Reading Spark Plugs
Close
    
    
Page 1 of 3 123 LastLast
Results 1 to 10 of 23
Like Tree23Likes

Thread: Reading Spark Plugs

  1. #1
    Senior Member elime's Avatar
    Join Date
    Jul 2010
    Location
    San Jose, CA
    Posts
    7,001

    Reading Spark Plugs

    First two pictures are from the TW with the 68mm piston and it runs great. To me it looks a little on the lean side but since it runs so well I am not concerned.

    P4110031.JPGP4110032.JPG


    Next two pictures are from The Parts Bike with the 70mm piston. It runs OK but wide open throttle it misses and just doesn't seem to do as well overall as the other TW does. To me it looks a little on the rich side, but again, not horribly so. Just a very slight amount.

    P4110029.JPGP4110030.JPG

    Comments, insights, opinions sought. What do you think?
    Long live the internal combustion engine!

  2. #2
    Super Moderator Purple's Avatar
    Join Date
    Mar 2015
    Location
    Ynys Môn
    Posts
    4,643
    What's the mileage on (both) those plugs - before you pulled them ?

    And when was the last time you serviced the air-filter (again, on both bikes) ?
    (Warning - Forum may contain nuts) ...... Hidden Content

    TW200 - 1998 - Japanese import - 7000 miles on the clock - TW225 Special Edition 2007
    - Hidden Content

  3. #3
    Senior Member admiral's Avatar
    Join Date
    Jul 2010
    Location
    Frosty Hollow
    Posts
    13,174
    I'm confused at what I thought I knew.

    Hard to tell in the pictures from here. I'm actually reading them opposite than what you are, but not entirely. 1st plug confuses me a bunch.

    Has the plug been in the 68mm for a while or was it a new plug to start?

    The 2nd plug or 70mm to me looks like it's running lean. Again confusing as it looks lean on one side and closer to normal on the other.
    grewen and GaryL like this.
    Hidden Content A ride in the woods helps me relax and release tension. The fact I'm dragging a body should be entirely irrelevant?

  4. Remove Advertisements
    TW200Forum.com
    Advertisements
     

  5. #4
    Senior Member elime's Avatar
    Join Date
    Jul 2010
    Location
    San Jose, CA
    Posts
    7,001
    Air filter has been cleaned on both bikes. First plug has 20K or 30k miles on it. I put it in a long time ago. Second plug about 2,000 miles, maybe 3,000 but not very many.

    As I write this, maybe the plugs look the same mixture wise and it is only the mileage the makes them look different.

    The miss could be something electrical and not related to mixture at all. I have new high speed jets on order.
    Last edited by elime; 10-19-2015 at 02:38 PM.
    Long live the internal combustion engine!

  6. #5
    Senior Member RockyTFS's Avatar
    Join Date
    Feb 2011
    Location
    Hailey, ID
    Posts
    3,409
    I'm with Admiral, did you maybe switch the pics and the captions?

    Also, without knowing if the cylinders have two different compression ratios it's hard to tell much. Neither of these plugs looks too far off optimum. If your parts bike is running rich enough to bog at WOT in 5th I'd think it would be much more obvious. Most likely it's running a bit lean. How much increase in displacement does the 70mm create? If it's more than just a few cc, I'd suspect the carb just isn't quite big enough.
    Rocky
    2018 TW200
    2014 BMW R1200GS LC

  7. #6
    Senior Member elime's Avatar
    Join Date
    Jul 2010
    Location
    San Jose, CA
    Posts
    7,001
    Compression ratio supposedly identical. 10.25

    Stock is 67mm = 196cc
    Over 68mm = 202 cc
    Over 70mm = 214 cc

    Small increases.

    Pics and captions correct.
    Long live the internal combustion engine!

  8. #7
    Senior Member admiral's Avatar
    Join Date
    Jul 2010
    Location
    Frosty Hollow
    Posts
    13,174
    I'll add having seen an extremely lean plug, it looked much much whiter than either of these. Same for a rich plug, really really black with soot baked on.

    If these were my plugs, I wouldn't be concerned thinking each is close enough to normal.
    Peterb and immgunn like this.
    Hidden Content A ride in the woods helps me relax and release tension. The fact I'm dragging a body should be entirely irrelevant?

  9. #8
    Senior Member elime's Avatar
    Join Date
    Jul 2010
    Location
    San Jose, CA
    Posts
    7,001
    Quote Originally Posted by admiral View Post
    I'll add having seen an extremely lean plug, it looked much much whiter than either of these. Same for a rich plug, really really black with soot baked on.

    If these were my plugs, I wouldn't be concerned thinking each is close enough to normal.
    I agree. I guess I better start looking for an electrical problem.
    admiral likes this.
    Long live the internal combustion engine!

  10. #9
    Super Moderator Purple's Avatar
    Join Date
    Mar 2015
    Location
    Ynys Môn
    Posts
    4,643
    The first plug is about past its sell by date - the colour is ok - just the build up of junk could become a problem

    The second plug is also "ok" - colour wise - like Admiral I was wondering about the one sided burn pattern

    Have you considered Iridium plugs ?
    admiral likes this.
    (Warning - Forum may contain nuts) ...... Hidden Content

    TW200 - 1998 - Japanese import - 7000 miles on the clock - TW225 Special Edition 2007
    - Hidden Content

  11. #10
    Senior Member admiral's Avatar
    Join Date
    Jul 2010
    Location
    Frosty Hollow
    Posts
    13,174
    Oh, I know it snowed back east, but it's way too early to be bringing these mid-winter topics up so early in the fall!


    Gee-dang-it, now I'm gonna go look at my plugs! Power of suggestion elime!
    Hidden Content A ride in the woods helps me relax and release tension. The fact I'm dragging a body should be entirely irrelevant?

Page 1 of 3 123 LastLast

Sponosred Links

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Similar Threads

  1. Spark Plugs
    By rm_hm in forum Technical Help
    Replies: 18
    Last Post: 04-17-2014, 04:04 PM
  2. Second opinion on spark plugs
    By BoatHands in forum Technical Help
    Replies: 6
    Last Post: 03-19-2013, 05:04 PM
  3. Spark Plugs stock vs. iridium
    By aztw200 in forum General Discussion
    Replies: 6
    Last Post: 10-26-2012, 06:17 AM
  4. Spark plugs
    By Delboy in forum Technical Help
    Replies: 8
    Last Post: 09-10-2012, 06:50 PM
  5. Spark Plugs
    By Two Shoes in forum TW200 Classifieds
    Replies: 4
    Last Post: 08-02-2010, 03:21 AM