makes! I own 3 and have worked on 100's of them.
Pipe turning blue is from one of two things!
1. un-burned fuel burning off in the pipe from a rich condition.
2. Running wide open (long hill climbs) for 90 seconds or more!
Neither of these will damage a motor!
The pipe running hot from un-burned fuel burning off in the expansion chamber does NOT mean the engine is running hot.
Even perfectly jetted bikes will turn a pipe blue if run wide open long enough. If you take a propane torch and heat your pipe for 10 seconds it will not do much, take the same torch and hold it there for 90 seconds and it will be glowing red/white! Same thing with your engine. What do you think is coming out for exhaust??? A FREAKIN TORCH!!!!!
Now for the rest of you and your jetting guesses and opinions!
The only bit i have read here that was somewhat accurate was the plug color/ throttle chop. GREAT way to see if you MAIN jet is close or not at wide open throttle. This has nothing to do with any other throttle position.
Jetting sequence:
start from wide open throttle and work backwards.
wide open throttle is the main jet only.
Get 4 new plugs
run it wide open through all gears, pull in clutch and kill engine with stop switch. Pull out your plug and check the color. you are looking for a light to medium chocolate brown. If the plug is to light increase the size of the main jet. If plug is to dark decrease the size of the main jet. Repeat until proper color is reached.
Now we are going to work on the proper idle/quarter throttle position.
First get the bike to idle the best you can.
The bike should idle clean and at a normal low rpm.
If it doesnt, adjust the air mixture screw in to 1/2 turn out from seated, if it runs better and your throttle response is perfect your idle/pilot jet is too lean. Increase the size one jet size. Turn air screw out to 1 1/4 - 1 1/2 out. Then find where the throttle has the cleanest response from 1 1/4 out to 2 turns out.
If the bike runs better at 2 1/2 to 3 turns out you are to rich, decrease the pilot jet one size. Then turn air screw out to 1 1/4 - 1 1/2 out. Then find where the throttle has the cleanest response from 1 1/4 out to 2 turns out.
Now for the mid-range throttle 1/4 to 3/4 - this is adjusted by the carb slide needle clip position. MOST STOCK NEEDLES WILL NEVER PERFORM PERFECT OR WELL! JD needles are great! They always have the right taper!
If you hit the throttle and the power completely falls on its face then comes on strong you have a lean condition. Move your e-clip on your needle down one position, this raises the needle up and gives more fuel delivery at that throttle position. Repeat if nesessary.
If you hit the throttle and it accelorates but is choppy and studders you have a rich condition and you need to move your e-clip up on the needle thus dropping the needle down. This will deliver less fuel at that throttle position. Reapeat if nessesary.
Just a Note - KTM's have the worst stock needles out of all makes! I own 3 and have worked on 100's of them.
Posted 20 May 2011 - 06:56 AM
gbmorph76 said:
OK - all of you guessing on this need an education!
Pipe turning blue is from one of two things!
1. un-burned fuel burning off in the pipe from a rich condition.
2. Running wide open (long hill climbs) for 90 seconds or more!
Neither of these will damage a motor!
The pipe running hot from un-burned fuel burning off in the expansion chamber does NOT mean the engine is running hot.
Even perfectly jetted bikes will turn a pipe blue if run wide open long enough. If you take a propane torch and heat your pipe for 10 seconds it will not do much, take the same torch and hold it there for 90 seconds and it will be glowing red/white! Same thing with your engine. What do you think is coming out for exhaust??? A FREAKIN TORCH!!!!!
Now for the rest of you and your jetting guesses and opinions!
The only bit i have read here that was somewhat accurate was the plug color/ throttle chop. GREAT way to see if you MAIN jet is close or not at wide open throttle. This has nothing to do with any other throttle position.
Jetting sequence:
start from wide open throttle and work backwards.
wide open throttle is the main jet only.
Get 4 new plugs
run it wide open through all gears, pull in clutch and kill engine with stop switch. Pull out your plug and check the color. you are looking for a light to medium chocolate brown. If the plug is to light increase the size of the main jet. If plug is to dark decrease the size of the main jet. Repeat until proper color is reached.
Now we are going to work on the proper idle/quarter throttle position.
First get the bike to idle the best you can.
The bike should idle clean and at a normal low rpm.
If it doesnt, adjust the air mixture screw in to 1/2 turn out from seated, if it runs better and your throttle response is perfect your idle/pilot jet is too lean. Increase the size one jet size. Turn air screw out to 1 1/4 - 1 1/2 out. Then find where the throttle has the cleanest response from 1 1/4 out to 2 turns out.
