1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Behind closed doors

Discussion in 'FZR250.com - Archives' started by natas, Dec 12, 2007.

  1. natas

    natas New Member

    Messages:
    0
    Likes Received:
    0
    Trophy Points:
    0
    Joined:
    Oct 10, 2006
    Hi all,

    After trying to fix my bike for 2 years now I feel that I am still chasing my tail. Like most fzr250's they have a common problem of stalling at lights, not wanting to start and run right when hot and bad fuel consumption.

    After scrolling through this website I have been finding the methods to try and fix such problems. Some people say to check float bowl heights, EXUP valve, and many other things that people have done.

    If anyone has successfully stopped their bike from committing such crimes could they please write their information below on how it was done.

    I think this will help a lot of people who have brought their bikes back to factory settings and are still have problems or is this topic a dead horse.
     
  2. dave

    dave Well-Known Member

    Messages:
    2,184
    Likes Received:
    23
    Trophy Points:
    503
    Joined:
    Apr 13, 2005
    Gender:
    Male
    Occupation:
    Instro tech
    Location:
    Tasmania
    My Bike:
    SV1000
    Natas, what have you done to your bike in this regard, how far down the process have you been?

    My bike used to stall a bit if I pulled up real quick, particurly when I come up my steep drive. I bumped the idle speed up slightly to compensate, seemed to solve that problem. I think idle speed should be around 1600rpm.

    The other things for bad performance/starting are
    * Low compression (worn rings or maladjusted valves)
    * Worn, dirty or badly adjusted/synchronised carbs
    * Air leaks around the carby boots
    * Camshaft(s) incorrectly refitted
    * Faulty or badly adjusted EXUP
    * Sometimes premium fuel (optimax in particular).

    Crook electricals in the ignition department may possibly be an issue although these are usually in the severe to no-go range.
    * Crook batteries and/or rectifier/regulators have been known to cause severe running problems.

    The worst problem I have seen is the one where the bike will start but is totally unresponsive to throttle, will not increase revs at all (in neutral) 5 minutes later it goes like a champion <!-- s:-? --><img src="{SMILIES_PATH}/icon_Eyecrazy.gif" alt=":-?" title="Eye Crazy" /><!-- s:-? --> <!-- s:???: --><img src="{SMILIES_PATH}/icon_confused.gif" alt=":???:" title="Confused" /><!-- s:???: --> Don't know the answer to this one <!-- s:???: --><img src="{SMILIES_PATH}/icon_confused.gif" alt=":???:" title="Confused" /><!-- s:???: --> Perhaps one of the other members has found the cure for it.. If so please enlighten us.. <!-- s:D --><img src="{SMILIES_PATH}/icon_biggrin.gif" alt=":D" title="Very Happy" /><!-- s:D -->
     
  3. natas

    natas New Member

    Messages:
    0
    Likes Received:
    0
    Trophy Points:
    0
    Joined:
    Oct 10, 2006
    Hi Dave,

    I have done everything possible to this bike. Starts first go everytime when cold. Does not stall at the lights but will not want to travel up short steepish driveways. This will cause the bike to slightly flood (possibly), plenty of revs up the driveway will leave the bike idling normal. The problem is when the bike has warmed up, it sometimes will have trouble starting after about 10 to 45 minutes. If the bike is stopped hot and started again within a short period of time (1-5 minutes) it will start and run normally. I have come to the conclusion that it is the condenser. Although all the electrical side comes up clean under diagnosis. I will just keep scratching my head, after all the bike still runs and gets me everywhere that I need to go.
     
  4. dave

    dave Well-Known Member

    Messages:
    2,184
    Likes Received:
    23
    Trophy Points:
    503
    Joined:
    Apr 13, 2005
    Gender:
    Male
    Occupation:
    Instro tech
    Location:
    Tasmania
    My Bike:
    SV1000
    Mine was really bad before I fixed the EXUP, but even so, these bike do not have a lot of torque at low revs compared to twin or single cylinder bike. See if you can find another member who can lend you their bike and try up the drive to compare.

    Possibly the float valves in the carbs have slight leak and the float bowls are filling up after a period of time. If you start the bike when cold, the extra richness does not cause a problem but when warm and given enough time to overfill, it would be almost impossible. To test this theory run your bike untill HOT then stop for 15 minutes, open the drain valves in all the float bowls to get rid of any petrol . Then close the valves and allow fuel pump to prime and see if it starts normally. Alternately, you could also try turning the fuel tank valve off as soon as you pull up and stop?

    I am sure these bikes don't have condensers. They certainly do not have points, as they have a magnetic pickup coil in the alternator case which drives the digital ignition module.
     
  5. natas

    natas New Member

    Messages:
    0
    Likes Received:
    0
    Trophy Points:
    0
    Joined:
    Oct 10, 2006
    Thanks Dave,

    You have raised another point that I have over looked, the float bowls are slowly filling up as the bike sits there over time. I have done short tests on this over a period of five minutes with no change in the float bowl levels. I will have to do longer and more comprehensive tests to solve the fzr250 puzzle. And yes I was talking about the pick up coil as another prolem. This tests fine but electrical can be like that.
     
  6. madmick82

    madmick82 Active Member

    Messages:
    2
    Likes Received:
    0
    Trophy Points:
    165
    Joined:
    Jul 23, 2007
    Location:
    Victoria
    I have the same issue trying to get out of my steep driveway aswell, i have had to replace both exup cables recently, didnt notice what it was like before then but maybe this is why my bike stalls\flutters trying to get up my driveway.
     
  7. natas

    natas New Member

    Messages:
    0
    Likes Received:
    0
    Trophy Points:
    0
    Joined:
    Oct 10, 2006
    This is a common problem with short stroke engines. They are designed to run at a higher rpm than longer stroked bikes. This is amplified with having four cylinders rather than two or one. One cylinder gives a bigger bang (producing more torque at lower rpm) because of the size of the piston given that it has the displacement of a 250. Therefore more torque will be generated at lower rpm. This is why engineers big bang or pulse motogp engines to smooth out the power and increase torque at lower rpm to preserve tyre life. The bottom line is more rpm for small multi-piston engines. Highest torque is at 10000 rpm for fzr250 versus maybe 4000 rpm for a single cylinder. You may look like a goose reving your bike to much up a driveway but it will not stall and the bike will start better when you go to leave.
     

Share This Page