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

Help 2008 V-Star 250 with fuel delivery problem.

Discussion in 'Yamaha 250cc Twins' started by dynaryder, Aug 9, 2018.

  1. dynaryder

    dynaryder Member

    Messages:
    9
    Likes Received:
    7
    Trophy Points:
    13
    Joined:
    Aug 9, 2018
    Gender:
    Male
    Location:
    B.C. Canada
    My Bike:
    Yamaha XV250
    Hi Everyone,
    I am new here but it looks like Yamaha XV250s will be part of my life for some years to come. My daughter loves this bike and I recently picked up an older on on the cheap for use as a "guest bike" (and a learner bike, I guess, for my grandkids).

    My daughter's 2008 model has been in my possession for a while due to it having been in an accident. She did not have the accident - someone else did....anyway the DAD Guarantee Insurance Company is paying to fix it. The bike has sat since last September. I repaired and upgraded a lot of parts on this bike and I am now down to making it run properly. I was not able to start it at first but I fed gas into the float bowl vent port and I was able to start it up - and ride it - although, unless I was running it at more than an idle it seemed to want to stall. It would restart and run though. I rode it for at least a half an hour and it ran "fine" (If I am feeding the fuel into the vent port, fine is a relative term.) Suffice it to say that in my mind there was nothing wrong with the idle/low speed or the high speed circuits in the carburetor.

    Now, the problem is that when I reconnect the fuel lines correctly, even though I can get flow through both the petcock (set at PRIme) and the vacuum fuel pump, the carburetor float bowl will not seem to either fill or fuel the engine. If I leave it set on prime for an hour or so, the engine will start for about literally two seconds and then die. I tried pumping fuel into the float bowl vent port and it will start and run briefly again. I was also surprised to find that there seems to be huge restriction in the fuel inlet port on the carburetor and the orifice (which looks to be about 1/16" or 1.5mm in diameter) for the seat in the float bowl.

    The first question I have is - Is the impression of a lot of back pressure - as in at least 1/2 a psi - a normal situation?

    The picture attached show two items. The larger item is the jet holder Internally, it is clear and clean. The smaller item seems to be a jet but it is not...there is a hole up through the center but it seems to dead end just prior to where the threads end. The bore, from the opposite end goes through the extension that had the bleed holes and dead ends about 1/16" high of the dead end from the opposite side. The next question - Is this correct? 20180808_151122.jpg

    I have, of course gone into the carburetor to get these parts in order to photograph them. There actually was some fresh gasoline in there - but less than I would expect.

    I have reason to believe that this is a simple problem .... What am I missing? Is the float level too low? This I find hard to believe because the bike ran fine prior to the accident.

    Can someone offer me some insight here?
     
    • Like Like x 1
  2. GreyImport

    GreyImport Administrator Staff Member The Big Cheese Contributing Member

    Messages:
    7,803
    Likes Received:
    4,635
    Trophy Points:
    943
    Joined:
    Jun 14, 2012
    Gender:
    Male
    Occupation:
    Troublemaker
    Location:
    North by NW NSW Oztralia - Tamworth
    My Bike:
    *Kawasaki ZXR250C *Yamaha FZR250R 3LN1 *Suzuki GSX250 *Triumph Bonneville 750 T140V
  3. TonyZXR

    TonyZXR Active Member Premium Member

    Messages:
    249
    Likes Received:
    117
    Trophy Points:
    88
    Joined:
    Apr 17, 2018
    Gender:
    Male
    Location:
    New South Wales
    My Bike:
    GPX250, ZXR250A, ZXR250C
    if no fuel is going into the carbs i would be pulling the needle and seats out and check that the mesh screen isn't blocked with rubbish
     
    • Agree Agree x 2
  4. Murdo

    Murdo The Good Doctor Staff Member Premium Member Ride and Events Crew Contributing Member

    Messages:
    4,636
    Likes Received:
    3,760
    Trophy Points:
    923
    Joined:
    May 4, 2013
    Gender:
    Male
    Occupation:
    Retired
    Location:
    Tamworth, NSW
    My Bike:
    Maico 250, Royal Enfield 250, CF 250 V5 and 650TK, XL250, CBR250, ZZR250 plus a few others.
    As above re blocked screen. Can you blow with compressed air back through the needle seat (ie in opposite direction to fuel flow)?
     
  5. dynaryder

    dynaryder Member

    Messages:
    9
    Likes Received:
    7
    Trophy Points:
    13
    Joined:
    Aug 9, 2018
    Gender:
    Male
    Location:
    B.C. Canada
    My Bike:
    Yamaha XV250
    So far ....thanx for the replies.... I now have fuel delivery. I benched the carb and cleaned it out (a second time) I considered chucking the seat in the lathe and boring the hole out to about twice the area but decided to try flowing fuel in to the carb. I also wanted to double check the operation of the vacuum pump. With the float bowl removed, a gas can on an upper shelf with a dip tube and fuel line, a hand held vacuum pump with an air bleed in the actuating line and rapid pumping I was able to flow fuel as fast as I could pump through the needle and seat. The carb was in a one litre plastic food saver container in a large plastic catch tray. I pumped a half a litre of gas through the carb fairly quickly. I reassembled the carb and put it back on to the bike. I primed it and cranked the engine over...It started briefly again - for like two seconds and died....(It runs on both cylinders when it fires)...and I could get it to briefly fire several times in a row. I checked the float level according to the way I read - with a clear plastic line off the drain. The carb definitely had fuel in the float bowl and the level may be a bit high. It was getting late, so I called it a night.

    So - next question - Is this other than a fuel deliver problem now? I found that the clutch lever safety switch was damaged and playing with handlebar position caused one of the wires to break off. I pulled the switch apart and soldered the wires together. The bike now cranks over with the clutch lever either pulled or not pulled. So, upon removal of my finger from the start switch, does the power to the coils get shut off due to a malfunctioning safety switch ....and does the power reset with turning off (and then back on) the key? This damaged switch became apparent AFTER my try out ride as described in my initial post.

    Am I chasing a "will o' the wisp" here?
     
  6. dynaryder

    dynaryder Member

    Messages:
    9
    Likes Received:
    7
    Trophy Points:
    13
    Joined:
    Aug 9, 2018
    Gender:
    Male
    Location:
    B.C. Canada
    My Bike:
    Yamaha XV250
    Update.... I got the bike to run again. After a good warm up, it seems that the carb is doing its job and the bike is running the way Yamaha meant it to run. I also pulled all the ignition electrical connectors apart and reconnected them as well. there was no corrosion or anything that led me to believe that an ignition problem was present. I ran the bike up to a good warm "operating temperature" and all seems to be well now.

    On the matter of the faulty clutch lever switch. It looks like it does not interrupt the circuit which is a potential safety issue to a newbie rider if they try starting the bike in gear. I do not know what we did all those years prior to safety items like this - bruised our bikes, our bodies and our egos, I guess....
     
    • Like Like x 2
    • Funny Funny x 1
    • Winner Winner x 1
  7. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

    Messages:
    3,012
    Likes Received:
    1,762
    Trophy Points:
    898
    Joined:
    Jun 18, 2016
    Gender:
    Male
    Occupation:
    Panel Beater, Spray Painter, Custom Fabricator
    Location:
    Adelaide, South Australia
    My Bike:
    Yamaha's, 1990 FZR250R 3LN3 , 1986 XT250TS 57R , 1984 IT200L 43G
    I've worked on my uncle's 1995 XV250 Virago before trying to get it running right, the Virago 250 and V Star's don't like the fuel level being too high.
    The earlier Virago 250's it should be 17.5mm below the accelerator pump piston valve.

    This is a picture below is for the earlier Virago XV250, might be the same ?
    You'll hear the engine sound change when you get the mixture screw set right, they seem to sound a bit bubbly when running rich

    I also fitted a #20 pilot jet to replace the standard #17.5 pilot, it made the power delivery a lot stronger, even in the top end.
    Throttle response was much better though.


    With the clutch switch try spraying some contact cleaner inside it, and move the lever a lot, then repeat.
    Could also try WD40 or similar if that's all you have.


    20161116_165155_zpsfq9jjw5n.jpg
     
  8. Dark Angel

    Dark Angel Member Premium Member

    Messages:
    25
    Likes Received:
    6
    Trophy Points:
    13
    Joined:
    Aug 8, 2018
    Location:
    Central West NSW, Australia
    My Bike:
    Megelli 250s (son's bike) Yamaha XV250 (wife's bike) Suzuki VZ800 (wife's other bike) BMW R1150RT (mine)
    You say "earlier" 250s, is there a different level for the later models?
    My wife's '94 has had nothing but drama with the fuel height. I replaced the needle and seat AND the float and have never been able to get it to sit at 17.5mm below the cast in mark. It is consistently higher no matter what I do. At this point I've basically given up and adjusted the idle mixture and slide needles to compensate.
     
  9. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

    Messages:
    3,012
    Likes Received:
    1,762
    Trophy Points:
    898
    Joined:
    Jun 18, 2016
    Gender:
    Male
    Occupation:
    Panel Beater, Spray Painter, Custom Fabricator
    Location:
    Adelaide, South Australia
    My Bike:
    Yamaha's, 1990 FZR250R 3LN3 , 1986 XT250TS 57R , 1984 IT200L 43G
    I have only experienced working on the 90's Virago's, so not sure on the 2000 onward's V Star's, might be the same?

