Flaming Exhaust

4 replies to this topic
  • gmiles

Posted April 24, 2005 - 07:34 AM


Rode today and my 426 was poping on deacceleration. Well it got louder and louder. I came off the track and grabbed a handfull of throttle and when I let go with each pop flames came out of the exhaust.

A bit of background....

I got the 426 which had a stock header and an Arrow pipe. I managed to get hold of a ProCircuit setup, header and a couple of pipes from H4B. I ran the PC header and the shorter of the pipes for the last year. The PC setup gave more bottom end and better throttle response. A couple of weeks ago I was racing at Canada Heights and decided that I would run the longer pipe. Well I had it sound checked and it was registered at 102db. This pipe is quiter than the shorter pipe. It also gives less power at the bottom end.

Anyway I thought I would do my bit for the noise problems, so I put the stock header and Arrow pipe back on. This is alot quieter but unfortunately not as powerfull.

I used to run Optimax in the bike but recently I have run on normal pump gas. My son said his bikes runs better on Optimax so this weekend I switched back.

So the difference between this weekend and the last time I rode was the stock header, Arrow pipe and running Optimax.

What could cause these flames. It did look good though. Some kid said he wished his bike did that. I said I wished it didn't.

  • gmiles

Posted April 24, 2005 - 08:05 AM


Sorry Gents, I pasted this from another forum in the uk. Optimax is premium pump gas from shell. Its rated at 97 Octane, standard pump gas is 95.

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  • grayracer513

Posted April 24, 2005 - 10:01 AM


Decel popping is caused by either an air leak in the exhaust, probably the mid pipe joint, or lean idle mixture. Do a quick check of the exhaust system. If it's OK, back the fuel screw out a quarter to a half turn. No big problem in any case.

  • MichiganMXer

Posted April 25, 2005 - 05:50 AM


Bad gas

  • gmiles

Posted April 25, 2005 - 08:06 AM


Found the problem. One of the bolts holding the header to the cylinder had fallen out.
Thanks for the help.....

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