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  #1  
Old 06-01-2016, 02:48 PM
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Unhappy KTM EXC 250 06 Runing very hot from all of a sudden??

     

Hello, @@@@@@@@@@@@@@@@@@PICTURES BELOW POST!!!@@@@@@@@@@@@@
*******************HEAT ISSUE SOLVED****************************
Straight to the point:

I did some work on my bike:

1) repacked silencer

2) sealed pipe properly to the cylinder (used fmf o'rings and high-temp silicone)
("Twisted pipes end a few milimeters to get a better seal")

3) Drained coolant and add refilled with same one.

4) Took of cylinders powervalve cover (front, "flange") put some silicone to work as a gasket and fitted it back. (Was leaking)

Thats it..
Now the PROBLEM:

Bike was always running cool and steady, now since everything is properly sealed and repacked no leaks occured (checked by spraying carb cleaner all around the areas of carburator boots all around the airbox, near the cylinder, spark plug)

From all of sudden pilot jet is way to rich (might be because the temprature riso to +25 celcius, summer ) Ran perfectly with the same setting last summer though.

Bikes pipe is getting really hot (changes colours) acts as if the catalyst converter was still in there. (we removed it a long time ago)
All around the whole engine, radiators are really getting hot.

I'm used to cool two stroke that a rode last summer, but this is the first time I sealed everything properly pipe wise and It's scaring me.
I rode it nicely and then pinned through all the gears (getting enough air to cool it down) for a while but still runs not reasonbly hot.
Spark plug is choco brown, mixture is almost PERFECT only pilot is a bit to rich (works better when I open up the air screw and smokes alot)

ANY IDEAS What I could have done to it or change anything?
Air bubbles in the coolant system??
I'm getting angry at this puzzle..

Last edited by Simonas; 06-04-2016 at 06:41 AM.
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Old 06-01-2016, 03:29 PM
2 stroke bloke's Avatar
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Do the 06 radiators have a bleeder valve? (Bolt in the top of the left radiator, Or. The side without the radiator cap).

If so, did you bleed the air out of the radiators? If it does have a bleeder bolt/valve, and you didn't bleed it, you will have air pockets in the cooling system.


EDIT: From what I can see on the 06 Flea Bay Radiators, looks like they do have a bleeder bolt. Take the bolt out of the top of the radiator, fill the system until water/coolant, comes out the top of the bleeder bolt hole. Then you will have forced all the air out.

Last edited by 2 stroke bloke; 06-01-2016 at 04:02 PM.
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Old 06-01-2016, 06:14 PM
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I agree, sounds like an air pocket in the cooling system.
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Old 06-01-2016, 06:17 PM
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Removing the cat will make it run lean.
You need to do a chop test to get a good plug reading.

Paw Paw
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Old 06-01-2016, 06:53 PM
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I am not familiar with a 2 stroke dirt bike having a cat in the pipe?? Anyhow, you may have plugged up some of the coolant passages in the cylinder if you applied too much RTV to that front plate. Just a thought.
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Old 06-02-2016, 11:17 AM
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Quote:
Originally Posted by PawPaw View Post
Removing the cat will make it run lean.
You need to do a chop test to get a good plug reading.

Paw Paw


Cat was removed a long time ago.
I guessed I could get a more accurate reading with a new spark plug..

---------- Post added at 09:10 AM ---------- Previous post was at 09:09 AM ----------

Quote:
Originally Posted by cowboyona426 View Post
I agree, sounds like an air pocket in the cooling system.

Today, I drained all of the coolant and added it with the bleeding screw removed, let it idle with opened radiator cap (for air to come out)
Still acted the same, was very hot.

