Welcome guest, is this your first visit? Create Account now to join.

Welcome to the Motorcycle Forum.

Register ButtonIf this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed.

+ Reply to Thread
Page 1 of 2 1 2 LastLast
Results 1 to 15 of 20
  1. #1
    Newbie
    My Bike(s)
    1981 Suzuki GN400
    Location
    Eugene, OR
    Posts
    2

    '81 Suzuki GN400 backfiring, hard to get running - New Rider :)

    Hey ya'all! I just got my first bike 4 days ago - an '81 Suzuki GN400, single piston, kickstart. On day 1 she started right up, but by day 4 she's getting rough.

    She's backfiring when I let off the throttle, nearly every time, and kicks pretty continuously while in gear, most noticably in 1st and 2nd gear. It's getting progressively more difficult to get her running (starts but then dies - tricky mixture of choke, throttle and clutch to keep her running). From what I gather, this is a fuel mixture issue(too strong or too lean) or my carb needs a good cleaning.


    How do I tell if my fuel mixture is too strong or too lean? And how do I adjust it? Any other tips/things I should look into? Thanks ya'all, this is exciting new business

  2. MotorcycleForums.net is the original Motorcycle Forum! Registered Users do not see these ads. Please Register - It's Free!

  3. #2
    Banned
    My Bike(s)
    Ilene
    Location
    the land of the setting sun
    Posts
    880
    find out if there is a timing chain tensioner. if there is remove it, check it out and clean it.

  4. #3
    M-J Lifetime Achievement Award
    My Bike(s)
    '10 Kaw Vulcan 900 Custom
    Location
    Ocala, FL
    Posts
    8,719
    Quote Originally Posted by limitedbyfourkawiby2 View Post
    find out if there is a timing chain tensioner. if there is remove it, check it out and clean it.
    Oh just stop with the moronic advice, please.

    Timing chain tensioners typically are INSIDE the engine and it is not a trivial matter to get to them.

    The first thing to do in a situation like he described would be to drain the tank and carbs, check or replace the fuel filter (if it has one) and
    put a double dose of carb cleaner in with fresh gas.

    Fuel mixtures, except at idle, typically are not "adjustable".
    Don't believe everything that you think.

  5. #4
    Banned
    My Bike(s)
    Ilene
    Location
    the land of the setting sun
    Posts
    880
    I had the same problem.

  6. #5
    Banned
    My Bike(s)
    Ilene
    Location
    the land of the setting sun
    Posts
    880
    Quote Originally Posted by Easy Rider View Post
    Oh just stop with the moronic advice, please.

    Timing chain tensioners typically are INSIDE the engine and it is not a trivial matter to get to them.

    The first thing to do in a situation like he described would be to drain the tank and carbs, check or replace the fuel filter (if it has one) and
    put a double dose of carb cleaner in with fresh gas.

    Fuel mixtures, except at idle, typically are not "adjustable".
    this guy is a nut.
    Last edited by limitedbyfourkawiby2; 02-26-2013 at 12:13 AM.

  7. #6
    Newbie
    My Bike(s)
    1981 Suzuki GN400
    Location
    Eugene, OR
    Posts
    2
    Found a clogged pilot jet, and a spark plug that was gapped at 40 instead of 28. Cleaned out the carb, replaced spark plug, bike idled great for about 3-4 minutes then died. Got her started, kinda rough but good enough to get her on the road, smoothed out in 3rd gear then died while coming to a stop after about 3 blocks.
    Pulled the carb again to inspect. Fine, rusty gas tank sediment in the float bowl and starting to clog that pilot jet again, but after cleaning it out again I still can't get her to run. Ideas? A friend mentioned timing. I don't know much about it, but if anyone can point me in the right direction I learn fast.

  8. #7
    Just Won't Go Away !
    My Bike(s)
    several
    Location
    Buford, GA
    Posts
    5,197
    Deal with the obvious problem first: the rusty gunk in the fuel system.

    Drain the gas tank. Take it off the bike, close the petcock. Get a gallon of distilled water at the local grocery store, and dump half of it in the tank. Add some marbles, nuts & bolts, BBs, or clean gravel. Put the gas cap on tight. Swirl the gas tank aroud, turning the tank around to get all of the inside. The nuts & bolts or whatever will gently grind off all the rust. Keep it up for a few minutes, then dump it all out. Use the other half of the distilled water to rinse. Use a hair drier or heat gun to dry the inside of the tank to prevent flash rust- the distilled water will dry without leaving a residue. Flush the fuel line with carb cleaner, clean the carb out again (make sure you get all the little passages), refill with frsh gas mixed with carb cleaner, and you should be good to go.
    Now that the gas is clean and free of contamination, and there is nothing to clog up the carb, see how she runs. As long as you have this 'rust in the fuel' problem it is never going to run right, and there is no point even attempting anything else.
    Last edited by DrBob; 02-22-2013 at 08:45 PM.
    You MUST obey the pug dog!


  9. #8
    Just Won't Go Away !
    My Bike(s)
    several
    Location
    Buford, GA
    Posts
    5,197
    Quote Originally Posted by limitedbyfourkawiby2 View Post
    this guy is a nut.
    ROTFLSHIADMTA!

