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Frustrated in California

  • Thread starter Thread starter reoccur
  • Start date Start date
R

reoccur

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> I have a 1979 Suzuki GS850. I bought this bike as a project 2 years ago. The bike is completely stock.I test rode it and it ran but not very well I figured tune up and carbs it had set for a few years. so I trailerd it home once of the trailer it would barley run ....So I went about refurbishing the bike looks great still wont run!
> I have tried everything I can think of..Set Valves to spec.
Went thru the carbs about 5 times There spotless Carb dipped then tried ultrasonically cleaning Floats set to factory spec as per manual Jets are correct, all new O rings and gaskets ..She will fire right up But any throttle and she dies.I converted it over to electronic ignition along with new coils and wire to no avail. Dynatex kit..
Timing looks spot on. I also put new crab tubes on it ( the rubber manifolds)It is presently only firing on two cylinders and at some point fired on all cylinders but not evenly. I check the heat on the header tubes and there all over the place from 85 to 300 degrees.. I use a FLUKE IR Thermometer
The compression seems ok I have never checked it when it was hot the cold reading was from 90 to 110 psi.
Any help would be appreciated
VM Carbs
Matt



>
> Matt
 
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Its not firing on all cylinders because the carb sync is all jacked up. You have VMs or CV carbs????
 
Fiches show VM carbs. Did you bench sync them before installing on the bike??? Have you freshened up the ends of the wires by clipping off about 1/4 inch and rescrewing the caps back on? Have you removed the resistors and replaced them with 1/8 inch brass or copper rods cut to the same length as the resistors?

Look inside the caps and youll see the slotted thing that grips the top of the plug. Unscrew it and dump the resistors out...they get weak and fail and thus cause spark and ignition problems. Note that 1 and 4 dont have a spring..drop in the replacement rods and then the slotted deal screws in. On number 2 and 3 there is a spring. Spring goes back in first...then the rods..and then the slotted thing.

New orings in the intake manifolds too???
 
Yes replaced O rings in the manifolds. All new spark wires and boots from dyna when I changed the coils.
 
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Never used a Dynatex kit..im sure someone that has is gonna chime in. I have covered all the basic things that effect the carbs and spark. I am thinking maybe the needles are a little different on the Dyna kit??? Someone thats used them will be better qualified than me to go into that rhelm. Someone will be along..be patient.
 
Do you have an airbox installed? :-k

The VM carbs are not quite as sensitive as the BS carbs, but they still run a LOT better with an airbox.

Also, what are your mixture screw settings? For a stock bike, the fuel screw (the one on the bottom) should be between 3/4 and 7/8 turn out from lightly seated, the air screw (the one on the side) should be about double that. When warmed up, slowly turn the air screw, listening for best idle.

.
 
Hi Guys Thanks for your feed back. The air box is sealed very well with rubber seal and some foam tape..the hoses from the box to the carbs are new as well as yhe tubes from the head to the carbs. I adjusted the cabs as per Steve's advice with some tinkering the Bike now idels with choke off. I had to turn the air mixture screws in to 1/2 turn out from seat to achieve this in order yo get all cylinders up to temp. two cylinders stayed cold at original settings once leaned they came on.. still not rideabul wants to die when throttled.. Pulled plugs two look good two Look fowled (black soot) The coolest cylinders of course.. Checked compression with engin still hot 1=120 2=110 3=110 3=120 2&3 were not as hot as 1&4 While running but only about 30 degrees. any ways better ill keep at it.
Matt
 
Are any of the pilot screw tips broke off and lodged in the carb bodies?
 
reoccur said:
No all jets are intact
Click to expand...

That's not what Ed asked

The fuel screw tips often break off, blocking the pilot circuits, which would cause the symptoms you describe

You need to pull the carbs (again!) turn them over and pull out all of the fuel screws, then shine a light down the carb throast and see if the light is visible down the hole the fuel screws sit in
 
I'd like to jump in here and let you know that I've felt much the same way. (and in CA, too!) I've pulled my VM carbs so many times so I'm quite familiar with them now. I'm running pods, bigger jets, and 4 into 1 pipes. I admit that I made it harder for myself. Let me run down the gotchas I encountered and maybe you'll get something out of it. 1. Assumptions - Tuning carbs seems like an art to me. I've re-written the electronic map in my car, but damn, carbs I had work on it to learn. Just when I'm so sure that it works the way I think it does, it doesn't and I have to take a step back and decide if I'm interpreting the symptoms right. 2. Throttle slide - ran much better after I double-checked what I thought were synced carbs and one was visibly off. 3. Parts - If I didn't put 'em in there, I needed to pull them out to make sure they were what they were supposed to be and installed the way I thought they were. 4. Air leaks - make sure your carb balancing screws on the engine-side boots are tight. 5. The floats - make sure of your float height and proper placement of your float bits. You probably know how to put it together, just make sure it stayed that way with all the carb pulling. 6. The mix - every part affects every other part to a certain degree. You have to have the right amount of fuel available (screw on the bottom) or no amount of turning of the pilot air screws will get you any love. You are good with the stock setting but make sure that is where it is actually set at. As mentioned, you might need to check your pilot screws, fuel and air. If they have been bottomed too hard they may not be broken off, but they may be blunted and need replacement. 7. Spark and spark order - I pulled the plug out and visibly observed the spark. Made sure of my plug gap. 8. Starting over - I had pull my carbs a few times and just go back to step one. I figured, I'm already in a hole, I should stop digging. I reset and checked everything before moving forward again. 9. The gas filter in the petcock - my screen held a lot of junk which made the flow a little anemic.

There are other gotchas for pods but that's all I've got for now without going into that. I sure hope you get it going. Maybe I'll see you out there.
 
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Just send it to me... Your frustration will completely disappear - I guaranteed it. Don't forget to put the title under the seat ;) :)

Seriously good luck with it. It's bound to be something simple.
 
Thanks guys
The fuel screw tips are fine and I checked the tiny orifices on all the carbs before reassembly ..Okay out to the garage :)
 
So I finally gave up and took took the bike to a shop! They said the compression is to low For the engine to function properly.
Leak down test indicated rings as the culprit.
They recommend rebuilding the top end and as I cant afford to have them do it I will give it a go.
I see ring kits are from $40 to $250 Dollars gasket kit $60 to 150 top end only, I don't want to buy junk so whats a reliable parts source. Quality brands...
 
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