Lots of carbon in the header

11 replies to this topic
  • sirthumpalot

Posted August 15, 2002 - 01:13 AM


Last night I removed the head pipe for the first time on my '01 and I was shocked at how much carbon buildup there was in there! It looked soooo thick and sooty. The jetting is stock and it runs like a champ so I don't think it's over rich. Has anyone else who's running on pump gas noticed this?

  • Shawn_Mc

Posted August 15, 2002 - 07:06 AM


Its rich.

  • yznvegas

Posted August 15, 2002 - 07:08 AM


Like Shawn said, spooge is a sign of being too rich.

Another thing, are you using the stock plug or did you accidentally put in a cooler plug?

[ August 15, 2002: Message edited by: yznvegas ]

  • sirthumpalot

Posted August 15, 2002 - 07:20 AM


It's the stock plug and jetting. It runs so crisp that I have a hard time believing that it's rich. No stumble or hesitation, always instant throttle response from bottom to top. Also it wasn't oily or anything, just dry soot. Are you guys telling me that you've removed your headers and there's not a lot of black soot inside? I'm not talking about mounds like you get in a 2 stroke pipe, but a good even coting all the way around the inside.

  • yznvegas

Posted August 15, 2002 - 07:24 AM


I guess some residue would be normal, I was picturing like that wet oily spooge you get from 2-smokes when they are too rich or your mix is too oily. If it's running crisp than don't worry about it.

If it's not broken, don't fix it. :)

  • MikeYarbrough

Posted August 15, 2002 - 07:40 AM


A coating of carbon in the header is normal, just like the exhaust manifold on a car. The thumpers spit hot carbon during the exhaust stroke which is why a spark arrestor is actually more important on a thumper than an oil burner...

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • Shawn_Mc

Posted August 15, 2002 - 09:35 PM


Im with Vegas on the "if it aint broke dont fix it" deal. But my header is grey on the inside. Heck, its grey all the way to the tail pipe

  • John_Lorenz

Posted August 15, 2002 - 09:38 PM


Well Shawn
if ya show up in Forest Hill in Sept, I wont have a beer but I will crack a Sarasparilla with ya :)

  • Wyatt

Posted August 15, 2002 - 10:18 AM


My vote is that it is a tad rich. Mine is grey from the head to the stinger. Lean your jetting out a tad and you may see your crisp throttle response get even better. Jetting is simply to easy to change to not give it a try.

  • DaveJ

Posted August 15, 2002 - 07:08 PM


Here's the deal.

The bike is rich. Your pipe is filling up with unburned fuel.

A rich mixture, will usually produce more power in the mid to top range, and less on the lower range. It also makes the bike run cooler.

Lean does the opposite and often leaning the idle circuit will make the bike snappy when coming off idle.

Stoichiometric is the term that refers to the "perfect burn". The ratio of the past has been updated in the last 15 years since we now sniff the tail pipe instead of reading quarter mile times.

This is why it's good to adjust the lower circuits lean and the top end circuits rich, (unless you like sitting still with the engine running).


  • phrog03

Posted August 15, 2002 - 08:09 PM


I spend alot of time building 4 stroke motors and pump gas is the cause. It has aditives in it that are being left behind. Its also hard on the piston. Mix your pump gas 50/50 with a race gas. you should clean the carbon out of the header and the valve area to alow for good flow.

  • Wyatt

Posted August 16, 2002 - 04:29 AM


I have heard the pump gas explanation before also. I use race fuel.

I totally agree with DaveJ. I run my bike lean on pilot circuit which gives me quick starting and a snappy throttle. I run it fatter on the top. This combination works best for me.

Related Content


Wilson the Blue Privateer by jetfuel

Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  50 replies

Megabomb Fitment by 288yz450

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • 1 reply

Chubby dad, looking at bikes , First trip to the orange/black forum ! by Slow_ride

Dirt Bike   Make / Model Specific   KTM   250-530 EXC/MXC/SXC/XC-W/XCR-W (4-Strokes)
  • Hot  28 replies

Snake pit oct 30th by The Anvil

Dirt Bike   Dirt Bike Regional Discussion   California
  • Hot  293 replies
WR Camshaft Swap Info - last post by jamesm113

WR Camshaft Swap Info

  • 0 replies

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.