Popping though carbs

Discussion in 'Motor' started by finatic@aol.com, Sep 27, 2018.

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  1. Sep 27, 2018 #1

    finatic@aol.com

    finatic@aol.com

    finatic@aol.com

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    I'm new to these bikes and I'm not sure what is normal. I have a 1986 Vmax and I have noticed that when idling if I crack the throttle and also on acceleration that I can hear a fairly faint popping what seems to be coming from under the air box. I'm wondering if it's an intake valve issue. If so, how much $$$ should I expect to pay for a valve job on that head. Also does the motor have to come out of the frame to do that?
     
  2. Sep 27, 2018 #2

    mabdcmb@yahoo.com

    mabdcmb@yahoo.com

    mabdcmb@yahoo.com

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    Popping thru the intake is typically an indicator of a dirty pilot circuit or too lean of a setting on the AF screws.

    Id try the shotgun and see if there is any improvement.

    Sent from my SM-G930V using Tapatalk
     
  3. Sep 27, 2018 #3

    caseyjones955

    caseyjones955

    caseyjones955

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    popping, no. When was the last time the carbs were synchronized? Also mine will try and do that occasionally if the idle is anything below ~1000. There are many more things that can do it but figured start with the easy-ish free stuff first. Also make sure it's running on all 4 cyl. I like to use the simple backyard downpipe spit sizzle test but an IR thermometer is ideal. It's surprising how well these bikes can run on only 3 cyl.

    Another move you can try is to remove the airbox lid and with the bike idling, blip the throttle and see that all the slides are doing the same thing, . If there is no airbox lid it will run like crap, thats normal. Has it been sitting?

    What are the modifications to the bike, exhaust system and that sort of stuff? Also if my answers fail to enchant there are wiser folks than myself rolling out of bed about now haha.

    It's normal to hear some induction noises during hard acceleration, but it should not queef.
     
  4. Sep 27, 2018 #4

    finatic@aol.com

    finatic@aol.com

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    I just purchased the bike a couple of weeks ago. It seems well cared for. The guy I bought it from said the bike is serviced at the dealer and they have all the records. He also said the the carbs were just synced before I bought it. He warned me about running it hard before it fully warms up or I would be in the shop replacing some o rings. I'm assuming its' the o ring in the intake manifold. I haven't run it hard at all yet but who knows how he ran it before I bought it. The guy is an older guy like me and doesn't seem like they type that would abuse the bike. It seems to run on all four. at an idle (about 1100 rpm) you can hear a slight bumping on one bank like a slight misfire but it's not a dead cylinder.
     
  5. Sep 27, 2018 #5

    finatic@aol.com

    finatic@aol.com

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    One other thing. The bike seems completely stock. No mods at all.
     
  6. Sep 27, 2018 #6

    Redbone

    Redbone

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    The o-ring he speaks of is more than likely for the oil pickup, if that pops the engine won't pump oil from the oil pan back to the engine. It could mean a toasted engine which I am told is not so much fun.
     
  7. Sep 28, 2018 #7

    Traumahawk

    Traumahawk

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    No, its probably not the O-ring. Like what was said above, a slight pop is usually indicative of the carbs being lean, for what ever reason.

    There are horror stories of how much a dealership DOESNT know about these bikes. Everything that you need to know about a Vmax can be found here.
     
  8. Oct 12, 2018 #8

    finatic@aol.com

    finatic@aol.com

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    The guy I took the bike to was stunned that the carbs had not been touched (drilled covers) since it was new. He is gonna work on them while he is doing the fork seals this week. Over all he says it idles well and doesn't think it will require anything other than adjustment. He is gonna look at the Vboost to make sure it's working as well. I can't wait to get it back just in time for Biketoberfest.
     

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