    Actually, he is a very helpful if somewhat gruf guy who has been around motorcycles probably twice as long as you have been alive, who knows enough not to chime in on subjects he obviously knows nothing about- something I sadly can not say about you. I have never seen him tell a guy with a shaft drive bike to adjust his drive chain & align his rear wheel; or tell someone with a two-stroke tthat doesn't even have a cam to adjust his cham chain tensioner; or ask a guy with a VTX1800 about a kick starter; or any of the dozen other nutty things you have posted. Great comic relief, not so great mechanical advice lol!
    Last edited by DrBob; 02-22-2013 at 10:45 PM.
    You MUST obey the pug dog!


  10. #9
    Banned
    My Bike(s)
    Ilene
    Location
    the land of the setting sun
    Posts
    880
    you might check the valve clearance it is possible that it is too tight.

  11. #10
    Banned
    My Bike(s)
    Ilene
    Location
    the land of the setting sun
    Posts
    880
    obviously if it is backfiring fire is getting past your valves.

  12. #11
    Clutch Cadet
    My Bike(s)
    2008 Suzuki M50
    Location
    Eastern Shore, MD
    Posts
    926
    Leoa, I'm going to side with Easy and Drbob on this one. Systematically work through the obvious problems. Personally, I've had my disagreements with Easy but his advice and logic have always been dead on. These two guys will not steer you in the wrong direction. I cannot say as much about Limited. I hate to bash anyone on the forums but this guy is just giving out advice that is not practical or applicable in this stage of your diagnosis. As you begin to eliminate possible factors for poor performance, other avenues may need to be explored. Start easy and cheap, then work your way on to other possibilities.

    Just my $.02 - take it or leave it.
    Last edited by Pheonix; 02-27-2013 at 04:24 PM.
    2k8 SE, 2k5 Red Parts, Mustang Vintage Wide Seat, Suzuki OEM Passenger Floorboards, 28" Drag Bars, Ken's 1" Spacers, 2nd Gen Chin Spoiler, Undertail Eliminator Kit, Relocated Turn Signals and Tag, Morton's Violators, K&N Drop In, PC-V retrofit, De-Paired, Custom Headlight, Blacking out the Chrome, Found better brakes - just have to get them on!!!

  13. #12
    Banned
    My Bike(s)
    Ilene
    Location
    the land of the setting sun
    Posts
    880
    ok, I am sorry if I jumped the gun and got too in detail. alot of bikes do backfire I have seen flameballs coming out of a 2000 and newer harley mine does it also and a lot. every time I let off the throttle as a matter of fact.
    try some fuel injector cleaner in the gas, which you would have to figure out how much to use.

  14. #13
    Newbie
    My Bike(s)
    1997 Suzuki intruder vs800
    Posts
    5
    Hi I have a 1997 suzuki intruder vs800 brought cheap cause it got wrecked . Anyway I want to see (I believe I can make it good again.) I took my time and got new forks rotor ect. new I need front rim so I can put it all back together again. difference between the suzuki intruder vs800 and the suzuki intruder boulevard s50 and can they use the same parts

  15. #14
    Newbie
    My Bike(s)
    1997 Suzuki intruder vs800
    Posts
    5
    any advise is helpful I got a book for the bike just not the right tools im sure I really want to try a rebuild this bike myself.

  16. #15
    M-J Lifetime Achievement Award
    My Bike(s)
    '10 Kaw Vulcan 900 Custom
    Location
    Ocala, FL
    Posts
    8,719
    Quote Originally Posted by Cruizz View Post
    any advise is helpful I got a book for the bike just not the right tools im sure I really want to try a rebuild this bike myself.
    The VS800 is also an S50 for most model years.
    Somewhere along the way they decided to change the name from Intruder to Boulevard.
    Dr. Bob can tell you more but all the important parts are the same......and for a given year, if it says a part fits a VS800 or an S50 it should be good.....because they are the same.

    P.S. I REALLY hope that you tested the engine and transmission (as much as possible) before you sank a lot of time and money into body parts ??????
    Don't believe everything that you think.


 

Ads

 

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts

Similar Threads

  1. 95 suzuki intruder vs800 backfiring
    By jasonmck1 in forum Mechanics Corner
    Replies: 9
    Last Post: 03-05-2013, 10:24 PM
  2. Suzuki Savage backfiring ?!
    By Firefighter in forum Cruisers
    Replies: 5
    Last Post: 08-31-2012, 02:39 AM
  3. Suzuki Boulevard Backfiring
    By adambecker in forum The Paddock
    Replies: 19
    Last Post: 08-16-2012, 10:15 PM
  4. Replies: 5
    Last Post: 09-02-2009, 02:03 AM
  5. Need 1980 Suzuki GN400 piston.
    By Cody400 in forum Bikes For Sale Street or Other
    Replies: 1
    Last Post: 03-12-2006, 08:40 PM

Search tags for this page

1980 suzuki gn400 forum
,
1980 suzuki gn400 valve lash adjustment
,

81 suzuki 400

,

81 suzuki gn400

,

gn400 carburetor

,
gn400 hard to starty
,

suzuki gn 400 carb adjust

,
suzuki gn 400 wont run under load
,
suzuki gn400 backfire
,
suzuki gn400 forum
Click on a term to search for related topics.

Tags for this Thread