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Generally running like crap. Vacuum questions.

  • DH

    I've had a 98 vt1100 that I have kept through the years to loan out to visitors, friends, etc.  It's found it's way back to my garage after quite some years and is showing the effects of being less than well taken care of.  Long story short[er], thanks to the pandemic, a loanee got stuck out of the country for a long time and the bike sat, uncovered, for many months.  When I finally found out, I picked it up, cleaned the carbs several times, rebuilt them, but it still ran for crap so I gave up and brought it into a shop.  They cleaned the carbs.  It still ran like crap, but it ran.  Friend apparently was OK riding it that way.  Fast forward to taday.  (It has again sat - this time for about 10 months).  

    It idles fine.  It sputters with the choke on. It struggles with acceleration but is fine once revs are up.  I tested the fuel pump.  It sounded a bit irregular but spit out double the required amount (48oz/min).  In my heart of hearts I feel like all the hoses drying up when it sat out has something to do with it.  I have watched this video explaining which ports are OK to plug -

    1. does that mean I trace each hose and just block up wherever they lead too?

    2. I do not have the Cal. version, so what is the remaing vacuum system there for if it is OK (or preferred) to remove it??

    3. Despite moving enough fuel during testing, should I still suspect the pump?

    If I can remove a bunch of hose, that will definitely help diagnose faster and reduce the parts I need to order to boot.  I assume.  Any other suggestions on what to check as I continue to troubleshoot are welcome.  Yes, I will get to the carbs too, but I want to address the vacuum system first.

    Thanks!

  • TJ

    @Daniel Holmstrom im gonna be straight with you, the VT1100 i owned - you could not let it sit more than 5 days. If it sat, then no matter what i did, drain the fuel before i park it, battery tender, it ran like shit, when i tried to styart it again. and required a carb rebuild every damn time, they need to be run and as long as i rode that thing every day, holy hell it was a ripper!!  Especially with all the modern fuels full of alcohol, the fuel even just a bit in the bowl, it turns to swamp goo within days sitting inside of the carb. 

    if it sat outside for a long time, you verey likely need to replace all the rubber including intake boots. 

    remembere the diagnostic tree is fuel, spark, compression. check the whole fuel syustem from the gas cap tot he carbs FIRST. each component inspect. fuel lines DO degrade and after time the insides can  just start falling aprt and going right in tot he carb. 

    DO FUN SHIT!
    Check the FAQ's here for tons of tuning info and more!! - t.ly/MA6r6

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  • DH

    OK, you win.  Compression test = 146 at both cylinders.  The low end of the scale in the book is 157.  What say you?

    Carbs are off.  Looks squeaky clean except for whatever goop the shop used at the gaskets.  Currently in the cleaner.  HOWEVER; one of the pilot jets is weird.  It's like there is a tiny piece of something inside it.  You can blow air through it, but you can't see through it.  A strand of wire will pass through 1 out of 10 times or so.  Odd.  New jets on the way.  

    Oh.  Also, there is a burn pattern behind the butterfly valve on the rear carb (leading to the cyllinder), with the smoke residue going up the port into the diaphragm chamber.  No, I was not smart enough to keep the jets separate when cleaning and can only assume the weird jet was in the rear carb.  Would a lean mixture lead to scorch marks in the carb?  Backfiring in the intake?

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  • DH

    I don't want to spend an hour re-writing another reply just to have it marked as spam and deleted, so here's a summary:

    Compression: 146 in both cylinders.  

    Carbs look(ed) squeaky clean EXCEPT for two things: 1) There was a burn pattern in the throat after the butterfly valve (leading to the cylinder) with some smoke also running up the port into the diaphragm chamber.  2) There is something seriously wrong with one of the pilot jets.  (I was not smart enough to mark which was which so not 100% sure it is from the blackened carb)  Looking from the top, no daylight.  Pass a guitar string through it from the top, now you can see through.  Turn it over - no daylight.  Try to pass the wire through - it gets hung up a few mm from the top.   Turn it over - no daylight.  Pass the wire - daylight.  Cleaning had no effect.  I looked at it under the microscope and could not see what the issue is from either end.  I cannot figure it out.  I was under the impression that the passage in the jet (the .42mm part) was just straight through, but it feels like there is a cavity in the middle with something moving around.  

    I only write about it because I hate being stumped.  New jets should arrive this weekend and more than likely that will turn out to have been the issue.

    I am planning to NOT re-attach the sub air cleaner between the two large plastic ports and just leave them open as per the JP Customs video.  Can/should I at least cap them with a little piece of filter?

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