Megabomb vs Powerbomb header question...

[Justin89]

Just a quick question...I currently have on my 2006 yz450f a Powerbomb header with Factory 4.1 exhaust and I'm thinking about buying a megabomb header. So my question is: Will I have to do any jetting changes to switch from the Powerbomb to the Megabomb? Any info will be greatly appreciated...thnaks!?

[KJ790]

It shouldn't have a big effect on the jetting, you may just have to adjust the fuel screw.

[Justin89]

It shouldn't have a big effect on the jetting, you may just have to adjust the fuel screw.

Okay thanks KJ. I know you have both headers and have ran them on your bike so that's good to know.?

[rdrata]

...and watch out for the burned pants!!! Wrap it up with the heat wrap (curved portion of header). I do notice that the expansion chamber of the megabomb actually is within an 1/8" of the engine top end - makes the engine get hot quick. Any others experience this? Solutions?

[Justin89]

...and watch out for the burned pants!!! Wrap it up with the heat wrap (curved portion of header). I do notice that the expansion chamber of the megabomb actually is within an 1/8" of the engine top end - makes the engine get hot quick. Any others experience this? Solutions?

O really? Never thought about the megabomb being close to the engine. I have some thermo srips I'll have to slap on somewhere ont that side to see how hot it is actually getting...

[grayracer513]

I do notice that the expansion chamber of the megabomb actually is within an 1/8" of the engine top end - makes the engine get hot quick.

No, it won't. The minuscule amount of heat that could be successfully radiated to the exterior surface of the liquid cooled cylinder and head will have little or no effect on the coolant temperature.

[rdrata]

well gray, perhaps it's just that i've never noticed it before, or the fact that i have been riding in this summer heat, but since the application of the megabomb, my YZ seems to have turned into a fire breathing beast! It seems a lot hotter than that of the stock exhaust. So, I'm okay with the exhaust being close to the head? At first i thought i had it mounted incorrectly, but it snugs up real tight at the back corner prior to attaching to muffler.

[grayracer513]

It's possible that your jetting is a little lean with that pipe, or as you say, you may not have noticed it before. But even if the pipe laid directly against the cylinder, it would add very little, if any, significant heat to the engine. Remember, all of that fire came out of there to begin with.

[rdrata]

okay, cool (or should I say hot ), I have a lot of things to observe on next outing, revised jetting, heat and the erv3 chain (flared out those pins ?) Anyway, glad to know not to worry about placement of pipe. Still it seems they could have designed it with better tolerances...