2009 Yamaha aerox pod air filter problems

Discussion in 'Newbie Scooter Tuning' started by Paul1574, Mar 8, 2021.

  1. Paul1574

    Paul1574 New Member

    Messages:
    26
    Yamaha aerox keeps bogging

    It has
    70cc airsal aluminium kit
    17.5 dellorto carb with 80 jet
    Stock air box with polini double layer air filter
    Full circle airsal crankshaft
    Tecnigas Q-Tre exhaust

    been running fine but recently bought a malossi air filter and it just won’t go right whatever I do. Started by trying to put a 110 jet in which I thought would be quite a bit too big and it idles and goes to about half throttle fine but when you open it up it dies it pretty much sounds like it just completely loses all air and fuel and has nothing to enter the engine. I dropped it to 100 and it did the same I went all the way down to 80 and it would do the same. Riding it down the road it rides completely fine at about a quarter throttle (pilot jet) but the second you open it up it dies then it will have a spike where it goes then dies then goes then dies.

    I’ve looked everywhere for answers and can’t find any.
     
  2. Buzz

    Buzz Active Member

    Messages:
    446
    In my opinion leave the stock filter on. The quantity of air required for a 70cc is highly unlikely to be too little with the stock. Have you got a cv carb or mechanical. If it’s mechanical then the throttle pulls the slide up to allow more air in and then an open filter will improve it when the engine is under load such as hills. If it’s a cv constant velocity carb then when you accelerate the butterfly valve will open up under vacuum and draw the air it needs. Cv carbs are very hard to rejet for an open filter and not worth the negligible gain in a small engine. A mechanical carb is far easier to rejet and tune so is worth the time to tune and add an open filter for the same negligible gain. Cv carbs are better so I wouldn’t swap out a cv for a mechanical just to add the filter.
    That’s my penny’s worth, others may disagree.
     
  3. Buzz

    Buzz Active Member

    Messages:
    446
    If you do take my advice then get it running smoothly on stock and the biggest gains in performance will then be in your clutch and variator. You’ve upsized the cylinder, carb is fine, stock box is sufficient so get it jetted to perform smoothly through the entire range without stutter or bogging. Once it’s running smoothly then consider clutch springs and contra spring changes to open the clutch nearer to the power band and rollers to help fine tune. Buy a red power band
     
  4. Paul1574

    Paul1574 New Member

    Messages:
    26
    It’s got a slide that goes up when you pull the throttle
     
  5. Buzz

    Buzz Active Member

    Messages:
    446
    If the throttle cable enters the top of the carb and pulls the slide up by its cable then that’s a mechanical carb and easier to rejet. I would still start with the standard air box and tune it. You may not like the look of it but it will not be improved upon much by adding an open filter. If you are determined to run the open filter then start with a main jet just 10% bigger than stock, probably just a couple of sizes up. See how that runs. If it stutters or bogs then wrap some tissue round the filter. This reduces the air a little so if it improves the response then it means there was too much air and the jet needs going up more, if it runs worse then a smaller jet is needed.
    Trial and error I’m afraid. Also check the spark plug colour. If it’s black or wet then you’re fouling the plug and it needs a smaller jet but if it’s light then you may be running lean and need a bigger jet. Light coffee colour is good. Read up on plug chopping as it’s an easy way to get an initial read but you need to really understand how to do it properly to be able to tune the bike
     
  6. Paul1574

    Paul1574 New Member

    Messages:
    26
    Main jet was 62 stock with a 12mm carb but then I put a 17.5mm carb on and used a 80 jet which ran okay. Put the open filter on and a 118 jet and it wouldnt run on main jet it would only work up to half throttle, I slowly lowered the main jet down till I got to 80 and it wouldn't work. Messaged ped parts support line and they said try a 135 main jet in it (because it was running really lean so would just die) so just waiting for the jets to turn up then ill let you know how it goes
     
  7. Buzz

    Buzz Active Member

    Messages:
    446
    Sounds good, always start with a larger jet and work down. Too rich will run poorly but is safe for the engine short term whereas running lean will kill the engine quickly when everything overheats and expands.
     
  8. Paul1574

    Paul1574 New Member

    Messages:
    26
    yes its working fine now
     

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