fbpx
Login

 

Jump to Forum..

Mag drop 350 on each side

in 912 / 914 Technical Questions 7 years ago
During 4000 RPM runup, what is the most probable cause of a consistent 350 mag drop with rough running on each side (both consistant rough and consistant drop) but super smooth running great on both mags. 10 year old 80 HP engine, dry climate, about 400 hours. Have never had this situation with many years of carbed 912's. Most common situations/fixes for this?

  • Re: Mag drop 350 on each side

    by » 7 years ago

    Most common and might as well start easy and simple.
    The 300-350 mag drop many times is one plug or firing in one cylinder not doing well. If it were me I would start with new plugs whether you think they are good or not (gap between .023 - .027). Unscrew the plug caps and trim each plug wire back 1/4" - 3/8" for fresh plug wire ends. Apply a tad of dielectric grease to each wire end and screw the caps all the way back on until they seat all the way in. Many times this will take care of this 300 rpm loss.

    Carb sync?

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
    Report

  • Re: Mag drop 350 on each side

    by » 7 years ago

    Why would you put "dielectric" grease on the wire ends? The definition of "dielectric" means that it is an insulator and does not pass electricity easily.
      
    Report

  • Re: Mag drop 350 on each side

    by » 7 years ago

    Dielectric grease is electrically insulating and does not break down when high voltage is applied. It is often applied to electrical connectors, particularly those containing rubber gaskets, as a means of lubricating and sealing rubber portions of the connector without arcing.

    A common use of dielectric grease is in high-voltage connections associated with gasoline engine spark plugs. The grease is applied to the rubber boot of the plug wire. This helps the rubber boot slide onto the ceramic insulator of the plug. The grease also acts to seal the rubber boot, while at the same time preventing the rubber from becoming stuck to the ceramic. Generally, spark plugs are located in areas of high temperature and the grease is formulated to withstand the temperature range expected. It can be applied to the actual contact as well, because the contact pressure is sufficient to penetrate the grease film. Doing so on such high pressure contact surfaces between different metals has the advantage of sealing the contact area against electrolytes that might cause rapid deterioration from galvanic corrosion.
    Thank you said by: David HEAL, Garrett Wysocki
      
    Report

  • Re: Mag drop 350 on each side

    by » 7 years ago

    What Dennis said. (Good explanation, That's worth a Karma for sure :))
    It's a very acceptable practice and helps keep corrosion at bay..

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
    Report

  • Re: Mag drop 350 on each side

    by » 7 years ago

    OK thanks Roger. Back to the basics. 1. plugs 2. plug connections 3. Carb Sync will by my priority order for this. Nice to do it in steps of possible to see what has the best effect. Just wanted to use some common practices/experience. Greatly appreciated. Yes Dennis very helpful.
      
    Report
You do not have permissions to reply to this topic.
Related Topics
Title Category Replies
Filter Mag for oil filter 912 / 914 Technical Questions 4
912is rpm drop 912iS Technical Questions 22
RPM Drop in 912ULS 912 / 914 Technical Questions 3
RPM Drop in 912ULS 912 / 914 Technical Questions 21
Damaged ECU casing 912iS Technical Questions 8
Follow Us

Recent Videos

Safety First!

 

To receive critical-to-safety information on your ROTAX Engine, please subscribe to
ROTAX-OWNER.COM

Prize Giveaway!


SUBSCRIBE NOW
to automatically enter this years draw!

Login