Adventure Motorcycle Magazine Subscribe Now

Results 1 to 9 of 9
  1. #1 Dangers of running lean 
    C-Moto Guru
    Join Date
    Jan 2012
    Location
    Norwich
    Posts
    408
    Hi. I've just installed a high flow air filter into my Sinnis max, I also bought a bigger main jet but I ordered the wrong one so I wasn't able to fit it. The bike runs fine but I would immagine that the fuel to air mixture is rather lean now and what worrys me is I've heard that this can cause damage to the engine if it runs too lean, is this true? Also when I accelerate I get this fairly loud roar which I assume is comming from the new air filter, is that normal?
    Reply With Quote  
     

  2. #2 Re: Dangers of running lean 
    Senior C-Moto Guru Kennon's Avatar
    Join Date
    Feb 2011
    Location
    Moscow
    Posts
    799
    it'll run hotter being more air to fuel but then again it'll run hotter having more fuel when you make it richer its the same sort of thing but it will definitely run dryer when lean

    Kennon
    Reply With Quote  
     

  3. #3 Re: Dangers of running lean 
    C-Moto Guru
    Join Date
    Jan 2012
    Location
    Norwich
    Posts
    408
    Sooooo is it going to cause damage to my engine or will it just reduce it's life span a bit? I was planning on getting an oil cooler to counteract the extra heat.
    Reply With Quote  
     

  4. #4 Re: Dangers of running lean 
    Senior C-Moto Guru Kennon's Avatar
    Join Date
    Feb 2011
    Location
    Moscow
    Posts
    799
    they run pretty lean standard so allowingmore air in has made it even leaning so it will make your engine life shorter, perhaps a oil change should be done to freshen things up once youve got it rejetted
    Reply With Quote  
     

  5. #5 Re: Dangers of running lean 
    C-Moto Guru
    Join Date
    Jan 2012
    Location
    Norwich
    Posts
    408
    Alright I'll do that, cheers.
    Reply With Quote  
     

  6. #6 Re: Dangers of running lean 
    Senior C-Moto Guru zhu's Avatar
    Join Date
    Jun 2011
    Location
    Chengdu
    Posts
    626
    unless you know what the standard jetting was you cant be sure its too lean now

    to check it

    hold it full noise in top gear on a flat road or very slightly uphill
    chop the throttle, pull in the clutch and hit the kill switch

    all at the same time ...hahaha

    when the bike comes to a halt remove the sparkplug

    correct mixture is shown by a light tan color on the center electrode

    rich is black

    lean is white or any kind of grey

    lean is bad because it is running hot and prone to detonation

    in extreme cases this can lead to an internal meltdown

    a rich mixture will actually run cold because all the fuel is not burning

    but it is evaporating so cooling the engine also the fuel is washing away oil in the cylinder so rich isnt good either

    one jet size up should be right if the mixture was correct before you started tinkering
    Reply With Quote  
     

  7. #7 Re: Dangers of running lean 
    C-Moto Guru
    Join Date
    Jan 2012
    Location
    Norwich
    Posts
    408
    Thanks for the advice, I'll have to try the spark plug thing soon. I've been for a 200+ km drive today and it didn't blow up or anything so I'm not in any immediate danger. Before the air filter change my spark plug was a little bit white so it must of been a little lean anyway so I'm moving from a 97.5 jet to a 105.
    Reply With Quote  
     

  8. #8 Re: Dangers of running lean 
    C-Moto Guru
    Join Date
    Aug 2011
    Location
    texas
    Posts
    266
    you have 3 jets whats lean at idle to 1/2 throttle , it pretty much ok to be lean , 1/2 to 3/4 you need littl more attention to but most importantly is 3/4 to wide open throttle

    you cannot ride normally stop and check plug , itll only show idle mix , as he said ride it get throttle to correct position and kill switch it then check plug , to know your lean condition thru all 3 jets

    to note , all 3 jets "stack" , each add toward WOT mixture , if your lean at idle to 1/2 and 1/2 to 3/4 you may still be lean at WOT even with a fairly large main jet

    I recently upped main to over a 105 , combined with my airflow (ram air) mods at 75 I am still lean , so I need to upsize my Needle jet ( 1/2 to 3/4 throttle jet ) as well


    popping and "chugging" under acceleration is a very good indicator of a "dangerously lean" condition ( I still pop n chug at almost full throttle , drive that way for long = dead motor )
    Reply With Quote  
     

  9. #9 Re: Dangers of running lean 
    C-Moto Guru
    Join Date
    Jan 2012
    Location
    Norwich
    Posts
    408
    well I've moved from a 97.5 jet to a 105; there's definitely a performance increase but it seems minor, I haven't had a chance to test it on a dual carriage way yet. I noticed no popping, chugging or any abnormalities before or after the re-jet so I guess I'm in the clear. Cheers for the advice guys!

    By the way the sound from the new air filter is incredible, espessially when accelerating hard! I'd definitely reccommend it to anyone! It only cost £6 which is a bonus and I celotaped half a fanta bottle around it so it dosen't suck up any water.
    Reply With Quote  
     

Similar Threads

  1. RMR 125 Running problem
    By shaun69 in forum Maintenance
    Replies: 12
    Last Post: 06-23-2011, 05:17 PM
  2. Cold Running
    By choldy in forum Maintenance
    Replies: 9
    Last Post: 12-27-2010, 02:03 PM
  3. Replies: 3
    Last Post: 01-07-2010, 04:00 PM
Bookmarks
Bookmarks
Posting Permissions
  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •