17.5 dellorto

Discussion in 'The Workshop' started by Undercover Runner, Nov 13, 2010.

  1. Undercover Runner

    Undercover Runner Member

    Messages:
    136
    Rides:
    Gilera Runner SP
    well, the bike now feels more powerful to ride but its not hitting the speeds and accell is wack.. what next?

    found it,

    http://www.youtube.com/watch?v=JmpXkBiKCG8&feature=mfu_in_order&list=UL

    that is happening

    i give it full throttle and nothing, its like theres no uuuumph, then when it eventually starts to pick up in rpm/speed it just hits a certain rpm then just dies down back to 8k
     
  2. capri dave

    capri dave Active Member

    Messages:
    5,076
    right next, take 3x of your 3.8g rollers out and replace with 3x 3.0g rollers.

    if you look at how the rollers are spaced, youve got segments of three rollers bunched together.

    take the middle roller out of each segment and replace with a 3.0g roller.

    if you get excessive vibration dont ride it, but it should be fine...
     
  3. Undercover Runner

    Undercover Runner Member

    Messages:
    136
    Rides:
    Gilera Runner SP
    could you shed some light on the rpm dips?
     
  4. capri dave

    capri dave Active Member

    Messages:
    5,076
    with the 3.8g rollers was there any difference in the top speed ??

    baring in mind you said yesterday that it was only doing 40 mph at 9500rpm.

    I need as much information as possible about what each change in roller weight is doing.

    just saying its wack doesnt help me im afraid :glare:
     
  5. Undercover Runner

    Undercover Runner Member

    Messages:
    136
    Rides:
    Gilera Runner SP
    going to have to try that 2moro after work, i haven't got a impact wrench so its a pain in the anus using wrench's and variator locking tools :(

    didnt find a long enough straight to get to 40mph let alone achieve that speed lol, thats how sluggish it was, but ill go test it now and come back to you
     
  6. Undercover Runner

    Undercover Runner Member

    Messages:
    136
    Rides:
    Gilera Runner SP
    ok, so here goes..

    sounds like a bus, accelerates like a bus.

    tops off @ just over 7000rpm i mananged to hit 38mph on a straight, although every so often when i give it throttle it does go up to 9000 rpm and the accell is wonderful, but then goes back to 7000rpm and slows down...
     
  7. capri dave

    capri dave Active Member

    Messages:
    5,076
    ok, can you tell me a little performance wise about when you tried the 4.2 gram rollers ?
     
  8. Undercover Runner

    Undercover Runner Member

    Messages:
    136
    Rides:
    Gilera Runner SP
    Terrible really slow acceleration barely 7000 rpm pretty much the same as 3.8 but even slower
     
  9. Undercover Runner

    Undercover Runner Member

    Messages:
    136
    Rides:
    Gilera Runner SP
    Should there be any washers/thick spacers where the variator is??? Its derestricted but there is a 1/2 inch washer behind variator!
     
  10. capri dave

    capri dave Active Member

    Messages:
    5,076
    ok, so whats happening is the engine is improving as the roller weight comes down :good:

    now because you have a lack of rollers, as an experiment your going to have to take 3 of your 3.8 gram rollers out and replace with 3 of your 3.0 gram rollers.
     
  11. Undercover Runner

    Undercover Runner Member

    Messages:
    136
    Rides:
    Gilera Runner SP
    Dave, I put in 3x 3.8 and 6x 3 which is 29.4grams the acceleration is good I can feel the power all the way to 9500 revs then it hits 40-42 revs then die down to 9000 and I stay at 40mph it's like there's still a restriction stopping the pulley, any thoughts? Could it be a fouled spark plug?
     
  12. capri dave

    capri dave Active Member

    Messages:
    5,076
    i would of tried 6x 3.8 and 3x 3.0 to give a total of 31.8 grams :glare:

    my thoughts on the 42 mph top speed is: either the rollers are still a little light, or your main jet isnt right...

    you can mark a line on your pulley face with a marker pen, then take it for a spin and check the line afterwards. the belt will wear the line off as it travels up the pulley, leaving a handy gauge as to how far up the pulley the belt is travelling.

    its a good idea to check if the pulleys are aligned with each other too, thats where your spacer behind the variator comes in.

    what size main jet have you in at the moment, and what colour is your spark plug after a run ??
     
  13. Undercover Runner

    Undercover Runner Member

    Messages:
    136
    Rides:
    Gilera Runner SP
    I have a 95 main jet at the moment but I need to change it as the bike bogs heavily at 7000rpm, I have not checked the spark plug as of yet but I have ordered a couple BR9IX's
     
  14. Undercover Runner

    Undercover Runner Member

    Messages:
    136
    Rides:
    Gilera Runner SP
    Well i had a 98 main jet in last week, but I don't understand if the main jet is too big can it radically slow you down?
     
  15. capri dave

    capri dave Active Member

    Messages:
    5,076
    yep if the main jet is too big it would slow you down :)

    a nice little check you can do is: ride along at full throttle on a nice straight road, and let the throttle off slightly to about 3 quarters throttle. if your ped seems to go slightly faster as you let the throttle off slightly, thats a good sign your main jet isnt correct ;)
     
  16. Undercover Runner

    Undercover Runner Member

    Messages:
    136
    Rides:
    Gilera Runner SP
    Well I tested a 85 jet at the engine stalled at full throttle down a straight so I guess I'll test a 88/90/92.

    I mean with a malossi 70 sport kit i should be expecting at least 60mph clock speed right? So even if the main jet is a tad too big surely it would drop top speed by 20 mph
     
  17. capri dave

    capri dave Active Member

    Messages:
    5,076
    if it was running so lean with an 85 main jet that it stalled at full throttle, then yes i would expect the jet to be at least 90 or so.

    which is why i think its a transmission related problem.
     
  18. Undercover Runner

    Undercover Runner Member

    Messages:
    136
    Rides:
    Gilera Runner SP
    Could it possibly be my malossi sponge filter or malossi carbon fibre reeds/block or even my polini derestricted inlet?
     
  19. Undercover Runner

    Undercover Runner Member

    Messages:
    136
    Rides:
    Gilera Runner SP
    Dave I think its a carb issue not a transmission issue, its really weird at times my bike will have great acceleration and reach top speeds of 45mph but then sometimes it's just sluggish and doesn't even get to 40 properly, what d'you think? I've got an open malossi air filter
     
  20. capri dave

    capri dave Active Member

    Messages:
    5,076
    yes it could possibly be a carb problem, you checked your plug colour yet ?

    also i once came across a scooter that had an issue like this, would accelerate fast but sometimes the acceleration was really sluggish, im talking bog city....

    turned out the variator centre bush was sticking on the crank splines, instead of sliding along it easily, this was due to surface rust.

    a quick rub of the crank shaft splines with wd40 and medium wet n dry and making sure everything was sliding silky smooth on the variator, restored the performance :)
     

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