Frustrated in California

[reoccur]

> 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

[chuck hahn]

Use these links..
Unsure if you have VM or CV carbs so there are both tutorials.

http://members.dslextreme.com/users/bikecliff/

http://www.mtsac.edu/~cliff/storage/gs/mc_maint/GS_CV_Carb_Cleaning_Series.pdf

http://members.dslextreme.com/users/bikecliff/images/vm_carb_rebuild.pdf

http://cycleorings.com/

Pilot jet plugs and carb gaskets available here..

http://www.siriusconinc.com/search_result.php?make=3&model=&part=1&partno=&x=20&y=13&search=search&start=0

[chuck hahn]

Its not firing on all cylinders because the carb sync is all jacked up. You have VMs or CV carbs????

[reoccur]

Mikuni VM Carburetors

[chuck hahn]

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???

[reoccur]

Yes replaced O rings in the manifolds. All new spark wires and boots from dyna when I changed the coils.

[chuck hahn]

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.

[Steve]

Do you have an airbox installed?

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.

.

[alke46]

[QUOTE=Steve;2155741]Do you have an airbox installed?


This was my 1st thought also. If installed, is it sealed?

[Guest]

[QUOTE=alke46;2155802]

Do you have an airbox installed?


This was my 1st thought also. If installed, is it sealed?

Yes. Make sure all the rubber boots are good and the lid has a good seal.

[reoccur]

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

[reoccur]

The Bike Has a new K&N air filter

[Nessism]

Are any of the pilot screw tips broke off and lodged in the carb bodies?

[reoccur]

No all jets are intact

[Big T]

No all jets are intact

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