Benefits of a 'Hotter' Spark Plug

[Oregon250]

I fouled a plug from running a bit rich on my KTM 200 and one of my buds suggested running a hotter plug? Not familiar with these at all. What does that mean to have a hotter plug and would it benefit me? Thanks!

[timmyp8823]

The thing that would benifit you the most would be to spend some time playing with your jetting. That's the real fix.

[ktmfred300]

Jetting is key. Also run a good oil something full syn. that would burn cleaner. Its not a 1975 DT 250. You could run the risk of a hole in the piston with a hotter plug if you ran it at high Rs for a long period of time.

[jersey_devil]

The above replies are correct. A hotter/colder plug refers to nothing more that the tip temperature of a particular plug. The change is made by changing the length of the insulating porcelain from the base. The heat is conducted into the engine head.

A "colder" plug would be needed if you are say a desert rider running across the flats at sustained WOT. 95% of the time the OEM heat range is ideal. Smaller engines, say from 200 down generally use a #8 while 250/300's use a step hotter #7. Use either and you should be fine.

Plug fouling is mostly a jetting issue, but can also be mechanical such as a weak spark or a tired top end or bad reeds. If your jet needle is of the NOZx series, they are known for an overly rich low throttle that tends to load up. If you ride slower technical trail for extended time, this is not the "ideal" needle series. This is the first thing many riders swap out.

[hardhitwarrior]

hi.

i have a BR8ecm plug. can i use a BR7eg or 8? im mostly thinking about the length internally inside the cylinder. like i dont want that the tip of the sparky hit my piston.

[jersey_devil]

Yes, the ECM is a "shorty" plug that makes it easier to service in tight places, like under the frame backbone. All current 2T heads are domed and there is almost no chance of the piston hitting it, however you don't want a plug hanging down for other reasons. Just to confirm to yourself, compare the thread reach from your ECM to the plug you want to replace it with.

[hardhitwarrior]

i have a ktm 250 sx 2003.

it fouls if im not careful but and i know its jetting. im just lazy bcoz that airboot is a pita to attach on.

anyways.

my cr250 is even MORE richer but never ever fouls. it also is using an 8 range which is BR8EG.

i want to change my KTM to that or even a 7 but on the BR*EG.

im curious if the plug is thesame length inside once tightend.

[KTM-548cc]

use what the manual says. different plug wont fix your carb problem. hate to say it but you should learn to tune the carb or have a shop do it.

[timmyp8823]

i have a ktm 250 sx 2003.

it fouls if im not careful but and i know its jetting. im just lazy bcoz that airboot is a pita to attach on.

anyways.

my cr250 is even MORE richer but never ever fouls. it also is using an 8 range which is BR8EG.

i want to change my KTM to that or even a 7 but on the BR*EG.

im curious if the plug is thesame length inside once tightend.

Take the air filter out so you can reach through the air box to make it easier to get the boot back around the carb.

[gmoss357]

The carb is not hard to get on at all if you use the method in my carb removal thread. A little more stuff to remove, but it does not take that much longer and makes install easier.

[hardhitwarrior]

hi gmoss. you mean twisting the carb to get under it? no work. no place for that carb to get under it withought taking that boot.

yeah i know the "inside the boot" trick and it makes it easier. still hard. i have no problems taking it out and such but it just takes aloooooooot of time doing so, just to change jets. plus i cant turn it on now. its out for winter storage.

BR8ECM and BR8EG thesame tip depth inside the cylinder? if so. ill use the 8EG.

[fender bender 59]

hi.

i have a BR8ecm plug. can i use a BR7eg or 8? im mostly thinking about the length internally inside the cylinder. like i dont want that the tip of the sparky hit my piston.

I changed my br8ecm to a br8es with only small problem. I now have to remove the tank to change the plug... but it last all year and damn sure cheeper

[gmoss357]

hi gmoss. you mean twisting the carb to get under it? no work. no place for that carb to get under it withought taking that boot.

yeah i know the "inside the boot" trick and it makes it easier. still hard. i have no problems taking it out and such but it just takes aloooooooot of time doing so, just to change jets. plus i cant turn it on now. its out for winter storage.

BR8ECM and BR8EG thesame tip depth inside the cylinder? if so. ill use the 8EG.

with the slide out, you should be able to rotate the carb enough to pull the bowl off to access the pilot. The main can be accessed thru the bowl drain.

Otherwise, it takes no time to pull everything off as in my removal thread and pull the carb. I am talking about reinstall. If you install the carb on the air boot first, then rotate the subframe into place into place it is much easier to install into the reed cage last.

[jersey_devil]

with the slide out, you should be able to rotate the carb enough to pull the bowl off to access the pilot. The main can be accessed thru the bowl drain.

On the "flat top" carbs, which I believe the '03 SX has, the pj is also accessed through the bottom cap. No need to remove the fuel bowl as on the older screw cap carbs.

[hardhitwarrior]

true on the 03 SX that one can access the PJ from the drain hole.

i doubt that the carb can fit between the rear main frame when the shock is installed.

also, i stillneeded to take the tankoff to get to the plug anyway. much safer and i get to torque the plug better/range.

[gmoss357]

On the "flat top" carbs, which I believe the '03 SX has, the pj is also accessed through the bottom cap. No need to remove the fuel bowl as on the older screw cap carbs.

that is even better.

HHW, have you read thru the carb removal thread?

and no it won't, I remove the shock.