Carb clean by Dealership killed my throttle response. Help!

Discussion in 'Mechanics Garage' started by bluegen1e, Feb 21, 2013.

  1. bluegen1e

    bluegen1e New Member

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    hey guys -

    Took my 95 VFR (17k miles) to the dealership last month to get the carbs cleaned. I bought the bike in 2011 and figured this would be good for the bike since i didn't know when the last time anyone cleaned them.

    Took it to a dealership (Suzuki/Yamaha dealership) and they cleaned the carbs, changed the spark plugs (NGK) and replaced the air filter (UNI).

    Now when I get on fifth and sixth gear, there is a very noticeable delay in throttle response. first through fourth gears seems to be fine. When I open the throttle on 5th or 6th there is a delay for the bike to pick up speed. I can close the throttle on either one of these gears and crack it wide open and the first few seconds nothing and then I feel the power coming on. even when it does the pick up, it's a pretty slow pick up. Or I would be running on sixth holding a steady 75 and feel like the bike is dragging.... They did mention that they tuned the air/fuel mixture.

    The dealership is giving me all kinds of bogus excuses:
    - its a UNI air filter and its a high flow filter so that might be why
    - I need a jet kit (yeaaaa, sure I do... :mad:)
    - since i have an aftermarket exhaust that might be why I have flat spots on the power band-- but mind you i had the exhaust over a year and had no issues.

    the a-holes are giving me the run around, but i took it back and asked them to look at it anyway since they didnt do it right the first time.

    any light you guys can shed on this IS A GREAT HELP. So I can call them up and talk to them with a little bit of knowledge.

    you think the mixture is wrong? possible running lean?
     
  2. slowbird

    slowbird Member

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    The bike pulls hard in every other gear?
     
  3. kennybobby

    kennybobby New Member

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    Were the carbs clogged? No reason to just clean carbs unless they are not working. Was it running good before they messed with them? The Uni may have leaned it out some.

    The mixture screw mostly affects the idle speed and idle mixture, usually adjusted with an exhaust analyzer to determine emissions or adjust idle fuel mixture. But it is the easiest to access without removing the carbs--could try opening up the mixture screws 1/4 or 1/2 turns and give it a try, but it is likely not going to fix the flat spot.

    A larger pilot jet will enrichen the mixture across all throttle ranges and the transition from closed to open throttle such as you mentioned. You might go from a 38 to a 40 and give it a try. Requires pulling the carbs to change. The main jet affects wide open throttle fuel, doesn't sound like that is your problem.

    Mark your throttle with tape and try to determine exactly how far open it is when you have issues, e.g. 1/8, 1/4, 1/2, 3/4, WOT, etc. that is the clue to which circuit needs adjusting.
     
  4. white_335i

    white_335i New Member

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    If they changed the air filter from stock to UNI, then they might be correct in recommending a jet kit. The air/fuel mixture is probably changed and there is a chance that you will have to increase your main jet(if you are in WOT).
     
  5. bluegen1e

    bluegen1e New Member

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    yup, 1-4 it pulls slightly harder than it used to. a bit more pep in the step, if you will.
     
  6. taylor65

    taylor65 New Member

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    If it pulls good in the other gears but not in the top two I dont beleive they could have done anything wrong. The carb doesnt care what gear you are in. It could possibly be starving itself of air in the higher gears due to higher speeds but I doubt it. Good luck
     
  7. Big_Jim59

    Big_Jim59 Member

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    If you changed the air filter from stock to aftermarket expect some difference in performance. On my old Suzuki Bandit 600 the UNI filters were not recommended, even with a jet kit. In that application I could never get the fueling right and so went back to the stock element elimination the problems.
     
  8. ridervfr

    ridervfr Member

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    Where are you testing getting into 5/6 gear? In New York City? Just asking because when I shift my gen 3 bike into 6th I am going at least 90mph or so.

    I switched to a K&N air-filter 18 years ago and never touched the jetting, bike ran fine with the stock exhaust system too. Recently, I ova-hauled the carbs with oem honda float needles, gaskets, etc, along with some new insulator boots. This time, I ended up shimming the needles with a .020 inch washers, this affects mid-range. I experienced no difference really.

    You bike is running on the main jets when your going at the higher speeds. If you pop for a jet kit, get one where they dont drill the slides, those are just my feelings.

    You have a lid on your air box? That can screw you up...dont get frustrated, just stay on them stealers!!!
     
  9. squirrelman

    squirrelman Member

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    Seems like the dealer just didn't do a good job, but what were the problems you were having that caused you to take it in ?? The only shop guys i'd ever trust to do proppa carb work are half-bald, short, poorly-groomed fellas at least45 years old, without tattoos, no 26 year old kids.


    The Dealer Shop has no way to tell unless they've ridden the bike, and where can that be done in NYC ?? If you didn't have a dyno you could try fatter mains to fix the problem, but if you did, you'd have dyno A/F and power curves you need. I agree, more likely too lean or an air intake problem, as a guess. You could try holding throttle at just below your problem rpms for awhile, then doing an old-school plug cut and quick inspection, checking for clues.

    In any IDEAL SERVICE SHOP -- dealer or independent-- the mechanic who worked on the bike or the service manager should take every bike out on a road test before delivery to verify the work has been done right (their customer's safety depends upon it !) while cautiously using as much of the power range as possible or prudent. Also, in that IDEAL shop, the last item out to door would be to check /verify that it rolls out with tire pressures set correctly + or - . Most shops don't seem to care.
     
    Last edited: Feb 25, 2013
  10. Pliskin

    Pliskin New Member

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    You guys make it seem like because he lives in NYC you can't leave. He ain't no Snake Plisskin trying to escape from NY.

    That being said, I think we need to sort through all the "fluff". Presumably the bike ran fine before cleaning the carbs. The only thing changed was to an aftermarket air filter. I presume that since they were Suzuki/Yamaha, they had no Honda OEM filters.

    Based on the other good advice given, I'd start with the simple thing: Go back to a stock filter, return the UNI to them, and get a credit for the cost of the UNI. Then see how it runs.
     
  11. squirrelman

    squirrelman Member

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    He woodn'ta taken it in if it ran fine, woodie ?? :crazy:

    Plaintiff stated he wanted the carbs cleaned, but what were his symptoms ? Dealer could't fix his problems or added more.
     
  12. taylor65

    taylor65 New Member

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    I think trying the original filter again would also be good but if you didnt get it chances are they have thrown it away by now. When trying to diagnose the running of it paying more attention to rpm and throttle opening rather than gear selection will help a lot more.
     
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