KTM 300 EXC Sparkplug Problems

[ofi]

Hi you all,

I Just bought a KTM 300 EXC. My problem is that following the engine start after warmup when I'm starting to go the spark plug going dead. (4 starts, 2 sparkplugs dead). Please help!. I'm new at the 2 stroke thing (previouse XR600R) so I'm realy need the help. thanks

 

[DanAKAL]

ofi,

I expect that one of two things ois going on with your bike. Either it is jetted extremely rich or you have a significant amount of blow by from worn rings. I would look at both of these by doing an engine compression test and pulling off the carb and having a look at it.

There is probably more help available for you at www.ktmtalk.com

 

[Norman Foley]

I don't know about KTM's, but some bikes if it calls for a resistor type plug and you use a non-resistor type it will start and die the way you describe. NGK resistor plugs have "R" in designation, eg BR8E.

 

[JG614]

Ofi,

What year is your KTM? I had a '94 300exec that fouled plugs allot until I went to a leaner slide. otherwise It could be many things, such as oil mix ratio, bad ignition components(check spark plug cap.) to other carb problems (jets, floats/needle) hope this helps.


Later
Jeffro

 

[Maverik]

I had a problem with plugs as well and the advice that has been offered so far is great, but you will want to check the reeds as well. I went through compression checks, tuning the carb, changing premix, running different plugs, checking for crankcase seal leaks, basically the whole nine yards. After all of that i discovered i had very slight fraying on the reeds. After i changed them, the plug fouling problem went away.

This may sound kinda like a DUH suggestion, but make sure you clean the air filter. Im not sure about all of the other KTMs, but mine was super sensitive to filter condition.

 

[ofi]

I dont understand, what do you mean by "reeds"?

 

[pobit]

I have a 05 300EXC. the correct jetting is 35 pilot, N3EH #3 160 main. The correct plug is a NGK BR7ES. Check your float height as many are too high. The bike comes with a 6 month warranty. If you have had the bike for less than 6 months, take it back to the dealer. Your problem is not normal. My bike starts easily and runs clean. Dave

 

[Higgsy]

Ofi the reeds that Maverick mentioned are reed valves. They control fuel flow to the cylinder on a 2 stroke. It's located on the inside between carb and the cylinder it neads to be replaced once and a while. Boyeseen has been making aftermarket replacement reeds for years and are worth the money when compared to using stock ones. The throttle response is greatly improved when you switch to an aftermarket reed because they are a little more flexable and they open up easier to draw fuel from the carb into the cylinder. But if you have a new bike that isn't the problem the reeds will be fine. Look to carb adjustments to fix your plug problems.