If the bike runs better at 2 1/2 to 3 turns out you are to rich, decrease the pilot jet one size. Then turn air screw out to 1 1/4 - 1 1/2 out. Then find where the throttle has the cleanest response from 1 1/4 out to 2 turns out.
Now for the mid-range throttle 1/4 to 3/4 - this is adjusted by the carb slide needle clip position. MOST STOCK NEEDLES WILL NEVER PERFORM PERFECT OR WELL! JD needles are great! They always have the right taper!
If you hit the throttle and the power completely falls on its face then comes on strong you have a lean condition. Move your e-clip on your needle down one position, this raises the needle up and gives more fuel delivery at that throttle position. Repeat if nesessary.
If you hit the throttle and it accelorates but is choppy and studders you have a rich condition and you need to move your e-clip up on the needle thus dropping the needle down. This will deliver less fuel at that throttle position. Reapeat if nessesary.
Just a Note - KTM's have the worst stock needles out of all makes! I own 3 and have worked on 100's of them.
Pipe turning blue is from one of two things!
1. un-burned fuel burning off in the pipe from a rich condition.
2. Running wide open (long hill climbs) for 90 seconds or more!
Neither of these will damage a motor!
The pipe running hot from un-burned fuel burning off in the expansion chamber does NOT mean the engine is running hot.
Even perfectly jetted bikes will turn a pipe blue if run wide open long enough. If you take a propane torch and heat your pipe for 10 seconds it will not do much, take the same torch and hold it there for 90 seconds and it will be glowing red/white! Same thing with your engine. What do you think is coming out for exhaust??? A FREAKIN TORCH!!!!!
Now for the rest of you and your jetting guesses and opinions!
The only bit i have read here that was somewhat accurate was the plug color/ throttle chop. GREAT way to see if you MAIN jet is close or not at wide open throttle. This has nothing to do with any other throttle position.
Jetting sequence:
start from wide open throttle and work backwards.
wide open throttle is the main jet only.
Get 4 new plugs
run it wide open through all gears, pull in clutch and kill engine with stop switch. Pull out your plug and check the color. you are looking for a light to medium chocolate brown. If the plug is to light increase the size of the main jet. If plug is to dark decrease the size of the main jet. Repeat until proper color is reached.
Now we are going to work on the proper idle/quarter throttle position.
First get the bike to idle the best you can.
The bike should idle clean and at a normal low rpm.
If it doesnt, adjust the air mixture screw in to 1/2 turn out from seated, if it runs better and your throttle response is perfect your idle/pilot jet is too lean. Increase the size one jet size. Turn air screw out to 1 1/4 - 1 1/2 out. Then find where the throttle has the cleanest response from 1 1/4 out to 2 turns out.
If the bike runs better at 2 1/2 to 3 turns out you are to rich, decrease the pilot jet one size. Then turn air screw out to 1 1/4 - 1 1/2 out. Then find where the throttle has the cleanest response from 1 1/4 out to 2 turns out.
Now for the mid-range throttle 1/4 to 3/4 - this is adjusted by the carb slide needle clip position. MOST STOCK NEEDLES WILL NEVER PERFORM PERFECT OR WELL! JD needles are great! They always have the right taper!
If you hit the throttle and the power completely falls on its face then comes on strong you have a lean condition. Move your e-clip on your needle down one position, this raises the needle up and gives more fuel delivery at that throttle position. Repeat if nesessary.
If you hit the throttle and it accelorates but is choppy and studders you have a rich condition and you need to move your e-clip up on the needle thus dropping the needle down. This will deliver less fuel at that throttle position. Reapeat if nessesary.
Just a Note - KTM's have the worst stock needles out of all makes! I own 3 and have worked on 100's of them.
In the 2 years since this thread existed...we figured it out.:smirk:
Nice dredge from the dead threads.:rolleyes:
Posted 20 May 2011 - 07:13 AM
gbmorph76 said:
MOST STOCK NEEDLES WILL NEVER PERFORM PERFECT OR WELL! JD needles are great! They always have the right taper!
Just a Note - KTM's have the worst stock needles out of all makes! I own 3 and have worked on 100's of them.
Just a Note - KTM's have the worst stock needles out of all makes! I own 3 and have worked on 100's of them.
I disagree. There are a bunch of stock needles that work better than the JD needles. The stock needles may not perform perfect, but I doubt any needle will. However, the stock needle that I am running right now is d@mn near perfect.
That's possible. A few guys on KTM Talk are trying some of the Jap OEM two stroke needles with good results.
