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Quick chain and valve clearance questions..

Discussion in 'Technical and Troubleshooting Torque' started by Toefa, Oct 30, 2007.

  1. Hi guys, just wanted to ask two quick questions... Can anyone tell me what the tell tale signs of incorrect valve clearances are (is it like when the tappets are out in a car)? Also, what effect, both immediate and long term, does having an old worn chain have? ...The reason for this question is, i have lost some low down power and have an overall dullness to the feel of my bike, and i am wondering if the chain can contribute to this...
    Thanks in advance :)

  2. A worn chain will become slack and need adjustment very often. It will result in jerky power, you should be able to hear it smacking against things if its really loose. You will have a jerk when you throttle on if its loose too. Chains last on average 25000kms-ish on most 250s at least. Cost me about 280 to have new chain and sprocks fitted (if your sprockets are buggered, replace them too as it'll only prematurely wear the new chain if it is) - worth every penny, made the bike smooth again! Also, worn chain will make for crap takeoffs from lights and be generally very annoying!
  3. Cheers for the reply Phizog.. The tension is still ok, however, the tight spots in it seem to make the bike quite 'surgy'. But i was kinda hoping that possibly the chain was dulling the performance a bit due to it stiffening with age or something, that way i wouldnt have to fork out to get the carbs cleaned or valve clearances checked/fixed, but i'm prolly dreaming.
  4. As I understand it, it will have an adverse affect on power if its bad, as power would be lost in the flapping around/not spinning smoothly.

    Lubed regularly?
  5. Yeah mate, lubed nearly weekly.. and a few weeks ago, even got the kero out, cleaned it all and then re-lubed. Seems to have happened really quickly though, about a month and a half ago it wasnt too bad, now there doesnt seem to be anyway to get the tight spots out?
  6. they are like 40 bucks for a cheapo and not hard to replace.
    get a mate and over a weekend and just do it.
    PLnety of guides ova the net.

    goodluck adjusting all 3 millio0n valves on the cbr yourself thou.
  7. Hard to start is one of the first signs your valve clearances are incorrect.
  8. Thanks mate, well valves may not be a problem then - so thats a good sign. She starts with no choke even in winter.

    Could a blocked airfilter cause a bit of dullness on response?
  9. Absolutely, could also be a problem with fluid in the airbox. Might also be worth checking the plugs since they can give a good indication of whether the engine is running properly or not.
  10. I'm pretty sure a loose, old chain can account for (depending on the bike) 2-5 HP. Especially if its not moving freely anymore.
  11. Typical sign of the engine getting too much petrol/not enough air.

    Yes. As above.

  12. Mmmmm..I could be wrong but I don't think that's always the case - or more so it can be an extreme symptom. An earlier sympton of valves being too tight or too loose is a loss/gain in power at the top or low end depending on the type of bike.
  14. I'm just going on my bike, which has valves made from swiss cheese that require the clearances adjusting reasonably often. I check 'em every 15hours, but so far if it has been starting beautifully the valves are perfect when I check. If it's been a bit of a prick to start, it sometimes is something else (plug usually), but often a valve or two has crept out.

    By no means am I a mechanic. /disclaimer/ ;)
  15. there is your problem, if you wash the thing with kero, you need to make sure lube is properly applied to o rings afterwards, if you dont, your chain will elongate rapidly as you have described. my chain on the baby vtr has lasted 35000 kms now and i will get another 5 thou out of it, i have not cleaned it with any solvent once, just lubed lightly EVERY 500kms with a el cheapo can of BP lubricant which only cost me 3 bucks.

    valve clearences, just stick to your service shedule and you'll be fine. although odo readings on CBR250s can be dodgey, might pay to do a major service now, ie replace plugs, aircleaner, oil and filter, carb sync, the works etc.
  16. And we know what you can do with your $3 can of BP chain lube.
    Are you sure it isn't spray paint? :p
  17. :LOL: na i regard it as corosion protection for my polished rims :LOL:
    at least your black wheels matched the black paint work afterwards :LOL: :LOL: :LOL: