can an engine get damaged from running lean?

10 replies to this topic
  • Shane_Bettin

Posted July 17, 2004 - 10:32 AM


i know the carb is set up almost spot on and the engine runs great, but i have a very small exhaust leak where the header connects to the pipe. i think this leak is making the engine run lean, but will it cause engine damage as opposed if the carb was set up lean?? ive done a 100 different things to try and patch it up but some how it still finds a way to leak.

  • Hamish

Posted July 17, 2004 - 11:36 AM


very unlikely. If you were lean on the MJ and did lot of WOT riding it would be a different story.

  • rsstom

Posted July 17, 2004 - 01:39 PM


I agree...I don't think that's a problem to worry about.
But a very lean engine can be damaged. LEAN=HEAT Of course, heat is the enemy.

  • Shane_Bettin

Posted July 17, 2004 - 07:47 PM


ok right on. ya i went one size bigger with my new pipe so thats alright. and the leak is barely noticable at all so i was hopen its nothin to worry about.

  • Moto-XXX

Posted July 17, 2004 - 09:11 PM


On a thumper i don't see how anything can get hurt internaly since lubrication is not part of the intake, it would ping probably a little, but nothing serious should happen.

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  • Hamish

Posted July 17, 2004 - 10:05 PM


On a thumper i don't see how anything can get hurt internaly since lubrication is not part of the intake

lean MJ = hot piston = melt or nip :thumbsup:
It wont do any damage to the bottom end if thats what you are refering to

  • R_Little

Posted July 18, 2004 - 03:20 PM


you're kinda right.
lean jetting will cause a motor to ping espcially in the winter.
you've gotta be very lean to melt the motor, it has happened though.

  • TexasDirtNap

Posted July 18, 2004 - 05:27 PM


I assume that this is a four stroke runnin lean. If so, you'd normally get lots of decelleration popping. Sounds like your exhaust leak is changing that behaviour. If it were causing a lot of decel popping I expect you'd richen it up so why not richen it up anyway.

  • nzer

Posted July 18, 2004 - 10:37 PM


has anyone found a decent way way of sealing up the pipe joint yet ive tried alsorts of sealers and they all seem to get blown out

  • crf450f

Posted July 19, 2004 - 05:13 AM


Welding it back is the only way. The pressure, and the heat will blow all sealers off of pipe. Belive me, I tried.
You may want to replace it. I found a header pipe on E-bay for 25.00 to replace my cracked one. Good luck :thumbsup:

  • Shane_Bettin

Posted July 19, 2004 - 02:24 PM


ya think stock is a 175.i think ive got a 180 or 82 in it. theres almost no popping at all on decel. but the plug is always white anyway.

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