    It took me a long time to work out the float height on the 1995 XV250.
    I ended up bending the arm that run's from the adjustment tab down to the float.
    It was the only way to keep the needle and seats' full flow, and keep the minimum and maximum height tab's at the right angle.
    I found bending the float tab up to drop the fuel level it would let the float jam on the fuel bowl.
    I don't know if maybe someone had bent the float originally and what i did had fixed it but it made a huge difference, the bike run's so much cleaner now.


    When researching the Virago float height drama's on the internet i found that most people just buy the chinese XV125/XV250 Mikuni 26mm CV pumper copy carby and run that, inc the standard jetting (think it's the same as the 250?)
    They about $80 inc delivery on ebay atm (were $120 - $140 when i was looking at them)
    https://www.ebay.com.au/itm/26mm-Ca...007874&hash=item3d45b180b3:g:2ZwAAOSw9itZnPEZ

    s-l1600.jpg
     
  10. Dark Angel

    Dark Angel Member Premium Member

    Messages:
    25
    Likes Received:
    6
    Trophy Points:
    13
    Joined:
    Aug 8, 2018
    Location:
    Central West NSW, Australia
    My Bike:
    Megelli 250s (son's bike) Yamaha XV250 (wife's bike) Suzuki VZ800 (wife's other bike) BMW R1150RT (mine)
    That's exactly the problem I've had. Bend the tang that you're supposed to bend up far enough to limit the fuel height and you end up blocking it entirely. Bring it down so that it flows properly and you can't get the level down. Very frustrating.
     
    • Agree Agree x 1
  11. dynaryder

    dynaryder Member

    Messages:
    9
    Likes Received:
    7
    Trophy Points:
    13
    Joined:
    Aug 9, 2018
    Gender:
    Male
    Location:
    B.C. Canada
    My Bike:
    Yamaha XV250
    With the fuel delivery problems all worked out now, the bike has been tweaked yet a little bit more. I have had to get a roadworthiness inspection and re-certification done in order for me to re-license and insure it. That all went well.

    I have been riding it the last several days - logging several hundred kilometers. I may have found an additional problem. Please read on:

    Prior to getting into describing my present "problem", I will say that I am a pretty big guy - weighing it at about 115kg, wearing my riding gear. I am XXL size in the chest, so I probably act a bit like a parachute while riding at higher speed too. I have also re-sprocketed the bike to 17 teeth on the countershaft and 40 teeth on the rear wheel (about a 16 1/2% change), which was as per recommendations from an acquaintance who claimed familiarity with these bikes.

    The bike runs and performs well up to about 95km/hr....after that, the performance seems to be a little lacking. If I am on flat road, I can coax it up to 110km/hr or a bit more but to hold it there, I need to gear down and take the revs "way up". (Now, I am used to riding Harleys, so it has been deeply embedded in my mind that you just twist the throttle and the bike goes faster. I guess that a 250cc bike won't act the same as a bike with 1000 or more cc's of displacement.) If I gear down though, I can accelerate up to 110km/hr but it feels like I am revving the engine way too high.

    So, am I experiencing "normal" with this bike? Is there any tricks to increase the power some at highway riding speed/engine rpm range? Or will a much lighter rider (my daughter - at half my body weight) "cure" the problem?

    Your thoughts? Thanking you in advance.
     
  12. Dark Angel

    Dark Angel Member Premium Member

    Messages:
    25
    Likes Received:
    6
    Trophy Points:
    13
    Joined:
    Aug 8, 2018
    Location:
    Central West NSW, Australia
    My Bike:
    Megelli 250s (son's bike) Yamaha XV250 (wife's bike) Suzuki VZ800 (wife's other bike) BMW R1150RT (mine)
    There is a saying in car circles that "there is no substitute for cubic inches". Quite simply, a 250cc machine will never have the same grunt as a 1000cc plus machine (without epic levels of forced induction anyway) so it's really not fair to demand the little Virago perform like a much much bigger bike. The top speed of these bikes under ideal conditions is only about 130kph anyway, and that's with stock gearing and a smaller rider laying pretty flat on the tank. The little XV makes 21.5NM compared to the Softtail's 110NM. Bit of a difference.
    With your daughter riding the bike will be much more lively due to the reduced load.
    If you want the engine to not rev so hard you need to go back to the stock sprocket sizes, but then you will lose acceleration. If you want the acceleration you need the engine to be reving more and thus either use a lower gear or change the drive ratio as you've done.
     
