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Discussion Starter · #1 ·
I've seen posts about others with a red hot header. Some say its normal, some say its too lean. The bike also pop's a bit on deceleration. There is an aftermarket Yosh off-road exhaust installed. Trying to figure out the best option to fix either or both of the issues.

Here's the posts I found from others with red hot headers.
http://www.supermotojunkie.com/show...ermoto-glows&highlight=drz+400+red+hot+header
http://www.supermotojunkie.com/show...ipe-question&highlight=drz+400+red+hot+header
http://www.supermotojunkie.com/showthread.php?104389-Header-red-hot&highlight=drz+400+red+hot+header

Thanks,
Mike
2010 FZ1
2004 DRZ 400
 

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Too lean.

Possibly also an exhaust leak at the head. Try reassembling the exhaust system with high-temp (copper infused) gasket sealer. I believe perma-tex is the brand I used to do mine and it stopped a lot of the exhaust popping on deceleration.
What's happening i believe is unburnt oxygen is getting into the exhaust pipe at the header fitting, post internal combustion and creating another combustion in the super hot exhaust pipe.

Someone please correct me if I'm wrong but that's my simple minded understanding.
 

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+1 on the Lean Team

You've probably got the stock jetting in the stock carb and running it all; JD jet kit is cheap and will sort you right out
 

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Eddie Ciznieros on Thumpertalk could probobly get you cose to spot on but 160 mian and 25 pilot, 3rd needle clip should be close with the Yosh pipe. Thats what I ran on my DrZ sm with a yoshimura but i had the full header and 3x3 mod with k&n filter at sea level so you might need a little different jet set. Might have smoked your header gasket too. Cheap part, no worries your motor is fine.
 

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I get the same thing if I leave it idling too long with the choke pulled out. Regular idle it's not an issue. Is this happening all the time or just while you're in a dim garage warming it up ?
fwiw, I'm running the Yosh RS2 (corked), the 3x3 mod, and JD kit w/ jetting as recommended by Eddie. I definitely recommend getting an extended fuel screw as well so you can fine tune it a bit.

I've seen plenty of people leave the vacuum line that normally goes to the petcock disconnected after doing some work or fitting a non-vacuum operated petcock. The bike will still run (as long as it's getting fuel somehow), but it'll be super lean and popping at idle.

Here's the jetting spreadsheet from over on TT
 

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Discussion Starter · #13 ·
As far as I know, the bike hasn't been re-jetted by the original owner. When I picked it up, it idled nice but I didn't leave it idle long enough and didn't ride it long enough to hear some of the popping or see the glowing header etc. It idles nice and smooth, but I agree a rejet should do the job. I'll look into the longer idle screw too.

I believe the Yosh exhaust is the full header too.

The 160/25 jets and 3rd notch sound like a good way to go.

Since my post, I crashed the bike last wednesday while visiting family in Tennessee. Broke my left leg, the bent the handlebar and broke nib off the shift lever. Parts already received, just need to do the swap once I'm stable enough to sit and do the work.

I might bring it to a local shop to do the rejetting. I've done jetting on an 85cc 2 stroke without much of an issue. I'll see how I feel though. Any good sources for these parts from a single dealer? I've read that the jet kits don't come with the 25 size jet and has to be ordered separate.

Thanks for the all of the input.

Mike
 
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