Welcome to Netrider ... Connecting Riders!

Interested in talking motorbikes with a terrific community of riders?
Signup (it's quick and free) to join the discussions and access the full suite of tools and information that Netrider has to offer.

VTR250 - Only one cylinder firing?

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by Jimmyz, Dec 28, 2008.

  1. So, I let dad start up my bike today even though he apparently hates the thing. (YEAH RIGHT DAD!)

    He notices straight away that its firing on only one cylinder! It was pretty obvious to me as well, very rough engine sound instead of the usual putt-putting V-twin.

    Now I'm fairly certain that its only happened today, because the engine's idle speed was roughly half the usual, accompanied with BACKFIRING.... Never ever heard my bike backfire til today :mad: so I am confident I haven't been riding on one cylinder before.

    Checked the temperature of the exhausts, sure enough back one was cold, front was hot, so pretty certain the back cylinder decided to take a holiday on me.

    I haven't really ridden the bike lately, partly due to awaiting my license and being away for a couple of weeks. Even so it HAS been started/stopped many times when being inspected and generally stuffed around with by me/friends, hasn't been revved hard while cold or anything.

    What could cause this? My guess is the spark plugs need replacing, or are dirty? Any suggestions as to what else I should check?

    I gave it a small rev, and the back cylinder seemed to want to come to life with a bit of spluttering, but then died again after one or two wobbly ones, didn't exactly want to rev it hard - worried it may damage something if only one cylinder is going (would it? :shock:)

    Now, the bike is a 2007 model VTR250, only 5000kms, so I don't think anything is seriously wrong with it (or so I hope!), its still under warranty anyhow, but still... the baby is in pain! :(.

    Any help would be much appreciated.

    The mechanically inept! :p
  2. ah thats a shame, its so new! if its still under warranty i would just take it straight to the shop and let them deal with it, unless you've wrung its neck and damaged it or something then you're laughin

    this stuff usually happens to people just out of warranty, for what its worth, these bikes are usually pretty bulletproof and with regular maintenance just don't die
  3. checked all your connections? take the plug out of no 1 cylinder, earth it against the frame and crank it, you should see the spark.

    i doubt on a brand new bike with those kays its an electrical problem.

    my money is on:
    stuck float needle on the number 1 carb (rear one :grin: )

    get something soft like a pencil or a screw driver if you dont care about scratching it, and give the float chamber a few taps with a hammer. if that doesnt free it up, take it back to honda and tell em what the issue is. cause otherwise youd need to take the carby apart and that might void your warrenty.
  4. Yep, did exactly what you said, earthed against the tank, no spark. Substituted another plug, earthed it and VOILA!... a spark :D, so no, not an electrical system fault thankfully.

    So it's definitely the plug. Was covered in oil, what might that mean?

    I attempted to clean it, but still no spark, so its off to get a new set of plugs today.

    Thanks guys :)
  5. fouled plug, WD40 didnt clean it up enough to get it working? in the 60,000kms or so i had my VTR250, i never had a fouled plug.

    real unlucky mate.

    new plugs are 10 bucks from mr honda.

    before you run off to mr honda, check the other plug, is it fouling at all? you may need to get a hotter range of spark plug, i dont remember the part number but your parts bloke will know what you are talking about.
    also, take it for a ride for at least 20 mins, make sure the choke is off and get a quick whiff of the exhaust, smell like petorl? she is running rich. either your pilot mixtures need adjusting, or your choke is sticking. not real good for engine.