Author Topic: Gs550 running bad  (Read 1657 times)

Offline yozzer74

  • SOHC Pro
  • Posts: 699
    • View Profile
Gs550 running bad
« on: June 20, 2018, 08:33:01 PM »
Hi long shot this question. My gs550 is running really bad I've fitted k&n pod filters custom 4 into 2 pipe .Bike as c.v carbs dyno jet stage 3 kit fitted .problem is bike ticks over nice first part of throttle is good .When stood revs all way to red line .but when under load doesn't want to rev and pops and bangs bogs down .I've tried lifting needles up bigger main jets but makes no difference at all.im thinking it could be a timing issues. Anyone got any ideas I'm a little stuck .Cheers yozzzer 

Offline K2-K6

  • Grogu
  • *
  • Posts: 5234
    • View Profile
Re: Gs550 running bad
« Reply #1 on: June 20, 2018, 08:52:09 PM »
You could try a "quick and dirty " test by wrapping the pods with a towel or fleece around them to see if it changes at all, and if it does then better or worse.?

Popping and banging sounds like weak mixture initially. Timing, have you confirmed with a strobe if it's advancing as it should?

Offline yozzer74

  • SOHC Pro
  • Posts: 699
    • View Profile
Re: Gs550 running bad
« Reply #2 on: June 20, 2018, 08:56:48 PM »
K2 tried covering the filters didn't make any difference .but when I covered them up about 80% was worse .I've not checked with timing light I've got one on order .it does have electronic ignition with a ignitor box .bike is a 1982 model

Offline Johnwebley

  • SOHC Jedi
  • Posts: 3204
    • View Profile
Re: Gs550 running bad
« Reply #3 on: June 20, 2018, 09:59:22 PM »
check the plug gap,

  I had popping with a lean mixture
lifelong motorcycle rider,and fan

Offline yozzer74

  • SOHC Pro
  • Posts: 699
    • View Profile
Re: Gs550 running bad
« Reply #4 on: June 20, 2018, 10:15:19 PM »
Plug gap ok I should have said when I had it on dyno the technician said I had other issues other than carbs as it is only making 27bhp should have around 47bhp .I did a compression test and results were from 140psi to 150psi.

Offline K2-K6

  • Grogu
  • *
  • Posts: 5234
    • View Profile
Re: Gs550 running bad
« Reply #5 on: June 20, 2018, 10:17:10 PM »
Generally with electronic ignition they either go or stop so hopefully it'll check out ok. But it would be good to confirm it else you could be chasing your tail unnecessarily.

I don't know how much you know of the carbs or how they work?  The throttle butterfly is opened by the twist grip but the main slide is pulled up with a vacuum so has some means of sealing to get the vac to lift the slides, often a rubber diaphragm.  Have you checked anything relating to this area to make sure you've not got any impairments?

Offline yozzer74

  • SOHC Pro
  • Posts: 699
    • View Profile
Re: Gs550 running bad
« Reply #6 on: June 20, 2018, 10:23:23 PM »
K2 the carbs have been totally overhauled. And I agree with you that the ignition works or doesn't work .the bike also has new dyna coils fitted .And has a a nice blue spark .

Offline K2-K6

  • Grogu
  • *
  • Posts: 5234
    • View Profile
Re: Gs550 running bad
« Reply #7 on: June 21, 2018, 08:52:47 AM »
I can see why you're puzzled by it,  doesn't seem to make sense.

Static with no load it should get to red line with something like one third throttle opening so you are not using much carb range to do that.  It suggests the ignition is advancing also.

A bit left field but, could you do a run out with the pods removed and something like a go-pro looking at the carb slides to see what they are doing? They should be rising as a match to the engine revs as air volume increases and drop shut when you close the throttles. They shouldn't flip straight open as you apply throttle as it'll screw the jetting.

Has cam timing been worked on at all?

Offline kevski

  • SOHC Pro
  • Posts: 508
    • View Profile
Re: Gs550 running bad
« Reply #8 on: June 21, 2018, 09:56:06 AM »
Did it run right with standard air box and filter, pods and CV's don't mix you either get top end or bottom, never perfect due to disruptive air flow.

Offline MarkCR750

  • Professional half wit and member
  • SOHC Master
  • Posts: 1173
    • View Profile
Re: Gs550 running bad
« Reply #9 on: June 22, 2018, 10:32:02 PM »
I’ll second the disruptive airflow theory, try it with the standard airbox if you can, or fit velocity stacks, long ones if you can get them.
Suzuki GT250A (Nostalgia)
1977 K7 CR750 (lookalike, what of I’m not sure)
Ducati 900SS (Soul & Speed)
Ducati M900 Monster (Handling & character)
Thruxton 1200 (suits me)
James Captain 197 (pure adrenaline, i.e. no brakes!)
"Eff yir gitten awvestear yir gooin te farst"
Sir J.Stewart.

Offline yozzer74

  • SOHC Pro
  • Posts: 699
    • View Profile
Re: Gs550 running bad
« Reply #10 on: August 23, 2018, 08:23:32 PM »
Well got the bike running a lot better now when I took the cam cover off found the cams out of time by one link .bike also had a head gasket leak so I did that at same time had head skimmed valve seats recut along with valves and all valve gaps set .only a few shims needed .still getting a little poping from carbs on first part of throttle when it's on pilot jets .air mixture  screw is now 31/2 turns out which made it a lot better .so still a little work to do to get it bang on .

Offline yozzer74

  • SOHC Pro
  • Posts: 699
    • View Profile
Re: Gs550 running bad
« Reply #11 on: August 23, 2018, 08:28:45 PM »
Pic of bike [ Guests cannot view attachments ]

Offline Greg65

  • SOHC Member
  • Posts: 214
    • View Profile
Re: Gs550 running bad
« Reply #12 on: August 25, 2018, 07:27:38 AM »
Hi Yozzer.

Good to hear your making progress. I’m running a 78 GS 1000 and found this forum to be invaluable for all thing GS, https://www.thegsresources.com . Hope it helps, nice bike by the way.

Cheers,
Greg
Keep smiling it makes the management nervous.
Honda CB400 1976
Suzuki GS1000 1978

Offline K2-K6

  • Grogu
  • *
  • Posts: 5234
    • View Profile
Re: Gs550 running bad
« Reply #13 on: August 25, 2018, 07:29:32 PM »
Slowly sorting out the issues then. Sounds like progress at least.

Bike looks good.

You could try raising the fuel level by changing the float settings to see if you can just bring the mixture up a bit at the bottom end of carb opening and see if you get a more normal airscrew position.

Offline philward

  • SOHC Jedi
  • Posts: 2795
    • View Profile
Re: Gs550 running bad
« Reply #14 on: August 25, 2018, 10:29:03 PM »
Nice bike Yozzer - whats it ride like on the 'knobblies'?
Current Bikes:-
Honda CB750K2 (1975)
Honda CB500K2 (12/1972)
Honda CR750 Replica (1972)
Honda CB350K0 (1969)
Kawasaki ZZR1100D3 (1995)
Kawasaki ZZR250 (1990) Project (Going on eBay ASAP)

 

SimplePortal 2.3.5 © 2008-2012, SimplePortal