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---------- Post added at 09:13 AM ---------- Previous post was at 09:13 AM ----------



---------- Post added at 09:14 AM ---------- Previous post was at 09:13 AM ----------



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---------- Post added at 09:17 AM ---------- Previous post was at 09:16 AM ----------

Strange enough I think the black silicone has burn't off from the cylinder cover part..
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Old 06-02-2016, 01:05 PM
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After seeing your photos....A couple of things stick out.
The exhaust silencer is dripping spunge. It could be soaked and interfering with exhaust flow creating excess heat.
The exhaust valve system is very dirty and gummed up.
Black silicone will burn off, but the Red holds up better.
Have you replaced the pipe gaskets and seals with OEM parts?
Have you done a plug reading ?
The engine sure seems to be way rich for some reason.

Paw Paw
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Old 06-02-2016, 03:50 PM
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Quote:
Originally Posted by PawPaw View Post
After seeing your photos....A couple of things stick out.
The exhaust silencer is dripping spunge. It could be soaked and interfering with exhaust flow creating excess heat.
The exhaust valve system is very dirty and gummed up.
Black silicone will burn off, but the Red holds up better.
Have you replaced the pipe gaskets and seals with OEM parts?
Have you done a plug reading ?
The engine sure seems to be way rich for some reason.

Paw Paw

I just repacked the silincer I guess I'll check it out to be sure..

The exhaust valve system is asking for a clean, but I'm scared to disassemble it, because I haven't tried it yet.

I used FMF pipe O'rings that go on the pipe's end (2 rubber rings)
Both rings are cracking and are in terrible shape after 2-3m/h of use.. disappointing

From my bike "feel" I can tell the pilot is way to rich (smokes and sometimes even bogs, even when air screw is 2,7 turns out) 42 pilot.
Mid-top is now very crisp and responsive, I upped to 165 main jet yesterday and It made a big difference up top, since It always used to scream wide open but lose lose power on the top, now It's perfect.

I bought a 40 pilot jet and gonna be trying that out, maybe the excess fuel that burns in the pipe itself creates the unwanted heat?

Gonna do a plug chop test with a clean spark plug as soon as I put it all back together.

Step by step I'll figure this heat problem!

*THANK YOU EVERYBODY FOR YOUR INPUT, ANY IDEAS ARE WELCOME AND APPRECIATED!
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Old 06-02-2016, 06:13 PM
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Quote:
Originally Posted by Simonas View Post
I just repacked the silincer I guess I'll check it out to be sure..

The exhaust valve system is asking for a clean, but I'm scared to disassemble it, because I haven't tried it yet.

I used FMF pipe O'rings that go on the pipe's end (2 rubber rings)
Both rings are cracking and are in terrible shape after 2-3m/h of use.. disappointing

From my bike "feel" I can tell the pilot is way to rich (smokes and sometimes even bogs, even when air screw is 2,7 turns out) 42 pilot.
Mid-top is now very crisp and responsive, I upped to 165 main jet yesterday and It made a big difference up top, since It always used to scream wide open but lose lose power on the top, now It's perfect.

I bought a 40 pilot jet and gonna be trying that out, maybe the excess fuel that burns in the pipe itself creates the unwanted heat?

Gonna do a plug chop test with a clean spark plug as soon as I put it all back together.

Step by step I'll figure this heat problem!

*THANK YOU EVERYBODY FOR YOUR INPUT, ANY IDEAS ARE WELCOME AND APPRECIATED!
It's pretty hard to do a chop test with a new plug. Hard to read the plug that is.
Much better to tune by feel and ear anyway IMO.

To me, the plug looks too lean if anything. Ie. It looks grey to me. Should be a nice chocolate brown.


Paw Paw. It's spooge mate. Spooge .
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  #10  
Old 06-03-2016, 02:39 AM
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Quote:
Originally Posted by 2 stroke bloke View Post
It's pretty hard to do a chop test with a new plug. Hard to read the plug that is.
Much better to tune by feel and ear anyway IMO.

To me, the plug looks too lean if anything. Ie. It looks grey to me. Should be a nice chocolate brown.


Paw Paw. It's spooge mate. Spooge .
True, the plug looks a bit leanish, but when I added 168 main jet on top from 165, the spark plug tip went black and it just wasn't pulling out wide open on top. (Not as good of a scream)
I'll update you this weekend on how she will be doing with a smaller pilot
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