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Clean or replace these spark plugs? And a few more questions

Discussion in 'Bling and Appearance' started by Supplied, Mar 9, 2008.

  1. I ride Honda 2005 CB900F and I've been having a few issues with with gear changes, running (rough), and and a bit of power loss on occasions. This started happening around august/september last year, so I booked it in for it's full 12,000k service even though i had only ridden 9,500 k's. Since then i've ridden 2,000k's since.

    There was no noticeable difference after the service performance-wise, with the exception of the brakes being tighter, and the clutch a hell of a lot tighter.

    The running rough and gear changes seems to be linked, and have gotten worse. The running rough part feels as if i'm engine breaking at the same time. When this occurs, my gear changes become very clunky, especially from first to second. It's not so bad doing down hill, if it's on flat, and especially up hill, it is very noticeable. Even selecting first gear from neutral makes a loud clunk. Previously I could usually take off in first and fly through all the gears without barely noticing the transition through the gear changes.

    Now I have to hold the clutch in for 3 to 4 times longer, until i can fell it's ok to disengage and slip into gear.

    At the start, I noticed a pattern with the symptoms. When I filled up the bike with petrol, it would be fine. At around 120k's into the tank, it would start getting the above mentioned problems. About 15 to 20 k's before the fuel light would come on (180+ k's) , it would start running fine again.

    I've had a few false neutrals in higher gears aswell. At the start I thought it was because I had tapped into gear just a touch before the clutch had fully engaged, but not it happens too often if I try high speed acceleration.

    And in the last month i've notice a subtle power loss around the 3,000 rpm mark. At first i thought i might have closed the throttle slightly, but it's happened a few more times,and it only last a second.

    I don't know anything about bikes, and I was fine with sticking to the service schedule, but the next one is 3,000k's away, and I don't want to keep wasting my money getting it serviced earlier, especially if it wont fix he problems.

    I'm finally living at a place with a car port, so I picked up my bike stand, gave the chain the most thorough clean of it's life with some kero. Checked all liquid levels, the air filter, and took out the spark plugs to see if there was any signs of... whatever ;)

    They didn't look too good. Especially number 1.



    I'm planning on changing the oil and filter, even though i had a look at the oil and it was clean; because i read in a post that different oils can affect gear changing and clunking etc, and I loosened the clutch cable a bit. But i'm not sure if I need to replace the spark plugs, or if they can just be cleaned with a brush. They were a pain to get to, so i'd rather leave them out if i'm going to replace them.

    When i first got my bike i would use either BP Ultimate or Mobile 8000, but in the past 4 months it's always been BP from the same store location. I might try changing store aswell.

    And suggestions on what could be causing these problems or things to try would be greatly appreciate. Keep in mind, i only have the toolkit from the bike.

    Also, how tight should spark plugs be when i put them back in? When i was trying to take them out it took a huge amount of force to loosen them, and i wondering if that was from the soot, or it they need to be very very tight.

    But on a good note, hopefully me chain will stay cleaning for longer now that i discovered this deposit around the ...sprocket cover?


    Cheers! :)
  2. Re: Clean or replace these spark plugs? And a few more quest

    Not an unusual thing as engine and transmission parts wear in. The type of oil can affect the way it "drops" into gear from neutral but these differences are not important as far as your performance issues go - they are not related.

    From viewing the number 1 sparkplug it appears that cylinder is running a way too rich mixture (at times), which would explain why the bike feels a bit retarded.

    Not sure how this would occur with fuel injection, but you will probably need specialist help, someone who can look at issues like that. That should mean a good Honda dealer.

    It is possible that you have a shift drum malfunction, but it is also quite possible that you are losing sync and rushing the change and not completing the lever movement. Let someone else (mechanic at dealer) take it for a ride - if they report no issues it is usually a case of rider technique.

    That's the part that really suggests a fuel injection/ecu problem, as well as that plug being black.

    A scheduled service, by itself, won't necessarily fix a problem unless you go into great detail when booking it in. Since you have identifiable issues you need to make sure that they are going to do something about it. Ask around what the problem might be - some folk have more experience and better techniques at solving these sorts of issues.

    Plugs are often overtightened in bikes. Once loosened off the seat they will remove easily unless you or someone else decides to ease them in with WD40 or similar.

    This is great to get them in, but changes to a type of paste after a while through all the heat, which can make it hard to remove the plugs later. Use a copper or nickel anti-seize if you want them easier to remove and replace.

    Just tighten them till they are firm - then untighten to see how tight you had them, and compare with how tight they were when you first removed them. I usually find they are much tighter than they need to be.

    Be especially careful to only screw them in by hand at first - if you need to use a tool, to get them started you have cross-threaded them.

    In other words, never use a tool with its lever to insert the plug - just turn the spark plug spanner by hand. If it won't turn, remove it and start again

    That muck is not making your chain dirty. Dirt is a natural result of lubing chains, and if you overlube the excess (or some of it) will fling off and get caught in there.

    Use less lube - the chain should not look all oily when you finish. If it does, you have over-oiled it and the excess will fling off. Less lube more frequently applied (at least each tank fill) is better. That's about as long as any spray will last, and drip-on oil is only a little better on the outside. It does penetrate inside much more than spray, though.

    All the best

    Trevor G
  3. If you are not noticing improvements in your bike after a major service is done change mechanics :wink:
  4. Unless they were made aware of the issue, how would a shop be able to "service away" an intermittent problem?

    Such things are frequently not solved through regular servicing, but through careful detective work (sometimes involving many hours) and as a repair. That is far away from a service...


    Trevor G