    • Agree Agree x 2
  13. GreyImport

    GreyImport Administrator Staff Member The Big Cheese Contributing Member

    Messages:
    7,803
    Likes Received:
    4,635
    Trophy Points:
    943
    Joined:
    Jun 14, 2012
    Gender:
    Male
    Occupation:
    Troublemaker
    Location:
    North by NW NSW Oztralia - Tamworth
    My Bike:
    *Kawasaki ZXR250C *Yamaha FZR250R 3LN1 *Suzuki GSX250 *Triumph Bonneville 750 T140V
    Weight will make a big difference .... having myself gone from 110kg to 80kg , it was like riding a different bike

    I also started out with gearing for more 'acceleration' when I rebuilt the FZR years ago .... absolutely useless when cruising out on the highway at 100kmh ... rpm was too high and chewed thru the fuel and u were always looking for another gear ..... back to stock gearing and its spot on

    Alot of these bikes are designed for 'Japanese jockeys' .... not for fat arse westerners :D
     
  14. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

    Messages:
    3,012
    Likes Received:
    1,762
    Trophy Points:
    898
    Joined:
    Jun 18, 2016
    Gender:
    Male
    Occupation:
    Panel Beater, Spray Painter, Custom Fabricator
    Location:
    Adelaide, South Australia
    My Bike:
    Yamaha's, 1990 FZR250R 3LN3 , 1986 XT250TS 57R , 1984 IT200L 43G
    Fitting a 17T front and 40T rear sprocket is a 19.5% difference
    You must be losing a bit of torque as you've increased the top speed by 25 km/h

    I fitted a 17T front sprocket to my uncle's XV250 (standard 45T rear), he weigh's close on 100kg's and it easily sit's on 110km up most hill's
    The ratio difference is only 6.3% which is only just noticable but give's you a bit more through each gear
     
  15. dynaryder

    dynaryder Member

    Messages:
    9
    Likes Received:
    7
    Trophy Points:
    13
    Joined:
    Aug 9, 2018
    Gender:
    Male
    Location:
    B.C. Canada
    My Bike:
    Yamaha XV250
    I am revisiting this post as I think that the little V-Star may still have a tuning problem although that gearing info is interesting (my67xr),

    When the exhaust baffles have been "removed" what, if any tuning changes should have been performed? The baffle modifications were done prior to us coming into possession of the bike.

    The symptom that I am dealing with is that at close to wide open throttle, there seems to be a "dead zone". My tuning of this sort of stuff was usually left to others back in the day... I do understand how to tune a Harley Keihen CV carb; this carb is basically the same principle. So - there is a low speed (pilot, I think they call it) jet which seems to be okay. (The number was, I think 17.5) ..... It idles okay and feels good for power at lower rpms, although, it does seem to take at least 5 minutes to get warmed up enough to not "lean bog" when starting out prior to full warm up. The "choke", which appears to actually be an enrichener, does not actually seem to work. Putting it on will "kill" the engine (whereas on any of my Harleys, that is the "cure" for riding away prior to full warm up).

    So - with the baffles being removed, is there a need to raise the needle and/or increase the main jet size?

    Do you guys have any ideas?

    Thanx
     
  16. Murdo

    Murdo The Good Doctor Staff Member Premium Member Ride and Events Crew Contributing Member

    Messages:
    4,636
    Likes Received:
    3,760
    Trophy Points:
    923
    Joined:
    May 4, 2013
    Gender:
    Male
    Occupation:
    Retired
    Location:
    Tamworth, NSW
    My Bike:
    Maico 250, Royal Enfield 250, CF 250 V5 and 650TK, XL250, CBR250, ZZR250 plus a few others.
    As 67xr said, go to #20 pilot jet. Your problem may be too rich at full throttle. What is the air cleaner like? Clean/new? Does the engine have good compression in both cylinders? Low compression will give some of the symtoms you describe.
    You can do a 'plug chop' to get an idea of what the mixture is doing at full throttle. Ride the bike on a quiet road at around 100Km/h for a few Kms then pull in the clutch and hit the kill switch and coast to a stop. Remove the plugs and see what colours they are in the combustion end. White = lean, black = rich.
     
    Last edited: Nov 24, 2018
  17. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

    Messages:
    3,012
    Likes Received:
    1,762
    Trophy Points:
    898
    Joined:
    Jun 18, 2016
    Gender:
    Male
    Occupation:
    Panel Beater, Spray Painter, Custom Fabricator
    Location:
    Adelaide, South Australia
    My Bike:
    Yamaha's, 1990 FZR250R 3LN3 , 1986 XT250TS 57R , 1984 IT200L 43G
    Up the pilot jet to a #20, warm the bike and adjust the mixture screw to get it idling nice.
    You fixed the float level ?
    If not they give a slightly bubbly idle sound, you'll hear the difference when you get it right.
    The Virago 250 will just die off with a high float level when sitting over 100km/h, you come to a stop, wait a few second's and you can fire it up again, after i got the float/fuel level right i dropped the main jet one size to fix rich top end,
    The exhaust baffles being removed shouldn't affect the carb setting's or adjustment's too much.
     
    • Like Like x 1

Share This Page