Ktm 250sx with 300 barrel

I'm setting up my 250sx (300barrel) to run more like a 300EXC. I have installed the green power valve spring. I'm having spark plug trouble. The 250sx (BR8ECM)standard plug is a colder plug than the 300.(BR7ES) because the 250sx engine is assumed to be revving at high revs more often than the 300exc it produces more heat. it runs a colder plug to reduce the risk of overheating.

I'm considering running the 300exc plug. Has anyone done this experiment?

Just run the BR7. It makes little to no difference....

Spot on mate. Problem solved running the br7 now

  'it runs a colder plug to reduce the risk of overheating.'


your theory is rediculous. if that were true everyone would use #10 and be done for ever with boiling issues :lol:

Edited by harryhandshake

Heat Range

Controlling the operating temperature of the plugs firing tip is the single most important factor in spark plug design. Heat range is the relative temperature of the spark plugs core nose, and it is determined by the length and diameter of the insulator tip, as well as the ability of the plug to transfer heat into the cooling system. A cold plug transfers heat rapidly from its firing end into the cooling system and is used to avoid core nose heat saturation where combustion-chamber or cylinder-head temperatures are relatively high. A hot plug has a slower heat transfer rate and is used to avoid fouling under relatively low chamber or head temperatures. Whats confusing is that a hotter (higher performance level) engine requires a colder plug because more power equals higher cylinder temperatures.

Read more: http://www.carcraft.com/techarticles/spark_plugs_tips/#ixzz2npTGcsgv

Harry hand tugger. Before you throw your uneducated opinions around log on to the NGK website and read about spark plugs and how they operate

whoops wrong post...sorry

Edited by Lmiinch

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now